| 1. |
- Akbari, H., et al.
(author)
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Optimization of baker's yeast drying in industrial continuous fluidized-bed dryer
- 2012
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In: Food and Bioproducts Processing. - : Elsevier Ltd. - 0960-3085 .- 1744-3571. ; 90:1, s. 52-57
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Journal article (peer-reviewed)abstract
- Instant active dry baker's yeast is a well-known product widely used for leavening of bread, produced by fermentation, and usually dried by hot air to 94–96% dry matter content. Multi-stage fluidized bed drying process is a commercial effective method for yeast drying. In this work, optimum operating parameters of an industrial continuous fluidized bed dryer for the production of instant active dry yeast were investigated. The dryer contained four zones separated with moving weirs. The operating conditions such as temperature, loading rate of compressed yeast granules, and hot air humidity had direct effects on both yeast activity and viability. The most important factors that affected the quality of the product were loading rate and the operational temperature in each zone on the bed. Optimization was performed for three loading rates of the feed to the dryer, using response surface methodology for the experimental design. The most significant factor was shown to be the loading rate with mean fermentation activity values of 620, 652, and 646 cm3 CO2/h for 300, 350, and 400 kg/h loading rates, respectively. The data analysis resulted in an optimal operating point at a loading rate of 350 kg/h and temperatures of zones 1, 2, 3, and 4 controlled at 33, 31, 31, and 29 °C, respectively. The best activity value was predicted as 668 ± 18 cm3 CO2/h, and confirmation experiments resulted in 660 ± 10 cm3 CO2/h. At the same operating point, the average viability of the cells was predicted as 74.8 ± 3.7% and confirmed as 76.4 ± 0.6%. Compared with the normal operating conditions at the plant, the optimization resulted in more than 12% and 27% improvement in the yeast activity and viability, respectively.
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| 2. |
- Arandia, Kenneth, et al.
(author)
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Development of a fluid dynamic gauging method for the characterization of fouling behavior during cross-flow filtration of a wood extraction liquor
- 2021
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In: Food and Bioproducts Processing. - : Elsevier BV. - 0960-3085 .- 1744-3571. ; 128, s. 30-40
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Journal article (peer-reviewed)abstract
- A method based on fluid dynamic gauging (FDG) was developed to investigate the membrane fouling behavior of streams containing dissolved wood components and small particles extracted using a mild steam explosion pretreatment. Industrially chipped softwood was subjected to saturated steam at 7 bar for 20 min, followed by cross-flow filtration of steam explosion liquors using 10 kDa polysulfone membranes at 2 bar transmembrane pressure. The results showed a severe decline in permeate flux during the initial stages of the cross-flow filtration. The FDG profiles from five filtration experiments revealed that thicker fouling layers were formed during initial fouling on pristine membranes compared to subsequent fouling on non-pristine membranes. The difference in fouling behavior suggests that cake layer formation was dominant during initial fouling, whereas pore blocking was more pronounced during refouling. This study highlights how FDG can be used to gain a better mechanistic understanding of the fouling behavior of extracted wood components.
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| 3. |
- Botha, G.E., et al.
(author)
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Quality optimisation of combined osmotic dehydration and microwave assisted air drying of pineapple using constant power emission
- 2012
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In: Food and Bioproducts Processing. - : Elsevier BV. - 0960-3085 .- 1744-3571. ; 90:2, s. 171-179
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Journal article (peer-reviewed)abstract
- Combination of osmotic dehydration with microwave assisted air drying offers increased flexibility for process control and product quality. Osmotic dehydration (55°Brix solution at 40 °C for 90 min) combined with microwave assisted air drying (MWAD) was tested on smooth cayenne pineapples. The influence of the four most relevant processing parameters (osmotic treatment time, microwave power, air temperature and air velocity) was studied using a 2 4 circumscribed central composite experimental design. The product quality was evaluated in terms of charred appearance at the surface, moisture content, soluble solids content, water activity, firmness, colour and volume. Microwave power and air temperature were the two most important processing parameters that influenced the quality of the dehydrated pineapple, with the parameters most affected by the operating conditions being water content and percentage of charred pieces. Only in the latter was a significant quadratic effect found, all others were approximately linear. There was also a significant interactive effect between microwave power and air temperature affecting the percentage of charred pieces. Model predictions using a quadratic surface for water content and % charred pieces were validated with an additional experiment. Quadratic models were used to indicate optimum drying conditions for various targets. © 2011 The Institution of Chemical Engineers.
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| 4. |
- Castro-Mayorga, J. L., et al.
