Combined peracetic acid: power ultrasound disinfection process enhances bioactive compounds and preserves quality attributes of fresh-cut lettuce (cv. Vera)

Abstract

Lettuce (Lactuca sativa) is one of the most consumed vegetables, being an important source of carotenoids and polyphenols. Sanitization is a crucial step in fresh-cut production to ensure product safety, where non-thermal technologies like ultrasound (US) can enhance disinfectant effects. This study assessed the impact of combining peracetic acid (PAA) and power ultrasound (US) on the disinfection of fresh-cut lettuce and its quality parameters. Lettuce was treated with PAA (80 mg L−1, 5 min) and PAA—US (5 min) at different acoustic power densities (APD) and frequencies: 25 W L−1 at 25 kHz and 45 kHz, and 45 W L−1 at 37 kHz and 80 kHz. Microbial load reduction ranged from 1.6 to 2.1 log CFU g−1 for treated lettuce. While combined technologies generally improved microbial reduction, no clear trend was observed for APD or frequency variations. Wash water quality indicated the need for decontamination to prevent cross-contamination. Total Antioxidant Capacity (TAC), Total Phenolic Content (TPC), and lutein increased compared to untreated lettuce, possibly due to treatment-induced abiotic stress. Total chlorophyll decreased after treatment. Power US showed potential for disinfecting fresh-cut lettuce, inducing positive changes in relevant bioactive compounds with no significant impact on visual quality. Further optimization is needed to enhance microbial inactivation compared to PAA alone.