|Rayas-Duarte, Patricia - OKLAHOMA STATE UNIVERSITY|
Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 2005
Publication Date: May 1, 2006
Citation: Mohamed, A., Peterson, S.C., Grant, L.A., Rayas-Duarte, P. 2006. Effect of jet-cooked wheat gluten/lecithin blends on corn and rice starch retrogradation. Journal of Cereal Science. 43(3):293-300. Interpretive Summary: Lecithin is a byproduct of the soybean processing industry. It is used as an addition in food and nonfood applications. Wheat gluten is a byproduct of the wheat starch wet milling industry. Blends of the two byproducts were prepared to obtain a product with unique functional properties. The blend was used to prevent water in corn and rice starch gels from separating during storage of different food products such as pudding and yogurt. The price of the blend is expected to be lower than lecithin alone. This research impacts the baking and adhesive industries, wheat growers, wheat starch industry, and prepared foods industries.
Technical Abstract: Vital wheat gluten and lecithin (GL) (50:50) were dry blended in a coffee grinder and a 9.5% (W/V) slurry was jet-cooked under steam pressure of 65 psi/g inlet and 40 psi/g outlet. The jet-cooked material was lyophilized and stored at 0ºC for future use. The GL blend was added at 0 (control), 6, 11, 16, and 21% to pure food grade common corn and rice starch. Starch gelatinization and retrogradation temperature transitions were determined using Differential Scanning Calorimetry (DSC). From the DSC profiles, the change in the delta-H value was used as an indication of starch retrogradation, where a higher delta-H value indicated higher retrogradation. The delta-H values of the blends at 4ºC had higher values than the -20ºC and the ambient (25ºC) storage temperatures. Overall, the 21% GL/starch blends reduced retrogradation by 50%. Rice starch showed lower peak viscosity, as measured by Rapid Visco Amylograph (RVA) indicating lower amylose content. The same phenomena was also noticed in the firmer corn starch gel, relative to rice starch, as measured by Texture Analyzer (TA). Low concentrations (0.2-0.3%, w/w) of GL significantly reduced G', the shear storage modulus, of corn starch. Rice starch, however, showed an increase in G' in the presence of GL due to its lower amylose content and the increase in the solids content from the added GL blend.