| 1. |
- Abitbol, Tiffany, et al.
(författare)
-
Cellulose nanocrystal/low methoxyl pectin gels produced by internal ionotropic gelation.
- 2021
-
Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 260
-
Tidskriftsartikel (refereegranskat)abstract
- The biotechnological applications of cellulose nanocrystals (CNCs) continue to grow due to their sustainable nature, impressive mechanical, rheological, and emulsifying properties, upscaled production capacity, and compatibility with other materials, such as protein and polysaccharides. In this study, hydrogels from CNCs and pectin, a plant cell wall polysaccharide broadly used in food and pharma, were produced by calcium ion-mediated internal ionotropic gelation (IG). In the absence of pectin, a minimum of 4 wt% CNC was needed to produce self-supporting gels by internal IG, whereas the addition of pectin at 0.5 wt% enabled hydrogel formation at CNC contents as low as 0.5 wt%. Experimental data indicate that CNCs and pectin interact to give robust and self-supporting hydrogels at solid contents below 2.5 %. Potential applications of these gels could be as carriers for controlled release, scaffolds for cell growth, or wherever else distinct and porous network morphologies are required.
|
|
| 2. |
- Bergentall, Martina, et al.
(författare)
-
Malolactic fermentation in lingonberry juice and its use as a preservative
- 2024
-
Ingår i: Food microbiology (Print). - 0740-0020 .- 1095-9998. ; 121
-
Tidskriftsartikel (refereegranskat)abstract
- Lingonberry is a common wild berry that is often sold as jams and beverages. It naturally contains high amounts of the weak acid preservative benzoic acid making it an interesting ingredient for shelf-life extension. Despite this, their use as a raw ingredient is limited by the inherently intense sour taste. This study aimed to improve the taste of lingonberry juice by subjecting it to malolactic fermentation in order to reduce the sourness, and to investigate the benzoic acid in lingonberries as a natural preservative in juice blends by determining the microbial stability. After initial screening of lactic acid bacteria, a Lactiplantibacillus plantarum strain was used as the starter for subsequent investigations. Upon raising the pH, all malic acid was completely converted to lactic acid after seven days. The fermented juice was mixed with blackcurrant juice in different proportions. Challenge tests of the blends showed Listeria monocytogenes could not grow in any juice samples, while Candida albicans only grew in the pure blackcurrant juice. Aspergillus brasiliensis growth was delayed in all samples containing benzoic acid in a concentration-dependent manner. The sourness and astringency were substantially reduced in the juice with added L. plantarum compared to the unfermented juice. © 2024 The Authors
|
|
| 3. |
- Bergentall, Martina, et al.
(författare)
-
Reduction of malic acid in bilberry juice by Lactiplantibacillus plantarum-mediated malolactic fermentation
- 2024
-
Ingår i: European Food Research and Technology. - : Springer Science and Business Media Deutschland GmbH. - 1438-2377 .- 1438-2385. ; 250:3, s. 811-
-
Tidskriftsartikel (refereegranskat)abstract
- Bilberries (Vaccinium myrtillus) are the most common wild berries in Northern Europe. A substantial amount of the berries are picked with the objective to extract highly valued products such as anthocyanins. A smaller amount of the bilberries is used to make jams and drinks, and these are generally restricted to the domestic market. One reason is the sour taste, partly as a result of the high content of malic acid. By using certain strains of lactic acid bacteria with the ability to convert malic acid to lactic acid, the taste is predicted to be more pleasant. This process is called malolactic fermentation, and historically it has mostly been used in winemaking. After testing five different starter cultures, we identified that the strain, Lactiplantibacillus plantarum LP58, can rapidly convert malic acid to lactic acid without any loss of sugar or citric acid, which strongly indicates a successful malolactic acid fermentation. As it has been reported that other strains of L. plantarum can be used as biopreservative agents, the resulting product was also tested in terms of microbial safety after prolonged storage, and by means of metagenome sequencing. The obtained product was quite tolerant to microbial growth, but this observation was rather due to an initial heat treatment than the addition of lactobacilli. Potentially, starter cultures with documented biopreservative activity can be combined with L. plantarum LP58 to obtain a more stable product. Until then, the fermented bilberry juice must be processed and preserved like non-fermented bilberry products. © 2023, The Author(s).
|
|
| 4. |
- Malafronte, Loredana, et al.