(author)
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The impact of zinc oxide particle morphology as an antimicrobial and when incorporated in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) films for food packaging and food contact surfaces applications
- 2017
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In: Food and Bioproducts Processing. - : Institution of Chemical Engineers. - 0960-3085 .- 1744-3571. ; 101, s. 32-44
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Journal article (peer-reviewed)abstract
- In this work, zinc oxide (ZnO) micron and nano sized-particles with different morphologies were synthesized by aqueous precipitation and evaluated as antimicrobial agents against foodborne pathogens. The most effective bactericide system was selected to prepare active poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) films by three different methods (i) direct melt-mixing, (ii) melt-mixing of preincorporated ZnO into PHBV18 (18 mol% valerate content) fiber mats made by electrospinning, and, (iii) as a coating of the annealed electrospun PHBV18/ZnO fiber mats over compression molded PHBV. Results showed that ZnO successfully improved the thermal stability of the PHBV18, being the preincorporation method the most efficient in mitigating the negative impact that the PHBV18 had on the thermal stability, barrier and optical properties of the PHBV films. Similar behavior was found for the coating structure although this film showed effective and prolonged antibacterial activity against Listeria monocytogenes. This study highlights the suitability of the PHBV/ZnO nanostructures for active food packaging and food contact surface applications.
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| 5. |
- Faryar, Reza, et al.
(author)
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Production of prebiotic xylooligosaccharides from alkaline extracted wheat straw using the K80R-variant of a thermostable alkali-tolerant xylanase
- 2015
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In: Food and Bioproducts Processing. - : Elsevier BV. - 1744-3571 .- 0960-3085. ; 93:Online 22 November 2014, s. 1-10
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Journal article (peer-reviewed)abstract
- Agricultural by-products are raw materials of importance for increased utilization of renewable biomass. Wheat straw is a raw material of significant production volume and is in this work used for production of xylooligosaccharides (XOS). Extraction of xylan by dilute alkali was followed by hydrolysis using a variant of the alkali-tolerant Bacillus halodurans S7 endoxylanase A mutated at K80R. The xylan yield was on average 56.5 g xylose equivalents per kg dried, ground wheat straw, with 1 arabinose per 12 xylose residues. The K80R variant, which displayed higher specific activity than the wild-type enzyme, was added at a load of 96 U/g extracted xylan. The XOS-yield (xylobiose – xylopentaose) was evaluated at time intervals in the temperature range of 50 to 65 degrees C, at pHs from 7 to 10. The enzyme was optimally active at 60 degrees C up to pH 9. Hydrolysis was completed within 7 h, resulting in 36 % conversion of the xylan to predominantly xylobiose. Xylose content was low (2.4%) despite extended incubation, which is desirable for XOS-production. The XOS-containing hydrolysate was confirmed as a suitable carbon source for the putative probiotic strain Lactobacillus brevis DSM 1269, showing the applicability of the method to obtain prebiotic XOS.
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| 6. |
- Gourdon, Mathias, 1980, et al.
(author)
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Performance evaluation of falling film evaporators in the dairy industry
- 2017
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In: Food and Bioproducts Processing: Transactions of the Institution of of Chemical Engineers, Part C. - : Elsevier BV. - 1744-3571 .- 0960-3085. ; 101, s. 22-31
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Journal article (peer-reviewed)abstract
- Falling film evaporators constitute an essential part of dairy powder production facilities. Evaporation belongs to the thermal separation processes; consequently, the evaporation plant is fundamentally energy intensive. Hence, improvements to its operation can have a significant impact on the energy usage. A simulation tool that is based on experimental correlations developed at conditions similar to the industrial scale is presented to provide insight into the fundamental mechanisms occurring along the heat transfer surface of industrial evaporators. The model includes the complex interaction between the produced vapor and the liquid flow. The results demonstrate that the pressure drop, through its influence on the saturation temperature, is of high importance in the performance of evaporators. The tool can be used to investigate different design configurations, and it exemplifies how a change in the tube diameter for the same temperature difference and length of the surface will affect the maximum heat load per area as well as the pressure drop.
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| 7. |
- Guiamba, Isabel, 1963, et al.
(author)
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Retention of beta-carotene and vitamin C in dried mango osmotically pretreated with osmotic solutions containing calcium or ascorbic acid
- 2016
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In: Food and Bioproducts Processing: Transactions of the Institution of of Chemical Engineers, Part C. - : Elsevier BV. - 1744-3571 .- 0960-3085. ; 98, s. 320-326
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Journal article (peer-reviewed)abstract
- The retention of vitamin C and carotenoids was studied in the cv. 'Tommy Atkins' mango as affected by osmotic dehydration prior to hot air drying. Osmotic dehydration (OD) was carried out over 15 h at 25°C using sucrose solutions of 45°BRIX with and without 1% (w/w) calcium chloride or 1% ascorbic acid with a fruit to solution ratio of 1:10 (w/w), and the OD-treated mango samples were then dried in an air convection oven at 50°C or 70°C. An osmotic pretreatment before drying significantly reduced the drying time and prevented colour change in dried mango. Addition of calcium in the OD solution significantly improved vitamin C retention, on average from 44% to 57%. However, the addition of ascorbic acid to the osmotic solution highly increased the retention of vitamin C content in the dried mango. The retention of all-trans-β-carotene was significantly lower in all OD treated mango samples dried at 50°C but remained unchanged in OD-treated mango samples with calcium or vitamin C dried at 70°C. Moreover, osmotic dehydration with and without additives reduced the ratio of 13-cis-β-carotene to all-trans-β-carotene. The results showed that the addition of calcium or vitamin C to the osmotic solution can improve the nutritional value of dried mango.
