Effects of virgin olive oil and grape seed oil on physicochemical and antimicrobial properties of pectin-gelatin blend emulsified films Mehran Dolat Khah a, Babak

The active emulsified blend films based on gelatin-pectin (5% w/w) containing virgin olive oil (VOO) (0.1-0.3 g/g biopolymer) and grape seed oil (GSO) (0.1-0.3 g/g biopolymer) were prepared by casting method. GSO showed slightly more decreasing effect than VOO on ultimate tensile strength (UTS) and strain at break (SAB) of blend films however; VOO had more reducing effect than GSO on the water vapor permeability (WVP). The scanning electron microscopy (SEM) images showed that incorporating 0.3 g GSO and VOO oils had not considerable effect on the morphology of the emulsified films. Atomic force microscopy (AFM) topography images indicated that adding of oils considerably could increase roughness of emulsified film. Fourier transforms infrared (FTIR) revealed that no new chemical bond formed by adding oils into biopolymermatrix. The minimum inhibitory concentration (MIC) of VOO, GSO and Savory essential oil (SEO) against four important spoilage bacteria showed that GSO had higher antibacterial effect than VOO however; both showed very lower antimicrobial effect than SEO. All active films showed lower inhibitory zone for S. aureus than S. typhimurium and P. fluorescence. The chicken breast fillets wrapped in the films containing VOO-GSO-SEO (0.15-0.15-0.02 g/g polymer) showed considerably lower total viable count (TVC), Pseudomonas spp., Enterobacteriaceae, E. coli 157:H7 and S. typhimurium count than the control one during 12 days storage. Also, it caused significant decrease in peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and total volatile basic nitrogen (TVB-N) of fillet samples. (C) 2021 Published by Elsevier B.V.

Automated summary

Active emulsified blend films based on gelatin-pectin can extend the shelf life of food and reduce bacterial and microbial levels. Different types of oils have varying effects on the mechanical properties and antibacterial effects of the films, with savory essential oil showing the highest antibacterial effect.