| 1. |
- Choteborska, P, et al.
(author)
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Processing of wheat bran to sugar solution
- 2004
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In: Journal of Food Engineering. - 0260-8774. ; 61:4, s. 561-565
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Journal article (peer-reviewed)abstract
- In accordance to better exploitation of raw material for bioethanol production we try to find the method for saccharification of problematic cover part of grain, so called bran. The bran consists of three main components: residual starch, hemicellulose and cellulose. Whereas hydrolysis of starch is easy and well solved, there are questions how to optimise hydrolysis of all polysaccharides together, including hernicellulose and cellulose. The bran was treated with starch degrading enzymes (Termamyl 120 L and AMG 300 L) in order to remove the starch from the solid particles and use the starch-free residue for hydrolysis of hernicelluloses to pentoses. This starch-free residue (SFR) was treated with sulphuric acid and high temperature during exact time. Different times of pre-treatment (10-50 min), different temperatures (110-180degreesC) and different concentrations of sulphuric acid (1-4% of weight of slurry) were tested, as well as presence of furfural and 5-hydroxy-methyl-2-furaldehyd (HMF), substances causing inhibition of fermentation, was evaluated. The best yield of sugars (52.1 g/100 g of SFR) was achieved by using 1% of sulphuric acid at 130degreesC for 40 min and this method generates very low content of furfural and HMF (0.28 g/l, resp. 0.05 g/l). (C) 2003 Elsevier Ltd. All rights reserved.
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| 2. |
- Fincan, Mustafa, et al.
(author)
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Effect of osmotis pretratment and pulsed electric field on the viscoelastic properties of potato tissue.
- 2003
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In: Journal of Food Engineering. - 0260-8774. ; 59:2-3, s. 169-175
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Journal article (peer-reviewed)abstract
- Compression stress relaxation of potato tissue exposed to pulsed electric field (PEF) treatment, with or without osmotic pretreatment, was measured and modelled with five parameter generalised Maxwell model. The changes in viscoelastic model coefficients were quantified as a response to applied field strength, pulse length, and pulse number and were correlated with conductivity changes. Using the same approach, additional effects of different osmotic treatments along with constant PEF treatment were also studied. As measured by the post-PEF conductivity, the residual elasticity was the parameter most affected at lower levels of PEF treatment. At high PEF levels, the longer of the relaxation times dropped from 10 to 2–3 s range. Maximal PEF treatment had a similar effect to 0.7 M hyper-osmotic treatment, implying that the effect of PEF on relaxation behaviour was dominated by loss of turgor. Neither hypo-osmotic nor hyper-osmotic pretreatment appeared to interact with the PEF treatment.
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| 3. |
- Fincan, Mustafa, et al.
(author)
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In situ visualization of the effect of a pulsed electric field on plant tissue
- 2002
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In: Journal of Food Engineering. - 0260-8774. ; 55:3, s. 223-230
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Journal article (peer-reviewed)abstract
- A new method was developed for in situ visualization of changes related to electropermeabilization of plant tissue. Onion epidermis stained with neutral red was subjected to a pulsed electric field (PEF), and serial images were captured by a camera connected to a stercomicroscope. Sample resistance was recorded simultaneously. Above a threshold level of a field strength of 0.35 kV/cm, it was possible to distinguish the individual permeabilized cells by their colour. Over 90-95% of the PEF-induced colour changes occurred during the first 2-3 min after the electric pulse and the rest after some 20 min. The size and rate of the observed changes were correlated with the severity of PEF, and were further influenced by the pH and conductivity of the solution used in mounting the epidermis, the sampling location on the onion epidermis, and cell size and number. The final conductivity increase was directly proportional to the number of permeabilized cells. Permeabilization was not randomly distributed but occurred along preferential paths connecting the electrodes. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 4. |
- Karlsson, Camilla A-C, et al.
(author)
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β-Lactoglobulin fouling and its removal upon rinsing and by SDS as influenced by surface characteristics, temperature and adsorption time
- 1996
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In: Journal of Food Engineering. - 0260-8774. ; 30:1-2, s. 43-60
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Journal article (peer-reviewed)abstract
- The extensive fouling common in the food industry puts high demands on equipment cleaning. The adsorption of β-lactoglobulin and its removal by the anionic surfactant sodium dodecyl sulphate (SDS) were followed at pH 6.0 using in situ ellipsometry. Hydrophilic chromium oxide and stainless steel together with hydrophobic methylated silica were studied at different temperatures. Differences between chromium oxide and steel were small, while hydrophobic silica showed significantly different initial adsorption kinetics and adsorbed amounts. Also, the temperature-dependence of the amount desorbed upon rinsing as well as of the overall cleanability differed greatly. At around the β-lactoglobulin denaturation temperature, multilayer build-up at the surface was seen, and the cleanability was very low. Of two protein adsorption times employed, the longer resulted, for metal oxide surfaces, in less desorption during rinsing.
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| 5. |
- Lipnizki, F, et al.
(author)
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Scale-up of pervaporation for the recovery of natural aroma compounds in the food industry. Part 1: simulation and performance
- 2002
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In: Journal of Food Engineering. - 0260-8774. ; 54:3, s. 183-195
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Journal article (peer-reviewed)abstract
- The possibility of using pervaporation for the recovery of natural aroma compounds in the food industry has been widely recognised. The aim of this study was to build a bridge between experimental studies of multi-component systems and potential applications of pervaporation in the food industry. Therefore, a novel process simulation of pervaporation has been developed for multi-component mixtures. By applying this simulation to 10 aroma compounds of relevance in the food industry, the influence of process parameters such as permeate pressure, feed temperature, degree of aroma folding and membrane area, on the performance of pervaporation has been investigated. Based on the results of the simulations, it has been demonstrated that process simulation can play an important role in integrating and optimising pervaporation in the food industry.
