Herzallah S, Holley R.

Significance and Impact: When the plant glucosinolate, sinigrin (SNG), was incorporated into a transparent, nanoparticulate, carboxymethyl cellulose (NCMC) film, the viability of E. coli O157:H7 was substantially reduced, suggesting the antimicrobial film may have value in enhancing the microbial safety of intact fresh meats.

Abstract: Nanocomposite carboxymethyl cellulose films containing sinigrin (SNG) were prepared by stirring 2% (w/v) carboxymethyl cellulose (CMC) and 2% (w/v) glycerol (as a plasticizer) in distilled water with or without SNG (an antimicrobial precursor) as a 99% pure reagent (pSNG) or as a crude extract (cSNG). These films plus normal CMC film with or without SNG were tested on Escherichia coli O157:H7- inoculated beef for antimicrobial activity. Beef pieces measuring 6 x 5 x 2 cm³ (L x W x H) were dipped in an E. coli O157:H7 broth suspension containing > 8 log₁₀ CFU.ml^-1 and were drained for 3 min over a sterile cloth. They were wrapped in CMC or NCMC films, placed in a high oxygen barrier film (Deli *1), vacuum-packaged and stored at 8°C for 5, 8, 12 and 18 d. The CMC and NCMC films without SNG were not antimicrobial against E. coli O157:H7; however, NCMC and CMC films with SNG were highly antimicrobial. After 5 d at 8°C, E. coli O157:H7 was reduced more than 4 log₁₀ by the NCMC●pSNG film and this reduction remained almost the same until 18 d at 8°C when E. coli O157:H7 was reduced  > 5 log₁₀ CFU.g^-1 meat.

Keywords: nanocomposite CMC film, sinigrin, antimicrobial film, E. coli O157:H7, fresh beef.