Effect of sorghum bran addition on lipid oxidation and sensory properties of ground beef patties differing in fat levels

Abstract

Oxidation of lipids influences the color and sensory qualities of meat products. Meat with a high fat content, such as ground meat, is susceptible to lipid oxidation that leads to the development of negative flavor and color changes. Antioxidants, such as butylated hydroxanisole (BHA), butylated hydroxytolune (BHT) and extracts of rosemary, are used in meat products to control the effects of lipid oxidation. Awika (2000, 2003) found that sorghum bran phytochemicals have high antioxidant properties. Our objective is to evaluate the pH, color, sensory and antioxidant effect of 10, 20 and 30% ground beef patties containing rosemary, BHA/BHT, and three levels of sorghum bran during 5 d of aerobic storage at 4°C. Beef trimmings containing either 50% or 90% lean were formulated into three meat blocks containing either 10, 20 or 30% lipid. Within a fat content, ground beef was equally divided into one of six treatments: 1) control-no added ingredients; 2) BHA and BHT at .01% of the meat weight; 3) rosemary at 0.2% of the meat weight; 4) high level of sorghum at 1.0% of the meat weight; 5) medium level of sorghum at 0.5% of the meat weight; and, 6) a low level of sorghum at 0.25% of the meat weight. The ground beef was aerobically packaged and stored for 0, 1, 3, or 5 days at 4°C. pH, thiobarbituric acid reactive substances (TBARS), fatty acid methyl esters (FAME), sensory color, Minolta color space values and descriptive sensory evaluations were determined. Antioxidant addition reduced TBARS values and increased hardness (P<0.020) and springiness (P=0.002) over time compared to controls. The addition of the high sorghum bran level resulted in lower raw color scores (2.0 vs. 2.9) (P<0.0001) and slightly increased bitter basic taste (2.47 vs. 2.65) (P=0.0069) when compared to control patties. The high sorghum level slightly increased pH (6.33 vs. 6.41) (P<0.0001) and resulted in darker (P<0.0001) and less yellow colored (P<0.0001) patties. With storage, patties had higher pH (P<0.0001) and color space values decreased (P<0.0001). Sensory properties of the patties differed across fat levels (P<0.05); however, interactions between fat level and antioxidant treatment were not significant (P>0.05). Moreover, the addition of sorghum bran at low levels can retard oxidative rancidity in ground beef patties without causing detrimental color changes and negatively affecting sensory attributes.