Mechanisms underlying the formation of non-thermal deamidated zein via synergistic treatment of cold plasma with acid: Improved foam performance

Zein with a modified fibrosis conformation has been demonstrated to be an effective surface component for stabilizing Pickering foam. In this study, a non-thermal deamidation method was developed using cold plasma (CP) in synergy with hydrochloric acid (HCl), tartaric acid (TA), and gluconolactone (GDL). The structure and properties of the material were investigated to better understand the mechanism of non-thermal deamidated zein synthesis. The results demonstrated that within 12 min, the degrees of deamidation (16.21, 14.14, and 8.35%) were regulated by the varying proton catalytic rates of HCl, TA, and GDL in the CP field. Following treatment, notable enhancements were observed in the solubility (0.12-0.28 mg/mL), foamability (50.00-166.67%), and foaming stability (106.67-128.00%) (P < 0.05). The increase in beta-sheet, random coil, and loose structure of deamidated zein was revealed by employing FTIR and UV spectroscopy. The unfolding of structure resulted in the exposure of hydrophobic groups, thereby enhancing the protein's foaming properties. Deamidated zein has increased interfacial adsorbability, which was demonstrated by atomic force microscope and scanning electron microscopy. Better interface performance was shown by CP synergistic TA treatment for 12 min (CPT12-zein), offering the possibility of commercial manufacturing of foamed foods in the future.