Crisp Nile tilapia (Oreochromis niloticus) is a valuable fish product with high muscle firmness and chewiness generated by dietary faba beans (Vicia faba L.). However, the overconsumption of faba bean could induce intestinal inflammation in Nile tilapia due to its endogenous anti-nutritional factors (ANFs). Germination has been cited as an effective method for reducing ANFs in faba beans. But, the effects of germinated faba beans on the tilapia remain unclear. In this report, Nile tilapia were fed a diet supplemented with dry faba beans (FB0), or germinated faba beans (FB5), or a basal diet (control) for 75 days. Thereafter, samples of the fish were examined for textural quality, digestive enzyme activity, histology of the inner intestinal wall, expression of related genes, and composition of intestinal microbes. The hardest fillets were obtained from the FB5 (406.17 ± 42.51 gf) group, followed by the FB0 (301.17 ± 24.70 gf) and control (117.50 ± 8.19 gf) groups. The amylase levels were lower in the FB0 and FB5 groups, whereas the trypsin activities were up to 1.9-fold higher than in the control group. The gene expressions of IL-1β, CCL3, and TNF-α were significantly up-regulated in both the FB0 and FB5 groups, whereas metallothionein expression was down-regulated in the intestine relative to control group. Moreover, expression of IFN-γ and Hsp70 decreased in FB5, but increased in FB0. In particular, the diversity of intestinal microbiota was higher in the FB5 group than in the FB0 group (Fusobacteria abundance significantly decreased from 79.18% to 55.87%, while Proteobacteria abundance decreased from 8.12% to 7.02%), indicating that the intestinal microbiota structure was affected by altered diets. These results indicate that germinated faba bean could be a good substitute for dry faba beans in tilapia culture.

Tilapia (Oreochromis niloticus) is a kind of worldwide farmed fish that is commercially cultured in more than a hundred nations. The tilapia dietary faba bean (Vicia faba L.) for 90- 120 d improves muscle quality such as higher muscle hardness and crispiness. However, faba bean contain a wide variety of antinutritional factors such as phenolics, tannins, trypsin inhibitor activity, and phytic acid. Antinutritional factors through themselves or their metabolic products affect the health of fish. This study was compared growth, antioxidant activity, carbon metabolic enzyme activity and immune-related gene expression profiles between the ordinary and crisp tilapia. The results indicated that crisp tilapia (888.00 +/- 200.83 g) had a significantly lower body weight compared with ordinary tilapia (1078.67 +/- 162.56 g) (P < 0.05). There were no significant differences in superoxide dismutase (SOD) and antioxidant capacity (T-AOC) between crisp and ordinary tilapia in both serum and liver. The crisp tilapia recorded significantly lower acid phosphatase (ACP), and alkaline phosphatase (AKP) in contrast to the ordinary tilapia in serum (P < 0.05), but not significant in liver. The crisp tilapia (serum: 8.05 +/- 1.23 U/mL, liver: 7.59 +/- 1.09 U/mL) exposure could significantly inhibit glucose 6-phosphate dehydrogenase (G6PD) activities compared with ordinary tilapia (serum: 5.07 +/- 0.91 U/mL, liver: 4.10 +/- 1.18 U/mL) (P < 0.05). The lysozyme (LZM) and triglyceride (TG) of ordinary and crisp tilapia were similar. The heat shock protein70 (Hsp70) and tumor necrosis factor-alpha (TNF-alpha) expression of crisp tilapia demonstrated significant upregulation when compared with ordinary tilapia in the haemocytes and liver, whereas the interleukin-1 beta (IL-1 beta), metallothionein (MT), and chemokine C-C-Motif Ligand 3 (CCL) expression of crisp tilapia were significantly deregulated in the liver. In conclusion, the crisp tilapia can decrease growth, ACP, AKP, and G6PDH activity, whereas Hsp70 and TNF-alpha expression of crisps demonstrated significant upregulation. The results would contribute to comprehend the physiological parameters during tilapia crisping process and exploring the mechanism of tilapia brittleness.

Crisp Nile tilapia (Oreochromis niloticus) is a kind of valuable fish product with high muscle firmness and crispiness texture. However, with the change of physicochemical in crisp Nile tilapia, the frozen storage parameters and quality would be different comparing to normal Nile tilapia. Thus, the aim of this study was to analyze the changes in texture, chemical quality indices and volatile compounds of Nile tilapia fillets during frozen storage. The remaining storage time of the crisp Nile tilapia fillets could be estimated within 120 days. During frozen storage, fillets resulted in softer started at 90-day, and 36.75%, 45.74%, 48.81% and 20.37% reduction of hardness, springiness, gumminess and chewiness were observed at 120-day. Thiobarbituric acid reactive substances (TBARS) for frozen samples showed similar with fresh fillets within 60 days, while the TBARS was 1.97 folds higher than fresh one at 120-day. Low-field nuclear magnetic resonance (LF-NMR) indicated that the water loss of Nile tilapia fillets was significant changed at 120-day, which reduced more than 12.5% water out of weight. The volatile compound analysis showed that more free fatty acid will be detected at 120-day comparing to the fresh fillets. The combined results demonstrated that the crisp Nile tilapia fillets had the best quality before 60 days frozen storage then loss of some quality properties in longer freezing. Thus, these results identified the ideal storage strategy for the preservation of crisp Nile tilapia without affecting sensory appeal and commercial value.

为了比较脆化养殖尼罗罗非鱼和普通尼罗罗非鱼肌肉中挥发性风味物质的组成和含量,采纳固相微萃取-气相色谱-质谱技术,对两种尼罗罗非鱼肌肉中的挥发性风味物质进行检测.结果表明,两种尼罗罗非鱼生肉样品所含有的挥发性风味物质组成和含量不完全相同,确定了尼罗罗非鱼主体风味物质是:庚醛、辛醛、癸醛、壬醛、2牞4-癸二烯醛、1-辛烯-3-醇和2牞3-辛二酮等化合物,且脆化养殖尼罗罗非鱼的主要风味物质如庚醛、辛醛、壬醛和1-辛烯-3-醇较普通尼罗罗非鱼多,而癸醛以及2牞3-辛二酮较普通尼罗罗非鱼少,2牞4-癸二烯醛无明显差异.脆化养殖尼罗罗非鱼经不同烹饪方法处理后样品之间的风味差异主要来源于其所含的比例不同.然而,对两种尼罗罗非鱼鱼肉进行热处理均能降低腥味物质的含量并改变挥发性物质的化学组成.其中,烤制处理能增加鱼肉的奶油香味和产生清香味物质柠檬烯,赋予鱼肉特殊的香气.探究两种尼罗罗非鱼以及不同热处理对鱼肉挥发性风味物质的影响,为食品加工及储藏技术提供一定理论指导,为脆化养殖罗非鱼预制菜的开发,加工工艺选择,产品后续推广提供风味相关的研究数据.