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

• Main Authors: Khairuddin, Nozieana, Muhamad, Ida Idayu, Wan Abdul Rahman, Wan Aizan, Siddique, Bazlul Mobin
• Format: Article
• Language: English
• Published: IOP Publishing 2019
• Online Access: http://psasir.upm.edu.my/id/eprint/81351/1/Microbial%20study%20of%20pH%20sensitive%20starch%20based%20film%20using%20agar%20diffusion%20method%20%28zone%20inhibition%20assay%29.pdf; http://psasir.upm.edu.my/id/eprint/81351/; https://iopscience.iop.org/article/10.1088/1757-899X/607/1/012007

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% and 22.1 - 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.