# The Efficacy of Calcium Hypochlorite and Peroxyacetic Acid Treatments in Inactivating Enterohemorrhagic Escherichia coli on Alfalfa Seeds and Sprouts

## TL;DR

This study shows that calcium hypochlorite and peroxyacetic acid can reduce harmful E. coli on alfalfa seeds and sprouts, though effectiveness varies by bacterial strain.

## Contribution

The study evaluates two sanitizers' efficacy against specific EHEC isolates on alfalfa seeds and sprouts, revealing isolate-dependent effectiveness.

## Key findings

- Calcium hypochlorite and peroxyacetic acid reduced EHEC levels on seeds and sprouts to undetectable levels.
- Sprouts from treated seeds had significantly lower EHEC populations compared to untreated seeds.
- E. coli O157:H7 K4492 showed the highest mean population among tested isolates on harvested sprouts.

## Abstract

For several decades, recurring outbreaks of human gastrointestinal infections associated with contaminated sprouts have posed an enduring challenge, highlighting the necessity of controlling the etiological agents on contaminated sprout seeds. This study investigated the efficacy of calcium hypochlorite and peroxyacetic acid treatments in inactivating the cells of four enterohemorrhagic Escherichia coli (EHEC) isolates—viz. E. coli O157:H7 K4492, F4546, and H1730, as well as E. coli O104:H4 BAA-2326—on alfalfa seeds and sprouts. The 2–3 log CFU/g of EHEC cells inoculated to sprout seeds became undetectable (≤1.40 log CFU/g) after treatment with the two sanitizers, even with the enrichment steps. Sprouts grown from calcium hypochlorite- and peroxyacetic acid-treated seeds had mean EHEC populations that were 4.54–4.60 log CFU/g and 1.25–1.52 log CFU/g lower, respectively, compared to those on sprouts grown from the untreated control seeds. Significantly (p ≤ 0.05) different from one another, the mean populations of the four EHEC isolates on harvested sprout samples were in the descending order of E. coli O157:H7 K4492, F4546, H1730, and E. coli O104:H4 BAA-2326. The results suggest that both sanitizing treatments effectively suppressed EHEC growth on alfalfa seeds and sprouts, but their effectiveness was bacterial-isolate-dependent.