Modeling Inactivation of Candida inconspicua Isolated from Turnip Juice using Pulsed UV Light

Abstract

Turnip juice (Shalgam) is a traditional Turkish beverage with sour flavor and purplish red color, which is produced by the lactic acid fermentation of black carrot. Due to its rich antioxidant content, Turnip juice offers some health benefits. However, the preservation of Turnip juice is a main challenge for the producers. While the growth of bacteria is supressed by lactic acid, wild yeasts can readily grow in Turnip juice. In this study, the effect of pulsed UV light (PUV) on Candida inconspicua in Turnip juice was evaluated. Inoculated Turnip juice samples were treated in a pulsed UV light system at different distances from the quartz window (5, 8 and 13 cm) and for different times (5, 15, 30, 45 and 60 s). A maximum log reduction of 2.80 was obtained after treatment at 5 cm for 60 s. To describe the inactivation of C. inconspicua by pulsed UV light, the first-order kinetics and Weibull model were used. Weibull model was found to be suitable for fitting the inactivation data. Practical ApplicationsTurnip juice (Shalgam) is a traditional fermented beverage produced from black carrots, which is a suitable growth medium for yeasts. The wild yeast Candida inconspicua was identified as a microorganism causing spoilage in Shalgam. The only methods utilized in industry to preserve shalgam are heat pasteurization and addition of chemical food additives. Due to the fact that thermal methods can cause the loss of anthocynanins and colorants, a nonthermal method could be a good alternative to preserve Shalgam. In this research, the effect of pulsed UV light, a novel method considered to be nonthermal for short treatment times, on the yeast C. inconspicua which was isolated from Shalgam was investigated. The results were supported with models to understand the effect of pulsed UV light on C. inconspicua cells for future applications in food industry and to direct other related inactivation studies.