ANTIOXIDANT SYNERGY EFFECT OF ROSEMARY AQUEOUS EXTRACT AND GREEN TEA FLAVANOL-RICH CONCENTRATE FOR SUPERIOR PROTECTION OF BUFFALO MEATLOAVES

Hani M. A. Mohamed

Abstract
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 50°C. 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 ~ 74°C then stored at 4°C. 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

EFECTUL PROTECTIV ANTIOXIDANT SINERGIC AL EXTRACTULUI APOS DE ROZMARIN ŞI AL CONCENTRATULUI DE CEAI VERDE BOGAT ÎN FLAVANOL ASUPRA FLEICILOR DE BIVOL

Hani M. A. Mohamed

Rezumat
Extractele fenolice din ceai verde si rozmarin prezinta potential de utilizare ca antioxidanti alimentari. Din acest motiv, rozmarinul si ceaiul verde au fost considerati ingrediente "naturale" în alimente, prezentând un grad de acceptabilitate mai mare de catre consumatori, comparativ cu alti antioxidanti de sinteza. Scopul lucrarii a fost de a studia efectele antioxidative si interactiunile sinergice dintre extractele apoase de rozmarin (WSR), de ceai verde (TWE) si concentratul bogat în flavonoizi (GTF). Cantitatea de fenoli în fiecare extras s-a determinat în acord cu metoda Folin-Ciocalteu. WSR, TWE si GTF au fost utilizate individual sau în combinatie pe emulsii omogenizate de carne de bivol (30% grasime), fiind investigate activitatile lor antioxidative, pe baza modificarilor β-carotenului din grasimi, dupa încalzirea produsului studiat la 50°C, timp de 10, 20, 40 si 60 min. Rezultatele obtinute au fost comparate cu cele reiesite din probele tratate cu α-tocopherol si BHA/BHT, utilizati în mod obisnuit ca antioxidanti. Inhibitorii cei mai eficienti ai degradarii β-carotenului au fost, în ordine descrescatoare: amestecul WSR/GTF, urmat de BHA/BHT, GTF, WSR, WSR/TWE, TWE si α-tocoferol. Mai mult, în cercetari adiacente, fleicile de carne de bivol au fost preparate prin adaos de 500 ppm WSR; 400 ppm WSR + 100 ppm GTF; 300 ppm WSR + 200 ppm GTF, respectiv 500 ppm GTF. Fleicile au fost apoi procesate termic, pentru a atinge o temperatura interna de 74°C si au fost apoi depozitate la 4°C. Probe din acest material au fost supuse analizelor pentru peroxidare lipidica (valori TBA) si pentru cantitatea totala de bacterii psihrotrofice (PCs), dupa 6 zile de pastrare la refrigerare, în scopul investigarii proprietatilor microbiene si non-microbiene ale produsului la raft. Rezultatele au indicat ca WSR si GTF pot fi utilizate ca antioxidanti în produsele de carne, prezentând siguranta si contribuind la mentinerea starii de sanatate a consumatorilor. Efectul superantioxidativ a fost obtinut în urma utilizarii combinatiei WSR₃₀₀/GTF₂₀₀, care a prezentat, de asemenea, si cea mai eficienta activitate antimicrobiana.

Cuvinte cheie: carne de bivol, antioxidanti naturali, extract de rozmarin, extract de ceai verde, fleici