No description available.

Statistically designed experiments were conducted on a bench-scale ultrafiltration (UF) system using 10 kDa and 100 kDa polyethersulphone membranes to study the effect of operating conditions on membrane performance during whey processing. Experiments have underlined the importance of and provided a deeper understanding of factors influencing rejection. During filtration, a dynamic layer controlled protein fouling, reducing the effective molecular weight cut-off of the 100 kDa membrane and resulting in partial rejection. As pressure increases, the cake becomes denser allowing fewer and smaller passages for permeation, thereby increasing rejection of smaller solutes. Whey should be processed at high UF cross-flow velocities, relatively low transmembrane pressures, low feed concentrations and low temperatures. Low pressures help improve fractionation efficiency; high cross-flow velocities limit cake build-up and control cake thickness, thereby reducing specific cake resistance. Temperatures less than 10??C and pH values away from the protein iso-electric point inhibit bacterial growth and are compatible with protein, mineral and membrane stability. An existing model of dairy UF plants enabled determination of factors that affect membrane age and operational measures that minimise the effect of ageing. No significant effect of ageing was observed on performance at different volume concentration ratios (VCR). Operation at VCR 37 and 38 was capable of producing 80% whey protein concentrate (WPC). The effect of diafiltration water is improved when introduced over two loops with reallocation. Prevention of reallocation will dilute the total solids concentration in the retentate producing product that is out of specification. High protein rejections, lactose and ash rejection values between 5-15%, and non-protein nitrogen rejections below 50% are essential for producing 80% WPC. Fat rejection did not influence product quality although experimental studies show that fat concentration in liquid whey affects performance. Flux was the most influential measure of membrane life. Membrane elements in loops 11-12 did not require as frequent replacement compared to elements in loops 5-7 which are most susceptible to ageing. Emphasis should be placed on these elements for cleaning routines and operating conditions that minimise the effects of fouling in order to produce 80% WPC.

Errata pasted onto front end paper. / Bibliography: leaves 193-211. / xiv, 211 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Describes the development and application of an in vitro model used to investigate the cytoprotective effects of a whey-derived growth factor extract in reducing epithelial cell death caused by chemotherapy agents. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 1998

Stable retorted whey protein beverages with 5% protein concentration were prepared. The effect of protein concentration, fat concentration and homogenization pressure on the heat stability and the stability of emulsions of sterilized whey protein beverages was determined. Beverages containing >1% protein formed aggregates during the heat treatment. Food grade additives were added to the beverages with >1% protein to determine if the heat stability could be improved. Lecithins and polyphosphates improved the heat stability while hydrocolloids decreased the heat stability. Lecithins improved the heat stability of emulsions better than polyphosphates but polyphosphates were more effective in beverages without fat. Lecithins modified by acetylation or hydrolysis provided more protection against heat denaturation of proteins than regular lecithin. Acetylated lecithin created the emulsions most stable against creaming. Improvement in the emulsion stability by the use of phospholipids was associated with a more negative charge at the interface of the fat droplets. The effect of polyphosphates on the heat stability was related to the chain length of the polyphosphates. Short chain polyphosphates (dp~4) were more effective than other polyphosphates. Polyphosphates probably improved the heat stability of the systems by changing the structure of water and this prevented aggregation of whey proteins. Hydrocolloids decreased heat stability most probably through thermodynamic incompatibility that locally increased the concentration of proteins and promoted aggregation during the heat treatment.The effect of homogenization pressure, concentration of acetylated lecithin, and the concentration of short chain polyphosphate on the storage stability of retorted whey protein beverages containing 5% protein and 3% fat was determined. The creaming index and particle size index changed over 28 d of storage and indicated creaming of the emulsions. The use of homogenization pressures of 55 and 90 MPa compared to 20 MPa reduced the magnitude of the change of the particle size index and creaming index during storage. Inclusion of polyphosphates reduced the storage stability of the emulsions. Optimization of parameters showed that emulsions formulated with 5% protein, 3% fat and 0.3% lecithin without polyphosphates and homogenized at 90 MPa had the best stability after 28 d of storage.

Thesis--PlanA (M.S.)--University of Wisconsin--Stout, 2003. / Includes bibliographical references.

Drying is an energy intensive process. The conventional heat-based drying methods often produce changes in the physico-chemical properties of products. A newly developed electrohydrodynamic (EHD) drying technique may be much less destructive to these heat-sensitive materials. This thesis presents comparative analyses of product deterioration in EHD-dried whey proteins, using electrophoresis, differential scanning calorimetry (DSC), and color measurements. Gel electrophoresis showed the disappearance of bands and reduction in band intensities depending upon the temperature of the oven in which the whey protein was dried. The thermograms of the differential scanning calorimeter varied considerably as the temperature of oven-drier increased. EHD, air-drying, and their combination showed no significant change in the electrophoretograms and thermograms compared with the native protein. Color measurements also indicated no significant change in color of EHD-dried whey protein whereas oven-drying produced darker colors from the original. These results allowed us to conclude that physico-chemical properties of whey protein remained intact after drying with EHD.

No description available.

No description available.

Statistically designed experiments were conducted on a bench-scale ultrafiltration (UF) system using 10 kDa and 100 kDa polyethersulphone membranes to study the effect of operating conditions on membrane performance during whey processing. Experiments have underlined the importance of and provided a deeper understanding of factors influencing rejection. During filtration, a dynamic layer controlled protein fouling, reducing the effective molecular weight cut-off of the 100 kDa membrane and resulting in partial rejection. As pressure increases, the cake becomes denser allowing fewer and smaller passages for permeation, thereby increasing rejection of smaller solutes. Whey should be processed at high UF cross-flow velocities, relatively low transmembrane pressures, low feed concentrations and low temperatures. Low pressures help improve fractionation efficiency; high cross-flow velocities limit cake build-up and control cake thickness, thereby reducing specific cake resistance. Temperatures less than 10??C and pH values away from the protein iso-electric point inhibit bacterial growth and are compatible with protein, mineral and membrane stability. An existing model of dairy UF plants enabled determination of factors that affect membrane age and operational measures that minimise the effect of ageing. No significant effect of ageing was observed on performance at different volume concentration ratios (VCR). Operation at VCR 37 and 38 was capable of producing 80% whey protein concentrate (WPC). The effect of diafiltration water is improved when introduced over two loops with reallocation. Prevention of reallocation will dilute the total solids concentration in the retentate producing product that is out of specification. High protein rejections, lactose and ash rejection values between 5-15%, and non-protein nitrogen rejections below 50% are essential for producing 80% WPC. Fat rejection did not influence product quality although experimental studies show that fat concentration in liquid whey affects performance. Flux was the most influential measure of membrane life. Membrane elements in loops 11-12 did not require as frequent replacement compared to elements in loops 5-7 which are most susceptible to ageing. Emphasis should be placed on these elements for cleaning routines and operating conditions that minimise the effects of fouling in order to produce 80% WPC.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1985. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 366-372).