Effect of Trichrome Removal and UV-C on Populations of E. coli O157:H7 and Quality of Peach Fruit
2020
Yan, Ruixiang | Gurtler, Joshua | Mattheis, J. P. (James P.) | Fan, Xuetong
The objective of the study was to evaluate the effect of trichome (fuzz) removal on the efficacy of UV-C in inactivating E. coli O157:H7 on peach fruit, and quality of peach fruit as affected by fuzz removal and UV-C. Peach (cultivar PF25) fruit, with and without fuzz removal, were inoculated with a 5-strain cocktail of E. coli O157:H7 and treated with UV-C at doses of 0, 221 and 442 mJ/cm2. Fuzz was rubbed off using damped cloths. Survival of E. coli populations were determined at day 1, 4 and 7 at 20°C. To study fruit quality, non-inoculated fruit with and without fuzz removal were treated with UV-C at the same doses. Results demonstrated that UV-C at 442 mJ/cm2 reduced the population of E. coli by 1.2-1.4 log CFU/fruit on peach with fuzz, and 0.9-1.1 log CFU/fruit on fruit without fuzz 1 day after UV-C treatment. However, E. coli populations of all samples were similar with additional storage time, resulting in no significant difference among the treatments after 7 days of storage at 20°C. UV-C at doses up to 442 mJ/cm2 did not have any significant effect on the surface color of peaches during 7 day storage, although fruit with fuzz removal increased L*, hue and chroma values. In addition, fuzz removal promoted the loss of firmness during storage. Furthermore, UV-C at 442 mJ/cm2 increased antioxidant capacity of peach skin with fuzz. Overall, our results suggested that fuzz removal had marginal effects on the efficacy of UV-C, and UV-C did not negatively affect the quality of peaches.
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