Cellulose nano-fibers (CNF) - Sakacin-A active material: production, characterization and application in storage trials of smoked salmon

BACKGROUND: Sakacin-A due to its specific antimicrobial activity may represent a good candidate to develop active packagingsolutions for food items supportingListeriagrowth. In the present study a protein extract containing the bacteriocin sakacin-A,produced byLactobacillus sakeiLb 706 in a low-cost culture medium containing deproteinized cheese whey, was adsorbed ontocellulose nanofibers (CNFs) to obtain an active material to be used as a mat (or a separator) in direct contact with foods.RESULTS: The applied fermentation conditions allowed 4.51g L−1of freeze-dried protein extract to be obtained, characterizedby an antimicrobial activity of near 16 700 AU g−1, that was used for the preparation of the active material by casting. The activematerial was then characterized by infrared spectra and thermogravimetric analyses. Antimicrobial trials were carried outinvitrousingListeriainnocuaasindicatorstrain;resultswerealsoconfirmedinvivo,employingsmokedsalmonfilletsintentionallyinoculated withListeria innocua: its final population was reduced to about 2.5 – 3 Log cycles after 28 days of storage at 6∘Cinpresence of sakacin-A, compared with negative control mats produced without the bacteriocin extract.CONCLUSION: This study demonstrates the possibility of producing an antimicrobial active material containing sakacin-Aabsorbed onto CNFs to decreaseListeriapopulation in smoked salmon, a ready-to eat-food product.