Detection And Analysis Of Low-purine And Defatted Soybean Curd Powder

Soybean meal is a product of soybean after being extracted fat, which retained most of the nutrients insoybean except fat. The reaserch team had developed a kind of food called low-purine and defatted soybeancurd powder for the patients with gout by high temperature soybean meal.In this study, two ways for detectingcontent of purine in soybean meal has been established, which are HPLC and determination of phosphate. Inthe last of study, the physicochemical property of low-purine and defatted soybean curd powder has beenanalyzed.（1）Research of method for detecting content of purine in soybean mealThrough selecting flow rate and mobile phase, the optimal conditions of HPLC for detecting content ofpurine in soybean meal was as follows: Waters symmetry shield Ultimate AQ-C18,5μm,4.6×250mm; thecolumn temperature was at25℃;the injection volume was10μL, flow rate was1.0mL/mim, UV detector was254nm;water,acetic acid, tetra butyl ammonium hydroxide（997:1.5:1.5）: methanol=99:1was the mobile phase.The precision of Ade,Gua,Xan and Hyp was0.31%,0.27%,0.50%,0.41%and the recovery was89.00%,86.90%,88.10%,81.30%.The content of purine in soybean detected in HPLC was253.0mg/100g andsoybean meal is high-prine foods.（2）Detection and analysis of low-purine and defatted soybean curd powder①The content of purine, protein, total sugar and fat in low-purine and defatted soybean curd powder is123.5mg/100g,56.2%,28.4%and0. Low-purine and defatted soybean curd powder is high-nutrition andlow-fat foods. Color, appearance, smell, taste and impurities of low-purine and defatted soybean curd powderconform the requirements. Content of ash and copper exceed. Solubility is poor and precipitation index washigh. Coli form bacteria, pathogens and mildew conform the requirements. Micro floras exceed. Mobility andpacking density are poor. Gel property of CaCl₂, CaSO₄and GDL is different from each other.②According to the picture of soybean curd powder by SEM, grain of soybean curd powder was large,shriveled and porous and the solubility of soybean curd powder with ultrasonic treatment was better than thatwithout ultrasonic treatment. The secondary structure of soybean curd powder had been changed by analyzingthe FT-IR chromatogram. The content of β-sheet and random coil had risen. The content α-helix and β-turn haddeclined. The solubility of soybean protein had been improved.Low-purine and defatted soybean curd powderproduced by the soybean milk without protection has poor solubility.③According to the feeding experiment of mice, the soybean protein had been degraded with ultrasonictreatment and the utilization and digestive rate of low-purine and defatted soybean curd powder had beenimproved significantly.