| 1. |
- Wendin, Karin, 1963-, et al.
(author)
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Dynamic analyses of sensory and microstructural properties of cream cheese
- 2000
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In: Food Chemistry. - 0308-8146 .- 1873-7072. ; 71:3, s. 363-378
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Journal article (peer-reviewed)abstract
- Flavour and texture in cream cheese depend on the microstructure. The objective of this work was to study the influence of fat content, salt content and homogenisation pressure on the microstructure and sensory properties of cream cheese. Twelve types of cream cheese were produced according to a full-factorial design, whereby the fat content was set at three levels, the salt content at two levels and the homogenisation pressure at two levels. The cheeses were analysed by a sensory panel, using both quantitative descriptive profiling and time intensity (T1) evaluation, and by using a confocal laser scanning microscope, CLSM, whereby the microstructure of the cheeses was analysed. All the design parameters had a significant influence on the flavour and texture, although fat had the largest effect. Interaction effects between the design parameters were also found to influence the character of cream cheese. The results showed that it is possible to create a cream cheese with lower fat content and with sensory attributes similar to the attributes in cream cheese with high fat content, by modification of production parameters.
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| 2. |
- Lindborg, PerMagnus, 1968-
(author)
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A taxonomy of sound sources in restaurants
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In: Applied Acoustics. - 0003-682X .- 1872-910X.
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Journal article (peer-reviewed)abstract
- Restaurants are complex environments where all our senses are engaged. Physical and psychoacoustic factors have been shown to be associated with perceived environmental quality in restaurants. More or less designable sound sources such as background music, voices, and kitchen noises are believed to be important in relation to the overall perception of the soundscape. Previous research publications have suggested typologies and other structured descriptions of sound sources for some environmental contexts, such as urban parks and offices, but there is no detailed account that is relevant to restaurants. While existing classification schemes might be extendable, an empirical approach was taken in the present work. We collected on-site data in 40 restaurants (n = 393), including perceptual ratings, free-form annotations of characteristic sounds and whether they were liked or not, and free-form descriptive words for the environment as a whole. The annotations were subjected to analysis using a cladistic approach and yielded a multi-level taxonomy of perceived sound sources in restaurants. Ten different classification taxa were evaluated by comparing the respondents' Liking of sound sources, by categories defined in the taxonomy, and their Pleasantness rating of the environment as a whole. Correlation analysis revealed that a four-level clade was efficient and outperformed alternatives. Internal validation of the Pleasantness construct was made through separate ratings (n = 7) of on-site free-form descriptions of the environment. External validation was made with ratings from a separate listening experiment (n = 48). The two validations demonstrated that the four-level Sound Sources in Restaurants (SSR) clade had good construct validity and external robustness. Analysis of the data revealed two findings. Voice-related characteristic sounds including a ‘people’ specifier were more liked than those without such a specifier (d = 0.14 SD), possibly due to an emotional crossmodal association mechanism. Liking of characteristic sounds differed between the first and last annotations that the respondents had made (d = 0.21 SD), which might be due to an initially positive bias being countered by exposure to a task inducing a mode of critical listening. We believe that the SSR taxonomy will be useful for field research and simulation design. The empirical findings might inform theory, specifically research charting the perception of sound sources in multimodal environments.
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| 3. |
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| 4. |
- Wiklund, Johan
(author)
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Ultrasound Doppler Based In-Line Rheometry - Development, Validation and Application
- 2007
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Doctoral thesis (other academic/artistic)abstract
- The trend within fluid industry is towards continuous production, leading to an increasing demand for new and improved methods that allow real-time monitoring of quality parameters and fast process control. The consistency and viscosity can be described by fluid rheology and are frequently used as quality control parameters. Rheological properties can be correlated with product microstructure, they govern the performance of unit operations and detailed knowledge is fundamental for the design of new process equipment and for predicting e.g. heat transfer. The determination of rheological properties in-line, in real time, thus has a great economical impact and is important from a quality perspective for the development of innovative and competitive products and a prerequisite for efficient process control. A method for in-line rheometry combining the Doppler-based Ultrasound Velocity Profiling (UVP) technique with Pressure Difference (PD) measurements, commonly known as UVP-PD, has recently been developed. It has a strong potential to be commercialized and the method allows measurements not possible with common rheometers such as radial velocity profiles and yield stress directly in-line. Furthermore, it has advantages over commercially available process rheometers and off-line instruments in being non-invasive, applicable to opaque and concentrated suspensions, having small sensors dimensions and relatively low cost. However, there exists even to this date no UVP-PD system in commercial production. This thesis describes an extended methodology and a complete UVP-PD system for in-line rheometry and flow visualization under realistic processing conditions. In contrast to systems described earlier, the present set-up allows direct access to demodulated echo amplitude (DMEA) or ?raw data? from the UVP instrument. DMEA provides new valuable information about the investigated fluid through spectral analysis and gives important information about the quality of acquired data. It further enables the implementation of a new fast Fourier transform (FFT) based algorithm for velocity estimation. New software based on MATLAB ® graphical user interface (GUI) and Active X library that allows synchronized data acquisition and provided powerful and rapid tools to process and visualize data was developed, a prerequisite for in-line real-time monitoring and process control. New flow adapter cells and methods for data enhancement, wall detection and in-line measurements of sound velocity and attenuation are introduced. This leads to greater measurement accuracy and provides a feasible tool for determining particle concentration and possibly also particle size distribution in-line. The UVP-PD system presented here was validated against conventional off-line rheometers, theoretical model predictions, laser Doppler anemometry (LDA) measurements and computational fluid dynamics (CFD) simulation, with good agreement. The UVP-PD system was then successfully applied to a range of model and industrial fluids and suspensions, including fluids containing large particles and fibers. Changes in rheology were monitored in real-time directly in the process line, with respect to changes in profile shape, in rheological parameters, as well as in terms of variations in the attenuation of transmitted ultrasound and changes in sound velocity. It was concluded that the UVP-PD methodology and system presented can be used to monitor changes in rheology in industrial unit operations such as rapid start-up or shutdown of the process, liquid displacements during rinsing or product change and in-line mixing. It may also be an interesting option for studying structure degradation and the position of macroscopic particles in the flow field, which would not have been possible without the present system.
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| 5. |
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| 6. |
- Skoglund, Tomas
(author)
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Dynamic Modelling and Simulation of Liquid Food Process Lines
- 2007
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Doctoral thesis (other academic/artistic)abstract
- In the present work a dynamic model library of components for process lines was developed. The analysis addressed characteristic aspects of liquid food process lines, and new models were developed for fluid transitions, dispersion, mixing zones and first-order chemical reactions in pipes and heat exchangers. The computational efficiency and accuracy of the models were analysed. It was demonstrated that classical models of fluid propagation in process lines could be combined with modern numerical methods to obtain computationally efficient dynamic models for the simulation of dispersed convective flow, with and without chemical reactions. In particular it was demonstrated that a transport delay model was well suited for the simulation of thermal transients due to fluid transitions in heat exchangers. It was shown that the model could be extended to account for dispersion with a method that, although classical in approach, enables a certain freedom in the choice of degree of discretization depending on the demand for accuracy vs. computational speed. Further extension of the model with first-order chemical reactions to account for microbial deactivation was demonstrated. The usefulness of the dispersed-convection model to predict the extent of mixing zones and the amount of product rejects in continuous processing was demonstrated. The relevance concerning product traceability is discussed and the concept ?fuzzy traceability? introduced.
