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Call number: LD2668 .T4 1986 O38 / Master of Science / Animal Sciences and Industry

Whey Protein Concentrate (WPC) is used as a functional ingredient in many food products. To increase the applicability of WPC as well as other food proteins, it is often necessary to enhance the functional properties of the protein. Various protein modification techniques can be used for this purpose; this includes chemical, physical and enzymatic modification. In present study acid hydrolysis, a chemical modification, was investigated as a means to improve functionality of WPC, emulsifying, foaming and gelatin. Most of the previous work on WPC has been directed at enzymatic hydrolysis. / Dispersions of WPC (8%) in organic acids (0.5 N, 1 N and 1.5 N acetic acid, citric acid phosphoric acid and mixture of these acids) were subjected to acid hydrolysis (6, 18 and 48 h) and the effects of this modification on functional properties was assessed. The degrees of hydrolysis were measured and freeze-dried hydrolysates were evaluated for their foam capacity and stability, emulsifying activity and stability index and toughness. Highest foam capacity was found in the hydrolysate obtained using 0.5 N acetic acid (6 h hydrolysis, foaming capacity of 140%); acid hydrolysis increased foam stability, in general. In addition, acid hydrolysis did not affect emulsifying activity index but gave higher emulsifying stability index and toughness of prepared gels. / Results of PAGE indicated that acidic modification led to progressive decrease in the $ alpha$-lactalbumin and BSA. $ alpha$-lactalbumin was found to be the most sensitive protein with significant degradation after 6 h hydrolysis. (Abstract shortened by UMI.)

Thesis (Ph. D.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on June 29, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Bioresource and Food Engineering, Department of Agricultural, Food and Nutritional Science, University of Alberta. Includes bibliographical references.

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With the increased utilization of whey powders in food products there is a need to investigate the storage stability of whey powders. The objectives were to determine the effects that compositional factors of whey powders had on the Maillard reaction during storage. The Maillard reaction is the major deteriorative reaction limiting the shelf-life of whey powders. Eight commercial whey powders were stored at accelerated storage conditions (35°C) and at five different water activities, a_ws, (0.32, 0.44, 0.52, 0.63, and 0.74) for up to 120 days. Small quantities of the hydrolyzates of lactose- glucose and galactose (less than 2% dry wt.) caused a sizable increase in the relative rates of the Maillard reaction in whey powders. The relative rate of the Maillard reaction rate was determined by measuring brown pigment formation at 420 nm. Increasing the amount of nonprotein nitrogen (NPN) significantly increased the relative rates of the Maillard reaction in the whey powders. Increasing ash content had a positive but statistically insignificant effect on the Maillard reaction. The influence of water activity on the storage stability of whey powders was also investigated. Increasing the protein content of the whey powders increased the a_w, where the maximum rate of brown pigment formation was observed. In the highest protein whey powders (46% and 82%) however, the browning rate maxima shifted to lower a_ws. The loss in protein quality of the whey powders was determined by examining the loss of available lysine using the dye-binding method. Intermediate protein whey powders (31-40% protein) and unprocessed sweet dried wheys lost the greatest relative percentages of available lysine during the storage period. / Master of Science

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1978 C5269 / Master of Science