Physical-mechanical and antimicrobial properties of konjac glucomannan/ethyl cellulose film incorporated with gallic water extract

Edible antibacterial film was prepared by adding gallnut water extract into konjac glucomannan( KGM) /ethyl cellulose( EC) sol.The tensile strength( TS),elongation at break( EAB),water vapor permeability( WVP),and oxygen barrier properties of composite films were measured.The composite films were used to package fish fillet stored at 4 ℃.The p H,total volatile basic nitrogen( TVB- N),and total numbers of colonies were tested at 0,2,7,10 and 15 day respectively to determine effects of edible antibacterial films on the storage of fish fillet. The results showed that with the increase of gall water extract content in composite film,TS of composite films decreased significantly( p < 0.05),when the contents of gallnut was more than 15%,TS showed no significantly difference.With the content of gallnut water extract content increasing from 0% to 20%,EAB and WVP were significantly increased and decreased( p < 0.05),respectively.Moreover,oxygen barrier properties were enhanced significantly( p < 0.05).KGM / EC films incorporated with 20% gallic water extract were used to fish fillet packaging,the values of p H,TVB- N,and total numbers of colonies of fish fillet had significantly difference,respectively,compared with fish fillet and fish fillet packaged with films without gallnut during storage( p < 0.05). Considering the total numbers of colonies as a reference index,KGM / EC composite film containing 20% gallnut water extract could prolong the shelf life of fish fillet stored at 4 ℃ for 3 days,compared with fish fillet without film packaging. Konjac glucan-mannan- ethyl cellulose antibacterial membrane had a certain application prospect in food preservation.