The Oxidative and Color Stability of Beef from Steers Fed Pasture or Concentrate during Retail Display

Abstract

Beef production in Uruguay is based on pasture (~85%) or concentrate (~15%), resulting in differences in meat quality. The objective of this study was to compare the oxidative stability and color of beef from these two systems during refrigerated retail display. For these purposes, the Semimembranosus muscle was removed from ten Aberdeen Angus steers raised and fed on pasture (130 days prior to slaughter) and from another ten steers fed concentrate (100 days prior to slaughter), sliced. The muscles were placed in a refrigerated showcase for 3, 6, and 9 days. The contents of β-carotene, α-tocopherol, and fatty acids were determined before the meat was placed on display. Lipid and protein oxidation, color, and heme iron content were determined before and during display. The meat from pasture-fed steers had a lower intramuscular fat content (1.78 ± 0.15 vs. 4.52 ± 0.46), lower levels of monounsaturated fatty acids, a lower n-6/n-3 ratio, less lipid and protein oxidation, lower L* and a* values, and higher levels of α-linolenic acid, DHA, total n-3, β-carotene, and α-tocopherol. In conclusion, the meat from pasture-fed steers was more stable during retail display from an oxidative point of view, which may be due to its higher levels of antioxidant compounds such as β-carotene and α-tocopherol and had a healthier fatty acid profile for consumers.

Keywords: beef; concentrate; fatty acid; heme iron; lipid oxidation; pasture; protein oxidation; α-tocopherol; β-carotene.

Figure 1

Lipid oxidation (a) and protein oxidation (b) before and during retail display in Semimembranosus muscles from Aberdeen Angus steers fed pasture or concentrate. Values are means ± SEM (n = 10). Different capital letters show significant differences between feeding systems on each day of the display (p < 0.05). Different lowercase letters show significant differences between days of display in each feeding system (p < 0.05).

Figure 2

α-tocopherol and β-carotene contents (μg/g fresh meat) in Semimembranosus muscles from pasture- or concentrate-fed Aberdeen Angus steers prior to being placed in a retail display. Values are means ± SEM (n = 6). Significant differences between feeding systems are indicated as * (p < 0.05) or ** (p < 0.0001).

Figure 3

Color parameters, (a) L* value, (b) a* value, and (c) b* value, before and during retail display in Semimembranosus muscle of pasture- or concentrate-fed Aberdeen Angus steers. Values are means ± SEM (n = 10). Different capital letters show significant differences between feeding systems on each day of the display (p < 0.05). Different lowercase letters show significant differences between days of display in each feeding system (p < 0.05). NS: not significant.

Figure 4

(a) Hue angle (°) and (b) chroma values before and during retail display in Semimembranosus muscle of pasture- or concentrate-fed Aberdeen Angus steers. Values are means ± SEM (n = 10). Different capital letters show significant differences between feeding systems on each day of the display (p < 0.05). Different lowercase letters show significant differences between days of display in each feeding system (p < 0.05). NS: not significant.

Figure 5

Heme iron content (ppm) in Semimembranosus muscle from pasture- or concentrate-fed Aberdeen Angus steers before and during the retail display. Values are means ± SEM (n = 6).