Use of a nanoparticulate carboxymethyl cellulose film containing sinigrin as an antimicrobial precursor to kill Escherichia coli O157:H7 on fresh beef.

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 6×5×2cm(3) (L×W×H) were dipped in an E.coli O157:H7 broth suspension containing >8log10 CFUml(-1) and were drained for 3min 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 18days. 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 5days at 8°C, E.coli O157:H7 was reduced more than 4log10 by the NCMC•pSNG film and this reduction remained almost the same until 18days at 8°C when E.coli O157:H7 was reduced >5log10 CFUg(-1) meat. Transparent nanoparticulate carboxymethyl cellulose (CMC) films containing sinigrin (SNG), an antimicrobial precursor, controlled surface contamination of packaged fresh beef by the pathogen Escherichia coli O157:H7 when stored at 8°C. Films with nanoparticulation that carried pure SNG or the naturally occurring SNG in Oriental mustard were significantly more antimicrobial than similar films without nanoparticulation. As films without sinigrin were not antimicrobial, the combinations studied showed that nanoparticulation of the packaging film enhanced delivery of the antimicrobial incorporated within the film.