Abstract
Storage properties of an extruded mixture of fish meat and rice flour were investigated. These properties included the determination of an isotherm for equilibrium moisture content vs. water activity at 30oC. Vitamin-A and total tocopherols and gain in peroxides and free fatty acid were measured during storage at this temperature. The acceptability of the extruded meal in terms of sensory characteristics were studied at the end of the storage period (45 days). Sorption isotherm indicated that the safe aw levels of the extrudates were 0.4-0.7. During the first 15 days of storage a loss of 53.1 % and 50 % of vitamin-A (IU/g) and total tocopherols (%) was observed. The peroxide and free fatty content increased from 46 to 109 mg/kg and 3.8 to 7.7 %, respectively during the same period. Non-linear model described the best the loss of vitamin-A, and tocopherols and gain in peroxide values and free fatty acid content. The loss of vitamin-A and total tocopherols almost followed a similar trend during the complete storage period of 45 days. The gain in peroxides was more prominent compared to free fatty acid content during the initial 15 days of storage. The ANOVA table indicated that the sensory attributes of the product fried for different times (15-120 s) were significantly and the product fried at 15 sec were most acceptable.