Table 4.

Impact of packaging film on the calculated relative spectral values of ground beef.

	Calculated Relative Spectral Parameters 1
	Hue Angle (°)	Red-to-Brown (RTB)
Packaging Treatment 2
T1	33.61 a	2.59 b
T2	31.07 b	2.83 a
T3	30.19 b	2.91 a
Storage Day 3
0	33.90 W	2.80 Y
7	29.38 Z	3.13 W
14	29.61 Z	3.01 WX
21	30.67 YZ	2.88 XY
28	31.75 XY	2.59 Z
35	32.6 WX	2.52 Z
42	33.90 W	2.49 Z
p-value (Day) *	<0.0001	<0.0001
p-value (Treatment) **	<0.0001	<0.0001
p-value (Day × Treatment) ***	0.3306	0.4393
SEM (Day) *	0.658	0.069
SEM (Treatment) **	0.431	0.045

¹ Calculated relative spectral parameter refers to hue angle (°), representing the change in color from the true red axis (a larger number indicates a greater shift from red to yellow); RTB is the reflectance ratio of 630 nm ÷ 580 nm and represents a change in the color from red to brown (a larger value indicates a redder color). ² TRT: packaging treatments are defined as follows—T1 (150 µ polyethylene/EVOH/polyethylene coextrusion), T2 (175 µ polyethylene /EVOH/ polyethylene coextrusion), and T3 (200 µ polyethylene /EVOH/ /polyethylene coextrusion). ³ Storage day refers to 42 days of refrigerated storage with constant light exposure in the retail cases following 21 days of frozen storage. ^a,b Mean values within the main effect of treatment for color measurements lacking common superscripts differ (p < 0.05). ^W–Z Mean values within the main effect of day for color measurement lacking common superscripts differ (p < 0.05). p-value *: packaging treatment main effect, p-value **: effect of storage day main effect, and p-value ***: packaging treatment × storage day interaction. SEM *: standard error of the mean for packaging treatment, SEM **: standard error of the mean for storage day.