Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 176-182). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 176-182). Also available on the Internet.

Whey from a commercial cheese plant, taken at draining on five separate days, from cheese made with a Mucor miehei coagulant was cooled within 1 h to 4 C. Portions were adjusted from pH 4.2 to 6.4 at .2 pH intervals and subjected to HTST pasteurization at 73.9, 76.6, and 79.5 C for 25 sec. Milk clotting activity in whey was determined before and after pasteurization. Resistance to heat in-activation increased with decreasing pH. All measurable activity was destroyed above pH 5.4 by pasteurization at 79.5 C, above pH 5.8 at 76.6 C and above pH 6.0 at 73.9 C. Milk clotting activity in Cheddar cheese mad with Mucor miehei remained unchanged for 26 weeks. Four commercial sterile liquid-milk-based consisting of infant formula, concentrated infant formula, nutritionally complete food, and diet food was aseptically inoculated with sterile Mucor miehei protease solutions to concentrations ranging from 5 x 10-3 to 1 x 10-7 chymosin units/ml of product. The samples were stored at 30 C. After 20 weeks there was no change in the nutritionally complete food. The diet food showed slight whey separation and thickening at 1 x 10-4 CU/ml and coagulation at higher concentrations. The infant formula showed definite whey separation and thickening at 1 x 10-4 CU/ml and coagulation and higher concentrations. The concentrated infant formula showed visible thickening at 1 x 10-3 CU/ml and coagulation at higher concentrations.

No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

The main aim of this research was to utilise whey as a fermentation substrate for the production of microbial biopolymers.Of the three commercial biopolymer producers tested for biopolymer production in whey, only Pseudodomonas elodea produced significant apparent viscosities of up to 470cP at 2 s-1 on enriched whey broths. In these broths lactose utilisation was poor (14% w/v). A strain of P. elodea that had improved lactose utilising capacity was selected after six serial transfers on whey and lactose rich broths. After screening more than 60 bacterial isolates, a strain of Klebsiella oxytoca that initially produced a broth apparent viscosity of 36 cP at 12 s-1 in whey was isolated from raw milk. Biopolymer production was optimised in the K. oxytoca isolate.Concentrations of over 16 g/1 and broth apparent viscosities greater than 20,000 cP at 0.6 s-1 were obtained after optimisation. The biopolymer produced by the K. oxytoca isolate was shown to contain rhamnose, glucose and cellobiose, a composition not comparable to any reported polysaccharide. Polymer application studies indicated that it had potential to be used as a thickener, stabiliser, and binder. / Doctor of Philosophy (PhD)

Thesis (Ph. D.)--Washington State University. / Includes bibliographical references.

No description available.

Protein co-precipitates were prepared from whey powder and soybean flour using various extraction and co-precipitation techniques. The effect of extraction and co-precipitation on co-precipitate yield was investigated. Native and sodium dodecyl sulfate polyacrylamide gel electrophoresis (Native-PAGE, SDS-PAGE) and light compound microscopy (LCM) were used to study the structure of the co-precipitates. The rheological and gelation properties of the co-precipitates were determined. Highest yield (45%) for NaOH/Isoelectric Point IEP-Heating-Cooling, co-precipitate was obtained using the following conditions of extraction; extraction temperature, 40°C; temperature of precipitation 95°C, and pH of precipitation was 4.5. The yield of co-precipitates was affected by chelating agents and pH of precipitation and temperature of precipitation. Native-PAGE showed that 2 new protein bands result from the interactions between whey and soybean proteins during preparation of the co-precipitate. SDS-PAGE showed that the new proteins dissociated to give the protein subunits of whey and soybean proteins. LCM results showed differences in microscopic structure between the whey and soybean protein precipitates and the protein co-precipitates. Gels were characterized by measurement of water holding capacity (WHC), gelation start temperature (GST) and denaturation start temperature (DST) and gel strength (GS). Gels (16%) from a protein co-precipitate Mixed Powder MP:NaOH/IEP-Cooling had higher WHC and GS than gels from whey protein precipitate, soybean protein precipitate and protein co-precipitates Mixed Extract ME:NaOH/IEP-Cooling and co-precipitates MP: and ME:NaOH/IEP-Heating-Cooling. The DST of protein co-precipitates was dependent on protein concentration and pH, while GST was relatively dependent on protein concentration.

The gelling characteristics of whey proteins is governed by factors which affect the structural properties of the protein. To understand this structure gelling relationship, the following factors were investigated; protein concentration, heating temperature and time, pH, NaCl and sugars. The effect of these factors on the molecular structure and gelatin properties of whey protein concentrate (WPC), $ beta$-lactoglobulin ($ beta$-lg), $ alpha$-lactalbumin ($ alpha$-lac) and bovine serum albumin (BSA) were studied using polyacrylamide gel electrophoresis, HPLC, mass spectrometry, differential scanning calorimetry and Fourier transform infrared spectroscopy. The results showed that protein concentration affected textural properties without affecting the molecular structure of the whey proteins while heating temperature, pH and NaCl affected both molecular structure and the textural characteristics. NaCl and sugars increased the stability of whey proteins to thermal denaturation but decreased gel formation. $ beta$-lg formed an opaque gel at pH 3 and a translucent gel at pH 9; the peak temperature of denaturation was 84$ sp circ$C at pH 3 and 70$ sp circ$C at pH 9. At both acid and alkaline pH, denaturation of $ beta$-lg resulted in the formation of intermolecular $ beta$-sheet structures associated with aggregation. These $ beta$-sheet aggregate structures were also observed when $ alpha$-lac was heated at pH 3 and 5 but not at pH 7 and 9. At pH 7, heating $ alpha$-lac resulted in a loss of $ alpha$-helix, $3 sb{10}$-helix and $ beta$-sheet and an increase in turns. DSC showed two reversible transitions at 39.6$ sp circ$C (A) and 64.8$ sp circ$C (B). At pH 3, transition A was partially reversible (14%) while transition B was completely reversible. At pH 9, transitions A and B were completely irreversible and a translucent gel was formed. Bovine serum albumin (BSA) showed maximum stability to thermal denaturation at pH 5. Denaturation of BSA resulted in the loss of $