Table 4. Mechanical and antibacterial propertiesof OPP/gelatin bilayer films with different concentrations of oregano or mustard essential oils

Essential oil	Concentration (%)	Tensile strength (MPa)	Elongation at break (%)	Colony count (Log CFU/mL)
Oregano essential oil	0	26.81±0.52^c	158.35±28.84^a	6.48±0.01^a
	10	61.23±5.22^a	60.66±2.63^b	6.31±0.02^b
	20	43.20±2.31^b	37.39±6.32^b	6.17±0.05^c
	30	31.54±2.45^c	30.28±7.08^b	6.14±0.07^c
	40	28.79±3.69^c	29.37±5.08^b	6.05±0.08^c
Mustard essential oil	0	26.81±0.52^b	158.35±28.84^a	6.48±0.01^a
	20	29.81±3.37^b	56.36±12.33^b	6.35±0.03^b
	40	32.12±2.53^b	36.33±6.98^bc	6.29±0.05^b
	60	74.92±8.21^a	32.47±8.85^bc	6.14±0.07^c
	80	38.02±5.10^b	15.85±4.77^c	6.02±0.03^d

Antibacterial properties was done as follow: Bilayer film containing essential oil was placed in the center of the Petri dish containing bacteria. The stronger the inhibition of bacteria, the fewer colonies could grow in the Petri dish.
For each essential oil, lowercase letters in each column represent significant differences (p<0.05).
OPP, oriented polypropylene.