Antimicrobial activity of whey protein films supplemented with Lactobacillus sakei cell-free supernatant on fresh beef.

The aim of this work was to evaluate the antimicrobial activity of whey protein isolate (WPI) films supplemented with Lactobacillus sakei NRRL B-1917 cell-free supernatant on beef inoculated with Escherichia coli ATCC 25922 or Listeria monocytogenes Scott A; additionally, sensory evaluation was performed on wrapped beef cubes. Supernatant concentrates were obtained from Lb. sakei cultures in MRS broth after centrifugation, filtering, and freeze-drying. Films were prepared with WPI (3% w/w), alginate (0.625% w/w), rehydrated supernatant (18 mg/ml), and glycerol. Films were used to wrap beef cubes inoculated with ≈10(3) CFU/g E. coli or L. monocytogenes. Sensory evaluation was carried out on grilled beef wrapped or not with the studied antimicrobial films. During refrigerated storage, antimicrobial films reduced 1.4 log10 CFU/g of L. monocytogenes after 120 h, while E. coli decreased 2.3 log10 CFU/g after 36 h. Grilled beef wrapped with antimicrobial film was well accepted by panelists, besides scores evidenced no significant differences (p > 0.05) between wrapped and unwrapped beef.