Effects of stevia (Stevia rebaudiana Bertoni) leaf extracts on the quality and shelf life of refrigerated catla (Gibelion catla) fillets

The effects of stevia leaf extracts (SLE) on the quality and shelf life of catla (Gibelion catla) fillets were assessed during refrigerated storage for 20 days. The fish fillets were treated with aqueous ethanolic (80%) extracts of stevia leaf at various concentrations (1% SLE, 2% SLE, and 3% SLE). The control (distilled water only) and SLE-treated fillets were preserved at 4 +/- 1 degrees C, and chemical (pH, peroxide value (PV), free fatty acid (FFA), thiobarbituric acid reactive substances (TBARS), and total volatile basic-nitrogen (TVB-N)), bacteriological and sensory evaluation was performed periodically for quality assessment. During refrigerated storage, 2% SLE-treated fillets exhibited significantly (p < 0.05) the lowest pH, PV, FFA, TBARS, and TVB-N values compared to other SLE-treated and control fillets. Aerobic plate counts (APC), psychrotrophic bacterial counts, Enterobacteriaceae, lactic acid bacteria, H2S-producing bacteria and Staphylococcus counts of 2% SLE-treated fillets were significantly lower than those of other SLE-treated fillets and control fillets. The maximum APC were 7.22, 7.29, 6.85, and 7.17 log CFU/g for control, 1% SLE, 2% SLE, and 3% SLE-treated fillets at the 12th, 16th, 20th, and 20th days of the storage period, respectively. However, sensory evaluation results revealed that 2% SLE- and 3% SLE-treated fillets had better sensory attributes up to 16th days followed by 1% SLE (12th days) and control (8th days) fillets. Pearson's correlation test and principal component analysis confirmed the relationship among chemical, bacteriological and sensory attributes of refrigerated catla fillets. Based on the chemical, bacteriological, and sensory evaluation results, 2% SLE could be used as a natural additive for catla fillets preservation during refrigerated storage.