Biological activity of biopolymer edible furcellaran-chitosan coatings enhanced with bioactive peptides

Abstract

The aim of the study was to develop novel antimicrobial coatings which could be used for extending the microbiological quality of perishable food products. Seven different antimicrobial peptides (Lfcinβ, PLGG, MBP-1, LL-37, Cys-LL-37, RW4 and melittin) have been investigated as possible agents for implementation into the previously developed chitosan/furcellaran (CHIT/FUR) coatings. The study included several steps of microbiological analysis, starting with minimum inhibitory concentration (MIC) analysis of crude peptide solutions (concentration from 0.78 to 100 μg/mL) against selected pathogens. The analysis showed that only RW4 and melittin proved effective against all studied pathogens in the investigated doses, except for Aspergillus flavus. The second examination included in-vitro analysis regarding antimicrobial activity of developed coatings with peptides at a concentration of 5 μg/mL, against chosen pathogens. This analysis allowed to indicate a complementary effect of antimicrobial activity between all peptides and the CHIT/FUR complex since the coatings inhibited the growth of the tested pathogens. Afterwards, the coatings were used to coat smoked pork ham slices stored for 10 days and analysed for the increase in total viable counts (TVC). The analysis demonstrated a high efficiency of the CHIT/FUR complex, even without the addition of peptides. Only RW4 and LL-37 did not cause a decrease in antimicrobial power of the control coating. Therefore, in the final trial, the effect of different doses (1.25–10 μg/mL) of RW4 and LL-37 peptides on the TVC of cold-stored coated pork loins. The coatings almost completely inhibited the increase of TVC in the pork loins and the peptides were effective at all studied doses. The newly-developed coatings had strong antimicrobial properties and can be used to extend the shelf-life of perishable food products.