Ultrasonic-assisted coating and UV irradiation as hurdle technology to augment anti-browning and disinfection efficacy on fresh-cut apples

Fresh-cut fruits are prone to quality deterioration from enzymatic browning and microbial contamination. Ultraviolet (UV) irradiation is a conventional method for disinfection and browning inhibition but does not provide prolonged effects post-treatment. Coating serves as a preservation technique offering continuous protection for fresh produce through solution immersion. However, this method involves solution waste and potential cross-contamination. Ultrasonic atomization coating (UA) is an emerging non-thermal technology that generates less waste and eliminates cross-contamination risk compared to traditional methods. In this study, ascorbic acid (AA), a common anti-browning agent, was selected as coating solution. Results showed that 1 % AA applied via UA for 3 min and UV irradiation for 10 min were optimal single treatment conditions, and 7 min of UV followed by 3 min of UA was optimal combined treatment. The effects of UV-UA, UV, and UA on physiological characteristics and microbial inactivation of fresh-cut apples during storage (0-2 days) were evaluated. UV-UA treatment more effectively inhibited peroxidase and polyphenol oxidase activities, reaching 57-60 % and 72-84 % of control group levels during storage, thereby reducing browning index. The disinfection efficacy against Salmonella Typhimurium and Escherichia coli O157:H showed UV-UA was comparable to UV at day 0, and achieved lowest microbial counts (3.84-4.04 log CFU/g) during storage (days 1-2). Similarly, UV-UA's disinfection efficacy against aerobic mesophilic bacteria, molds, and yeasts matched UV at day 0, resulting in lowest counts (2.09-2.46 log CFU/g) during days 1-2. In conclusion, UV-UA integrates UV disinfection with UA's sustained effects while avoiding liquid waste and cross-contamination issues of traditional coating methods.