Investigating the mechanical, physical and antimicrobial properties of gelatin films containing Cinnamomum verum hydrosol

Hydrosol is a side product of essential oil extraction from plants. In this study, the effect of various ratios (5-100 %v/v) of cinnamon hydrosol replacement in the formulation of edible gelatin films was investigated. Physical properties were evaluated and the antibacterial properties of gelatin films against Staphylococcus aureus, Staphylococcus saprophyticus and Staphylococcus epidermidis were assessed. Evaluation of chemical component of cinnamon hydrosol was performed by GC - Mass chromatography. After production control film, modified gelatin films were made by replacement different ratios of cinnamon hydrosol (5, 30, 50, 80 and 100 %v/v) instead of the water in gelatin film formulation. Physical and mechanical properties of resulted films such as water vapor permeability, film thickness, transparency, light transmittance were evaluated. FTIR and SEM were also carried out. Antimicrobial characteristic of gelatin films were evaluated against Staphylococcus aureus, Staphylococcus saprophyticus and Staphylococcus epidermidis by measuring inhibition zone diameter. Results showed that the use of cinnamon hydrosol increased barrier property of gelatin films. Tensile strength increased by adding hydrosol in the edible film formulation (from 15.3 ± 1.5 MPa in control sample to 32.3 ± 3.3 MPa in gelatin film incorporated with 100% cinnamon hydrosol), but the elongation of the films, decreased (from 175 ± 5.5% in control sample to 92 ± 3% in gelatin film incorporated with 100% cinnamon hydrosol). Furthermore, addition of various hydrosol ratios significantly decreased the WVP values (p ≤ 0.01).  Staphylococcus aureus was most sensitive to gelatin films incorporated with cinnamon hydrosol and its inhibition zone at 100% hydrosol was 33 mm.