Microbial decontamination of alfalfa seeds for sprout production by atmospheric cold plasma

Alfalfa sprouts are rich in phytochemicals, essential enzymes, minerals, and vitamins, making them highly popular among consumers. However, numerous outbreaks of foodborne illnesses have been linked to alfalfa sprouts. Traceback investigations have revealed that contaminated seeds were the source of these pathogens. As a result, there is a growing demand for effective decontamination methods for alfalfa sprout seeds. This study aims to evaluate the effectiveness of atmospheric cold plasma (ACP) in inactivating Shiga toxin-producing E. coli on alfalfa sprout seeds and to assess the potential impact of ACP and bleach treatment on seed germination. Germination studies of alfalfa seeds were conducted for a three-day period. The treatments included chlorine 20,000 ppm and 200 ppm, ACP, ACP combined with chlorine 200 ppm, and RO water as control. For inactivation study, seeds inoculated with a cocktail E. coli O157:H7 culture were treated by the same treatments as in germination study, with untreated inoculated seeds as control. Germination and inactivation data were analyzed using the SAS program’s general linear model to perform variance of analysis and mean comparisons. The results from the germination studies revealed that the treatments had no significant effect on the vitality of alfalfa seeds. For the inactivation studies, there was a synergistic effect in the combined treatment of ACP+200 ppm chlorine, resulting in a significantly (p<0.05) higher pathogen reduction (4.9 log CFU/ml) than ACP and 200 ppm chlorine alone (2.06 and 1.89 log CFU/ml, respectively). Results from this study demonstrated that ACP in combination with chlorine treatment has the potential to be used in the decontamination of alfalfa sprout seeds.