Effect of green tea (Camellia sinenses) extract and onion (Allium cepa) juice on lipid degradation and sensory acceptance of Persian sturgeon (Acipenser persicus) fillets

This study was established to contrast the effectiveness of red onion (Allium cepa) juice and green tea (Camellia sinenses) extract on lipid oxidation and sensory characteristics of refrigerated sturgeon fillets (Acipenser persicus). For this, fillets were tumbled in 1%, 2.5%, and 5% (v/v) aqueous solutions of onion Juice (OJ) and tea extract (TE), and then stored for up to 8 days at 4°C. Chemical indices of lipid oxidation as assayed by heme iron, thiobarbituric reactive substances (TBARs) and free fatty acid (FFA) contents indicated much more reduction in 2.5%TE, 5%TE and 5%OJ-treated samples relative to other samples (P<0.05). For 5%OJ treatment, the pH remained constant during storage (P>0.05) while gradual changes were detected in pH values of other treatments. Generally, the order of effectiveness for inhibiting the oxidation in fillets was found to be: 5%TE=5%OJ = 2.5%TE > 2.5%OJ>1%TE = 1%OJ. Based on sensory scores, higher amounts of onion juice (>1%) were more effective to improve attributive characteristics of fillets.