(författare)
-
Coalescence and agglomeration of individual particles of skim milk during convective drying
- 2016
-
Ingår i: Journal of Food Engineering. - : Elsevier. - 0260-8774 .- 1873-5770. ; 175, s. 15-23
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents a methodology, which combines experiments and modelling, for investigating the coalescence and agglomeration ability of a product and to support the modelling of product properties during spray drying. Two particles were dried simultaneously and contact tests were performed along the drying time. A validated mathematical model describing the drying kinetics of milk particles was used to predict surface conditions during contact tests. Three major mechanisms were observed, coalescence, stickiness, and non-stickiness, which were related to adhesion and cohesion forces. The simulation model allowed evaluation of the surface Ohnesorge dimensionless number and surface glass transition temperature, which showed to be good parameters for predicting contact mechanisms. The model was also used to predict shell formation in drying particles. Wet and dry shell formation was simulated over the drying time, to improve understanding of observed contact behaviour.
|
|
| 5. |
- Malafronte, Loredana, 1986, et al.
(författare)
-
Combined convective and microwave assisted drying: Experiments and modelling
- 2012
-
Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 112:4, s. 304-312
-
Tidskriftsartikel (refereegranskat)abstract
- The drying process is largely used in many different industrial applications, such as treatment of foods,production of cosmetics and pharmaceuticals, manufacturing of paper, wood and building materials,polymers and so on.Physical and mathematical models can constitute useful tools to establish the influence of the main process variables on the final product quality, in order to apply an effective production control. In this work, simulation model was developed to describe combined convective/microwave assisted drying. In particular, a multi-physics approach was applied to take into account heat and two mass balances (for liquid water and for water vapor) and Maxwell’s equations to describe electromagnetic field propagation.Potato matrix was selected as food material; a waveguide with a rectangular cross section, equipped with a hot air circulator device, was used as microwave applicator. The proposed model was found able to describe the process, being thus a useful tool for design and management of the process itself.
|
|
| 6. |
- Malafronte, Loredana, 1986
(författare)
-
Drying kinetics, coalescence and agglomeration of dairy products particles
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Spray drying is used in the food, pharmaceutical, and chemical industries for producing powder from a liquid feed. The unique advantages of spray drying are producing powders of a specific particle size and moisture content, handling heat sensitive products, and high capacity. However, spray drying is a complex process. It involves numerous phenomena, such as feed atomization, airflow, particle heat and mass transfer, and particle interactions, which make the design and scale-up of the process an arduous task. For this purpose, modelling tools can be used to reduce time and cost for designing and scaling up the spray-drying process. This research aims to develop modeling tools and an experimental procedure to quantify and better understand the drying-kinetics, coalescence, and agglomeration of particles of dairy products during spray drying. The drying-kinetics model consisted of a distributed parameter model able to simultaneously simulate water content and temperature profiles within a particle, and in which physical properties were considered as a function of the local temperature and moisture content. The effective diffusion coefficient of water in skim milk as a function of solid content and temperature, which is one of the most important physical properties of the drying-kinetics model, was evaluated using a new approach that combines Nuclear Magnetic Resonance (NMR) with a parameter estimation method. The effective diffusivity values over a full range of water contents and temperatures were obtained and experimentally validated for dairy products. The experimental single-particle drying-kinetics device used for model validation allowed the assessment of the effect of the composition of dairy products on drying time and changes in morphology. The higher the fat content, the lower the diffusivity of water and, consequently, the longer the drying time. A higher fat content and a slower drying-rate resulted in less shrivelled particles. The validated drying model was combined with a CFD simulation model of a pilot spray dryer to investigate the drying-kinetics, and preconditions for the coalescence and agglomeration of skim milk powders. The results showed the need of accurate values for water diffusivity and stickiness conditions to predict the surface properties of the particles and, consequently, the regions of coalescence and agglomeration. To further understand the coalescence and agglomeration mechanisms of particles during spray drying, inter-particles behaviour during drying was studied by combining experiments and modelling. The drying-kinetics device was adapted to dry two individual particles at the same time and to perform contact tests throughout the drying time. The validated drying-kinetics model was used to predict surface conditions during contact tests. Three major mechanisms were observed; coalescence, stickiness and non-stickiness, which were related to the adhesion and cohesion forces of particles. The physical conditions of coalescence and agglomeration were evaluated, based on the Ohnesorge dimensionless number and the glass transition temperature. The model was then used to simulate the formation of wet and dry shells throughout the drying time, and the results provided a better understanding of particle-particle interactions.In conclusion, the methodologies developed can be used to optimize, design, and scale-up spray-drying equipment and to understand product properties during spray drying.
|
|
| 7. |
- Malafronte, Loredana, et al.
