Optimization of Cold Nitrogen Gliding Arc Discharge Plasma Treatment using Box-Behnken Design for Microbial Decontamination and Quality Preservation of Apricot Kernels
摘要
The effects of cold nitrogen Gliding Arc Discharge (GAD) plasma species on natural microbial contamination, physicochemical quality, and storage stability of apricot kernels were investigated. Plasma parameters, including gas flow rate (GF, 0.5–0.9 mL/min), electrode tip distance (ED, 0.6–1.0 cm), and treatment time (2–10 min) were optimized using a Box-Behnken design. Optimal conditions were determined for single-objective reduction of total mold-yeast count (0.9 mL/min GF, 0.6 cm ED, 4.18 min; plasma-I) and for multi-objective reduction of both total mold–yeast and total mesophilic aerobic bacteria (TMAB) counts (0.9 mL/min GF, 0.6 cm ED, 7.65 min; plasma-II). Plasma-II treatment achieved the highest microbial reductions of 22.1% for total mold–yeast and 7.7% for TMAB, indicating a modest decontamination effect. These microbial reductions persisted after 30 days of storage at 25 °C. Quality parameters, including moisture content, water activity, color, total phenolics, FRAP, ABTS, tocopherol isomers, free fatty acids, and fatty acid composition, were preserved after plasma-II treatment (p > 0.05). However, DPPH value decreased by 59.5% and 40.1% in plasma-I and II-treated samples, respectively, compared to the control (p < 0.05). After accelerated storage at 60 °C for 30 days, both plasma treatments led to a decrease in DPPH as well as FRAP and ABTS values of samples compared to control, but the highest decrease was determined for plasma-I (p < 0.05). This study showed that cold nitrogen GAD plasma treatment resulted in modest but measurable reductions in natural microbial contamination while maintaining storage stability of apricot kernels without compromising their physicochemical quality attributes.