Abstract:

This study deals with comparisons of nutritional components in surface mucus and muscle of catfish (Silnrus asotus) from Dongting Lake area. Results showed that water content, crude protein, crude fat and crude ash were (95.34 ± 2.38) %, (2.54 ± 0.22) %, (0.52 ± 0.08) % and (1.55 ± 0.17) % in surface mucus; (77.68 ± 3.14) %, (13.81± 0.43) %, (3.79 ± 0.11) % and (4.54 ± 0.15) % in muscle of catfish, respectively. The water content in surface mucus of catfish was significantly higher than that of muscle (P＜0.01), while crude protein, crude fat and crude ash in muscle were significantly higher than those of surface mucus (P＜0.01). In dry samples, minerals such as Ca, Zn, Fe and Cu in surface mucus were much higher than those in muscle. The ratios of Zn and Cu, Zn and Fe were rational. Surface mucus of catfish contained 18 kinds of amino acids; so did muscle. The contents of total amino acids (WTAA), total essential amino acids (WEAA), total half-essential amino acids (WHEAA), total nonessential amino acids (WNEAA) in dry samples were (80.46 ± 0.89) %, (25.62 ± 0.69) %, (4.94 ± 0.19) % and (49.91 ± 0.38) % in surface mucus; (81.65 ± 0.80) %, (32.74 ± 0.29) %, (7.35 ± 0.07) % and (41.57 ± 0.55) % in muscle of catfish, respectively. The content of WEAA, WHEAA and WNEAA was significantly difference between surface mucus and muscle (P ＜0.05). The essential amino acids index (EAAI) was 59.43 and 64.53, respectively. According to nutrition evaluation, amino acid score (AAS) and chemical score (CS), limited amino acids in surface mucus and muscle were Trp, Met and Cys. There were 6 saturated fatty acids (SFA), 5 mono-unsaturated fatty acids (MUFA) and 5 poly-unsaturated fatty acids (PUFA) in surface mucus of catfish, while 6 SFA, 2 MUFA and 4 PUFA in muscle of catfish were observed. The SFA, MUFA and PUFA in fatty aids were (30.98 ± 1.91) %, (28.76 ± 0.68) % and (30.93 ± 0.73) % in surface mucus; (35.03 ±1.31) %, (21.64 ± 0.83) % and (21.41 ± 0.85) %, respectively. The amount of EPA + DHA in fatty acids was (22.27 ± 0.28) % and (7.40 ± 0.22) %, respectively. The amount of MUFA, EPA, DHA, OUFA and EPA + DHA in surface mucus of catfish was significantly higher than muscle (P＜0.01). The amount of SFA in surface mucus was significantly lower than muscle (P＜0.05). The ARA in fatty aids of surface mucus was (3.21 ± 0.38) %, but not detected in muscle.

Key words: catfish, mucus, muscle, nutritional component, mineral, amino acid, fatty acid