Citric acid performance as alternative to sodium hypochlorite for washing and disinfection of experimentally-infected spinach leaves

Abstract

This research aims to investigate citric acid (CA) 0.5% as alternative to sodium hypochlorite (SH) 200 ppm for washing and disinfecting spinach leaves (Spinacia oleracea L.). The initial disinfection achieved in leaves spot-inoculated with Escherichia coli and Listeria innocua, pathogen surrogates, was investigated along with the effects of time and temperature conditions before processing on the performance of CA and SH. Next, the effectiveness of CA and SH was evaluated throughout refrigerated storage (6.5ºC, 9 days) at a low and high contamination load, 5-6 and 8-9 log CFU.g-1, respectively. And lastly, sensory impact was assessed through a trained panel and instrumental color. Results indicated that there were not significant differences between the initial disinfection achieved by CA and SH. Storing infected spinach under refrigeration, between harvest and processing, played a key role not only in reducing their deterioration but also in assuring their safety by maintaining CA and SH effectiveness against the inoculated surrogates. Citric acid performance was better in controlling surrogates´ regrowth along refrigerated storage. And there were not significant differences between CA and SH treated samples with respect to their sensory quality. Therefore, CA could constitute an alternative washing and disinfection method for spinach leaves.