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| 7. |
- Henningsson, Marcus
(author)
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Loss Minimisation in Dynamic Food Processes
- 2005
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Doctoral thesis (other academic/artistic)abstract
- The overall aim of the present work was to reduce losses during product changes or during rinsing in continuous food processing, with particular attention to dairy plants. The concept of sensor fusion of common process instruments was implemented as a tool to monitor the milk and fat concentrations in a dairy processing line. Special interest was drawn to the dynamic processes such as start-up, rinsing and product change-overs. These dynamic processes are causes for loss of raw material and a better control can efficiently decrease this wastage. The three process instruments used were an optical instrument, a conductivity meter and a density meter. The system was indirectly calibrated; partly from literature data, partly from sets of water-milk mixtures of varying fat content and temperature. A numerical evaluation algorithm evaluating the overdetermined equation system and allowing the derivation of a measure of uncertainty was written in Matlab. The method used on dynamic measurement data was shown to predict the milk in water concentration within 2% and the fat concentration within 0.1%. The relations between conductivity, temperature, fat content and degree of dilution of milk were studied with respect to the validity of Kohlrausch's law and the Debye-Hückel-Onsager theory. It was shown that the Debye-Hückel-Onsager theory could correctly describe the relationship between concentration and temperature for concentrations up to 25% milk in water. To be able to use the conductivity meter as one of the sensors predicting the milk and fat concentrations, an empirical relation was derived that adequately described the conductivity as a function of temperature and degree of dilution in the temperature range from 2 ? 70°C and the milk fraction range from 0 ? 1 milk in water. In order to decrease the loss of yoghurt, its rheological properties during pipe flow were studied by cross correlation of dual plane Electrical Resistance Tomography (ERT). The use of two ERT planes allowed the determination of the local velocity in the whole cross section of the pipe. The results showed that at low velocities, i.e. up to 0.25 m s-1, yoghurt could flow as a plug. In addition to the experimental evaluation of yoghurt rinsing with water by ERT, Computational Fluid Dynamics (CFD) was used as a tool to predict the three dimensional rinsing behaviour of yoghurt, taking into account its rheological properties and higher density. Various flow velocities and rheological properties of the yoghurt were simulated and an overall agreement of experimental and calculated results was achieved. The simulations showed that high flow velocity, high yield stress of the yoghurt and wall slip decreased the mixing zone between water and yoghurt and therefore also the loss of yoghurt.
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| 8. |
- Malmgren, Bozena
(author)
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Evaluation of UHT milk processed by direct steam injection and steam infusion technology
- 2007
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Doctoral thesis (other academic/artistic)abstract
- UHT direct steam injection and steam infusion are widely used; however there is no comparison of their impact on milk components. This study evaluates the structural changes at different steps during the UHT processing of whole milk in a full-scale UHT plant by transmission electron microscopy (TEM) and particle size measurements, and follows the enzymatic activity. The results of structural analyses by TEM show the formation of agglomerates during the final heating step using both technologies; however in samples from steam injection, the agglomerates were larger and more frequent. Regardless of the heating system, big agglomerates were still present after the vacuum cooling, but very rarely in the final product. The creation of big protein agglomerates in the milk from steam injection could be a result of the accumulation of proteins on the surface of steam bubbles formed during the introduction of steam into the product and may influence its stability at the early stage of storage (Paper II.). Sedimentation was the only parameter significantly dependent on the final heating technology and preheating temperature. The amount of sediment was significantly higher in milk processed by steam injection and when preheated to 75ºC compared to 80ºC. Sediment in all samples contained large protein particles, some of them containing fat globule agglomerates covered by a thick protein layer (Paper III.). The casein micelles in milk stored at 5ºC, 22ºC and 30ºC had an irregular surface that reduced in size on storage while tendrils became extended. These structural changes led to gelation within four or five months? storage at 22ºC and 30ºC. At 40ºC the tendrils dissociated and the samples never gelled. The absence of gel formation could be a combined effect of plasmin activity and lactosylation (Paper III.). The volume-weighted mean diameter of casein micelles in samples produced by steam infusion was larger than in samples from steam injection. This could be explained by the b-lactoglobulin/?-casein complex being better anchored to the casein micelle surface than in samples from steam injection, where the complex was released to a greater extent or mechanical damage of casein micelles during steam injection leading to micelle disintegration and disaggregation (Paper III.). The structural changes and localization of the individual proteins in UHT milk kept at 22ºC or 40ºC for 6 months were followed using transmission electron microscopy combined with immunogold labelling on total caseins, ?-casein and ?-lactoglobulins A and B. In the freshly produced UHT milk, the labelling of total casein concentrated mainly on the micelles, while ?-lactoglobulin and ?-casein were localized in the serum phase and on the micelle surface. In the stored samples, tendrils protruding from the micelles showed positive labelling against all the analyzed proteins. The heavy particles that sedimented after 6 months storage showed positive labelling for total casein but not for ?-casein suggesting that the sediment composition based on caseins was most probably the hydrophobic parts of the casein micelles or protein fragments from proteolyses by plasmin (Paper IV). The enzymatic activity was the same in milk produced in both systems; however the sedimentation rate was greater in samples treated with steam injection. Based on that, we can say that analyses of results of proteolytic action measured by capillary electrophoresis of supernatant cannot alone be used for predicting the shelf life or stability of UHT milk (Paper I.). Plasmin activity was negligible at 5ºC, increased with temperature at 22ºC and 30ºC, but decreased at 40ºC. Gel formation occurred in samples stored at 22ºC and 30ºC, but not at 5ºC and 40ºC. Lactosylation started at 22ºC and increased with increasing storage temperature. After 6 months storage at 40ºC, all ?-lactoglobulin molecules contained at least 2 lactose residues, and the proteose-peptones were also lactosylated. The extensive lactosylation at 40ºC may play an important role in the absence of gelation. Destabilization of casein micelles and restructuring of proteins have a huge impact on both sediment and gel formation (Paper I.).
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| 9. |
- Sjöö, Malin
(author)
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Starch in Processed Potatoes -Influence of Tuber Structure, Thermal Treatments and Amylose/Amylopectin Ratio
- 2005
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Doctoral thesis (other academic/artistic)abstract
- The potato is one of our most important food crops, being sold in its natural state or processed into a wide range of products. Starch, by far the most abundant component in the tuber, is greatly affected by heat processing. Therefore it is logical to study starch thermal properties within the tuber tissue, although most previous studies have focused on starch-water model systems. One of the main purposes of this work was to analyse thermal events such as gelatinisation, retrogradation and annealing in both tissue samples and starch-water systems, and to relate starch thermal effects to the characteristics of potato tubers and processing conditions. The main methods used were differential scanning calorimetry (DSC) and microscopy. The DSC method has been widely used to study starch and is also applicable to the analysis of potato tissue samples. Several microscopic techniques were used to study the potato microstructure at different levels of magnification. Information obtained from micrographs was further used to interpret results from DSC analyses. Several characteristics of the raw material were shown to influence the thermal properties of starch. Potato variety and cultivation year, as well as properties related to dry matter components and their distribution within the tuber, were very important, whereas the tuber size was insignificant. The gelatinisation of starch within tissue is shifted to higher temperatures as compared with starch-water systems, a fact that also influences the effects of annealing. Furthermore, starch from the central parts of the tuber had categorically higher gelatinisation temperatures than starch from other tuber tissue zones. Retrogradation rate, in terms of increased enthalpy of melting recrystallised amylopectin with time, was affected by variety whereas melting temperatures were not. However, the differences in gelatinisation and retrogradation between varieties could not be related to cooking type, i.e. mealiness. To understand more about the influence of amylose and amylopectin respectively on different starch characteristics, potatoes with large variations in amylose content were analysed. Amylose content roughly ranged from 1 to 78 %. In high-amylose starch, properties such as granule morphology, gelatinisation, and retrogradation were severely altered compared with normal starch. In starch with 99 % amylopectin differences were less extensive. When subjecting some of these starches to different temperature treatments, it was shown that important nutritional features such as resistant starch content and starch hydrolysis rate are mainly affected by amylose content. A synergistic effect between retrograded amylopectin and amylose may have an additional effect on these properties.
