Effctes Of Preserving And Cooking On The Content Of Purine In Trichiurus Haumela

Aquatic resources are very abundant in China and Trichiurus haumela is one of the most important marine economical species. There is a high purine content in aquatic products, especially in viscera and fish soup, in which the content could reach more than1%. Long-term intake of high purine food with the addition of some inducing factors will cause the deposition of uric acid, which is the metabolic end product, and could finally lead to gout. In this study, Trichiurus haumela was used as experimental material and the purine content was determined by high performance liquid chromatography (HPLC). The conditions for hydrolyzation and separation of several purines by HPLC were optimized. Then different ways of preservation on the quality and the content of purine, and effects of different cooking methods on the content of purine in Trichiurus haumela were studied. The main results were presented as follows:1. A reversed-phase high performance liquid chromatography method for the quantitative determination of free purine and total purine content after hydrolyzing in fishery products was studied. The optimized conditions was hydrolyzing sample with mixture of trifluoroacetic acid:formid acid:water(5:5:1:v/v/v)for12min at90℃. The method had a good resolution, whose r2was>0.9998and the RSD was<2%. The optimized chromatography conditions were as follows:Waters Atlantis dC18column was used as the stationary phase and0.02mol/L KH2PO4O(pH3.62)as mobile phase. Flow rate was at1.0mL/min, and column temperature at30℃with254nm by DAD detector. The results showed that Guanine was the most in free and total purines, then was Hypoxanthine. Guanine was far more than other three after hydrolyzing. The content of free purines was46.95mg/100g, which accounted for40%of the total purines, whose value was119.53mg/100g.2. Changes of freshness and content of purines of Trichiurus haumela after storing at25℃、4℃and-20℃were studied. Sensory quality was unacceptable and Xanthine was increased while total purines didn’t have a clear change under the storage period at25℃for16h. The similar changes were observed under the storage period at4℃for4d but change of Xanthine at25℃occurred at a faster rate than at4℃. The value of T-VBN as well as sensory quality were acceptable, and the content of purines except Xanthine had no significantly change under the storage period at-20℃for60d. In addition, Xanthine increased at a lower rate than at25℃and4℃, and the content of total purines decreased. Thus, long term frozen storage could not only keep freshness but also reduce the content of total purines.3. Poaching(for10.20.30.40.50and60min), steaming(for5.10.15.20.25and30min) and frying (for1.2.3.4and5min)were introduced to treat Trichiurus haumela. These three treatments could significantly decrease the purine content in Trichiurus haumela compared with the content in raw ones. Moreover, the content of different constituents of purines had also decreased to varying degrees. Among which, the content of Guanine and Hypoxanthine decreased significantly after heat treatments, which was in accordance with the change of total purine content. The content of purines decreased firstly and then became stable in the process of poaching, steaming and frying. But the content of purines in Trichiurus haumela decreased at a higher rate after poaching than after steaming and frying, especially for Guanine and Hypoxanthine.