Effect of UV-C radiation on quality of minimally processed spinach leaves

BACKGROUND: The fresh-cut vegetable industry commonly uses sodium hypochlorite (NaOCl) for disinfection. However, certain problems with NaOCl usage have led to the investigation of alternative sanitisation treatments. In this respect, UV-C radiation could be of interest. RESULTS: The effect of four pre-packaging UV-C radiation doses (0, 4.54, 7.94 and 11.35 kJ m(-2)) and two storage temperatures (5 and 8 degrees C)on the quality of minimally processed spinach (Spinacia oleracea L.) leaves was studied over a period of 13 days. UV-C radiation decreased mesophilic and psychrophilic counts just after its application compared with conventional sanitisation washing (150 mg L-1 NaOCl). However, UV-C had no residual effect on microbial growth from 6 to 13 days at 5 and 8 degrees C. During shelf-life a slight loss of lightness was found, probably related to superficial tissue damage induced particularly in higher-UV-C treated leaves. Total antioxidant activity and polyphenol content decreased gradually throughout storage, being more evident in higher-UV-C treated leaves stored at 8 degrees C. The general trend was to maintain the initial chlorophyll content during shelf-life. CONCLUSION: Low to moderate UV-C radiation can be an effective alternative to chlorine for sanitising minimally processed spinach leaves and preserving their quality. (C) 2008 Society of Chemical Industry