Submitted to: Journal of Food Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/26/2009
Publication Date: 3/1/2009
Citation: Min, B., Chen, M., Green, B.W. 2009. Antioxidant activities of purple rice bran extract and its effect on the quality of low NaCl, phosphate-free patties made from channel catfish (Ictalurus punctatus) belly flap meat. Journal of Food Science. 74(3):C268-C277. Interpretive Summary: Recently, consumers’ interest in the health benefits from foods has increased rapidly. Many studies have shown that the consumption of whole grains and grain-based products can reduce the incidence of many chronic diseases such as cardiovascular disease, diabetes, and cancer. The health benefits from whole grains are attributed mainly to the natural antioxidants primarily present in the bran of the whole grains. Colored rice bran contains very high amounts of natural antioxidants that consist of water-soluble and oil-soluble compounds. These natural antioxidants can decrease the development of rancidity and microbial growth in meat products, so that they can improve the stability and safety of meat products as well as sensory characteristics such as texture and flavor. We developed a low sodium, phosphate-free patty from catfish belly flap meat. This catfish patty is susceptible to the development of rancidity during storage because of the high fat content in catfish belly flap meat. Therefore, we investigated the application of colored rice bran extract to the catfish patties in order to inhibit the development of rancidity, microbial growth, and changes in textural properties. The water-soluble and oil-soluble portions of natural antioxidants extracted from colored rice bran were applied separately. Both portions improved the stability of catfish patty against rancidity and retarded the changes of textural characteristics such as hardness and chewiness during storage. Only the oil-soluble portion showed retardation of microbial growth during storage. In conclusion, the addition of rice bran extract not only can improve the stability, safety and quality of the catfish patty, but also allows consumers to eat natural antioxidants with the patty to get their health benefits.
Technical Abstract: Hexane-insoluble and hexane-soluble fractions were separated from a 100% methanolic extract from purple rice bran (RBE-HI and RBE-HS, respectively). Total anthocyanin, tannin, flavonoid and phenolics contents were determined in those fractions, and the antioxidant capacity of those fractions were evaluated by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capability, oxygen radical absorbance capacity (ORAC), and iron chelating capability (ICC). RBE-HI and RBE-HS were also added to restructured patties made from minced channel catfish (Ictalurus punctatus) belly flap meat. Lipid oxidation, color, and/or textural properties were determined for raw and cooked patties during a 12-day storage at 4 degrees C. Microbial growth was observed in only raw patties during 8-day storage at 4 degrees C. All antioxidant indices, except for ICC, of RBE-HI were significantly higher than those of RBE-HS due to its higher anthocyanin content (P < 0.05). RBE-HS showed higher ICC (P < 0.05). However, both fractions showed similar antioxidant activity in raw and cooked patties during storage, resulting from the complexity of antioxidant action in food systems. Textural properties (hardness, cohesiveness, chewiness, and springiness) in cooked patties with RBE-HS and RBE-HI were well-maintained during storage, but changed significantly in the control (P < 0.05). Only RBE-HS limited microbial growth in raw patties during the storage (P < 0.05), but its inhibitory effect was marginal because of low dose and physical interactions with the matrix. Addition of both fractions changed color attributes (L*, a*, b*, and whiteness) significantly (P < 0.05). In conclusion, we suggest that purple rice bran extract is applicable to meat products as a natural preservative, but color change in the products may limit its application.