磷对生长期草鱼肌肉理化参数、游离氨基酸、呈味核苷酸和游离脂肪酸组成的影响

目的]本实验探索了磷对生长期草鱼肌肉常规营养组成和理化特性，肌肉中游离氨基酸、呈味核苷酸和游离脂肪酸组成的影响。方法]实验选择初始体重为（256.22 ± 0.60 g）的健康草鱼540尾，随机分为6组，每组3个重复，分别饲喂含有效磷0.95（基础饲料组，未添加）、2.46、3.96、5.68、7.10和8.75 g/kg的饲料60天。结果]结果显示，饲料中适宜水平的磷显著提高了生长期草鱼肌肉蛋白质、水分、羟脯氨酸、∑氨基酸、∑鲜味氨基酸（UAAs）、∑甜味氨基酸（SAAs）、肌苷酸（IMP）、∑不饱和脂肪酸、∑多不饱和脂肪酸（PUFA）含量以及pH0和pH12，而肌肉剪切力、组织蛋白酶B和L活力、乳酸、饱和脂肪酸（SFA）含量显著降低（P < 0.05）。适宜水平的磷还显著提高了PUFA/UFA及n-3 PUFAs/n-6 PUFAs比值，IMP和∑呈味氨基酸（UAAs+SAAs） 的滋味活性值（TAV）均大于1。结论]结果表明，适宜水平有效磷提高了生长期草鱼（254.56-898.23 g）肌肉蛋白质含量、肌肉嫩度、系水力和pH值，增加肌肉风味氨基酸、核苷酸和脂肪酸含量，进而提高鱼类肌肉品质。

Effect of dietary phosphorus on physicochemical properties, composition of free amino acid, flavor nucleotide and free fatty acid in muscle of grass carp (Ctenopharyngodon idella)

To assess the effect of dietary phosphorus on physicochemical properties, composition of free amino acid, flavor nucleotide and free fatty acid flavor in muscle of grass carp, a 60d growth trial by feeding graded levels of available phosphorus (0.95-8.75 g/kg diet) was conducted. Results demonstrated that optimal available phosphorus levels increased the protein and hydroxyproline contents and pH value, while decreased the contents of lipid and lactate, cooking loss, shear force, and cathepsin activity to improve fish muscle physicochemical characteristic. In addition, optimal available phosphorus levels increased the contents of total essential amino acids (EAAs), umami taste AAs, sweet taste AAs and inosine monophosphate (IMP) contents enhancing fish muscle flavor. And optimal available phosphorus levels increased muscle total polyunsaturated fatty acids (PUFAs) contents and the fatty acid ratio of PUFAs/saturated fatty acids (SFAs), and n-3/n-6 to improve fish healthcare function. In conclusion, appropriate available phosphorus supplementation improved flesh quality might be in part attributed to the enhancement of tenderness, water holding capacity and pH, and increasement of flavor amino acid, nucleotide and fatty acid contents in muscle of fish.