ANTIOXIDANT SYNERGY EFFECT OF ROSEMARY AQUEOUS EXTRACT AND GREEN TEA FLAVANOL-RICH CONCENTRATE FOR SUPERIOR PROTECTION OF BUFFALO MEATLOAVES
Hani M. A. Mohamed
Phenol-containing extracts of green tea and rosemary have potential for use as food antioxidants. Due that rosemary and green tea extracts were considered as "natural" ingredient, it had more acceptances by the consumer than synthetic antioxidants. The objective of this work was to study the antioxidant effects and the synergistic interactions between the water-soluble extract obtained from rosemary (WSR), green tea water extract (TWE) or its flavanol-rich concentrate (GTF). Total phenolics in each extract were determined according to the Folin-Ciocalteu procedure. WSR, TWE and GTF alone or in combinations were examined first on buffalo meat emulsion homogenates (30% fat) as single or combined ingredients and their antioxidative activities were determined based on β-carotene changes in buffalo meat lipids after 10, 20, 40, and 60 min of heating at 50ºC. Results so obtained were compared with those of samples containing α-tocopherol and BHA/BHT as commonly used food antioxidants. The most effective inhibitors of β-carotene decomposition were the mixture of WSR/GTF, followed by BHA/BHT, GTF, WSR, WSR/TWE, TWE then α-tocopherol in descending order. Besides, in subsequent experiments buffalo meatloaves were prepared containing 500 ppm WSR; 400 ppm WSR + 100 ppm GTF; 300 ppm WSR + 200 ppm GTF or 500 ppm GTF. The loaves were baked to an internal temperature of ~ 74ºC then stored at 4ºC. Samples were analyzed for lipid oxidation (TBA values) and total psychrotrophic bacterial counts (PCs) throughout 6 days of refrigerated storage to assess non-microbial and microbial shelf-life properties. Results suggest that WSR and GTF may be used as meat antioxidants that are safe and heath promoting. Super antioxidative effect was achieved by utilizing the mixture of WSR300/GTF200 that exhibited also some antimicrobial activity.
Key words: Buffalo meat; natural antioxidants; rosemary extract; green tea extract; meatloaf