Sprouts, such as broccoli, are a popular and nutritious food source. The microbial contamination of sprouts is often associated with seeds.... Show moreSprouts, such as broccoli, are a popular and nutritious food source. The microbial contamination of sprouts is often associated with seeds. The optimal conditions for germination and growth of seeds are similar to those needed for the proliferation of microorganisms such as Salmonella and Escherichia coli. These conditions, along with the fact that sprouts are usually consumed raw or lightly cooked contribute significantly to the risk of sprouts in causing foodborne illness outbreaks. This study evaluated the effect of temperature on the growth of Salmonella in broccoli sprouts during sprouting and post-harvest storage. The impact of pathogen load and seed treatment were also examined. Five hundred grams of broccoli seeds inoculated with 1 or 5 log CFU/g of Salmonella were treated either with water or 20,000 ppm Ca(OCl)2 for 15 min. Treated seeds were sprouted in glass jars at 4°C for 21 days or 20°C for 7 days. Harvested sprouts were stored at 4, 7, 10 for 21 days or at 25°C for 7 days. Samples were taken for analysis of Salmonella levels by plate count and culture enrichment. For seeds inoculated with a high or low level of Salmonella and treated with water, the pathogen grew and reached ~8 logs during sprouting at 20°C, while it decreased by 3 or 2 logs, respectively, during 21 days of sprouting at 4°C. For sprouts grown at 20°C, Salmonella population did not change during postharvest storage regardless of storage temperature. For sprouts grown at 4°C, no Salmonella proliferation was observed when the harvested sprouts were stored at 4, 7, or 10°C. But during storage at 25°C, the pathogen increased by 4 or 2 logs in sprouts grown from seeds inoculated at the high or low level, respectively. Seed treatment with 20,000 ppm Ca(OCl)2 reduced Salmonella on seeds by less than 1 log CFU/g. Salmonella growth during sprouting and storage of sprouts grown from Ca(OCl)2 treated seeds followed the same trend as that observed in sprouts grown from seeds treated with water. Sprouting at low temperatures inhibited pathogen proliferation. It was concluded that maintaining the cold chain (at below 10°C) during storage of sprouts is critical to prevent pathogen regrowth. Show less
