Functionalized polycaprolactam as an active food package for antibiofilm activity and extended shelf life

Papain is covalently crosslinked on polycaprolactam and tested as a wrapper for packaging cottage cheese, against E. coli biofilm. The bacterial count on neat polycaprolactam (NP) was 50 × 106/ml on the 5th day which dramatically increased to 300 × 106 colony forming units (CFU)/ml by the end of 30th day. The corresponding CFU/ml on papain functionalized polycaprolactam (FP) was 10 × 102 on 5th day and 20 × 102 by the end of 30th day. Fourier transform infrared spectroscopic (FTIR) analysis of biofilm on NP showed the presence of polysaccharide, protein, lipid and metabolites which was three times reduced on FP. FT Raman spectroscopy showed the effect of papain on functional groups such as hydroxyl, amino, carbonyl, phosphoryl and aliphatic, leading to the inhibition of the biofilm. Motility, hydrophobicity and zeta potential of E. coli on NP and FP were 10.67 and 5.65 μm/s/V/cm; 88 and 20%; 8.93 ± 2.09 and 2.65 ± 0.52 mV respectively, thereby decreasing the biofilm forming ability of E. coli.