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| 10. |
- Trifunovic, Olivera
(author)
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Mass transport mechanisms and module design aspects in the recovery of dilute volatile organic compounds by hydrophobic pervaporation
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Hydrophobic pervaporation has gained a lot of attention as an alternative process for mild aroma recovery, but the real commercial applications of this process are still in their infancies. Better understanding of mass transport phenomena in composite pervaporation membranes is essential from the point of view of membrane manufacturing, while process simulation is an important tool for predicting pervaporation module performance. With this in mind, the aim of this thesis was to investigate both the composite membrane performance and the module design aspects for pervaporative aroma recovery. When evaluating the composite membrane performance, the resistance of the membrane was divided into two parts, the active layer resistance and the support layer resistance. Pervaporation experiments were performed on homologous series of alcohols and esters in order to evaluate the influence of component properties, such as molecular size, volatility, chemical nature and polarity on the performance of the composite membrane. Additionally, the sorption experiments on the active layer polymer material were performed and the average diffusivity coefficients were calculated from a steady-state pervaporation flux. Both solubility and diffusivity studies show that there is a tendency towards the clustering of water and small polar molecules, which in turn causes the decrease in diffusivity of the polar permeating species. Regarding the influence of the support layer, a suitable compromise between the nature and geometric characteristics of the support structure and the thickness of the active layer should be made in order to improve the mass transfer characteristics, especially for pressure-sensitive compounds. Process simulation was performed using a modified version of an existing pervaporation simulation tool for aroma recovery, in order to investigate module design aspects of pervaporation. By applying the simulation to four aroma compounds, two alcohols and two esters, the influence of major process and module design parameters on the performance of a single module has been investigated. The results of the simulation show that detailed modelling of single module behaviour is an important aspect of the optimisation of pervaporation plant performance.
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| 11. |
- Trigo, João Pedro, 1995, et al.
(author)
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Mild blanching prior to pH-shift processing of Saccharina latissima retains protein extraction yields and amino acid levels of extracts while minimizing iodine content
- 2023
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In: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 404
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Journal article (peer-reviewed)abstract
- The seaweed Saccharina latissima is often blanched to lower iodine levels, however, it is not known how blanching affects protein extraction. We assessed the effect of blanching or soaking (80/45/12 °C, 2 min) on protein yield and protein extract characteristics after pH-shift processing of S. latissima. Average protein yields and extract amino acid levels ranked treatments as follows: blanching-45 °C ∼ control > soaking ∼ blanching-80 °C. Although blanching-45 °C decreased protein solubilization yield at pH 12, it increased isoelectric protein precipitation yield at pH 2 (p < 0.05). The former could be explained by a higher ratio of large peptides/proteins in the blanched biomass as shown by HP-SEC, whereas the latter by blanching-induced lowering of ionic strength, as verified by a dialysis model. Moreover, blanching-45 °C yielded a protein extract with 49 % less iodine compared with the control extract. We recommend blanching-45 °C since it is effective at removing iodine and does not compromise total protein extraction yield.
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| 12. |
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| 13. |
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| 14. |
- Risman, PO, 1943, et al.
(author)
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Retro-modelling of a dual resonant applicator and accurate dielectric properties of liquid water from −20 °C to +100 °C
- 2007
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In: Measurement Science and Technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 18, s. 959-966
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Journal article (peer-reviewed)abstract
- A critical analysis is made of literature reports on the dielectric properties of pure water from liquid water supercooled at −20 ◦C, to +100 ◦C, in principle in the frequency range 0 to 3 GHz. Measurements using completemulti-step numerical modelling of a dual resonant cavity at about 920 MHz and 2230 MHz are presented. The measured data at about +20 ◦C are used as reference for the calculation of data at other temperatures. Due to the high resolution and considerations of various error sources, the resultingaccuracy becomes high and allows the construction of improved empiricalformulae for the Debye relaxation behaviour.
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| 15. |
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| 16. |
- Teixeira, Cristina, 1986
(author)
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Barley malt products for improved intestinal health
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Barley is a good source of dietary fibre, particularly β-glucan and arabinoxylan, to increase formation of short-chain fatty acids (SCFAs). Butyric and propionic acid are involved in the preservation of colonic barrier function, thus decreasing the risk of inflammation. Previous studies have shown that malting barley increased formation of butyric acid in caecum of rats and had abundance of butyrate-producing bacteria than unmalted barley. However, this differed between malts, probably due to the differences in fibre functional characteristics.The aim of this work was to investigate the impact of barley variety and malting conditions on the functional properties of the dietary fibre in barley malt products, with the overall aim of improving intestinal health. Focus was given to β-glucan functional properties, but also arabinoxylan. The influence of these fibres on substrate delivery to the colon, SCFAs formation, microbiota composition and gene expression was investigated.In the first study, rats fed commercial barley malts had a higher level of butyric and propionic acids in the caecum and portal serum than those fed control diets (cellulose). β-glucan with broader molecular weight seemed to better increase the caecal SCFA formation. In addition, the malts contributed to improved mucosal barrier function and inflammatory state by decreasing mRNA expression of tight junction protein and toll-like receptors in the small intestine and distal colon. However, malt with high amounts of advanced glycation end-products seemed to attenuate the effect on occludin (tight junction protein) in the small intestine.To evaluate the possibility of using malting to tailor functional characteristics of the fibre, three barley varieties were malted using different temperatures and levels of lactic acid in the steeping water. The extent to which barley components changed depended on the variety. Steeping at 35°C with 0.4% lactic acid preserved soluble fibre and β-glucan content better, but not the soluble arabinoxylan, compared with steeping at 15°C and without lactic acid. However, no changes in β-glucan molecular weight (> 10 kDa) were observed. β-glucan molecular weight analysed with AF4 at a wider molecular weight range (> 2 kDa), was shown to be affected by both variety and processing (steeping or mashing) to different extents. Addition of proteolytic enzymes shifted the β-glucan of high molecular weight to a lower molecular weight range, suggesting that proteins are involved in the structure of β-glucan, which might result in an apparently higher molecular weight.After passage through a dynamic gastrointestinal in vitro model (TIM-1), it was observed that β-glucan molecular weight gradually decreased in the different barley products investigated. The longer in vitro transit time of soluble fibre and β-glucan was related to their high content and/or molecular weight, which also seemed to be linked to a higher degree of fermentation in an in vivo model (rats).In the last study it was investigated the differences of microbiota composition in rats fed barley malt products. Rats fed malt products had higher microbiota diversity (negatively associated with ulcerative colitis and obesity) than those fed barley extracts rich in arabinoxylan or β-glucan, and control. Malts contributing with a higher content of β-glucan increased the abundance of Lactobacillus and Blautia and tended to increase butyric acid, whereas soluble arabinoxylan increased Akkermansia and propionic acid in the caecum. By mixing barley products (brewers’ spent grain and malt) it was possible to modulate the microbiota into an intermediary abundance of taxa, with slight increase of butyric acid compared with malt alone.In conclusion, malting seems to be a potential processing method for tailoring barley composition to promote intestinal health. Both the selection of barley variety and the processing conditions affected the composition of malt products. The resulting barley products with a high content of soluble fibre, β-glucan and soluble arabinoxylan, enhanced colon fermentation, microbiota composition and, to some extent, the SCFA formation.
