In most food applications, whey proteins are used, rather than the individual proteins and this accounts for the high functional variability among commercially available whey protein products, and limits their applications. The overall objective of this study was to investigate the structural and thermal properties of individual alpha-lactalbumin (alpha-Lac) and beta-lactoglobulin (beta-Lg) fractions isolated from different whey protein sources. / A common non-chromatographic process that isolate alpha-Lac and beta-Lg, with relatively high purity and yield from liquid whey (LW), whey protein concentrate (WPC) and whey protein isolate (WPI) using different chelating agents, was developed. The use of sodium citrate (NaC) and sodium hexametaphosphate (SHMP) were more effective than other chelating agents. Yield results indicated that 47 to 69% of beta-Lg originally present in the whey preparations was recovered, with purities ranging from 84 to 95%, and protein contents ranging from 40 to 99%, while the yields of alpha-Lac were 23 to 89%, with purities ranging from 83 to 90%, and protein contents ranging from 65 to 96% depending on the source of whey protein preparations and type of chelating agents. / Structural and thermal properties of beta-Lg and alpha-Lac isolated fractions were studied using polyacrylamide electrophoresis (native and SDS), RP-HPLC, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and electrospray ionization mass spectrometry (ESI-MS). Results showed that all beta-Lg and alpha-Lac isolated fractions exhibit increased thermal stability and reversibility over standard proteins and difference in thermal properties were dependent on protein source. The relative intensity of the 1692 cm-1 band in the beta-Lg isolated fractions was dependent on the nature of the chelating agent, and disappearance of this band occurred at temperature higher than that of beta-Lg standard, indicating increased thermal stability of beta-Lg isolated fractions. Denaturation of apo-alpha-Lac was related to the gradual decrease in the alpha-helix band and accompanied by the gain in intensity of 1653 and 1641 cm-1 bands, while denaturation of holo-alpha-Lac was associated by breakdown of beta-sheet structure and increase in turns and unordered structures. / Changes in charge state distribution (CSD), as measured by ESI-MS of beta-Lg and alpha-Lac in response to pH and storage time, were only qualitative and were of relatively low resolution at basic pH. The hydrogen/deuterium (H/D) exchange results demonstrated that the conformation of holo-alpha-Lac was more stable than that of apo-alpha-Lac and conformation of beta-Lg variant B was more stable than beta-Lg variant A. Kinetics of H/D exchange indicated that alpha-Lac and beta-Lg fractions isolated from different whey protein sources have the same or improved conformational stabilities compared to that of alpha-Lac and beta-Lg standard. The covalent binding of 3 or more hexose residues to alpha-Lac enhanced its conformational stability, but covalent binding of two hexose residues to beta-Lg resulted in less stable conformation.

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 72-74).

No description available.

Sweet whey powder is mainly used as an ingredient in foods and has a potential for increased use with the development of new foods. In view of the many whey powder producers, there is need to establish the quality of the whey powders currently on the market in terms of conformance to specifications, consistency over different seasons, and keeping quality. Selected sweet whey powder from different processors was analysed for microbiological, physicochemical and sensory quality. The whey powder was in most the cases within specifications. There was suggestive evidence of seasonal variability in the cooked flavor and sweet taste. In regard to storage, there was no significant difference in the flavor and aroma of the whey powder with storage except for the oxidized flavor which was marginally significantly different in at least one product. Most of the variation was in the microbiological and physicochemical properties. Of three products considered, rate of deterioration by the Maillard reaction, one was significantly different from the other two, having lower activation energy. Accelerated shelf-life testing deterioration rates compared well with those at ambient conditions for two products, implying that ASLT can be used for shelf-life determinations only if Maillard reaction inhibitors are absent. The flavor and aroma of sweet Cheddar cheese whey powder from one processor over 12 months, was consistent. However, the physicochemical, and microbiological properties were variable mainly between the fall and summer production with the fall production being higher in L* (lightness) and pH, but low in solubility index, and conversely, the summer production being high in solubility index and titratable acidity but low in L*. / Graduation date: 2005

The objective of this study was to identify aroma volatiles in sweet whey powder. Volatiles were isolated by solvent extraction and solvent assisted flavor evaporation. Fractionation was followed to separate acidic volatiles from nonacidic volatiles. Gas chromatography/olfactometry and gas chromatography-mass spectrometry were used for the identification ofaroma compounds. Osme methodology was applied to assess the relative importance of each aroma compound. Major free fatty acids detected were acetic, propanoic, butanoic, hexanoic, heptanoic, octanoic, decanoic, dodecanoic and 9-decenoic acids. Major non-acidic compounds detected were hexanal, heptanal, nonanal, phenylacetaldehyde, l-octen-3-one, methional, 2,6-dimethylpyrazine, 2,5- dimethylpyrazine, 2,3-dimethylpyrazine, 2,3,5-trimethylpyrazine, fiirfuryl alcohol, p-cresol, 2-acetyl pyrrole, maltol, furaneol and several lactones. The aroma of whey powder comprises mainly of curd fermentation products and compounds formed during further chemical processes such as lipid oxidation and Maillard reaction. / Graduation date: 2005

In this work, glucose isomerase (GI) activity was measured with several sugar substrates. Lactase was also used with several carbohydrate substrates to observe its hydrolytic action. In order to observe the enzymes' action, a small batch reactor was designed and used in the entire project. Paper partition chromatography, was the analytical method of choice to measure the reaction end products. It proved to be a valuable technique in combination with other analytical methods for determination of various carbohydrates. GI showed positive activity with glucose, fructose, xylose and L-sorbose but none with mannose, galactose, lactose, maltose, melibiose and cellobiose. Lactase was active on maltose, cellobiose, raffinose, lactose and sucrose but not with maltiol, melibiose or melezitose. Whey proteins were removed either by ultrafiltration or heat precipitation. This deproteinized whey was treated with the two enzymes to produce a syrup composed mainly of galactose, glucose, fructose and small amounts of oligosaccharides. The syrup had a predominantly sweet taste with a slight salty attribute. The proper utilization of whey lactose has potentially valuable features in the production of a sweetening ingredient for foods. This is especially true after the lactose has been hydrolyzed by lactase and then the glucose in the hydrolyzate isomerized to fructose with glucose isomerase.

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

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.

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).