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| 8. |
- Hagsten, Carin, et al.
(author)
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Removal of UHT dairy fouling — An efficient cleaning process by optimizing the rate controlling alkaline cleaning step
- 2019
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In: Food and Bioproducts Processing. - : Elsevier BV. - 0960-3085 .- 1744-3571. ; 113, s. 101-107
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Journal article (peer-reviewed)abstract
- A rigid mineral-based deposit, termed ultra-high temperature (UHT) fouling, is formed on heat exchanger surfaces during milk processing at 140 °C. The removal of this type of fouling is for the first time assessed using a laser triangulation sensor and a camera, to measure changes in the thickness and to visualize structural changes in the fouling in situ. The process was monitored during both the alkali and acid cleaning steps. There was no global swelling of the fouling layer during alkali cleaning under the investigated conditions. However, significant degradation of the protein network was observed, which affected the acid cleaning step and the efficiency of the cleaning process. We conclude that treatment with alkali is required to facilitate the removal of deposits with high mineral content during the acid cleaning step. The results have implications for optimizing the cleaning process so as to minimize energy expenditure, while ensuring efficient heat transfer and maintaining product quality.
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| 9. |
- Håkansson, Andreas, 1983-, et al.
(author)
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Model emulsions to study the mechanism of industrial mayonnaise emulsification
- 2016
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In: Food and Bioproducts Processing. - 0960-3085 .- 1744-3571. ; 98, s. 189-195
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Journal article (peer-reviewed)abstract
- Mechanistic understanding of industrial food-emulsification is necessary for optimal operation and design. Industrial mayonnaise production is yet poorly understood, partly due to a lack of experimental data and partly due to the complexity of the product.This study suggests a systematic method for building mechanistic insight, by investigating successively more complex model emulsions in industrial rotor–stator mixers, comparing to idealized theories identifying points of departure. As a first step, a high volume fraction (>50%) and high viscosity (>100 mPa s) model emulsion with a non-ionic surfactant acting as emulsifier is investigated in two industrial-scale mixers (one batch and one continuous inline mixer) at varying rotor tip-speeds.The resulting drop diameter to rotor tip-speed scaling suggest turbulent viscous fragmentation of the model emulsion in both mixers despite the high volume fraction of disperse phase which could be expected to lead to significant non-idealities such as extensive coalescence and concentration effect-dominated fragmentation. If the other non-idealities (e.g. egg yolk emulsifying system and non-Newtonian rheology) would not influence the emulsification, this suggests the same mechanism for mayonnaise emulsification. An outline for continued work on successively more complex model-emulsions is discussed in order to further enhance understanding.
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| 10. |
- Håkansson, Andreas, et al.
(author)
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Model emulsions to study the mechanism of industrial mayonnaise emulsification
- 2016
-
In: Food and Bioproducts Processing. - : Institution of Chemical Engineers. - 0960-3085 .- 1744-3571. ; 98, s. 189-195
-
Journal article (peer-reviewed)abstract
- Mechanistic understanding of industrial food-emulsification is necessary for optimal operation and design. Industrial mayonnaise production is yet poorly understood, partly due to a lack of experimental data and partly due to the complexity of the product. This study suggests a systematic method for building mechanistic insight, by investigating successively more complex model emulsions in industrial rotor–stator mixers, comparing to idealized theories identifying points of departure. As a first step, a high volume fraction (>50%) and high viscosity (>100 mPa s) model emulsion with a non-ionic surfactant acting as emulsifier is investigated in two industrial-scale mixers (one batch and one continuous inline mixer) at varying rotor tip-speeds. The resulting drop diameter to rotor tip-speed scaling suggest turbulent viscous fragmentation of the model emulsion in both mixers despite the high volume fraction of disperse phase which could be expected to lead to significant non-idealities such as extensive coalescence and concentration effect-dominated fragmentation. If the other non-idealities (e.g. egg yolk emulsifying system and non-Newtonian rheology) would not influence the emulsification, this suggests the same mechanism for mayonnaise emulsification. An outline for continued work on successively more complex model-emulsions is discussed in order to further enhance understanding.
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