Cellulose nanofiber (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 packaging solutions for food items supporting Listeria growth. In the present study a protein extract containing the bacteriocin sakacin-A, produced by Lactobacillus sakei Lb 706 in a low-cost culture medium containing deproteinized cheese whey, was adsorbed onto cellulose nanofibers (CNFs) to obtain an active material to be used as a mat (or a separator) in direct contact with foods. The active material was then characterized by infrared spectra and thermogravimetric analyses. Antimicrobial trials were carried out in vitro using Listeria innocua as indicator strain; results were also confirmed in vivo, employing smoked salmon fillets intentionally inoculated with Listeria innocua: its final population was reduced to about 2.5-3 Log cycles after 28 days of storage at 6 °C in presence 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-A absorbed onto CNFs to decrease Listeria population in smoked salmon, a ready-to eat-food product.