Four Factor Response Surface Experimental Design for Evaluating the Role of Processing Variables Upon Protein Denaturation in Heated Whey Systems

Abstract

Computer analysis of a response sur- face experimental design evaluated the role of four factors, e.g., temperature, 60 to 90 C; time of heating, 1 to 30 min; pH, 4.5 to 8.5; and total solids, 6 to 60%, upon protein denaturation in Cottage and Colby cheese whey. Re- sponse surface plots were generated by the computer for protein denaturation as functions of time versus temperature, pH versus temperature, and total solids ver- sus temperature. Ranking of the equa- tion's linear term coefficients indicated that the order of decreasing importance of the different parameters upon protein denaturation in heated Cottage cheese whey was temperature, total solids, time, and pH, whereas, for Colby cheese whey the order was temperature, total solids, pH, and time. Maximum protein dena- turation was at intermediate heating from 15 to 25 min for Colby and from 12 to 20 min for Cottage cheese whey. Mini- mum protein denaturation was interme- diary between pH 6 and 7 for all total solids and heating times. An inverse re- lationship was generally observed be- tween extent of denaturation and total solids. The relative amount of denatura- tion of individual whey proteins at se- lected experimental conditions was shown by polyacrylamide gel electrophoresis. A protective effect against denaturation of fl-lactoglobulin was at high total solids.