Evaluating the Physical, Mechanical and Antimicrobial Properties of Isolated Soy Protein Film Incorporated with Peppermint (Mentha piperita) Essential Oil: A Study on Bio-edible Film on Raw hamburger

Bioedible films combined with essential oils have recently attracted much attention due to their advantages as antimicrobial (AM) active coating. This study was aimed to evaluate the Physical-Mechanical properties and antimicrobial activity of Isolated Soy Protein (ISP) film containing peppermint essential oil (PEO) on shelf life and sensory characteristics of raw hamburger. The ISP film incorporated with PEO at ۱, ۲, and ۳% (v/v) were fabricated by solvent casting method. The results represented that the addition of PEO caused a noticeable reduction and an increase (p < ۰.۰۵) in tensile strength and elongation-at-break, accordingly. Increase of Thickness, Water Vapor Permeability (WVP), and reduction in moisture content were observed as the amount of oil increased (p < ۰.۰۵). In addition, lightness/darkness (L*), Whiteness index (WI), and redness/greenness (a*), and yellowness/blueness increased (b*) while the total color difference (ΔE) declined by adding PEO. PEO-incorporated film (at ۳% v/v) exhibited higher inhibitory activity against Staphylococcus aureus, Escherichia coli, and lower for Salmonella enterica using the disc diffusion method. Microbial analysis and pH measurement of raw hamburger coated with ISP-PEO film showed no inhibitory effect against test bacteria when utilized on the raw hamburger, whereas inhibited total bacterial growth exceeded the acceptable limit until the end of refrigerated storage. This film was able to extend the shelf life of hamburgers for up to ۷ days. Therefore, this new antibacterial film has a considerable potential to be applied as a meat packaging material.

Keywords:

Isolated Soy Protein , Bioedible film , Peppermint essential oil , Raw hamburger , Antimicrobial activity