Effects of ultrasound-assisted extraction on the structural, functional and antioxidant properties of Dolichos lablab L. Protein

In this study, the effects of ultrasound-assisted alkali extraction (UAE) on the yield, structural, functional and antioxidant properties of dolichos lablab L. protein (DLP) were investigated. Based on Plackett-Burman design (PBD), the parameters of UAE were screened and then optimized by response surface methodology (RSM). The results showed that, under optimum conditions (ultrasound time of 30 min, pH of 10, and liquid to solid ratio of 60 mL/g), the DLP extraction rate of UAE (69.98 %) was significantly higher than that of traditional alkali extraction (TAE) method (40.95 %). Besides, compared with TAE, UAE significantly altered the protein secondary structure, enhanced the thermal stability and increased the foaming ability and oil holding capacity of DLP by 40 %. Moreover, the DLP extracted by UAE showed higher antioxidant activities. These findings revealed that ultrasound-assisted extraction not only increased the yield of DLP, but also enhanced its functional properties and antioxidant activities, which is probably related to the changes of DLP structure. All these suggest that ultrasound can be applied to augment the functional properties of DLP and make them more suitable for industrial needs.