Table 5.

Calculated relative spectral values for the packaging treatment effect on the myoglobin forms of ground beef.

Relative Myoglobin Forms 1
	Metmyoglobin (MMb)	Deoxymyoglobin (DMb)	Oxymyoglobin (OMb)
Packaging Treatment 2
T1	24.49 a	29.06 c	46.45 b
T2	21.22 b	31.25 b	47.52 a
T3	20.00 b	32.72 a	47.28 ab
Storage Day 3
0	29.65 U	22.51 Z	47.84 V
7	16.30 W	33.26 VW	50.44 U
14	17.85 W	35.14 U	47.02 V
21	18.68 W	34.15 UV	47.18 V
28	23.00 V	31.81 WX	45.20 W
35	23.97 V	30.63 XY	45.40 W
42	23.90 V	29.58 Y	46.53 VW
p-value (Day) *	<0.0001	<0.0001	<0.0001
p-value (Treatment) **	<0.0001	<0.0001	0.0460
p-value (Day × Treatment) ***	0.2810	0.2284	0.1033
SEM (Day) *	1.036	0.617	0.470
SEM (Treatment) **	0.678	0.404	0.308

¹ Calculated relative spectral values for myoglobin forms: metmyoglobin (MMb), deoxymyoglobin (DMb), and oxymyoglobin (OMb). 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 retail cases following 21 days of frozen storage. ^a–c Mean values within the main effect of treatment for color measurements lacking common superscripts differ (p < 0.05). ^U–Z Mean values within the main effect of day for color measurement lacking common superscripts differ (p < 0.05). p-value *: packaging treatment effect, p-value **: effect of storage day, 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.