Cranberry inhibits lipid oxidation in mechanically separated turkey.

Lipid oxidation is one of the major causes of quality deterioration in foods when they are processed and stored. Incorporating antioxidants into products can effectively retard lipid oxidation. However, due to consumers' concerns over the safety and potential toxicity of synthetic antioxidants, there has been an increasing interest in developing antioxidants from natural sources.

The objective of scientists at the University of Wisconsin was to evaluate the antioxidant activity of cranberry components in muscle foods. Their efforts suggest that cranberry components may be used as natural antioxidants to enhance the oxidative stability and shelf life of muscle foods.

Cranberry juice powder was fractionated with water, aqueous ethanol, methanol and acetone. The researchers obtained cranberry press cake isolate by undertaking various solvent extractions incorporating butanol, chloroform, dichloromethane, ethyl acetate or ether. The scientists determined the level of thiobarbituric acid reactive substances (TBARS), indicators of lipid oxidation products, in order to evaluate the inhibitory effects on lipid oxidation in a mechanically separated turkey (MST) system. Antioxidant active cranberry components were partially characterized by reversed-phased high-performance liquid chromatography.

Adding cranberry fractions, obtained by an ethanol-methanol elution at a level of 200 micromols of quercetin-equivalent per kg in MST, extended the induction time of TBARS formation and reduced the TBARS values by 60% to 84%, as compared to the control sample. Cranberry press cake isolates delayed the onset of lipid oxidation. At a level of 0.04% (w/w), the inhibitory effects of dichloromethane, ether and ethyl acetate isolates were greater than those of the chloroform and butanol isolates.

Quercetin turned out to be one of the most active antioxidant components in the cranberry fractions tested. The researchers effectively inhibited lipid oxidation in turkey at 2 C storage by adding a level of 210 micromols of quercetin per kg of MST.

Further information. Mark Richards, Department of Animal Sciences, Meat and Muscle Biology Laboratory, University of Wisconsin, 1805 Linden Drive W., Madison, WI 53706; phone: [phone]; fax: [phone]; email: [e-mail].