Sorghum Bran as an Antioxidant in Frozen Meat and Poultry Products


Executive Summary

In phase one, high tannin and onyx sorghum bran at 0.125 percent, 0.25 percent, 0.50 percent and 0.75 percent was added to cooked pork crumbles and cooked chicken dark meat patties. The other treatments included a control (no added ingredients), rosemary (the most common natural antioxidant), and BHA/BHT (the most common antioxidant). These treatments were added to determine if high tannin or onyx sorghum bran could be added to control lipid oxidation, the most common reaction in meat and poultry products that causes flavor deterioration. The products were stored in conditions that have been shown to result in high levels of lipid oxidation (aerobic storage under lights at refrigerated temperatures). The effect on flavor, cook yield, color and pH also was examined. These attributes were evaluated to determine if high tannin and onyx addition changed any of these attributes. Ideally, the addition of any antioxidant ingredient should not affect flavor, color, pH or cook yield. Lipid oxidation occurred at a high level in control pre-cooked pork crumbles and chicken patties. The addition of these sorghum brans at levels of 0.50 percent and 0.75 percent had minimal effect on flavor, color, pH or cook yield in these products; however, slight changes in color and flavor were reported at the higher level of addition. Lipid oxidation was similar in products containing BHA/BHT, and 0.50 and 0.75 percent high tannin and onyx sorghum brands. The other treatments were intermediate for TBARS values, the measurement of lipid oxidation. These results indicate that high tannin and onyx sorghum bran addition did not negatively impact flavor and quality of pre-cooked pork crumbles and chicken patties.

For phase two, control (no added antioxidants), rosemary addition and 0.50 percent high tannin and onyx sorghum bran was added to pre-cooked pork pizza toppings and fully-cooked dark meat ground chicken. These products were stored aerobically at frozen temperatures and evaluated after 0, 3, 6, 9 and 12 months of storage. As in phase one, lipid oxidation was measured using TBARS values, and pH, color, cook yield and flavor was evaluated. Similar results were reported for pre-cooked pork pizza toppings as found for pre-cooked pork crumbles in phase one. While high tannin and onyx sorghum bran addition slightly affected color, pH, cook yield and flavor were minimally affected. Lipid oxidation occurred in frozen pre-cooked pork pizza toppings over the 12-month storage time, but not to the same extent as reported in phase one under refrigerated storage. As a result, the effect on lipid oxidation for treated products versus the control were not as effective. Rosemary provided a slight advantage to limiting lipid oxidation compared to sorghum bran addition, but the addition of antioxidants provided much more protection against lipid oxidation than controls. In frozen fully cooked dark meat ground chicken, limited lipid oxidation occurred, even in control product, over 12 months of storage. However, the addition of sorghum bran, especially onyx sorghum bran, resulted in slightly darker, less red and yellow meat products. Fully cooked dark meat ground chicken containing rosemary had more off-flavors associated with rosemary addition than either the control or sorghum bran addition.

In conclusion, either high tannin sorghum or onyx sorghum can be added to precooked fresh or frozen meat products as natural antioxidants. There addition does not impact pH, water holding capacity or flavor of pork and chicken products. It is recommended that 0.5 percent levels of either high tannin or onyx sorghum bran be added for control of lipid oxidation. In products where color is not an issue, 0.75 percent addition of sorghum bran can be added to gain a slight advantage in retarding lipid oxidation.

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