Comparative analysis of physicochemical and nutritional properties between crisp and normal Oreochromis niloticus

Nile tilapia (Oreochromis niloticus) is a main aquaculture fish product in China, which is famous for its delicious taste, no intermuscular bone and high nutrition. Currently, it has been observed that the muscle elasticity of O. niloticus can be effectively improved by feeding with Faba bean meal. This kind of O. niloticus was named crisp O. niloticus which has become an economically important freshwater fish species with high economic value. However, little is known about the muscular features between crisp and normal O. niloticus. To investigate the differences of texture properties and nutritional components between crisp and normal O. niloticus, the texture properties, basic chemical composition, free amino acid composition, fatty acids composition and sensory evaluation were measured in this study. Both texture profile analysis and sensory evaluation results indicated that the hardness, springiness and chewiness between crisp and normal O. niloticus muscles were significantly different (P <0.05). For the basic chemical composition, the contents of crude protein and ash content of two kinds of O. niloticus were similar, while the water content of crisp one was lower whereas crude fat was higher than the normal one (P <0.05). Fatty acids composition analysis revealed that the polyunsaturated fatty acids level of crisp O. niloticus was significantly higher than the normal O. niloticus with great nutritional value (P <0.05). Especially, the content of linoleic acids, eicosapentaenoic acids and docosahexaenoic acids of crisp O. niloticus were 2.12, 3.36 and 3.71 times higher than the normal ones, respectively. For free amino acids, the essential amino acids and umami amino acids of crisp O. niloticus were significantly higher than normal one excepting lysine (P <0.05). This study showed that the physical texture, water content, fatty acid content and free amino acid composition of crisp O. niloticus were significantly different when compared with the normal one.