Large-scale gaseous acetic acid treatment to disinfect alfalfa seeds inoculated with Escherichia coli.

Most outbreaks of foodborne illness related to sprout consumption are ascribed to bacterial contamination of its seeds, and they need disinfection before sprouting. Recently, gaseous acetic acid (GAA) treatment received great attention as a method for seed disinfection. In this study, the effect of GAA treatment on alfalfa seed disinfection was evaluated in a large-scale device to simulate practical applications. Alfalfa seeds (3 kg) inoculated with Escherichia coli were treated with 8.7% (vol/vol) GAA at 55°C for 1-3 h. The population of E. coli was significantly reduced (p<0.05), and the reduction was larger with longer exposure times. After 3-h treatment, a maximum decrease by more than 5 log colony-forming units/g was observed. The germination ratio of alfalfa seeds was not affected by the treatments under all the conditions. The results indicated that the GAA treatment has a potential for practical application to reduce the risk of foodborne illness caused by consumption of sprouts.