Microbial study of pH sensitive starch based film using agar diffusion method(zone inhibition assay)

摘要

Active and smart packaging is a promising form of food packaging that offers a great economical potential due to consumer demand for a packaging that accommodate a hectic way of life.An antimicrobial film with pH colour indicator(pHF)can be made by incorporating suitable antimicrobial(AM)agent and colour indicator into food package matrices whilst applying a bio switch concept to inhibit the pathogenic microorganisms and respond automatically to changes(external stimuli)in the environment.The present work aimed to study the developed formulation of hydroxyethylcellulose(HEC)/wheat-starch based pHF film in which the active compound,thymol(0.5,1,1.5,2,and 2.5% w/w)and 50:50% w/w bromothymol blue and methyl red(as the colour indicator)against microbial growth.A solution casting method was used in the film preparation while thymol and colourant were incorporated prior to casting.The effect of thymol showed a range of microbial inhibition zones of 16.3 -26.4% and22.1 - 39.9% towards E.coli and B.subtilis,respectively.Whilst,a lower inhibition zone of 0.4 - 5.1% was demonstrated for fungus A.niger.