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The objective of this work is to obtain a new phosphate modified peanut protein (PMPP) with good physicochemical properties by using a simple and reliable method. For this purpose, response surface methodology (RSM), based on a Box-Behnken design, was used to optimise conditions for the microwave-assisted formation of phosphate modified peanut protein isolate (PPI) with sodium tripolyphosphate (STP) as the substrate. The results indicate that emulsification activity index (EAI) was optimised at 65.04 m(2)/g under the following conditions: substrate mass fraction of 10%, initial pH of 9.90, STP mass fraction of 7.70%, microwave power of 800 W, reaction temperature of 43.0 °C, and incubation time of 3.15 min. The emulsification activity of PPI improved after phosphate modification. Phosphatisation of both the Ser and Thr hydroxyl groups and the Lys amino groups was confirmed for the reaction between STP and PPI according to analysis of FTIR, XRD, TG/DTA, NMR-(31)P and SEM of the product. Physicochemical properties of PMPP were better than those of PPI.

Insects have been relatively unexplored as potential sources of natural antioxidants. We report the antioxidant activity of extracts of the adult large black chafer beetle Holotrichia parallela Motschulsky, a common crop pest in China. The antioxidant activity of the ethanolic extract (EE) and the water extract (WE) of adult H. parallela were evaluated by four different in vitro assays. EE showed potent metal-chelating activity and inhibition of lipid peroxidation. WE proved to be an excellent antioxidant in the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and metal-chelating activity. Catechin was identified in the ethanolic extract and proteins were the main components in the water extracts. Both compounds could contribute to the antioxidant activity of the species. These results suggest that adult H. parallela might be used as a nutraceutical to alleviate oxidate-induced diseases and as a natural antioxidant additive in the food industry.