The effect of different thawing methods on the physicochemical quality of edible oyster (Saccostrea cucullata)

Oyster (Saccostrea cucullata) is one of the most important edible oysters in Iran and the world. In this project, about 500 g of fresh oyster meat, which was collected from the rocky shores of Bandar Molem (Banderlange city) in the winter season, was extracted. For separate waste materials, the process of self-purification of oysters was carried out for 72 h in the environment of chlorine (2.5 ppm) and citric acid (0.2 g.l-1). oyster meat was washed with clean and cool water and frozen at -24°C for 10 days and then thawing was done using ambient temperature (24°C), water (20°C), refrigerator with still air; RTSA (4±2°C) and refrigerator with blasting air; RTBA (4±2 °C). Then were calculated the thawing time (Tt), pH, water holding capacity (WHC), drop loss after thawing (DLt), drop loss after cooking (DLc), peroxide value (PV), thiobarbituric acid (TBA) and volatile nitrogen bases (TVB-N). The results of thawing time for a 120±10 g block of oysters in thawing methods in air, water, refrigerator with still air, and refrigerator with blasting air were calculated as 42.3, 25, 56, 31.6 min, respectively. In general, pH, WHC, DLt, DLc, PV, TBA and TVB-N of S. cucullata oysters for thawing in the refrigerator with blasting air were reported, respectively; 6.38, 92%, 2.35%, 8.13%, 3.48 meq g O2/Kg Fat, 1.12 mg MDA/Kg Fat and 10.91 mg N/100g flesh. The highest amount of TBA and TVB-N in the thawing at ambient temperature was 2.35 mg MDA/Kg Fat and 17.84 mg N/100g flesh, which was significantly different (p<0.05) from the thawing in the refrigerator with blasting air. Therefore, in order to preserve the quality of oysters, it is recommended to use the thawing method in a refrigerator with blasting air.