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| 17. |
- Wu, Haizhou, 1987, et al.
(author)
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Lipid oxidation and antioxidant delivery systems in muscle food
- 2022
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In: Comprehensive Reviews in Food Science and Food Safety. - : Wiley. - 1541-4337. ; 21:2, s. 1275-1299
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Research review (peer-reviewed)abstract
- Lipid oxidation accelerates quality deterioration in muscle-based foods (fish, red meat, and poultry), resulting in off-odors/flavors, color problems, texture defects, and safety concerns. Adding antioxidants is one approach to control lipid oxidation, and several delivery strategies have been applied, such as supplementing antioxidants to the feed, direct mixing into minces, or, for whole muscle pieces; spraying, glazing, and injection. However, some issues linked to these technologies hinder their wide utilization, such as low effectiveness, noncompatibility with clean label, and off-flavor. These shortcomings have promoted the development of new antioxidant delivery technologies. In this review, the main focus is on the principles, characteristics, and implementation of five novel antioxidant delivery methods in different types of muscle food products. Their advantages and drawbacks are also summarized, plus comments about future trends in this area. Among novel routes to deliver antioxidants to muscle foods are, for whole tissues, recyclable dipping solutions; for minces, encapsulation; and, for both minces and whole tissues, cross-processing with nonmuscle antioxidant-containing raw materials as well as applications of edible films/coatings and active packaging. Advantages of these technologies comprise, for example, low price, the possibility to control the antioxidant release rate, overcoming strong aromas from natural antioxidants, and allowing antioxidant-containing raw materials from the food industry to be valorized, providing an opportunity for more circular food production.
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| 18. |
- Bryngelsson, David, 1981
(author)
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Land-use competition and agricultural greenhouse gas emissions in a climate change mitigation perspective
- 2015
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Doctoral thesis (other academic/artistic)abstract
- Productive land for food production, bioenergy, or preservation of nature is a limited resource. Climate change mitigation puts additional pressure on land via higher demand for bioenergy to replace fossil fuels and via restrictions on deforestation—two processes that limit the availability of land for food produc- tion, and may thus also raise food prices. Methane and nitrous oxide emis- sions from agriculture may also need to be reduced to efficiently mitigate climate change. This thesis deals with this in three ways.In papers I–II, we estimate greenhouse gas emissions from food production for current diets and expected future developments, together with alternative di- etary developments and potential technical improvements in the agricultural sec- tor. Costs and possibilities for reaching climate goals are analyzed for the differ- ent diets. The results indicate that a phase out of ruminant products would cut mitigation cost in half, for staying below a 2◦C limit, and it may be necessary if the climate sensitivity is high.In papers III–IV, a conceptual and transparent partial equilibrium model of global land-use competition is developed, analyzed and applied. The model is to a large degree analytically explored and price differentials between crops are derived. The model is subjected to a detailed characterization of its mechanisms and parameters that are critical to the results. We conclude that the total amount of productive agricultural area and bioenergy yields are of crucial importance to the price impacts from large-scale introduction of bioenergy. We also show how limiting bioenergy production to marginal land could be difficult to implement in practice.In paper V, we use two established indicators for poverty and sensitivity to food-price changes to capture peoples’ vulnerability to rising food-prices in four Sub-Sahara African countries/regions. In contrast to previous studies, we include all food products instead of just one or a few main staples. We found that the vast majority of people are net consumers of food and that the inclusion of more than main staples increases their net position as consumers and thus vulnerability to high food prices.
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| 19. |
- Elfstrand, Lidia
(author)
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From Starch to Starch Microspheres. Formation of an Ordered Structure during Processing
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Starch microsphere is a dosage form suitable for the encapsulation of protein drugs. The starch microspheres investigated in this thesis are intended for release of the drug in a pre-designed way, or in controlled manner. For this purpose the starch microspheres can be coated by poly(DL-lactide-co-glycolide) (PLG) film, which is a release controlling. The term microsphere quality is complicated and includes parameters ranging from the microscopic appearance (i.e. shape, surface morphology) and physical properties (e.g. crystallinity), to the yield of the microspheres, encapsulation efficiency and release kinetics. The ideal starch particle should be of spherical or close to spherical form, of desired size, with well-defined and sharp particle contours, non-damaged, non-aggregated and non-brittle at handling, since these properties might impact the coating of the particles, as well as administration through the injection and the subsequent release. These ideal particles should be produced with high yield, be able to encapsulate a high level of the protein available and be able to release the protein in the controlled manner. In this thesis it has been shown that the microspheres can be produced of different qualities. The quality has been shown to be influenced by the type of starch, by the type of protein, by the buffer used, by individual incubation times at the two temperatures, 6 ?C and 37 ?C, by the total incubation time, and by relationships between the incubation times at these two temperatures. The process of producing starch microparticles in this thesis was described in terms of starch crystallization and obtained double helical and crystalline order. This ordered structure could be related to efficiency of entrapment of the active substance, its subsequent release and starch degradation rate. Crystallization of starch in the microspheres during the production was compared to crystallization of starch in stored dispersions. It was observed that crystallization of starch during microsphere production proceeded differently from what had been previously reported for stored starch dispersions. In order to investigate the crystallization within microspheres thoroughly this work has been carried out corresponding to a number of variables.
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| 20. |
- Helstad, Kristina
(author)
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Nanorheological Studies of Caseins
- 2006
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Doctoral thesis (other academic/artistic)abstract
- To be able to improve the quality of dairy products and dairy processes, knowledge of casein molecules, casein micelles and casein aggregates is important. The rheological properties of casein products, casein gels and adsorbed layers of casein, have been widely investigated. However, the micellar properties of casein could, until recently, only be studied by ensemble methods such as dynamic light scattering and microscopic techniques, using dried or frozen samples. Nano-techniques, such as atomic force microscopy (AFM) have now made it possible to make complementary nanorheological measurements in a liquid environment. In this thesis, the observed nanorheological properties of single casein micelles, adsorbed thin casein layers and rennet-induced casein-retentate gels, are presented and discussed. The ultimate objective of these studies was to investigate the relationship between the local and the macroscopic rheological properties of cheese. The renneted casein gels were produced from casein retentate from ultrafiltration (UF), as another objective of the work was to increase our knowledge on cheese production from concentrated milk. Natural rennet-induced cheese is essentially a particulate calcium phosphate-para-casein matrix, composed of interconnected and overlapping strands of partially fused para-casein aggregates, which are in turn made up of para-casein micelles. To increase our knowledge on the nanorheological behaviour of the building blocks of the casein matrix, the first step was to investigate single adsorbed casein micelles. In the AFM measurements, the nanorheological properties of adsorbed casein micelles could not be explained by any model describing an elastic material (Paper I). Preliminary results led to investigations of the possibility that surface tension phenomena could explain the rheological behaviour. Results from computer modelling confirmed that essential features of such model corresponded to the relation between force and indentation from AFM measurements. A surface tension of 10 mNm-1 was calculated for a casein micelle attached to a hydrophobic graphite surfaces in a Ca-imidazole buffer environment (Paper III).
