Continuous cold plasma reactor for the processing of NFC apple juice: Effect on quality control and preservation stability

Abstract

Cold plasma is an emerging non-thermal processing technique that effectively inactivates microorganisms while mitigating the degradation of food quality associated with thermal processing. To improve the performance of cold plasma in the quality control and preservation of liquid foods, a novel continuous reactor was established. We investigated the effect of reactor microbial control and quality preservation by processing Not from concentrate (NFC) apple juice. The Continuous Cold Plasma (CCP) reactor successfully reduced natural microorganisms in apple juice to levels below the detection limit, specifically achieving a 5-log reduction in Escherichia coli. The microbiological stability of CCP-treated samples is comparable to pasteurized (PT) samples. The CCP treatment did not significantly affect the physicochemical properties of the apple juice. Compared to PT, CCP treatment better preserves total phenolics, ascorbic acid, and antioxidant properties, especially ascorbic acid (only 4 % loss). When stored at 25 °C for 30 days, the CCP group exhibited a significantly lower color change (ΔE = 4.08) compared to the PT group (ΔE = 7.54). CCP treatment better preserved several polyphenols such as cianidanol, l-epicatechin and chlorogenic acid (only 24.9 %, 14.6 % and 1.3 % reduction respectively). In addition, CCP contributed to preserving the levels of characteristic volatiles such as isoamyl acetate, hexyl acetate and hexanal. Overall, CCP provides better inactivation of microorganisms in apple juice and maintains a more stable quality during storage.