14A-21

A. GAUTAM, FITC/SFOS, University of Alaska Fairbanks, Kodiak, Kodiak, 99615 and G. S. Choudhury, FITC/SFOS University of Alaska Fairbanks, Kodiak, AK 99615.

JUSTIFICATION: Studies in our laboratory have shown that addition of fish muscle to rice flour reduced energy input and produced undesirable attributes for expanded product. Enzymatic modification of fish muscle may provide an avenue to alter the intermediate process variables thereby affecting product attributes. OBJECTIVE: To evaluate the effect of added hydrolyzed fish muscle on energy input, residence time, mixing, and die temperature. METHODS: Arrowtooth flounder muscle was autolyzed by endogenous muscle protease and the degree of protein hydrolysis was varied by controlling the hydrolysis time (0, 5, 10 & 15 min). Four blends for each degree of hydrolysis were prepared by mixing rice flour (100%, 95%, 90%, 85%) with hydrolyzed fish powder (0%, 5%, 10%, & 15%). Each blend was extruded using a Clextral co-rotating, twin-screw extruder (BC 21). The length to diameter ratio was 32:1 and a 5 mm diameter circular die was used. Feed flow rate, screw speed, and moisture content were kept constant at 12 kg/h, 400 RPM, and 15%, respectively. The temperature profile in eight barrel sections were set at 0, 30, 30, 30, 70, 100, 150, and 150°C. Response variables evaluated were energy inputs (thermal, mechanical and total) residence time, mixing index, and die temperature. RESULTS: Higher die temperature, slightly higher mechanical energy input, and lower thermal energy input were observed with addition of hydrolyzed fish muscle compared to those for unhydrolyzed fish muscle. Residence times and mixing indices were similar in both cases. However, the values were significantly different for those obtained during rice flour extrusion. SIGNIFICANCE: The data suggest that the addition of enzyme modified fish muscle changes some of the intermediate process variables that may overcome the detrimental effects of protein on attributes of expanded products. This may lead to increased use of proteins in expanded products.