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| 21. |
- Olsson, Eva
(author)
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Jet Impingement and Infrared Heating of Cylindrical Foods. Flow and Heat Transfer Studies
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Rapid heat transfer methods such as jet impingement and infrared radiation can be used to speed up thermal processing in the food industry. The heating rate affects important food characteristics, such as colour. Jet impingement consists of directed jets of air with a high velocity that impinge on the food surface, which reduces the velocity boundary layer between the air and surface and gives a fast heat transfer. Infrared heating is a radiative heat transfer method with instant and effective heating of the food product, without heating the surrounding air. Flow and heat transfer from single and multiple jets impinging on a circular cylinder placed on a flat surface were studied numerically by computational fluid dynamics (CFD) simulations using the k-? SST and RSM models. The results concerning velocity obtained by CFD were generally in good agreement with experimental measurements using particle image velocimetry (PIV). The heat transfer distribution on the cylinder surface, expressed as local heat transfer coefficients, was non-uniform due to air flow characteristics that influenced the boundary layer thickness. The heat transfer was highest on the top of the cylinder, and lower close to the separation point and on the back of the cylinder. In addition to making CFD simulations, the local heat transfer coefficients were determined by an inverse heat transfer method, including a sensitivity analysis, using temperature profiles in the cylinder at different positions. The heat transfer coefficients were generally higher than what was predicted by CFD. The interaction between multiple jets strongly affected the heat transfer around the cylinder. The distance and opening between the jets were found to be important to achieving a high and even heat transfer rate using multiple jets. Jet impingement and infrared heating simultaneously was studied using CFD, which showed that there is a synergistic effect when the two heating methods are combined. A higher heat transfer was achieved by combining the methods than by using each method separately. The effect of impingement and infrared heating on colour and crust formation on partially baked baguettes was investigated experimentally. Impingement and infrared heating gave different temperature profiles in the crust, which resulted in different colour development and crust formation. A rapid heating increased the rate of colour development and shortened the total heating time, which resulted in a thin crust and reduction in the total moisture loss. The combination of jet impingement and infrared made it possible to create product properties that cannot be achieved by use of the heating methods alone. A thicker crust and better heating in the centre of the bread could only be achieved by combining infrared and impingement. For industrial thermal processes, prediction of flow and heat transfer with CFD can be used to design equipment and processes that offer optimal heat transfer to the product, thus resulting in high and even product quality.
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| 22. |
- Olstorpe, Matilda, et al.
(author)
-
Microbial changes during storage of moist crimped cereal barley grain under Swedish farm conditions
- 2010
-
In: Animal Feed Science and Technology. - Amsterdam, Netherlands : Elsevier. - 0377-8401 .- 1873-2216. ; 156:1-2, s. 37-46
-
Journal article (peer-reviewed)abstract
- This Study investigated feed hygiene during airtight storage of non-dried barley grain under farm conditions. Microorganisms on the grain were sampled and quantified in seven Swedish firms throughout the storage period using culture dependent methods. The dominant lactic acid bacteria (LAB) and yeasts were identified by rRNA gene sequencing and moulds by morphological characterisation. Moisture content (MC) and pH of the grain were also monitored. It was difficult to obtain the optimal MC(0.30-0.45 g/g) that is necessary to initiate fermentation in the grain. Feed hygiene was maintained during storage of cereals when MC below 0.17 g/g. Intermediate MC (0.17-0.23 g/g) of the grains was conducive to mould growth, including growth of potential producers of mycotoxins, which can diminish feed safety and nutritional value. Enterobacteriaceae were found in all barleys, even at low MC, but their numbers were substantially decreased when the number of LAB was high. True fermentation of moist crimped cereal grains was only obtained on one farm with all initial barley MC of 0.3 g/g. Here, LAB reached high numbers during storage, whereas numbers of spoilage microorganisms that may reduce feed hygiene decreased considerably. However, the pH of the barley did not differ among farms. Storage stability in airtight stored barley may thus be the result of low oxygen tension, viz. airtight storage, and competition for nutrients by the microorganisms, rather than formation of lactic acid. At harvest, Enterococcus caccae dominated the LAB Population in five barleys and Lactobacillus fermentum at the remaining two. The dominant yeast species were Aureobasidium pullulans, Cryptococcus wieringae, Kazachstania aerobia and Rhodotorula glutinis. After storage, L fermentum was dominant among the LAB. The yeast species composition was highly diverse and differed among barleys. Among others, C. wieringae, Debaryomyces hansenii, K. aerobia, R. glutinis and Sporobolomyces ruberrimus were detected. This Study shows that the microbial population in airtight stored moist barley is highly diverse and not predictable. Thus, it may be necessary to influence the microbial population in the storage system by adding a starter culture.
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| 23. |
- Olstorpe, Matilda, et al.
(author)
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Pichia anomala yeast improves feed hygiene during storage of moist crimped barley grain under Swedish farm conditions
- 2010
-
In: Animal Feed Science and Technology. - Amsterdam, Netherlands : Elsevier BV. - 0377-8401 .- 1873-2216. ; 156, s. 47-56
-
Journal article (peer-reviewed)abstract
- Preservation of moist crimped cereal grain is made feasible through fermentation by lactic acid bacteria. Climatic variations make it difficult to harvest at moisture contents (0.30-0.45g/g) to support optimal fermentation under practical conditions. Therefore, the yeast, Pichia anomala J121, previously found to prevent mould spoilage and improve preservation of moist grain in malfunctioning airtight silos, was added to moist crimped cereal grain stored in large plastic tubes. Freshly harvested barley grain was crimped and inoculated with P. anomala (105 colony-forming units/g grain). Due to the local weather conditions, harvest was delayed and moisture content in the cereal grain had decreased to 0.16-0.18g/g. P. anomala was inoculated into three batches of barley, each comprising 16tonnes packed into large plastic tubes. Three additional sets of plastic tubes were packed with cereal grain without addition of P. anomala. The grain tubes were left closed for 5 months, after which feeding to cattle commenced. In both the P. anomala inoculated and the control barley, the population diversity of lactic acid bacteria (LAB) was very high over the duration of storage. However, the dominant LAB shifted over the course of storage to Pediococcus pentosaceus and Lactobacillus paracasei, in inoculated and control barley, respectively. The yeast population in the inoculated barley was totally dominated by P. anomala during the entire storage period. In the control grain, the yeast population was more diverse, displaying shifts in the dominant species during storage. Pichia burtonii was the dominant species at the last sampling occasion. In P. anomala inoculated barley, numbers of naturally occurring moulds were reduced by about two log units, and the number of Enterobacteriaceae was reduced to below detection.
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| 24. |
- Williams, Helén, et al.
(author)
-
Consumer Perceptions of Food Packaging : Contributing to or Counteracting Envir onmentally Sustainable Development?
- 2016
-
In: Packaging technology & science. - : John Wiley & Sons. - 0894-3214 .- 1099-1522. ; 29:1, s. 3-23
-
Journal article (peer-reviewed)abstract
- Packaging has a fundamental role in ensuring safe delivery of goods throughout supply chains to the end consumer in good condition. It also has great potential to contribute to sustainable development. This paper explores and provides insights on Swedish consumer perceptions and knowledge of environmental aspects of food packaging and elaborates on how these can contribute to or counteract environmentally sustainable development. A study based on a consumer survey carried out in Sweden is presented. A review of recent packaging research emphasizes the protective function of packaging as its most important contribution to the environmental dimension of sustainable development. Contrary to this, consumers almost exclusively refer to the packaging material when it comes to their perceptions of the environmental impact of packaging. Paper-based packaging is strongly understood by the surveyed consumers to be environmentally advantageous, whereas plastic and metal are not. This study further indicates that a majority of the Swedish consumers surveyed are aware of their shortcomings in judging the environmental status of food packaging, indicating a need for guidance; otherwise, consumer choices can unintendedly counteract environmentally sustainable intentions
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| 25. |
- Raaholt, Birgitta, et al.