(författare)
-
Estimation of the effective diffusion coefficient of water in skim milk during single-drop drying
- 2015
-
Ingår i: Journal of Food Engineering. - : Elsevier Ltd. - 0260-8774 .- 1873-5770. ; 147:C, s. 111-119
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a new approach combining experimental methodology and modelling, developed to evaluate the effective diffusivity of water in skim milk during drying over a full range of water contents and temperatures. This parameter is important to support modelling of spray-drying processes and designing of equipment. The effective diffusion coefficient is evaluated using a combination of nuclear magnetic resonance (NMR) and parameter estimation. NMR is used to determine the temperature dependence and parameter estimation is used to estimate the water concentration dependence of the effective diffusivity of water in skim milk (0.90 on total weight basis) during drying by comparing the experimental data obtained using a suspended-drop method, which allows the recording of weight and temperature changes during drying, with the results of a distributed heat and mass transport model. The results indicate that the free-volume theory best predicts the dependence of the effective diffusion coefficient of water in skim milk. A mathematical correlation of effective diffusivity over a full range of water contents and temperatures (from 50 to 90 °C) was obtained and experimentally successfully validated for concentrated skim milk (0.70 on total weight basis).
|
|
| 8. |
- Malafronte, Loredana, 1986, et al.
(författare)
-
Exploring drying kinetics and morphology of commercial dairy powders
- 2015
-
Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 158, s. 58-65
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the effect of the initial composition of a liquid feed on the spray drying process and morphology of powders is important in order to reduce the time and costs for process design, and ensure the desired properties of the final product. In this work, seven commercial dairy products with different fat content were selected. The effect of initial composition on drying time during single drop experiments was studied. The morphology of powder particles and the influence of morphology changes on the drying rate were investigated in order to assess the effect of fat content on the effective diffusivity of water in dairy products. Results show that fat content influences drying time and morphology of powder particles. The higher the fat content the longer the drying time and particles appear to be less shrivelled. Changes in morphology and the drying rate seem to be related. Two falling drying periods were observed for most of the products. During the first period the drops shrink spherically, while during the second period shrivelling occurs. The effective diffusivity of water shows that high fat contents lead to a lower diffusivity of water in the products.
|
|
| 9. |
- Malafronte, Loredana, 1986, et al.
(författare)
-
Macroalgae suspensions prepared by physical treatments: Effect of polysaccharide composition and microstructure on the rheological properties
- 2021
-
Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X .- 1873-7137. ; 120
-
Tidskriftsartikel (refereegranskat)abstract
- The use of macroalgae in food products is growing due to their techno-functionality and nutritional properties. In this context, an increased understanding of the rheological properties which are relevant for manufacturing and texture is needed. Here we investigated the impact of thermal and mechanical treatments, including high pressure homogenisation (HPH), on the polysaccharide composition, microstructure, and rheological properties of brown algae Laminaria digitata suspensions (5 wt %). Monosaccharide analysis and immunolabeling of alginate in combination with confocal laser scanning microscopy, revealed a sequential release of different polysaccharides as result of the applied shear. Results showed that thermal treatment (70 °C 1 h) and mild shear lead to suspensions of clusters of cells and release of fucoidan and laminarin into the liquid phase, conferring shear thinning properties to the suspensions. High pressure homogenisation was able to completely break the macroalgae cells, reducing particle size and releasing other soluble polysaccharides, in particular alginate, conferring gel properties (G'>G'') to the suspensions. This study contributes to the knowledge of how to design sustainable, innovative and nutritious liquid/semiliquid food products containing macroalgae biomass.
|
|
| 10. |
- Malafronte, Loredana, 1986, et al.
