Short-wave ultraviolet-C light effect on pitaya (Stenocereus griseus) juice inoculated with Zygosaccharomyces bailii

Abstract

Fresh pitaya (Stenocereus griseus) juice was inoculated with Zygosaccharomyces bailii to be processed using a continuous ultraviolet-C light (UV-C) (57μW/cm2) system. Inoculated and uninoculated juices were processed at selected flow rates (16.49, 23.78, and 30.33mL/s) and treatment times (5, 10, 15, 20, 25, and 30min). Untreated, inoculated, and uninoculated pitaya juices were stored at 4°C during 25days. Microbiological (yeasts plus molds and total counts) and physicochemical (pH, total soluble solids, color, phenolic compounds, betalains, and antioxidant activity) characteristics were evaluated in fresh and processed juices. The net change in color increased as treatment time increased, reaching a maximum value of 3.9. A substantial reduction of phenolic compounds (11.6%), betalains (14.6%), and antioxidant activity (37.0%) were observed in juice treated at 30.33mL/s during 30min. A reduction of 1.8log cycles of Z. bailii was observed at the highest UV-C light treatment.