Microstructures of gels of swim bladder gelatins without EECH (A) and those added with EECH at levels of 0.5 mg g1 dry
gelatin (B) and 5 mg g 1 dry gelatin (C) are illustrated inFig. 5. All gelatin gels were sponge or coral-like in structure. Generally,the arrangement and association of protein molecules in the gel matrix directly contributed to the gel strength of the gelatin (Benjakul et al., 2009). The control gel showed the finest gel network with very small voids. When EECH at 0.5 mg g 1 was incorporated, the uniform structure with larger strands was formed. This was coincidental with the increase in gel strength(Fig. 2). However, non-uniform structure with disconnected large strands and large voids was obtained as EECH at 5 mg g1 was present. Gelatin could undergo the coagulation more effectively in the presence of EECH at an excessive amount. The coagulated gelatin chains could not undergo the gelation with the ordered structure. This led to poor gel strength (Fig. 2). Therefore, the extracts from coconut husk could be used as the natural gel strengthening agents for gelatins when the appropriate level was used