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

Authors: LIAO, NINGBO - Jiangxi Agricultural University; CHEN, XINYUN - Jiangxi Agricultural University; TANG, MENGXUAN - Jiangxi Agricultural University; Tian, Peng; LIU, CHENGDE - Jiangxi Province Key Laboratory Of Diagnosing And Tracing Of Foodborne Disease; RUAN, LU - Jiangxi Agricultural University; PAN, HONG - Jiangxi Agricultural University; SHU, MEI - Jiangxi Agricultural University; ZHONG, CHAN - Jiangxi Agricultural University; WU, GUOPING - Jiangxi Agricultural University

Submitted to: Innovative Food Science and Emerging Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2024
Publication Date: 3/22/2024
Citation: Liao, N., Chen, X., Tang, M., Tian, P., Liu, C., Ruan, L., Pan, H., Shu, M., Zhong, C., Wu, G. 2024. Grapefruit essential oil combined with UV-C treatment: A technology to improve the microbial safety of fresh produce. Innovative Food Science and Emerging Technologies. 93. Article 103639. https://doi.org/10.1016/j.ifset.2024.103639.
DOI: https://doi.org/10.1016/j.ifset.2024.103639

Interpretive Summary: Outbreaks of foodborne pathogens associated with fresh produce, such as Escherichia coli O157:H7 and norovirus, are becoming increasingly prevalent worldwide. In this study, we evaluated the anti-pathogen efficacies of grape essential oil (GEO) on the major gastroenteric pathogens. Escherichia coli O157:H7 and human norovirus substitutes (murine norovirus-1 and Tulane virus) were used as the pathogens in this study. We demonstrated that the anti-pathogen effect of the GEO was dose-dependent and time-dependent. A significant anti-pathogen effect of GEO was observed at 8% (W/V) for 12 min. A ten-fold reduction in three pathogens was observed when exposed to UV-C irradiation along at high dose (100 mJ/cm2 or more). When 8% (W/V) EO was combined with an UV-C treatment at 100 mJ/cm2 , further reductions of pathogens were observed. The reduction of Escherichia coli O157: H7, MNV-1 and TV was 2.42log10 , 3.22log10, and 2.80log10, respectively. Similar reductions (1.92-3.96log10) were also found in pathogen-loaded fruit and vegetable when samples were treated with 8% (W/V) GEO combined with UV-C. The results of transmission electron microscopy indicated that GEO caused denaturation of the viral capsid proteins which accounted for anti-pathogen effect of GEO and its enhancement for UV irradiation. Finally, the texture analysis and sensory evaluations suggested that the addition GEO to fruits and vegetables did not affect the flavor and quality of food. This study provides a novel approach to inactivate common food pathogens.

Technical Abstract: Outbreaks of foodborne pathogens associated with fresh produce, such as Escherichia coli O157:H7 and norovirus, are becoming increasingly prevalent worldwide. Although the inactivation of foodborne pathogens in food by shortwave ultraviolet light has become the main means of inactivation of microorganisms, it may affect the color, texture and oxidative stability of food due to its low penetration efficiency through solid food and the excessive irradiation dose required. Grapefruit essential oil (GEO) has antibacterial and antioxidant properties, but its activity against norovirus is rarely reported. The aim of this study was to evaluate the anti-pathogen efficacies of GEO alone and in combination with ultraviolet-C (UV-C) treatment for foodborne pathogens and for foodborne pathogens loaded on cherry tomatoes, lettuces, and blueberries. Escherichia coli O157:H7 and human norovirus substitutes (murine norovirus-1 and Tulane virus) were used as foodborne pathogens in this study. Proteinase K, PMSF and RNase enzymes were used to reduce the potential free viral RNAs in RT-qPCR assays. The anti-pathogen effect of the GEO was dose-dependent and time-dependent. A significant anti-pathogen effect of GEO was observed at 8% (W/V) for 12 min. Significant anti-pathogen effects of UV-C irradiation (a log reduction in pathogens) on all three pathogens were observed at 80, 100 and 200 mJ/cm2. In the presence of 8% GEO, UV-C treatment (100 mJ/cm2) resulted in further reductions in three pathogens tested. After the combination treatment, the reductions of Escherichia coli O157: H7, MNV-1 and TV were 2.42log10 CFU/mL, 3.22log10 PFU/mL and 2.80log10 PFU/mL, respectively. Similar results (1.9 to 3.96log10 CFU (PFU) /mL in pathogen reductions) were also found in pathogen-loaded fruit and vegetable samples treated with 8% (W/V) GEO combined with UV irradiation. The results of transmission electron microscopy indicated that GEO caused denaturation of the viral capsid proteins which accounted for anti-pathogen effect of GEO and its enhancement for UV irradiation. Finally, the texture analysis and sensory evaluation suggested that the addition of GEO did not affect the flavor and quality of food tested. This study provides more approach for the inactivation of foodborne pathogenic microorganisms in fruits and vegetables in the food industry.