Impact of 280 nm UV-C LEDs on the microbial safety and nutritional quality in tender coconut water

The efficiency and efficacy of 280 nm UV-C LEDs for processing Tender coconut water (TCW) have been investigated. TCW inoculated with E. coli, and L. monocytogenes were irradiated using collimated beam apparatus at a dose of 71 mJ/cm2 and 20.3 mJ/cm2 for ≥ 5 log CFU/mL reduction, resulting in the double Weibull model for E. coli with a 4D value of 61 ± 0.83 mJ/cm2 and the Weibull model with a 4D value of 13 ± 0.2 mJ/cm2 for L. monocytogenes. The irradiated samples were exposed to photoreactivation (365 nm) light for up to 120 min. PR (Photoreactivation) was eventually not observed for E. coli, and L. monocytogenes showed no repair. Scanning Electron Microscope results revealed that, unlike the control sample, 280 nm irradiation results in cell lysis, wrinkle, and distortion. UV treatment did not affect the pH, TA, Brix, total phenolics content, mineral content, and sugars of TCW but increased in a* and b* colour value, and ascorbic acid concentration reduced to 18.2% of its original concentration. Sensory evaluation studies reported that control samples scored high for freshness and pleasantness, and attributes like astringency, fermented and cooked aroma have been scored low. Overall, the quality of UV-treated samples has been preferred by panellists.