Effects of TiO₂-UVC photocatalysis and thermal pasteurisation on microbial inactivation and quality characteristics of the Korean rice-and-malt drink sikhye

Sikhye is a popular Korean rice-and-malt drink. This drink is prepared using a specific traditional process and has short shelf life. Commercial processing using ultra-high temperature affects characteristic colour and flavour attributes and disturbs the traditional method of sikhye preparation. The objective of this study was to compare the effect of TiO₂-UVC photocatalysis (TUVP) nonthermal processing with heat-pasteurised and untreated sikhye samples during storage at 4 and 10 °C. TUVP and heat treatments were both sufficient to inhibit regrowth of total aerobic bacteria and coliform during storage. Hunter colour parameter values showed that the colour of sikhye was less affected by TUVP treatment compared to the heat treatment. Higher sensory scores for flavour, taste and overall preference were attained for low-dosage TUVP-treated (0.24 J cm^-2) samples than for heat-treated samples but without a significant difference. TUVP treatment effectively controlled the microbial growth during storage at 4 °C for more than 18 days which was reported a serious microbiological safety issue. In summary, TUVP showed its suitability for commercialisation possibilities of fresh sikhye drink by inactivating the main micro-organisms and thus increasing significantly its shelf life with minimum impact on quality characteristics.