The use of medicinal plants as natural antimicrobial agents is gaining popularity. Sorrel (Hibiscus sabdariffa) is widely used for the treatment of diseases. The objective of this study was to investigate the antimicrobial activity of sorrel on Escherichia coli O157:H7 isolates from food, veterinary, and clinical samples. Phenolics of the calyces were extracted from 10 g of ground, freeze-dried samples using 100 mL of 80% aqueous methanol. Concentrations of 10%, 5%, and 2.5% methanol extract of sorrel were investigated for its antimicrobial activity. Inhibition zones were indicated by a lack of microbial growth due to inhibitory concentrations of sorrel diffused into semisolid culture medium beneath the sorrelimpregnated disk. The results of this experiment showed that the most potent sorrel concentration was 10%, then 5%, and finally 2.5%. The overall mean zone of inhibition for the sorrel extract was 12.66 mm for 10%, 10.75 mm for 5%, and 8.9 mm for 2.5%. The highest inhibition zones (11.16 mm) were observed in veterinary samples, and the lowest (10.57 mm) in the food samples. There were significant (P < .05) differences among mean zones of inhibition found in the food, veterinary, and clinical sources. Based on the source of samples and concentration of sorrel extract, the lowest mean inhibition was 7.00 -0.04 mm from clinical samples, and the highest was 15.37 -0.61 mm from a food source. These findings indicated that sorrel was effective at all levels in inhibiting E. coli O157:H7; thus it possesses antimicrobial activity and hold great promise as an antimicrobial agent.

No abstract

The efficacy of three sanitizers (10 mL/L peracetic acid, 10 mL/L hydrogen peroxide and 20 mL/L commercial GRAS disinfectant) for inactivating Salmonella spp. inoculated onto the surface of whole tomatoes stored up to 8 days was investigated when they were used alone or in combination with pulsed ultraviolet light (PUV). Ten mL/L peracetic acid alone resulted in an average 3 log 10 reductions throughout the 8-day storage. Ten mL/L hydrogen peroxide and 20 mL/L commercial biodegradable GRAS sanitizer alone yielded 1.41 and 1.29 log 10 reductions, respectively, on day 0, but from day 2 to day 8 of storage, their disinfecting effect dwindled, with no significant difference detected from control (water rinse) on day 8 (p ≤ 0.05). The 60s PUV treatments alone achieved less than 2 log 10 reductions, but when it was combined with 10 mL/L hydrogen peroxide, the bacterial reduction significantly increased to over 4 log 10 during the 8-day storage (p ≤ 0.05). Similarly, PUV also enabled 20 mL/L commercial GRAS sanitizer to have unchanged bactericidal effect throughout the 8-day storage period. Results from this study showed that sanitizers combined with PUV radiation could generate a significant and lasting inactivation of Salmonella spp. on the surface of tomatoes.

No abstract

No abstract