Impacts of intense pulsed light (IPL) on reduction of indigenous microorganisms and quality changes in leafy vegetables

Abstract

The minimal processing applied to fresh vegetables raises concerns about microbial contamination. This study examined how intense pulsed light (IPL) treatment influences the microbial reduction and quality attributes in lettuce, perilla leaves, napa cabbage stems, and napa cabbage leaves. IPL treatments were applied at voltages of 800-2000 V for 1-4 min, and their effects on indigenous microorganisms and their physicochemical properties. The bactericidal efficacy varied with the color and surface characteristics of each vegetable, but in all cases IPL significantly reduced indigenous microorganisms. Increasing the energy fluence increased the degree of microbial inactivation, with maximum reductions in lettuce, perilla leaves, cabbage stems, and cabbage leaves of 1.74, 1.91, 2.27, and 1.51 log CFU/mL, respectively, for total aerobic bacteria, and of 1.19, 1.46, 1.34, and 1.42 log CFU/mL for yeasts and molds. No significant changes were observed in moisture content or pH immediately after treatment, while the total phenolic content varied significantly with the vegetable type. After 10 days of storage, IPL-treated samples maintained better microbial safety without significant deterioration in quality compared to untreated samples. These findings demonstrate a potential of IPL as a non-thermal sterilization method for preserving the safety and quality of fresh leafy vegetables.