Abstract

The effect of incorporating organic acids in whey protein based edible film, and its antimicrobial activity has been studied. Four organic acids namely acetic, lactic, propionic and benzoic acids (5% v/v each) were incorporated in whey protein based edible film, and their antimicrobial activity was tested using Lactobacillusbulgaricus, Streptococcus thermophilus, Eschericia coli and Salmonella sp. There was a highly significant effect (P<0.01) of the organic acid on the inhibition zone of microorganisms, due to water vapor permeability (WVP) and protein solubility. A significant effect (P<0.05) was shown by different organic acids incorporated on the antimicrobial activity of the films. The highest inhibition zone was found at theE. coli tested sample (11.6 mm), whilst the lowest one was found at theSalmonella sp tested sample (9.77 mm). The highest inhibition zone was also found in the films that contained benzoic acid (11.76 mm), and the lowest was found in the film that contained lactic acid (10.44 mm). While the highest WVP value (0.0238 g.mm/m².kPa) was shown by the film that contained propionic acid, the lowest one was shown in the film that contained acetic acid (0.0116 g.mm/m².kPa). With regards to protein solubility, it was found that the film containing propionic acid had the highest value (44.4444%), while that with acetic acid showed the lowest protein solubility (35.5516%).

Key words: Organic acids, whey protein edible film, antimicrobial activity, WVP, protein solubility.