Effect of Cold Plasma and Plasma Activated Water on Polyphenols, Vitamins, and Volatile Compounds in Fresh-Cut Carrots

This study aimed to evaluate content of bioactive compounds (polyphenols and vitamins B2 and B3 by HPLC-MS/MS and spectrophotometric analysis, ascorbic acid by HPLC-DAD and the volatile profile by HS-SPME-GC-MS) in fresh-cut carrots treated with CP and PAW for 5-10-20-30 min. The polyphenol content was affected mostly by PAW; the ascorbic acid content statistically increased by CP and PAW, especially after 10 min of treatment; nicotinamide decreased in both treatments, while nicotinic acid increased in CP-treated samples. The volatile profile was also influenced by the application of CP and PAW: CP applied for 5 min slightly increased the abundance of volatile compounds whereas the PAW treatment completely changed the volatile profile. Finally, spectrophotometric analysis revealed the highest TPC value in CP-treated carrots for 20 min and PAW-treated for 5 min; the TFC value instead was higher in CP-treated carrots for 5 min and with PAW for 20 min; antioxidant activity was higher in carrots treated with CP for 5 min and with PAW for 20 min. In conclusion, this study shows that both CP and PAW treatments contribute to altering the chemical composition of fresh-cut carrots, with the PAW treatment having a greater impact on the content of some bioactive compounds, especially for polyphenolic compounds. In fact, a reduction of polyphenolic content of 29% and 26% was found in samples treated with CP for 10 and 30 min, respectively; while in PAW treated samples the reduction was around 70% regardless of the treatment time.