Utility of UV-C radiation as anti-Salmonella decontamination treatment for desiccated coconut flakes

This study established the ultraviolet-C (UV-C)-mediated reduction of a cocktail of Salmonella enterica serovars, artificially inoculated onto desiccated coconut flakes. Inoculated cells exhibited biphasic inactivation behavior, characterized by an initial, log-linear population reduction, followed by a slower log-linear population decline where sublethal injury accumulated. Decimal reduction times in the faster inactivation phase (Dfast) ranged from 0.65 to 0.82 min, equivalent to UV-C energy dose of 86.58-109.22 mJ/cm2. The Dslow values ranged from 21.19 to 24.21 min, equivalent to energy dose of 2822.51-3224.78 mJ/cm2. A total of 3-log cycles reduction in inoculated Salmonella were observed after 40 min exposure of desiccated coconut to UV-C. Further, this 40-min process resulted in changes in the Hunter L*, a* and b* color parameter values, but were not detected by a test consumer panel as evident in the non-significant difference in the color acceptability of UV-C treated and untreated coconut flakes. The UV-C process also did not affect the general acceptability of baked coconut macaroons made from UV-C treated coconut flakes. The results obtained in this work may serve as baseline information in the development of an in- or post-process integration of a UV-C radiation step against Salmonella spp. in the desiccated coconut production process flow.