Purpose: The aim of this research was to evaluate the effect of UV-C light on Saccharomyces cerevisiae inactivation in grapefruit and orange juice at two different temperatures.
Methods: Commercial pasteurized grapefruit and orange juices were obtained from a local supermarket of Puebla, Mexico. Juices were inoculated with Saccharomyces cerevisiae (108 CFU/ml) and treated with UV-C light (60 min) at different temperatures (5 and 40°C). First order kinetic reduction was used to calculate the decimal reduction time. Moreover, a sensory evaluation was performed in order to know the acceptability of treated juice.
Results: Maximum microbial reduction obtained in grapefruit juice treated with UV-C light were 1.3 and 1.1 cycles for 5 and 40°C, respectively; while in orange juice were 1.2 and 1.1 cycles for the same temperatures. In grapefruit juice, temperature treatment significantly affect decimal reduction times, showing values of 45.4 ± 2.8 and 59.2 ± 3.0 min for 5 and 40°C, respectively. However, for orange juice there was not significant effect of temperature treatment, showing values of 56.2 ± 0.4 and 57.2 ± 0.9 for 5 and 40°C, respectively. Sensorial attributes indicate that juices treated at short time (10 and 20 min) were preferred by the judges.
Significance: UV-C light treatment is a suitable manner to reduce the microbial load of spoilage microorganisms; although, it is important to combine with others treatments in order to increase the microbial reduction.