Evaluation of Green Tea (Camellia sinenses) Extract and Onion (Allium cepa L.) Juice Effects on Lipid Degradation and Sensory Acceptance of Persian Sturgeon (Acipenser persicus) Fillets: A Comparative Study

This study was carried out to evaluate the effects of red onion (Allium cepa L.) juice and green tea (Camellia sinenses) extract on lipid oxidation and sensory characteristics of refrigerated (۴ºC) sturgeon fillets (Acipenser persicus). Fresh fillets were tumbled in ۱%, ۲.۵%, and ۵% (v/v) aqueous solutions of onion Juice (OJ) and tea extract (TE), and then stored for up to ۸ days at ۴°C in a refrigerator. Chemical indices of lipid oxidation as assayed by heme iron, thiobarbituric acid and free fatty acid contents indicated much more reduction in ۲.۵%TE, ۵%TE and ۵%OJ-treated samples relative to the other samples (P<۰.۰۵). Significant (P<۰.۰۵) differences in pH values of treatments and the control were observed during the first ۲ days of storage time. For ۵%OJ treatment, the pH remained constant during refrigerated storage (P>۰.۰۵) whereas gradual changes were detected in pH values of the others. Generally, the order of effectiveness for inhibiting oxidation in sturgeon fillets was found to be: ۵% TE or OJ = ۲.۵% TE > ۲.۵ % OJ>۱% TE = ۱% OJ. Based on sensory scores, higher amounts of onion juice (>۱%) were more effective to improve attributive characteristics of the fillets.