Processing and properties of ready-to-cook tekwan

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Tekwan is a traditional food from Palembang, Indonesia. The existing problem is the tedious and long preparation time before cooking of dried tekwan. This study used extrusion cooking and drying to prepare ready-to-cook tekwan. Tekwan was made using a twin screw extruder with a circular die 20 mm in diameter. The raw material used was prepared by mixing minced tilapia and tapioca in 1:1 ratio, and salt (2.8%) prior to extrusion. The experiment was a 3x3x2x2 factorial design consisting of three extrusion moistures (45%, 50% and 55%), three extrusion screw speeds (50, 100 and 150 rpm), two types of post-extrusion process (with or without freezing) and two levels of final product thickness (10 and 15 mm). Screw speed had a significant effect on degree of gelatinization, lightness, redness and hardness of extrudates, while extrusion moisture had a significant effect on moisture, redness, hardness and chewiness of extrudates. Freezing had a significant effect on moisture and density of dried tekwan. Thickness had a significant effect on moisture, density, and rehydration assessment. Results showed that extrusion cooking improved water absorption of dried tekwan. Incorporating freezing as a pre-treatment of drying in tekwan production was a beneficial step in conventional method but not in extrusion cooking. Recooked tekwan produced from the combination of 55% extrusion moisture, 100 and 150 rpm screw speed with a thickness of 10 mm had a texture profile closer to the fresh sample (extrudates) and fresh tekwan sample from the conventional method.