Low temperature extrusion blown ε-polylysine hydrochloride-loaded starch/gelatin edible antimicrobial films

Edible antimicrobial films made from starch/gelatin (S/G) incorporated with different ε-polylysine hydrochloride (ε-PL) contents were developed by low-temperature extrusion blowing process. ε-PL addition reduced the complex viscosity and storage modulus of blends, while promoted the formation of hydrogen bonding among film components. The control film had an A-type crystalline structure, while increasing the ε-PL content promoted its transformation to B-shaped structure. Without ε-PL and under the processing temperature used, the starch granules were not sufficiently gelatinized. However, ε-PL addition significantly enhanced the gelatinization degree. Increasing ε-PL content in S/G films increased film flexibility, water contact angle value, swelling degree, antimicrobial effect, and storage period of fresh bread, but decreased water vapor permeability and tensile strength. S/G film with 4 wt% ε-PL had the highest water contact angle (94°) and elongation at break (149%). This research demonstrates the plasticizing effects of ε-PL and potential of S/G films containing ε-PL for food preservation/packaging.