Effect of Allium parvum and Allium cepa on Bacillus cereus isolated from fermented millet porridge

Bacillus cereus is a common and major food borne pathogen that can generate spores and form biofilms which makes them persistence and virulence at even harsh environments. The present study revealed the incidence of B. cereus in ragi millet porridge and the antibacterial activity of onion (A. parvum and A. cepa) against the B. cereus isolates. Contamination was observed in 87.5% of the samples with range of 2.07 ± 1.89 to 4.33 ± 0.45 mean log10 CFU/ml. Total phenol and flavonoid content of A. parvum was higher 344.66 ± 17.98 mg GAE/g and 136.66 ± 41.55 mg RE/g respectively. The higher antioxidant activity was observed for A. parvum DPPH (54.12%) and FRAP (19.59 mM Fe (II)/mg) when compared to A. cepa. The MIC (500µl) of A. parvum showed significantly the greater inhibition percentage, 3.19 to 23.38% compared to A. cepa which showed 0.67 to 21.42%. Natural antimicrobials, phenols and flavonoids present in the A. parvum and A. cepa helped in restricting the growth of B. cereus isolated from the ragi millet porridge.