Potential of pulsed light treatment to pasteurize pomegranate juice: Microbial safety, enzyme inactivation, and phytochemical retention

Abstract

The study explores the pasteurization condition of pomegranate juice using pulsed light (PL) treatment within a fluence domain of 312–2988 J cm−2. A 5-log reduction (microbial safety) in Escherichia coli ATCC 43888, aerobic mesophiles, yeasts & molds count in the juice was obtained at 761.4 J cm−2 (2.7 kV for 90 s). The thermal treatment attaining the equivalent lethality was 95 °C for 2 min. A complete inactivation in enzyme activity (polyphenol oxidase and peroxidase) along with microbial safety was attained for the treatments at 2988 J cm−2 (PL) and 95 °C/3 min (thermal treatment). The thermally pasteurized sample (95 °C/3 min) showed 30 and 37% depletion in phenolic compounds and antioxidant capacity, respectively, with only 34% vitamin C in the juice. The equivalent PL pasteurized (2988 J cm−2) juice retained 97%, 94%, and 83% phenolics, antioxidants, and ascorbic acid, respectively. The PL-pasteurized sample's quality attributes and sensory profile were on par with high-pressure and pulsed electric field pasteurized juices from the literature. In turn, PL treatment of the pomegranate juice at 2988 J cm−2 satisfies the criteria for all the stakeholders such as microbial safety (manufacturers demand), enzymatic stability (retailer's demand), and phytochemical retention (consumers demand).