Production of protein hydrolysate from four plant sources and its optimization with α-pinene and tea seed saponin to control olive fruit fly

Abstract

Types, source of production and optimization with some attractive compounds are the main requirements to produce a commercially efficient protein hydrolysate. The current study was designed to produce protein hydrolysate for the first time from Camelia sinensis (Tea) seeds, Cyamopsis tetragonoloba (Guar) seeds, Cucurbita pepo (Summer squash) seeds, Glycine max (Soybean) seeds and Olea europaea Kernels (Olive) optimized with α-pinene and Camelia sinensis saponin (CSS) aiming to availability of the products from the sources with low economic value and more attractance. Results revealed the highest extracted protein from Guar while the highest inhibition of DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) and hydroxyl radicals were recorded in the protein hydrolysates extracted from Summer squash, Soybean and Olive. The highest reduction potential of Fe3+ ion and radical scavenging activity were found in the protein hydrolysate extracted from Olive and Soybean, respectively. Exposure of protein hydrolysates extracted from plant sources were determined in choice and no choice assays. In choice experiment, the highest amount of ingestion was recorded on Tea, Guar and Summer squash but the adults ingested the most protein hydrolysate extracted from tea optimized with α-pinene. In no choice experiment, the highest ingestion was recorded on Guar while optimization with α-pinene caused the highest ingestion on both Tea and Guar. Bioassay of C. sinensis saponin against the adults of B. oleae demonstrated the LC50 and LT50 values of 0.35% and 1.41 days, respectively. Also, CSS decreased activities of digestive enzymes in B. oleae except for TAG-lipase and trypsin. The adults of B. oleae fed on protein hydrolysate containing CSS showed elevated activity of antioxidant enzymes including catalase, peroxidase, superoxide dismutase and ascorbate peroxidase except for glucose-6-phosphate dehydrogenase. Results of the present study showed that protein hydrolysate can be extracted from plant sources that have little commercial value like tea seeds and olive kernels. In addition, their optimization with compounds that are attractive to the olive fruit fly can provide products with the higher efficiency than the products available in the market.