Table 6. Color difference and light transmittance of OPP/gelatin bilayer films with different concentrations of oregano or mustard essential oils at 700 nm

Essential oil	Concentration (%)	CIE L*	CIE a*	CIE b*	Transmittance at 700 nm(%)
Oregano essential oil	0	55.42±0.80^a	2.81±0.27^a	3.36±0.34^c	92.03±1.32^a
	10	53.43±0.53^b	2.31±0.14^b	4.29±0.24^ab	91.27±0.17^a
	20	51.23±0.55^c	1.82±0.22^c	3.94±0.12^b	83.57±0.82^b
	30	51.81±1.15^cd	1.79±0.19^c	3.90±0.50^b	80.53±1.35^c
	40	50.79±0.93^d	2.14±0.16^b	4.56±0.16^a	78.70±1.64^c
Mustard essential oil	0	67.81±0.29^a	11.01±0.39^a	9.76±0.63^d	92.03±1.32^a
	20	63.38±0.86^b	8.70±1.21^b	9.93±0.68^cd	83.63±2.80^b
	40	59.66±1.11^c	8.54±1.03^b	10.67±0.5^bc	79.47±1.32^bc
	60	58.79±1.31^cd	8.13±0.66^b	10.83±0.45^b	75.23±3.77^c
	80	57.2±1.53^d	6.79±0.57^c	13.18±0.38^a	76.97±2.15^c

For each essential oil, lowercase letters in each column represent significant differences (p<0.05).
OPP, oriented polypropylene.