Effect of cold plasma on açai pulp: Enzymatic activity, color and bioaccessibility of phenolic compounds

Abstract

This study evaluates atmospheric cold plasma (ACP) effects on deteriorative enzymes, color, and phenolic compounds in açai pulp. The bioaccessibility of the bioactive compounds was also assessed after simulated digestion. Nine different treatments were applied, varying the excitation frequency (50, 500, 750 Hz) and processing time (5, 10, 15 min). ACP processing at low frequencies (50 Hz/15 min) was more effective in inactivating polyphenol oxidase (82.4%) and peroxidase (42.3%) (p < 0.05). Operation at medium excitation frequency and short application time (500 Hz/5 min) increased the phenolic content by 38.8% (p < 0.05). When treated at 500 Hz/5min and 500 Hz/15 min, the anthocyanin contents were similar to the untreated açaí pulp. The atmospheric cold plasma treatment 50 Hz/10 min increased the bioaccessibility of catechin (194.70%), epicatechin (383.44%), epigallocatechin gallate (68.84%), procyanidin B1 (130.71%), rutin (16.84%), caffeic acid (341.48%), and chlorogenic acid (57.63%). It increased the antioxidant activity of the bioaccessible fraction assessed by DPPH and ORAC assays. Cold plasma processing of acai pulp contributed to reducing PPO and POD activity; increased the phenolic compounds' bioaccessibility and antioxidant activity, facilitating the absorption of compounds after digestion.