Grapefruit essential oil combined with UV-C treatment: A technology to improve the microbial safety of fresh produce

Abstract

This study investigated the use of grapefruit essential oil (GEO) in combination with ultraviolet-C (UV-C) to improve the microbial safety of fresh produce. The potent components of GEO, including d-Limonene, tramadol, Ocimene, 1-(benzyloxy) urea, and linalyl propionate, were identified. The combined treatment of 0.8% (w/v) GEO followed by UV-C at 100 mJ/cm2 resulted in reduced levels of E. coli O157:H7 and HuNoV surrogates (MNV-1 and TV) on cherry tomatoes, lettuce, and blueberries, with observed reductions of 1.92–3.96 log10 CFU or PFU/g, exceeding the reductions achieved with either treatment alone. This approach also reduced the time to complete inactivation of the microbial population from 10 to 8 min. TEM showed that GEO induced denaturation of bacterial membranes and viral capsid proteins, which enhanced the UV-C antimicrobial effect. Furthermore, the microbial reductions achieved by this approach remained effective during 7-day storage at 4 °C, and subsequent sensory evaluations indicated no adverse effects on the quality of the fresh produce. This approach effectively improves the safety of fresh produce while maintaining quality. Industrial relevanceThis study shows that the combination of grapefruit essential oil (GEO) with UV-C significantly reduced E. coli O157:H7 and Norovirus surrogates on cherry tomatoes, lettuce and blueberries, shortened the time to complete inactivation of the microbial population and maintained efficacy during storage without compromising produce quality. This method demonstrated the potential to control foodborne pathogens while maintaining the quality of fresh produce.