Application of Plasma Activated Fine Bubble Water on Fresh-Cut Lettuce Quality and Safety

Abstract

Lettuce (Lactuca sativa L.) is an important horticultural commodity with high market demand, but it is highly susceptible to postharvest deterioration, microbial contamination, and pesticide residues. This study evaluated the effectiveness of plasma activated water (PAW) and plasma-activated fine bubble water (PAFBW) compared to distilled water (control) in maintaining the quality and safety of fresh-cut lettuce. A completely randomized design was used with four factors: dissolved ozone concentration (1 and 2 ppm), immersion time (1 and 2 min), washing solution type (distilled water, PAW, PAFBW), and storage temperature (15 °C and 25 °C) for two days. Parameters measured included weight loss, total color change (ΔE), total plate count (TPC), total phenolic content, qualitative and quantitative pesticide residue. Analysis of variance showed highly significant treatment effects (p<0.001) on weight loss (F=10.90), color change (F=61.94), and total phenolics (F=831.39). Storage temperature was the dominant factor affecting weight loss and color change. The PAW treatment at 2 ppm with 2-min immersion at 15 °C produced the lowest weight loss (0.87 ± 0.11%) and lowest ΔE (0.40 ± 0.04). The lowest TPC was obtained for PAW 2 ppm 2 min (17,000 CFU/g) and PAFBW 2 ppm 2 min (19,950 CFU/g). The highest total phenolic content was found in PAW 1 ppm 2 min (6.98 ± 0.05 mg GAE/g). PAW outperformed PAFBW on most quantitative parameters, while PAFBW showed advantages in qualitative pesticide residue degradation. The findings indicate that plasma-based washing technology has potential as an effective postharvest method for fresh-cut lettuce.