Listeria growth restricted by coated film, says study.

By Jane Byrne

01- Aug-2008 –


Source of Article:



Films coated with antimicrobial peptides were shown to inhibit the growth of Listeria innocua in the preservation of sliced ham, claims a Brazil-based research group.

Antimicrobial packaging inhibits or retards microorganism growth in foods, minimizing direct addition of preservatives and satisfying the actual demand of consumers for healthier foods that contain fewer additives, according to the study.

Researchers at the University of Viçosa in Brazil, according to findings published in Food Control, found that cellulose matrix films incorporating a pediocin (ALTA 2351) showed potential as a pathogen inhibitor to enable shelf life extension for ready-to-eat sliced ham.

They said their work was informed by the growing demand for easy-to-consume products, which are increasing the necessity for quality control and food safety, and the fact that there are few studies determining the effect of antimicrobial films over microorganisms that contaminate ham.

The researchers said that pediocins are bacteriocins, which are generally recognized as safe (GRAS).

"Bacteriocins are an attractive option of antimicrobial compounds as they constitute natural preservatives, avoiding the addition of synthetical compounds to food,” claims the study.

Method used

The films, using cellulose acetate, acetone and the pediocin ALTA 2351 provided by the Irish company, Kerry Bioscience, were produced using a casting process, according to the study.

The antimicrobial films were incorporated with pediocin in concentrations of 25 per cent and 50 per cent of cellulose weight in a cellulose base emulsion.

Film thickness and mechanical properties were measured using a micrometer and an Instron universal testing machine respectively.

The antimicrobial efficiency of the films against Listeria innocua and Salmonella sp on sliced ham was tested by means of a challenge test, in which the slices were immersed in 0.1 per cent peptone solution containing about 106 CFU/mL of L. innocua or Salmonella sp

The experiment involved overlapping the slices of ham with the films (control, 25 per cent and 50 per cent of pediocin). These systems were packaged under vacuum and stored at 12 °C. The slices of ham were analyzed for L. innocua and Salmonella sp. counts at intervals of 0 to 15 days of storage.

Positive outcome

The results, according to the study, showed that the antimicrobial films were more effective inhibiting growth of L. innocua.

“The 50 per cent pediocin-film presented a reduction of 2 log cycles in relation to control treatment after 15 days of storage,” reported the researchers.

The 25 per cent and 50 per cent pediocin-films, in relation to inhibition of Salmonella sp. showed 0.5 log cycle reduction in relation to control, after 12 days of storage.

“The films incorporated with pediocin showed potential use as one hurdle technology added in the storage period among other good manufacturing practices for preservation of sliced ham,” added the researchers.


Source: Food Control

Published online ahead of print

"Antimicrobial efficiency of film incorporated with pediocin (ALTA 2351) on preservation of sliced ham"

Authors: P. Santiago-Silva, N. Soares, J. Nobrega, M. Junior, K. Barbosa, A. Carolina, P. Volp, E. Zerdas, N Wurlitzer



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