(author)
-
Continuous tubular microwave heating of homogeneous foods: evaluation of heating uniformity
- 2016
-
In: The Journal of microwave power and electromagnetic energy. - London : Taylor & Francis Group. - 0832-7823. ; 50:1, s. 43-65
-
Journal article (peer-reviewed)abstract
- A pilot-scale process for continuous in-flow microwave processing of foods, designed and implemented at SP Food and Bioscience, was evaluated for heat treatment of a homogeneous model food for high-temperature short-time (HTST) conditions, at constant total input microwave power, at 2450 MHz. The microwave system has three consecutive cavities, one excited by the TM020 microwave mode that heats primarily in the tube centre, and two TM120 mode cavities that heat primarily in the tube periphery. The temperature uniformity of the homogeneous model food after microwave heating is here evaluated in terms of spatial distribution, for different set-ups of input microwave power in each cavity and for different order of the placement of the cavities, while maintaining the total input microwave power. The microwave heating uniformity is evaluated, based on measured and calculated radial temperature profiles. Combined TM020 and TM120 heating was found to result in more uniform heating by means of spatial temperature uniformity over the tube cross section. Furthermore, appropriately selected microwave power distribution between the centre and periphery heating cavities results in a stable heating profile in the studied food, that differs only about 10 °C or less between highest and lowest average values directly after microwave heating.
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| 26. |
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| 27. |
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| 28. |
- Eriksson, Mattias, et al.
(author)
-
Food chain sustainability in Sweden : value creation through research?
- 2016
-
Reports (other academic/artistic)abstract
- The productivity in Swedish food sector has significantly increased during the last decades as has the capacity in distribution networks. Food company mergers combined with reductions in relative price on input resources has created a food production system that is economically more efficient. On the other hand, with some businesses growing disproportionately in comparison to others, a few big players dominate nearly the entire Swedish market. This is especially relevant in the retailing sector and raises concerns on distribution of bargaining power. This could potentially affect economic viability and innovation opportunities of smaller producers and businesses, although the direction of these effects is ambiguous. There are newer trends like private labelling, food frauds and presence of inefficient practices in the chain which need to be understood. There are also concerns such as low Swedish competitiveness, inefficient price pass through and food waste which need to be addressed. This way the sector is confronted with challenges whose interplay is unknown territory. In the face of a dynamic food sector and evolving consumer behavior, the previous successes of the Swedish food industry may have unintendedly become threats to its future sustainability. This report, therefore, scopes the need and potential for greater scientific investigation on challenges in Swedish food sector with the objective of augmenting the sustainability of the overall sector. In doing so, it describes the research front on sustainable food production from a value chain perspective with a focus on the retailer-supplier interface. The report concludes by discussing briefly some challenges and the related potential research directions. The aim is not to provide answers but to illustrate the potential of value creation through systematic analysis.
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| 29. |
- Shchukarev, Andrey, et al.
(author)
-
Cryo-XPS analysis reveals surface composition of microalgae
- 2020
-
In: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 526
-
Journal article (peer-reviewed)abstract
- Green microalgae are widely used for wastewater treatment, food/feed and pigment production, as well as for aquaculture. However, very little is known about their surface composition, which can determine algae behavior in nature and influence their processing. In this work, we use cryo-XPS to characterize the surface chemical composition of three different microalgae species. We investigate the applicability of a data treatment method, developed for bacteria, deconvoluting C 1s with respect to protein, lipid and polysaccharide. We discuss how substances unique to algae contribute to the C 1s spectra and how this affects the transferability of the method to microalgae. Two species of green microalgae isolated from Northern Sweden, Chlorella vulgaris 13-1 and Coelastrella sp. 3-4, were compared to reference culture collection strain, Scenedesmus obliquus RISE (UTEX 417). Cryo-XPS data indicate that surfaces of Coelastrella sp. 3-4 and C. vulgaris 13-1 cells are dominated by protein and carbohydrates. However, the carbohydrate content was higher for C. vulgaris. The reference strain shows the highest content of proteins and has an increased amount of lipids compared to the other two. Estimation of the cell surface hydrophobicity suggests that the hydrophobicity increases in the order: C. vulgaris < Coelastrella sp. < S. obliquus.
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| 30. |
- Ahrné, Lilia, et al.
(author)
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Modelling textural changes of vegetables during acidification under isothermal and non-isothermal conditions
- 2001
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In: Acta Horticulturae. - 0567-7572. ; 566, s. 323-328
-
Journal article (peer-reviewed)abstract
- Acidification can be used to improve the quality of canned vegetables because it can decrease thermal processing requirements. Moreover, there is some evidence that acidified vegetables retain a better texture than non-acidified ones. Optimisation of the acidification processes requires the knowledge of the relationship between texture and thermal process at low/moderate temperature. The main objective of this work was the modelling of textural changes of vegetables during acidification under isothermal conditions, and the application of the model to predict textural changes in non-isothermal processes. Turnip was the vegetable used in the experiments. The effect of pre-treatments (blanching, freezing/thawing, calcium addition and vacuum infusion of water before acidification) on the kinetics of textural changes during acidification was also studied. Turnips were acidified in acetic acid under isothermal (20, 50, 70, 80, 90 and 100°C) and non-isothermal conditions (20 to 90°C). Texture was modelled by a two subtract first order kinetic model, assuming an Arrhenius-type dependence of the rate constants on temperature. The model parameters were estimated by nonlinear regression. At temperatures lower then 70°C no significant changes in texture were detected. At higher temperatures the model showed a good fit to the data for all the conditions tested. Acidification decreased the percentage of heat labile substrate from 96% to 62%, thus improving firmness retention. The parameters of the kinetic model estimated under isothermal conditions provided an adequate prediction of texture changes under non-isothermal conditions. The methodology developed in this work can be further applied to model the textural changes of vegetables during other thermal processes, such as drying, blanching, and frying.
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| 31. |
- Borch, Elisabeth, et al.
(author)
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Bacteriological safety issues in red meat and ready-to-eat meat products, as well as control measures
- 2002
-
In: Meat Science. - 0309-1740 .- 1873-4138. ; 62:3, s. 381-390
-
Journal article (peer-reviewed)abstract
- The importance of Eschericha coli O157, Listeria monocytogenes and Salmonella typhimurium DT104 as meat-borne pathogens is well established. Pathogenic bacteria such as Aeromonas spp., Arcobacter spp., psychrotrophic Bacillus cereus, Campylobacter spp., Clostridium botulinum and non-invasive Listeria monocytogenes can be regarded as rookies, but not yet firmly associated with today's production of red meat and meat products. The development of PCR and other DNA-based techniques will shed new light on so called emerging pathogens. Important safety issues in meat production, such as insufficient cleaning and disinfection (including the stable/lairage, processing environment), carcass decontamination and chilling, and cross contamination are discussed. Furthermore, probability modelling of survival and growth is identified as an important way to achieve a better understanding of how to deal with the complexity of further processing, including heat treatment and storage. © 2002 Elsevier Science Ltd. All rights reserved.
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| 32. |
- Fitzpatrick, J.J., et al.
(author)
-
Food powder handling and processing : Industry problems, knowledge barriers and research opportunities
- 2005
-
In: Chemical Engineering and Processing. - : Elsevier BV. - 0255-2701 .- 1873-3204. ; 44:2, s. 209-214
-
Journal article (peer-reviewed)abstract
- This paper highlights some of the outcomes from a EU Accompanying Measure focussing on food powders. The main goals of the work were to outline the major industrial problems, knowledge barriers, and research challenges and opportunities in relation to food powders, and to promote the creation of a sustainable network of excellence in the area of food powders. Food powders are powders first and foremost, thus many of the research challenges and opportunities are similar to handling and processing of other powders. As a result, much can be learned from other industries that deal with powders. What makes food powders different from many other powders is their composition, which is mainly of biological origin, and that they are eventually consumed by people and animals. Consequently, stability of food ingredient functionality and prevention of contamination are major issues right through from powder production to final application of the powder, which is usually in the form of a wet formulation. © 2004 Elsevier B.V. All rights reserved.