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| 6. |
- Lipnizki, F, et al.
(author)
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Scale-up of pervaporation for the recovery of natural aroma compounds in the food industry Part 2: optimisation and integration
- 2002
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In: Journal of Food Engineering. - 0260-8774. ; 54:3, s. 197-205
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Journal article (peer-reviewed)abstract
- In this study the integration and optimisation of hydrophobic pervaporation for the recovery of natural aroma compounds in the food industry has been studied. The simulation developed in the first part of this study was applied to the design and scale-up of pervaporation units for the recovery of natural apple juice aroma. Both semi-batch and continuous process configurations were considered and the process conditions were optimised taking the cost of the process into account. For the semi-batch process, the cost per kg concentrated aroma was between 31.30 and 33.60 euro, depending on the membrane type. When returning the recovered aroma to the apple juice after heat treatment, the cost of aroma recovery per kg concentrate was between 0.31 and 0.34 euro. In the case of the continuous process, the cost for the apple juice aroma recovery was between 2.19 and 5.38 euro, while the cost of aroma recovery per kg apple juice was between 0.03 and 0.05 euro. Upon analysing the optimised processes with a sensitivity analysis of the key cost factors associated with pervaporation, membrane life-time and membrane cost, it was revealed that the membrane life-time is more important than the membrane cost and that the continuous process is more sensitive to changes in membrane life-time and membrane cost. Overall, this study revealed that pervaporation has the potential to become an alternative to conventional processes in recovering and concentrating aroma compounds in the food industry.
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| 7. |
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| 8. |
- Mavroudis, Nikolaos, et al.
(author)
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Osmotic-treatment-induced cell death and osmotic processing kinetics of apples with characterised raw material properties
- 2004
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In: Journal of Food Engineering. - 0260-8774. ; 63:1, s. 47-56
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Journal article (peer-reviewed)abstract
- Three apple varieties cultivated in southern Sweden namely Jonagold, Kim and Mutsu were subjected to osmotic treatment at 5, 20 and 40 degreesC with a 50% sucrose solution. The evaluation of cell viability after osmotic processing, was carried out in Granny Smith apples from Argentina. The processing conditions were 50% sucrose solution at 20 degreesC and the viability assay used was based on the reduction of 2,3,5-triphenyltetrazolium chloride (TTC). The experimental samples were separated into inner (close to the apple core) and outer (close to the skin) specimens, due to the existence of pronounced structural differences between them. The kinetics revealed that for each apple variety and at each process temperature, samples of the outer structure exhibited higher water loss and lower solids gain than those of the inner structure. Overall, the Jonagold and Kim apples exhibited similarly high water loss, while Mutsu showed a lower loss. Jonagold absorbed the lowest amount of solids with Kim rating second and Mutsu apples showing the highest solids gain. The cell viability assay on the experimental samples revealed the first layer of cell in a depth 1-2 mm from the surface to die as a result of the severe osmotic shock. (C) 2003 Elsevier Ltd. All rights reserved.
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| 9. |
- Mavroudis, Nikolaos, et al.
(author)
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Studies on some raw material characteristics in different Swedish apple varieties
- 2004
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In: Journal of Food Engineering. - 0260-8774. ; 62:2, s. 121-129
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Journal article (peer-reviewed)abstract
- Some raw material characteristics were evaluated in three apple varieties cultivated in Southern Sweden, namely Kim, Mutsu and Jonagold. The study was undertaken to collect information in order to identify the effects of initial tissue properties on mass transport phenomena in general, and osmotic processing responses in particular. The texture profile analysis revealed cortex anisotropy of the three apple varieties studied. The porosity and bulk density varied depending on the sampling location within the apple. More specifically, in each variety the bulk density increased by about 10% on going from the skin to the core of the apple, while the porosity decreased by about 50-60% from the skin to the core of the apple. Experiments to evaluate the tissue pore accessibility, performed by immersion in apple juice, showed that for the agitation levels used in osmotic processing the Kim apple variety had the lowest pore accessibility. Following a simple analysis of the pore accessibility experiments it was inferred that, irrespective of the dominating mechanism driving the osmotic medium into the pores of apple tissue, the pore penetration of the osmotic medium alone cannot explain the extent and the speed of solids uptake during osmotic processing. (C) 2003 Elsevier Ltd. All rights reserved.
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| 10. |
- Elustondo, Diego, et al.
(author)
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Mathematical modeling of moisture evaporation from foodstuffs exposed to subatmospheric pressure superheated steam
- 2001
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In: Journal of Food Engineering. - 0260-8774 .- 1873-5770. ; 49:1, s. 15-24
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Journal article (peer-reviewed)abstract
- In this work, a reduced expression to calculate the drying rate of foodstuffs being dried with low pressure superheated steam is developed. It is based on a theoretical drying mechanism which assumes that water removal is carried out by evaporation in a moving boundary making the vapor to flow through the dry layer built as drying proceeds. The theoretical model can be applied to any form and features dimensionless parameters to allow for the influence of form, shrinking effect and boiling point rise. To make the application easier, a simplified expression was derived, which has only two experimentally determined parameters and allows the calculation of the drying rate of a given product. Different foodstuffs were dried with this technique and the empirical parameters were calculated from the experimental data fitting equation. Interestingly, those parameters can be considered constant within the 10000-20000 Pa pressure range and the 60-90°C temperature range
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