PEA FIBER AS A SOURCE OF NATURAL ANTIOXIDANTS IN FROZEN MINCED BEEF - LIPID OXIDATION AND COLOR STABILITY DURING RETAIL DISPLAY

The antioxidative effect of rehydrated fibre from yellow field pea in a minced beef product with 1% salt added has been compared to the antioxidative effect of rehydrated texturized soy protein. The oxymyoglobin autoxidation in the product surface was followed by tristimulus colorimetry during freezer storage (polyethylene tubes, diameter 8 cm, product temperature - 18-degrees-C) for 6 weeks in a display cabinet illuminated by fluorescent tubes. Lipid oxidation in the product center and in the product surface was followed by a determination of thiobarbituric-acid-reactive substances (TBA). Lipid oxidation in the product center was hardly significant in any of the products, whereas the TBA value in the surface layer of an all-meat reference product rose to 33 mg malonaldehyde/kg product when exposed to light, and to 26 mg/kg when protected against light. Both pea fibre and soy protein yielded an efficient protection against this surface lipid oxidation, and the antioxidative effect of the pea fibre was further verified in a model system for an aqueous extract. As for the pigment oxidation, pea fibre also had an antioxidative effect resulting in a better colour stability of the minced beef product, although soy protein yielded an significantly better protection against oxymyoglobin autoxidation.