Abstract:
This research aimed to develop steamed fish with soy sauce in retort pouch and steamed fish fillet in retort pouch and separated soy sauce packed separately for elderly. For the first product, Obtuse barracuda (Sphyraena obtusata, OB) and Indian salmon (Eleutheronema tetradactylum, IS) were selected. Fish slices were soaked in 0%, 2.5% and 5% sodium tripolyphosphate (STPP) solution for 1 hour. It was found that 2.5% STPP was the most suitable concentration, providing significantly highest yield and water-holding capacity of the fresh fish and significantly lowest cooking loss (p≤0.05) after steaming. The steamed fish with soy sauce were sterilized at 118 oC and F0 = 6 min. After sterilization, weight loss and L value of the fish samples decreased but firmness and b value increased (p≤0.05). For the soy sauce after sterilization, L, a, b values and pH increased (p≤0.05). From the consumer acceptance test using 5-point hedonic scale, the product from OB obtained higher hedonic scores of color, taste and overall acceptance than those from IS (p≤0.05). Therefore, the product from OB was selected for further studying of the optimum sterilization condition (118 oC, F0 = 6 and 10 min). The results showed that the OB slices sterilized at F0 = 6 min had the lower firmness, a and b values whereas L value was higher than those having F0 = 10 min (p≤0.05). The result of acceptance test showed no significant difference between both samples (p>0.05). Therefore, the best product was the OB sterilized at 118 oC, F0 = 6 min. For the second product, the Pangasiidae (Pangasius hypophthalmus, PS) fillet was sterilized at 118 oC, F0 = 6 min. It was found that the weight and L value of the sample sterilized at 118 oC, F0 = 6 min, decreased while the firmness increased (p≤0.05). However, a and b values did not change after sterilization (p>0.05). The soy sauce was sterilized separately at 118 oC, F0 = 3 and 6 min. The results showed that the b value decreased (p≤0.05) while the pH, total soluble solids, L and a values were not different (p>0.05). From the acceptance test, there was no difference between overall acceptance scores of the PS fillet sterilized at 118 oC, F0 = 6 min served with soy sauce sterilized at F0 = 3 or 6 min (p>0.05). Thus, the best product was the PS sterilized at 118 oC, F0 = 6 min and the soy sauce sterilized at 118 oC, F0 = 3 min. One serving size of both products (100 g, containing 60 g of fish slices) was high in protein, low in fat, and had acceptable amount of sodium for elderly consumers having chronic kidney diseases, diabetes, hyperlipidemia and hypertension.