Effect of casein hydrolysates on the survival of protective cultures of Lactococcus lactis and Lactobacillus sakei in PVOH films

The aim of this work has been to explore the potential of blending polyvinyl alcohol (PVOH) with casein hydrolysates (HCas) to obtain self-standing films capable to act as carriers of lactic acid bacteria (LAB) as biocontrol agents against food pathogens. For this purpose, PVOH was blended with HCas at different weight ratios and the blends were incorporated with Lactococcus lactis and Lactobacillus sakei. Blending HCas with PVOH resulted in the modification of some functional properties of the films whereas bacteria did not change them. Moreover, incorporation of HCas resulted in an increase in cell viability after film casting and in long-term film storage, and also in film antilisterial properties. These results could be related to the capacity of bacterial autoaggregation in the films during the drying process when HCas was added, as observed by fluorescence light microscopy. Blends could be used in the active packaging of foods.