(författare)
-
Prediction of regions of coalescence and agglomeration along a spray dryer-Application to skim milk powder
- 2015
-
Ingår i: Chemical Engineering Research and Design. - : Elsevier BV. - 0263-8762 .- 1744-3563. ; 104, s. 703-712
-
Tidskriftsartikel (refereegranskat)abstract
- Spray drying is a well-established method used in the food industry for production of powders, such as dry milk, coffee, tea, and soup. The operating conditions of spray dryers depend on the product and chamber design. Thus scaling up the process is complex, and simulation tools are needed to reduce time and cost, and to enhance quality of the final product. In this study a validated distributed-parameter model for predicting drying of single particles was combined with a CFD simulation model of an eight-meter pilot dryer to investigate drying kinetics of skim milk powders. A qualitative assessment of the effect of water diffusivity values on preconditions for agglomeration and a multi-scale analysis of coalescence and agglomeration regions were performed. Results showed that accurate water diffusivity values and sticky conditions have to be implemented when modelling spray drying to investigate preconditions for coalescence and agglomeration. The results also showed the need to simulate surface conditions of particles during spray drying to predict probable regions of coalescence and agglomeration. In conclusion, the applied methodology allows understanding of the stickiness ability of a product and size of the chamber. The methodology can be used to support preliminary design of spray dryers.
|
|
| 11. |
- Malafronte, Loredana, 1986, et al.
(författare)
-
Shear and extensional rheological properties of whole grain rye and oat aqueous suspensions
- 2023
-
Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X .- 1873-7137. ; 137
-
Tidskriftsartikel (refereegranskat)abstract
- Whole grain flours contain polysaccharides with techno-functional and nutritional properties which make them good candidates as natural texturisers in foods and beverages, thus reducing the use of highly refined ingredients. However, the use of plant components to develop complex fluids and soft materials, requires an enhanced understanding of the relationship between their physicochemical and rheological properties. Here, we systematically investigated the shear and extensional rheological properties of aqueous suspensions of whole grain rye and oat flours. Our results indicated that both types of suspensions (3.5 wt %) showed similar shear thinning behaviour (n = 0.4) however, oat suspensions presented higher viscosity and gel-like behaviour (G'>G'') compared to rye. Additionally, the oat suspensions exhibited an apparent extensional viscosity, which was not present in rye suspensions. The rheological properties of the continuous and disperse phases, separated by centrifugation, were investigated before and after starch hydrolysis and protein removal. Our results indicate that the distinct behaviour of oat suspensions is mainly due to the molecular structure of starch in the liquid phase of i.e oat starch had a higher amylose/amylopectin ratio than rye. Whilst the presence of protein and cell wall polysaccharides in the solid phase contribute to the overall rheology of the suspensions. Furthermore, our results show that the systems do not follow the Cox-Merz rule, indicating that they behaved as suspensions of soft particles rather than macromolecules in solution. Aqueous suspensions of whole grain rye and oat flours showed rheological properties that could be of interest to design low-medium viscosity food and beverage products.
|
|
| 12. |
- Wemmer, Judith, et al.
(författare)
-
Fabrication of a novel protein sponge with dual-scale porosity and mixed wettability using a clean and versatile microwave-based process
- 2021
-
Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 14:9
-
Tidskriftsartikel (refereegranskat)abstract
- An open-porous protein sponge with mixed wettability is presented made entirely from whey proteins and with promising applications in biomedicine, pharmaceutical, and food industry. The fabrication relies on an additive-free, clean and scalable process consisting of foaming followed by controlled microwave-convection drying. Volumetric heating throughout the matrix induced by microwaves causes fast expansion and elongation of the foam bubbles, retards crust formation and promotes early protein denaturation. These effects counteract collapse and shrinkage typically encountered in convection drying of foams. The interplay of high protein content, tailored gas incorporation and controlled drying result in a dried structure with dual-scale porosity composed of open macroscopic elongated foam bubbles and microscopic pores in the surrounding solid lamellae induced by water evaporation. Due to the insolubility and mixed wettability of the denatured protein network, polar and non-polar liquids are rapidly absorbed into the interconnected capillary system of the sponge without disintegrating. While non-watery liquids penetrate the pores by capillary suction, water diffuses also into the stiff protein matrix, inducing swelling and softening. Consequently, the water-filled soft sponge can be emptied by compression and re-absorbs any wetting liquid into the free capillary space. © 2021 by the authors.
|
|
