Retrogradation inhibition of wheat starch with wheat oligopeptides

Starch staling greatly reduces the cereal products quality, and the staling retardation becomes a focus in current research. The effect of wheat oligopeptide (WOP) on anti-staling properties of wheat starch (WS) was studied. Rheology property indicated that WOP reduced WS viscosity, showing more liquid-like behavior. WOP improved the water holding capacity, inhibited swelling power, and reduced the hardness of WS gels, which decreased from 1200 gf to 800 gf compared with the control after 30 days storage. Meanwhile, the water migration of WS gels were also reduced with WOP incorporation. The relative crystallinity of WS gel with 1% WOP was reduced by 13.3%, and the pore size and the microstructure of gels was improved with WOP. Besides, the short-range order degree reached the lowest value with 1% WOP. In conclusion, this study explained the interaction between WOP and WS, which was beneficial to the application of WOP in WS-based food.

Isolation and characterization of oligopeptides with vascular disease suppression effects derived from wheat gluten

Wheat gluten was hydrolyzed with both alkaline protease and neutral protease to produce high-protein and low-wheat-weight oligopeptides (WOP), which was subjected to a multistage purification. Then, high performance liquid chromatography was applied to separate WOP. In order to identify WOP sequences, six major fractions were gathered for mass spectrometry. A total of 15 peptides were synthesized for further in vitro analyses of their antithrombotic activity, vasorelaxation activity, and cholesterol reducing activity. Two antithrombotic peptides (ILPR and ILR), three vasorelaxant peptides (VN, FPQ, and FR), and four cholesterol-lowering peptides (QRQ, ILPR, FPQ, and ILR) were identified. These active peptides in WOP were also quantified. These peptides are novel candidate peptides with vascular disease suppressing effects. The results indicate WOP as good protein sources for multifunctional peptides.