EFFECT OF UV-C LIGHT ON THE INACTIVATION OF ZYGOSACCHAROMYCES ROUXII IN APPLE JUICE: EVALUATION OF PHENOLIC AND ANTIOXIDANT CONTENTS

Improved quality and safety can be achieved by UV-C light which is a non-thermal method for fruit juices. Zygosaccharomyces rouxii causes spoilage problems in sugar foods, fruit juices and concentrates. In this research, the effect of UV-C light in different doses (4, 8, 12 J/cm2) was investigated for inactivation of Z.rouxii in apple juice and also some quality properties were evaluated such as color, total phenolic and antioxidant contents. As a result, applying 4 J/cm2 irradiation gave the highest phenolic and antioxidant contents as 229.89±2.19 (mgGAE. mL-1) and 0.032±0.05 (EC50, µg/mL) respectively. Color values significantly affected from the increase in doses of irradiation (P<0.05), The reduction UV-C exposure in Zygosaccharomyces rouxii was achieved as 1.45 log CFU ml-1 for 4 J/cm2 ; 2.09 log CFU ml-1 for 8 J/cm2 and lastly, 1.94 CFU/ml for 12 J/cm2 treatment. These findings indicate that low doses of UV-C irradiation can effectively inactivate organisms while preserving quality characteristics of apple juice.