|Piler-Carvalho, Carlos - EMBRAPA-RIO DE JANEIRO|
Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: May 4, 2007
Publication Date: May 28, 2007
Citation: Carvalho, C.W.P., Onwulata, C.I., Tomasula, P.M. 2007. (Proceedings)Processing Whey Protein Isolate and Corn Starch Using a Torque Rheometer. The Polymer Processing Society 23rd Annual Meeting. In: Book of Abstracts. May 27-31, 2007. Salvador, Brazil. p.1-6. Technical Abstract: Processing a combination of starch and protein mixtures for food or nonfood applications involves shearing and heating to produce desired texture, appearance and thermo-mechanical properties. In this study, corn starch and whey protein isolate (WPI) were processed in a torque rheometer at varying rotational speeds (32 to 88 rpm), and corn starch and WPI weight ratio (0 to 1), using two mixer blade types (sigma or roller), at constant moisture (40%). The mixing temperature profile was: hold at 50 deg C for 10 min, heat at the rate of 2 deg C/min to 90 deg C; hold for 10 min, then cool at 2 deg C/min to 50 deg C, and hold for 10 min. Mixing torque using the roller blades was generally 5% higher than that from the sigma blades and ranged from 28.13 to 58.77 Nm. Torque for WPI were the highest (58.77 Nm) particularly during mixing. Fine structures seen with microscopy showed that starch granules were present in all starch mixtures after mixing, and that proteins tended to agglomerate into round shaped structures upon denaturation. Increased shearing or higher mixing energy could have enhanced net-working of starch and protein.