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| 33. |
- Henningsson, Marcus, et al.
(author)
-
The electrical conductivity of milk : The effect of dilution and temperature
- 2005
-
In: International journal of food properties. - 1094-2912 .- 1532-2386. ; 8:1, s. 15-22
-
Journal article (peer-reviewed)abstract
- The electrical conductivity of milk at various dilutions was measured at different temperatures from 2 to 70°C. The results showed that dilution has only a small influence on the temperature dependence of conductivity. A simple power-law model predicts that the conductivity is proportional to the milk concentration to the power of 0.84 and a two-term model describes the temperature dependency. The overall model has a standard deviation of 0.0067 mS cm-1, which corresponds approximately to 0.1% milk at 2°C and 0.07% milk at 70°C. It was further shown that for less than about 25% milk in water Kohlrausch's law and the Debye-Hückel-Onsager theory can be used to describe the relationship between the concentration, temperature, and conductivity using a representative limiting molar conductivity of milk ions of 75 mS cm2 mol-1. Copyright © Taylor & Francis Inc.
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| 34. |
- Jacobsson, Annelie, et al.
(author)
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Effects of type of packaging material on shelf-life of fresh broccoli by means of changes in weight, colour and texture
- 2004
-
In: European Food Research and Technology. - : Springer Science and Business Media LLC. - 1438-2377 .- 1438-2385. ; 218:2, s. 157-163
-
Journal article (peer-reviewed)abstract
- Five polymeric films were studied to determine their ability to retain the colour, weight and texture of broccoli (Brassica oleracea L. var. Italica "Monterey"). The materials were oriented polypropylene (OPP), polyvinyl chloride (PVC) and two different low-density polyethylenes (LDPE), one of which contained a sachet reported to absorb ethylene. The broccoli was packaged and stored at 4 and 10 °C for 4 weeks. The weight, colour, chlorophyll content and texture were monitored during storage as well as O 2 and CO2 concentrations inside the packages. Packaging prolonged the broccoli shelf-life by up to 14 days. The shelf-life varied depending on the packaging material and quality parameter considered. The atmosphere was modified inside the packages; however, no package provided the recommended atmosphere (O2 1-2% and CO2 5-10%) for broccoli. Packaging in OPP resulted in the highest CO2 concentration, 6%, while the lowest O2 concentration, 9%, was created in the LDPE package without a sachet for ethylene absorption. Storage in LDPE without ethylene absorber resulted in the overall longest shelf-life. Broccoli stored in PVC deteriorated faster than broccoli packaged in the other materials. The influence of packaging material was greater at the higher temperature.
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| 35. |
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| 36. |
- Kent, M., et al.
(author)
-
Intangible but not intractable : The prediction of fish 'quality' variables using dielectric spectroscopy
- 2007
-
In: Measurement science and technology. - : IOP Publishing. - 0957-0233 .- 1361-6501. ; 18:4, s. 1029-1037
-
Journal article (peer-reviewed)abstract
- In many fields the concept and measurement of quality is of prime importance. The fish industry is no exception to this and many sensory approaches have been devised to quantify this rather intangible property. The EU 5th framework project 'SEQUID' has concentrated on the measurement of the dielectric properties of fish tissue as a function of time both in frozen and chilled storage. The many deteriorative biochemical and microbiological processes that take place during the gradual spoilage of such materials have a subtle influence on the dielectric properties across the spectrum but notably in the microwave frequency region. In this region the complex interactions of water, solutes and structure-forming proteins are systematically changed by death and decay. Chilling or freezing may slow these processes but such preservation techniques do not halt them entirely. The SEQUID project has shown that it is possible, using a combination of time domain reflectometry and multivariate analysis, to predict certain quality-related variables, both sensory and biochemical, with comparable accuracy to existing methods. These results are presented in this paper. © 2007 IOP Publishing Ltd.
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| 37. |
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| 38. |
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| 39. |
- Langton, Maud, et al.
(author)
-
Texture as a reflection of microstructure
- 1996
-
In: Food Quality and Preference. - 0950-3293 .- 1873-6343. ; 7:42067, s. 185-191
-
Journal article (peer-reviewed)abstract
- The perception of texture has been correlated to the micro-structure of particulate whey protein gels. A full, two-level, factorial experimental design was used in which the processing conditions, pH, heating rate and addition of salt were used as design factors. The texture of the gels was analyzed by a sensory panel, and the microstructure was analysed by light and electron microscopy. The microstructure was quantified by using different types of image analysis. In this study of particulate whey protein gels, the test principles of analysing texture were divided into two groups: destructive tests and non-destructive tests. The micro-structural parameters can also be divided into two groups: overall network dimensions (pore size and particle size) and strand characteristics. The texture as measured with destructive methods was sensitive to overall network dimensions, whereas texture as measured with non-destructive methods was sensitive to the strand characteristics of particulate protein gels.
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| 40. |
- Mattsson, Berit, et al.
(author)
-
Environmental Life Cycle Assessment (LCA) of organic potatoes
- 2003
-
In: Acta Horticulturae. - 0567-7572. ; 619, s. 427-435
-
Journal article (peer-reviewed)abstract
- An LCA of organic potatoes cultivated in southern Sweden was carried out to gain more knowledge about the environmental impact and resource use along the food chain. Life Cycle Assessment (LCA) is a method for analysis and assessment of the potential environmental impact caused by products (ISO 14040). Included in the study were the production of inputs to agriculture, agricultural production, sorting and packaging, distribution and the household phase. The use of energy, water and other resources were also included as well as basic environmental impact categories such as global warming, acidification, eutrophication, toxicity, ozone depletion and photo-oxidant formation. A major finding was that the agricultural production accounted for almost all the emissions contributing to eutrophication and acidification. Other findings were that agricultural production, production of packaging materials and the household phase were the main contributors to global warming, while the energy use was rather evenly distributed among the life cycle stages. The primary improvement options identified in the study were to reduce nitrogen emissions contributing to acidification and eutrophication and to reduce potato losses due to poor quality. The organic potato yields are generally very low, typically about 60% of the conventional levels. Increased yields would be beneficial from an environmental point of view.
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| 41. |
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| 42. |
- Ohlsson, Thomas
(author)
-
Food waste management by life cycle assessment of the food chain
- 2004
-
In: Journal of Food Science. - 0022-1147 .- 1750-3841. ; 69:3, s. CRH107-CRH109
-
Journal article (peer-reviewed)abstract
- In the past, environmental activities in the food industry used to be focused on meeting the requirements set by authorities on waste and sewage disposal and, more recently, regarding emissions to air. Today environmental issues are considered an essential part of the corporate image in progressive food industries. To avoid sub-optimization, food waste management should involve assessing the environmental impact of the whole food chain. Life cycle assessment (LCA) is an ISO-standardized method to assess the environmental impact of a food product. It evaluates the resources used to perform the different activities through the chain of production from raw material to the user step. It also summarizes the emission/waste to air, water, and land from the same activities throughout the chain. These emissions are then related to the major environmental concerns such as eutrophication, acidification, and ecotoxicity, the factors most relevant for the food sector. The food industry uses the LCAs to identify the steps in the food chain that have the largest impact on the environment in order to target the improvement efforts. It is then used to choose among alternatives in the selection of raw materials, packaging material, and other inputs as well as waste management strategies. A large number of food production chains have been assessed by LCAs over the years. This will be exemplified by a comparison of the environmental impact of ecologically grown raw materials to those conventionally grown. Today LCA is often integrated into process and product development, for example, in a project for reduction of water usage and waste valorization in a diversified dairy.
