Potential application of DBD Plasma Technique for modifying structural and physicochemical properties of Soy Protein Isolate
The present study was designed and implemented to modify soy protein isolate (SPI) using dielectric barrier discharge (DBD) plasma and investigate the effects of this treatment on the protein's structural and physicochemical properties. For this purpose, SPI powder was treated with DBD plasma for 0, 5, 10, 15 min at 16, 18, 20 kV. Then, solubility, water holding capacity (WHC), emulsifying activity and emulsion stability, foaming capacity and foam stability, total and reactive sulfhydryl, free carbonyl, FTIR, electrophoretic patterns, as well as protein structures were evaluated. Results indicated that emulsifying properties, solubility, WHC, and foaming activity of SPI were enhanced, and the highest values were obtained after plasma treatment at 18 kV for 15 min. Free and reactive sulfhydryl and free carbonyl contents increased under prolonged exposure to DBD plasma at the applied voltage of 18 kV (p < 0.05). FTIR and circular dichroism (CD) results indicated partial denaturation and unfolding of the α-helix structure of SPI followed by the formation of protein aggregates resulting from 15 min plasma exposure; microscopic images also confirmed these results. The above changes indicate successful modification of the physicochemical and functional properties of SPI treated with DBD plasma.