不同南极磷虾产品中蛋白的营养价值评价

本文以南极磷虾为原料制备的虾肉、虾糜、普通虾粉、脱脂虾粉和脱氟虾粉这5种产品为原料,对其基本成分及产品中蛋白质的组成和分布状态、氨基酸组成促进行测定。用SDS-PAGE、显微观察、红外光谱进行分析。结果显示,五种南极磷虾产品中普通虾粉的蛋白含量最低(65.12%),但仍超过特级品的鱼粉(GB/T 19164-2003,蛋白含量>65%),对照FAO/WHO提出的氨基酸模式,分析产品中蛋白质的营养价值,5种南极磷虾产品的必需氨基酸含量均≥47.835%,高于酪蛋白(47.548%),必需氨基酸(EAA)/非必需氨基酸(NEAA)≥91.571%,营养指数(NI)≥56.432%,南极磷虾各产品蛋白的必需氨基酸之间的比例适宜,必需氨基酸指数(EAAI)也优于酪蛋白的75.627。由于受到热加工、乙醇脱脂、酸处理脱酰胺等的影响,磷虾产品中高分子量的蛋白发生降解,低分子量的蛋白增加,此外,产品蛋白中a-螺旋/β-折叠的比值由1.222降至0.835,β-转角的含量也从31.39%降至26.37%。通过对不同南极磷虾产品中蛋白的营养价值的研究,论证了该南极磷虾产品可作为良好的蛋白质来源。

Evaluation of Nutritive Value of Protein in Different Antarctic Krill(Euphausia superba)Products

The basic components,protein composition and distribution state,amino acid composition were measured. SDS-PAGE,microscopic observation,and infrared spectroscopy were used to analyze the protein in krill meat. Krill surimi,ordinary krill powder,skim krill powder and defluorination krill powder prepared from Antarctic krill as raw materials were analyzed. The results showed that the protein of ordinary krill powder in these five kinds of Antarctic krill products had the lowest protein content(65.12%),but still exceeded the fish meal of the special grade(GB/T 19164-2003,protein content>65%)the nutritive value of its protein was analyzed according to the amino acid model proposed by FAO/WHO,the essential amino acids content,the essential amino acids(EAA)to nonessential amino acids(NEAA)ratios and nutrition index(NI)of protein in these five kinds of Antarctic krill products were higher than 47.835%(>47.548% of casein),91.571%,56.432%,respectively. The ratio of essential amino acids of protein in the five Antarctic krill products was appropriate,and the essential amino acid index(EAAI)was also superior to 75.627 of casein. Due to thermal processing,ethanol degreasing,and acid treatment deamidation,the high molecular weight protein in the krill product was degraded,and the low molecular weight protein was increased,in addition,the ratio of a-helix to β-sheet in the krill products protein decreased from 1.222 to 0.835,and the the content of β-turn angle also decreased from 31.39% to 26.37%. By studying the nutritive value of protein in different Antarctic krill products,it was demonstrated that the Antarctic krill products can serve as a good source of protein.