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| 43. |
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| 44. |
- Olsson, E.E.M., et al.
(author)
-
Effect of near-infrared radiation and jet impingement heat transfer on crust formation of bread
- 2005
-
In: Journal of Food Science. - : Wiley. - 0022-1147 .- 1750-3841. ; 70:8, s. E484-E491
-
Journal article (peer-reviewed)abstract
- Rapid heat transfer methods can be used to speed up the baking process and create new product properties. This study investigates the effect of air jet impingement and infrared radiation (alone or in combination) on crust formation of par-baked baguettes during post-baking. The parameters investigated are crust color, crust thickness, total water loss, and heating time. The results show that infrared radiation and jet impingement, as compared with heating in a conventional household oven, increased the rate of color development of the crust and shortened the heating time. The fastest color development was obtained by combining infrared and impingement heating. The water loss rate was increased due to the high heat transfer rate, but the total water loss was reduced because of the shorter heating time. Crust thickness was most dependent on heating time and crust temperature. In general, the crust was thinner for infrared-heated baguettes. © 2005 Institute of Food Technologists.
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| 45. |
- Persson, Hans, et al.
(author)
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Binding of Cu2+, Zn2+, and Cd2+ to Inositol Tri-, Tetra-, Penta-, and Hexaphosphates
- 1998
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In: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 46:8, s. 3194-3200
-
Journal article (peer-reviewed)abstract
- myo-Inositol hexaphosphate, the salt of myo-inositol hexaphosphoric acid (IP6), is a common constituent of many plant foods, such as cereals and legumes. IP6 interacts with mineral elements, influencing their bioavailability. Processed foods contain a mixture of different inositol phosphates, i.e., IP6 and its degradation products with five or less phosphate groups (IP5-IP1). The interaction of the lower inositol phosphates with mineral elements is not well-known. In this study, the interaction between metal ions (Cu2+, Zn2+, and Cd2+) and isolated fractions of inositol phosphates with 6, 5, 4 and 3 phosphate groups (IP6-IP3) was investigated by using a potentiometric technique. The study was performed at pH 3-7, which is the pH range in the upper part of the duodenum, where mineral absorption takes place. The inositol phosphate fractions studied had a pronounced binding capacity between pH 5 and 7. Thus, mineral complex formation with lower inositol phosphates is likely to occur in the duodenum, which would be important from a nutritional point of view. The mineral binding capacity as calculated per phosphate group was similar for IP6, IP5, IP4, and IP3, but the binding strength was lower for the lower inositol phosphates (IP4 and IP3). At increasing pH, within the range (pH 3-7), the metal complex formation generally began in the order copper, zinc, cadmium for all inositol phosphates indicating the same order of binding strength, i.e., Cu > Zn > Cd. For IP6 the difference was small between Cu and Zn.
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| 46. |
- Prothon, Frédéric, et al.
(author)
-
Mechanisms and Prevention of Plant Tissue Collapse during Dehydration : A Critical Review
- 2003
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In: Critical reviews in food science and nutrition. - 1040-8398 .- 1549-7852. ; 43:4, s. 447-479
-
Journal article (peer-reviewed)abstract
- The appearance and functional properties are primordial in the quality assessment of semifinished fruit and vegetable products. These properties are often associated with shrunken, shriveled, darkened materials of poor rehydration ability after been subjected to air-drying - the most used drying method in the food industry. Fruits and vegetables are cellular tissues containing gas-filled pores that tend to collapse when subjected to dehydration. Collapse is an overall term that has different meanings and scale-settings in the literature depending on whether the author is a plant physiologist, a food technologist, a chemical engineer, or a material scientist. Some clarifications are given in this particular but wide field. The purpose of this work was to make a state-of-the-art contribution to the structural and textural effects of different types of dehydration on edible plant products and give a basis for preventing this phenomenon. The plant tissue is described, and the primordial role of the cell wall in keeping the structural integrity is emphasized. Water and its functionality at macro and micro levels of the cellular tissue are reviewed as well as its transport during dehydration. The effects of both dehydration and rehydration are described in detail, and the term "textural collapse" is proposed as an alternative to structural collapse.
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| 47. |
- Regner, Mårten, et al.
(author)
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Influence of viscosity ratio on the mixing process in a static mixer : Numerical study
- 2008
-
In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 47:9, s. 3030-3036
-
Journal article (peer-reviewed)abstract
- The mixing process in a Lightnin Series 45 static mixer, 40 mm in diameter, has been investigated using computational fluid dynamics and the volume of fluid (VOF) method, a method developed for immiscible fluids but here used for miscible. The mixing process was investigated for two liquids that had viscosities ranging from 0.003 to 51.2 Pa s, and the volumetric flow rate proportion between the liquids was varied between 1/1 and 4/1. The flow rate was 0.1 m/s, and two Reynolds numbers, 1 and 70, were investigated. The mixer performance was evaluated using the rate of striation thinning, and it was found that the greater the difference in viscosity the worse the mixer performance. This effect is due to the difference in elongation rate between the liquids, which exists until equilibrium in shear stress has been reached at the interface between the liquids. For higher Re numbers close to a point when secondary motions start to have significance for the rate of striation thinning, a lower viscosity of the added liquid results in an increase in mixing performance. It was further found that the VOF method can be used to model the mixing of dissimilar liquids in static mixers, but since the thickness of the striations decreases rapidly with the number of mixer elements, the VOF method is most suitable when investigating mixing processes over a small number of mixer elements. © 2008 American Chemical Society.
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| 48. |
- Regner, Mårten, et al.
(author)
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Predicting the displacement of Yoghurt by water in a pipe using CFD
- 2007
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In: Chemical Engineering & Technology. - : Wiley. - 0930-7516 .- 1521-4125. ; 30:7, s. 844-853
-
Journal article (peer-reviewed)abstract
- A numerical scheme based on the volume of fluid (VOF) method for predicting the displacement of one liquid by another has been verified versus electrical resistance tomography (ERT) and ultrasonic velocity profile (UVP) measurements for the displacement of yoghurt by water. The scheme using the VOF method predicts the skewed phase distribution as measured using ERT and the global structure of the velocity profile as measured using UVP. The phase distribution using the VOF method was compared with the results using the species transport model which allows for mixing between the phases. The species transport model was found to be less suitable for predicting the displacement of yoghurt by water since the turbulence model was unable to accurately predict the turbulent viscosity in the mixing zone between yoghurt and water, which resulted in a too high rate of mixing. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 49. |
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- Sonesson, Ulf, et al.
(author)
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Home transport and wastage : Environmentally relevant household activities in the life cycle of food
- 2005
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In: Ambio. - 0044-7447 .- 1654-7209. ; 34:42099, s. 371-375
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Journal article (peer-reviewed)abstract
- In environmental systems analysis of food production systems, the consumer phase (home transport, cooking, storing, and wastage) is an important contributor to the total life-cycle environmental impact. However, households are the least investigated part of the food chain. Information gathering about households involves difficulties; the number of households is large, and food-related activities are embedded in other household activities. In cooperation between researchers from environmental systems analysis and consumer research, Swedish households were surveyed by questionnaire, diary, and interviews. Data on home transport of food and wastage were collected. The average weekly driving distance was 28 to 63 km per household, depending on how trips made in conjunction with other errands are allocated. The wastage of prepared food ranged between 0 and 34% for different food categories, and wastage from storing between 0 and 164% (more food was discarded, e.g. by cleaning out a cupboard, than consumed). In both cases dairy products scored highest. © Royal Swedish Academy of Sciences 2005.
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