Inactivation of Escherichia coli O157:H7 by cinnamon extracts in carrot-kinnow mandarin blends

摘要

We investigated the antimicrobial efficacy of cinnamon extracts in laboratory prepared Kinnow-mandarin carrot blends challenged with Escerichia coli O157:H7. Freshly squeezed carrot and kinnow-mandarin juices were mixed to obtain a typical blend, inoculated with E. coli O157:H7 cultures at 10² CFU/mL with and without cinnamon extracts (0.3%) and stored at 4, 8 and 28°C for up to 10 hours. Counts on tryptic soy agar (TSA) selective medium (Mac conkey sorbitol agar) and thin agar layer (TAL) were determined at every 2 hour. The TAL method was used for recovery of sublethally injured cells. Inactivation of E. coli O157:H7 in blends containing 0.3% cinnamon extracts were observed, with killing effects being more pronounced at 28°C, similar trends were evident with blends stored under refrigeration conditions (4 and 8°C).The decrease in counts were attributed to several factors namely, pH, storage temperature and addition of cinnamon. The results of our study indicate that cinnamon extracts could be used as an effective, natural antimicrobial for assuring consumer safety at the point of preparation of carrot-kinnow mandarin blends, which is a popular, nutritional beverage consumed in India.