|
Shellfish daily food, marine products attracted people welcome because it contains very rich in nutrients, such as amino acids, unsaturated fatty acids and other nutrients, and these nutrients meet the requirements of a healthy diet. In addition, with the rapid development of modern, shellfish and other marine life contamination by heavy metals, people eating contaminated shellfish, may trigger some lesions. Therefore, it is essential to evaluate the nutritional value of shellfish. Key indicators to evaluate the nutritional value of the food, including the general content of nutrients, amino acids, fatty acids, and cholesterol composition and content. Amino acids (especially the essential amino acids) and polyunsaturated fatty acids on the growth and health of the people is very important. Thus, the analysis of these two nutrients essential. Heavy metals exceeded the hazards to human health is more important than reducing its nutritional value, Thus, the analysis of shellfish heavy metals is also of great significance. This paper is divided into two parts, a part of the establishment, improvement and evaluation of the method, on the other hand is established shellfish quality assessment. The details are as follows: The test established precolumn derivatization agent to the 2,4 - Dinitrochlorobenzene as RP-HPLC determination of 18 amino acids shellfish. Proteolytic conditions, such as hydrolysis time, temperature, acidity, and an amino acid derivative of time, temperature, acidity and derivatizing agent concentration is optimized. As well as to optimize the conditions of chromatographic separation and detection of amino acids. Using a gradient elution separation of amino acids, 18 amino acids of the working curve, its correlation coefficient ranges from 0.9915 to 0.9991; detection limit was 0.24 2.37μg/mL; spiked recoveries of 88.6% to 115.7%. The results show that the method of non-interference, easy operation, high sensitivity, can be used for shellfish in the detection of amino acid content. The trial also established shellfish seven kinds of unsaturated fatty acids by GC-MS analysis. Optimization of sample pre-treatment, such as extraction of the solid-liquid ratio, extraction of methyl esterification reagents, time and temperature conditions; derivative time, temperature, derivative dosage. Also optimize the the unsaturated fatty temperament separation and detection conditions. Eventually established seven kinds of unsaturated fatty acids calibration curve, the correlation coefficient ranges from 0.9925 to 0.9953, and the detection limit: 0.36 ~ 0.85μg/mL, recoveries: 76.68 to 106.68%. The results show that the method of non-interference, ease of operation, high sensitivity, and can be used for shellfish unsaturated fatty acid analysis and detection. This test also reference to national standards combined content of the sample and the laboratory conditions to make the appropriate changes measured shellfish in Pb, Cd, As and Hg of four heavy metals content. This study focuses on evaluation of the nutritional quality of the shellfish from three amino acids, fatty acids and heavy metals. Shellfish amino acid analysis results show that (1) the different varieties of shellfish samples, the growth of shellfish samples in different months and different waters of shellfish samples in the amino acid types are the same, but the content differences. Including clams, the variegated clams, oysters, Sinonovacula Clam higher nutritional value in the Bohai Sea. (2) the amino acid data on shellfish principal component analysis, the results showed that the the elected three main components, their cumulative contribution rate of 84.16%, the three main ingredients can be summed up most of the information in the original data. They include Asp, Glu, Thr, Val, His, Ile, Leu, Lys and Phe, etc.. (3) shellfish essential amino acids greater than 30% of total amino acids, high nutritional value, and the relatively high content of glutamic acid and aspartic acid is mainly determined by the flavor of the shellfish itself. (4) there are differences in the organization the scallop samples of amino acids, scallops Beebe side amino acid content. (5) through the work of the Independent-the Samples T Test two waters of variegated clams, oysters, clams, razor clams constriction, hair cockles of the amino acid content, the results show that the two different waters shellfish samples amino acids all contain 17 kinds, but the amino acid composition exist some differences (P lt; 0.05). The analysis results show that (1) different types of shell-like, shell-like growth of shellfish samples in different months and different waters contain palmitoleic acid, oleic acid, linoleic acid, linolenic acid, arachidonic shellfish fatty acid composition acid, EPA and DHA, but there are some differences on the content. (2) shellfish n-3/n-6 ratio is greater than 2, indicating that they are good n-3 polyunsaturated fatty acids provider. (3) unsaturated fatty acid content of two waters shellfish Independent-Samples T Test, the results showed that two different waters shellfish are unsaturated fatty acids containing 7, but on the composition of the unsaturated fatty acids there are certain differences (P LT; 0.05). (4) there are differences in the organization scallops fatty acid content Pui section content higher than scallops. Analysis, the results showed that the kind of shellfish taken (1) two waters, Hg and Pb were not exceeded, and no enrichment of four heavy metals content of shellfish Pb, Cd, As and Hg; Some shellfish Cd exceeded have varying degrees of enrichment; serious As exceeded the standard, and the degree of enrichment is the most serious. The scallops absorbing heavy metals there are differences in the organization, the fan the Babe edge sample Cd were excessive, excessive Chlamys farreri As, Pb and Hg were not excessive; scallops greater than Pb and Hg enrichment enrichment of Cd and As. (2) the scallop heavy metal content exist differences in the organization of the heavy metal content of the scallops were below the shell side of the content. (3) by calculating the value of the the two waters variegated clams, oysters, clams, Sinonovacula, Clam and Mytilus edulis the MPI, compared the level of heavy metal content of the two waters the same kind of shellfish samples.
|