Investigating the influence of pin-to-plate atmospheric cold plasma on the physiochemical, nutritional, and shelf-life study of two raisins varieties during storage

Cold plasma technology, a non-thermal food processing method, significantly enhances food quality and safety by modifying its physicochemical and nutritional attributes. Additionally, this treatment extends the shelf-life of food products, ensuring prolonged freshness and improved overall quality. The present study systematically examined the effect of cold plasma treatment on various attributes, including moisture content (MC), pH, hardness (H), antioxidant activity (AOA), total phenolic content (TPC), rehydration ratio (Rr), browning index (BI), and color difference (Delta E) in black raisins (BR) and golden raisins (GR). The comprehensive analysis delivers valuable insights into the transformative influences of cold plasma on the physicochemical and nutritional characteristics of these raisin varieties. A Box-Behnken experimental design (BBD) combined with response surface methodology (RSM) was used to determine the optimization of treatment time (5, 10 and 15 min) and voltage (10, 20 and 30 kV). The optimized time and voltage for black raisins was 10 kV with 15 min, whereas, for golden raisins, it was 20 kV with 10 min. Furthermore, the experimentation of shelf-life studies for both raisins illuminated the substantial impact of cold plasma treatment, notably enhancing H, Rr, BI, AOA and TPC. Concurrently, a decline in MC and pH was observed throughout the storage period. Furthermore, plasma treatment improved the quality of raisins by reducing the total mesophilic aerobic bacteria count as compared to untreated ones from 4.65-2.42 to 4.71-2.40 log CFU/g for BR and GR, respectively, and similar results were also noticed in mold and yeast count during the 15 days of storage period. However, Future research of this study should delve into long-term storage effects, scalability for commercial applications, and the underlying mechanisms driving these improvements in raisin quality.