Abstract
Background: Buckwheat deteriorates easily during storage, resulting loss of nutrients, rancidity flavor and poor consumer acceptability. Superheated steam (SS) was used to inactivate lipase of common buckwheat grains in this study, in order to retard lipid hydrolytic rancidity and maintain lipid nutrition of common buckwheat.Methods: Buckwheat grains were treated with SS at 110-200°C, for 0-7 min and SS treatment parameters were optimized by moisture content and lipase activity. The changes in free fatty acid (FFA) and lipase activity of SS-treated and untreated buckwheat during 12 weeks storage at 4°C, 25°C and 50°C were determined. Meanwhile, the effects of SS treatment on fatty acid compositions and lipidomics profile of buckwheat before and after storage were also evaluated. Moreover, the associations of hydrolytic rancidity with lipase activity and lipidomics profile were analyzed.Results: SS processing at 170 °C for 5 min was proved to be an effective method for buckwheat stabilization. Better stabilities based on lower FFA accumulation and lipase activity were observed in SS-treated buckwheat samples during storage. Meanwhile, SS could suppress oxidation of unsaturated fatty acids (UFA) in buckwheat, significantly retard the increase of saturated fatty acids (SFA) and the decrease of polyunsaturated fatty acids (PUFA) during storage. Moreover, the lipidomics profile results indicated that SS processing could retard the increased hydrolysis and oxidation of sulfoquinovosyl diacylglycerol (SQDG), phosphatidylethanolamine (PE), phosphatidylserine (PS) and lysophosphatidic acid (LPA) during storage.Conclusion: Thus, SS processing could effectively inactivate lipase, suppress UFA oxidation, change glycerolipids (GLs) and glycerophospholipids (GPs) subclass metabolism, and consequently retard hydrolytic rancidity and lipid nutrition loss of buckwheat during storage. This work was first time to demonstrate the application of SS processing for the effective quality control of buckwheat during storage.
Effects of superheated steam processing on common buckwheat grains: Lipase inactivation and its association with lipidomics profile during storage
