Table 1. Changes in Hunter color values of heat-treated (HT) and non-heat-treated (NHT)-PVA/PAA/NR@TOCNF colorimetric indicator films (CIFs) during storage at room temperature (25±2°C)

Sample	Storage period (days)	Hunter color value
Sample	Storage period (days)	L^*1)	a^*2)	b^*3)	ΔE⁴⁾
NHT-PVA/PAA/NR@TOCNF	0	41.95±3.47^5)a6)	39.17±1.72^a	18.09±1.04^a	-
	7	41.79±3.81^a	38.95±1.51^a	17.60±1.72^a	3.94±1.55^bc
	14	41.73±3.32^a	38.66±1.51^a	17.50±1.26^a	3.42±1.51^abc
	21	41.68±1.78^a	38.86±1.77^a	18.72±1.10^a	2.58±0.75^a
	28	41.34±1.96^a	38.29±1.34^a	18.79±1.12^a	2.66±0.84^ab
	35	41.25±3.19^a	38.63±0.92^a	18.85±1.34^a	3.46±0.81^abc
	42	42.40±3.62^a	37.80±1.71^a	18.83±1.19^a	4.06±1.28^c
HT-PVA/PAA/NR@TOCNF	0	37.84±2.08^a	31.74±3.39^a	18.73±2.05^a	-
	7	37.98±2.69^a	31.74±3.39^a	19.29±1.71^a	5.46±1.36^c
	14	37.75±3.31^a	32.36±3.49^a	19.43±1.47^a	4.38±2.11^bc
	21	37.23±0.91^a	32.13±1.95^a	18.19±1.41^a	2.33±1.16^a
	28	37.32±1.40^a	31.22±2.04^a	19.07±1.13^a	2.60±0.65^a
	35	37.50±1.35^a	31.26±2.33^a	18.62±1.61^a	2.78±1.22^a
	42	37.54±1.58^a	30.59±2.52^a	19.22±0.70^a	3.10±0.55^ab

L^*, degree of lightness (+100=white, 0=black).
a^*, degree of redness (+100=red, −80=green).
b^*, degree of yellowness (+70=yellow, −70=blue).
ΔE^*, total color difference ([(L^*_n − L^*₀)² + (a^*_n − a^*₀)² + (b^*_n − b^*₀)²]^1/2).
All values are mean±SD (n=5).
Values with different superscript letters (^a-c) in the same column are significantly different at p<0.05 by Duncan’s multiple range test.