A RESEARCH NOTE: EFFECT OF NATURAL ANTIOXIDANTS ON COLOR OF AN IRRADIATED BEEF MYOGLOBIN MODEL SYSTEM

ABSTRACT

To determine the effect of antioxidants and irradiation on meat color, myoglobin (Mb) was extracted from beef hearts. Mb was treated with one of three antioxidants (control, grape seed extract, rosemary extract [RE] or oregano extract) and irradiated at 0.00, 1.25 or 2.50 kGy. The samples were then evaluated for pH, Commission Internationale de l'Eclairage L*, a* and b* values, hue angle, chroma and thiobarbituric reactive substances (TBARS). Antioxidants influenced pH. RE-containing beef Mb samples had lower pH values before and after irradiation. Antioxidants also had significant effects on the color of the beef Mb model system. RE-containing samples had the best pre- and postirradiated color in terms of a* value (redness) and chroma (color intensity). TBARS values were very low and did not differ regardless of antioxidant or irradiation dose.

PRACTICAL APPLICATIONS

Irradiation can reduce the microbial load on meat products and improve product safety for consumers. However, irradiation, because of its potential to cause oxidative damage, can compromise the red color of fresh meat. Off-color will result in consumer rejection of products which may be safe. Antioxidants have the potential to preserve meat color by affecting the state of myoglobin and maintaining the iron in the reduced state such that it can oxygenate to the bright cherry red color, which consumers expect. However, studying these effects in vivo is challenging because of the complexity of the system. In this model system, devoid of enzymatic reducing systems and equivalents, natural antioxidants, including grape seed extract, rosemary extract (RE) and oregano extract, were evaluated for their potential to preserve color during irradiation. RE appeared to be the most effective in preserving red color intensity. Extracts of this herb appear to have potential for ameliorating some of the color damage that often accompanies the irradiation of fresh red meat.