Psyllium–kojic acid coatings modulate antioxidant metabolism and delay quality deterioration in ready-to-eat pomegranate arils during cold storage

Abstract

The rapid deterioration of ready-to-eat pomegranate arils during cold storage remains a major challenge limiting their commercial distribution and consumer acceptance. This study evaluated the effectiveness of psyllium (PSY) and kojic acid (KA), applied individually or in combination (PSY + KA), as natural coating agents for preserving quality, extending storage life, and suppressing microbial growth in minimally processed pomegranate arils during cold storage. Pomegranate arils coated with PSY + KA and stored at 4 ± 1 °C and 90–95% relative humidity for 12 days exhibited superior preservation compared with untreated and individually treated samples. The combined coating showed favorable barrier properties, creating a modified internal atmosphere that supported quality retention. PSY + KA-treated arils maintained significantly higher antioxidant capacity, reflected by enhanced DPPH and ABTS radical scavenging activities, together with increased activities of antioxidant enzymes (ascorbate peroxidase, superoxide dismutase, catalase, and peroxidase) and key phenylpropanoid pathway enzymes (phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, cinnamate-4-hydroxylase, 4-coumarate-CoA ligase, cinnamoyl-CoA reductase, and caffeic acid O -methyltransferase). These biochemical responses were associated with enhanced phenolic metabolism, reduced oxidative stress, delayed senescence, and improved preservation of color, nutritional quality, and sensory attributes. Moreover, PSY + KA reduced microbial proliferation by more than 30% compared with the control, demonstrating an antimicrobial effect. The combined PSY + KA coating effectively enhanced the postharvest quality and storage stability of minimally processed pomegranate arils by improving barrier properties, stimulating antioxidant and phenylpropanoid metabolism, mitigating oxidative stress, delaying senescence, and suppressing microbial growth. These findings highlight PSY + KA as a promising natural coating strategy for extending the shelf life and maintaining the marketability of ready-to-eat pomegranate arils.