Abstract:
Freshwater prawn (Macrobranchium lanchesteri) is a source of proteins containing amino acids and peptides as precursors that flavors and tastes can be developed during food processing. The objective of this study was to investigate the production of protein hydrolysates from freshwater prawn with Flavourzyme®. An optimal hydrolysis condition was established using the response surface methodology (RSM) with a central composite design (CCD). An enzyme/substrate ratio (E/S ; 5-15 LAPU/g protein), temperature (45-55 °C), and pH (6-8) were used as independent variables, while the dependent variable was a degree of hydrolysis (DH). The optimum conditions were found to be the E/S of 10 LAPU/g protein, temperature of 50 °C, and pH at 7. The highest DH obtained from optimal condition was 20.97±0.86 %. At this condition, the average molecular mass of the hydrolysate was about 48.3 kDa, which amount of free amino acids was increased compared to the control. It was also found that the hydrolysate contributed higher liking score of overall preference, flavor, and taste compared to the control. The spray drying was performed by varying inlet temperatures (120, 150, and 180°C), while the outlet temperature of 95°C and flow rate at 10 mL/min were kept constant. The results showed that the highest yield of hydrolysate was found when using 150°C as inlet temperature (72.41±0.53%). In addition, water activity (aw), moisture content, and whiteness index were 0.159±0.02, 4.29±0.36 %, and 69.83±0.50, respectively. The hydrolysate powders were vacuum packed in an aluminum foil laminated bags (aluminum/ LLDPE) and stored for 12 weeks at 25°C and the changes during storage were determined every 2 weeks. It was found that the moisture content was increased, while there is no change found in aw of the samples during storage. Furthermore, the whiteness index was decreased during storage. Moreover, the sensory evaluation indicated that the intensity of the shrimp aroma and flavor were gradually decreased, but the intensity of the sweetness was increased. These results were corresponding to the decrease in some flavor compounds such as N,N-dimethyl-methylamine, making the decreasing in fishy flavor. In contrast, the increase in 2-furanmethanol, maltol and vanillin which these compounds contribute sweet and caramel flavor.