Effect of atmospheric pressure non-thermal pin to plate cold plasma on structural and functional properties of soy protein isolate

The atmospheric cold plasma (ACP) effect on food macromolecules is a current area of interest in the nonthermal processing of food science researchers. The present study investigates the effect of atmospheric pressure non-thermal pin-to-plate ACP processing on the structural and functional properties of Soy Protein Isolate (SPI). The hydrated SPI liquid samples were treated at different input voltages, 170V, 200V, and 230 V, at different time intervals of 05, 10 and 15 min at room temperature. The primary and secondary structures of the protein were estimated by SDS-PAGE and FTIR. The protein morphological changes were observed by scanning electron microscope. The Differential Scanning Calorimetry system was used to determine the thermal property of treated proteins. Rheological pasting, in vitro enzymatic digestion, trypsin inhibition, water holding and solubility properties were observed on 09 samples of ACP-treated SPI. The primary structure was found unaffected. The treatment could alter beta -turns and beta -sheet's secondary protein structure by altering double bond region intensity. The enhancement of the surface area, etching phenomenon and aggregation were observed in electron micrographs. ACP reduced Protein denaturation temperature from 215.05 +/- 0.30 degrees C to 209.05 +/- 0.66 degrees C. The initial viscosity (40 degrees C) of water-based untreated SPI suspension samples 16.17 +/- 1.7 cP increased significantly to 42.82 +/- 0.5 cP in higher-level ACP-treated SPI suspension samples. ACP processed protein postdigestion amino acid quantity enhanced from 3.33 +/- 0.46 mu g/mL to 14.90 +/- 0.52 mu g/ml, which could be due to the reduction of trypsin inhibition activity up to 59.00 +/- 0.004%. Treated protein water holding capacity and solubility increased to 62.74 +/- 0.08% from 58.18 +/- 0.14%. Hence, ACP technology can be a promising solution for minimally processed, chemical-free food process technic to modify the protein techno-functional properties for enhanced product quality and digestibility.