Effect of Pulsed Ultraviolet Light on Natural Microbial Load and Antioxidant Properties of Fresh Blueberries

Abstract

Blueberries have been drawn more attention in recent years for their antioxidant capacities and proposed health benefits. Pulsed ultraviolet (PUV) light is known for its disinfection effects on the surface of fresh fruits. This study’s aim was to examine the effects of PUV light on naturally present microbial load, antioxidant capacity, and antioxidant enzyme activity of fresh blueberries. Fresh blueberry samples were treated for 30, 60, 90, and 120 s. Samples were stabilized at 13 cm away from the PUV lamp before treatment. Total Aerobic Plate Count (TAPC) and yeast and mold count reduction were observed the highest in samples treated for 90 s, 1.97 and 1.27 log CFU/g, respectively. Antioxidant capacity levels were significantly different for treated samples for 60 and 90 s in FRAP analysis, whereas no differences were observed in results of DPPH analysis. Superoxide dismutase (SOD) activity as antioxidant enzyme had no difference, however, glutathione peroxidase (GPx) increased by 50% with PUV treatment for 120 s. PUV light treatment of fresh blueberries for 90 s was determined as ideal exposure time among tested time intervals of this study. PUV light illumination can generally enhance antioxidant capacity and antioxidant enzyme activity of fresh blueberries and decrease the population of natural microorganisms of fresh blueberries and similar small fruits.