Atmospheric pin-to-plate cold plasma modification of amaranth starch & its application as a stabilizer in low-fat mayonnaise

This study investigates the changes in physicochemical, functional, rheological, and structural characteristics of the amaranth seed starch upon atmospheric cold plasma exposure with the generation/input voltages of 170, 200, and 230 V for 5-15 min and its potential as a fat replacer in a model emulsion system (mayonnaise). The surface modification by cold plasma is expected to enhance the native amaranth starch characteristics. Plasma treatment reduced the amylose content to a minimum of 9.00 % (230 V-15 min) resulting in a rise in relative crystallinity (74 %) and % syneresis (48.42 %). The hydratability remarkably elevated to a maximum rise of ~158 %, ~37 %, and ~41 % in solubility, absorption index, and swelling power respectively. Increased hydration, reduced the turbidity from 5.10 % (untreated) to a minimum of 3.42 % (230 V-15 min) of the pastes due to the cracked granular surface seen in electron micrographs. The rheological attributes improved up to 200 V-15 min with the peak viscosity of 5690 cP as the starch molecules tend to crosslink/aggregate which was confirmed by the increase in the COC stretching band area in FTIR spectra. On 30 % fat substitution with the plasma-treated amaranth starch (200 V-15 min), the mayonnaise viscosity increased significantly (p < 0.05) from ~7.60 Pa·s (control) to ~15.82 Pa·s (200 V-15 min) resulting in better emulsion stability (~82 %) and lightness. This proves the potential of cold plasma technology to modify under-utilized starches for sustainable food applications.