Enzymolysis kinetics of garlic powder with single frequency countercurrent ultrasound pretreatment

This research was to describe the enzymolysis process of garlic powder which was pretreated by single frequency countercurrent ultrasound. The kinetic constants for ultrasonic pretreated and traditional enzymolysis have been determined. Results showed the value of K_M in ultrasonic pretreated enzymolysis decreased by 12.7% over the traditional enzymolysis, which indicates a fast reaction speed induced by ultrasound pretreatment. Degrees of hydrolysis (DH) in the enzymolysis of garlic powder were determined and kinetics of the reaction was considered in detail in relation to substrate concentration, enzyme concentration, reaction time and DH. Our results suggested a general kinetic equation for the enzymolysis model of ultrasonic pretreated garlic powder. For the model system, the calculated values agree well with the experimental data with average relative error of 4.42%. The proposed kinetic equation can be used to model the bio-reaction process of protein enzymatic hydrolysis and optimize the operation parameters for bioreactor design.     

Purification of β-carotene 15,15′-monooxygenase from pig intestine and its enzymatic hydrolysis of pigment in soybean oil

β-Carotene 15,15′-monooxygenase was isolated and purified from the intestinal mucosa of pigs, and then, it was applied to hydrolyse the pigment in soybean oil, and thus, vitamin A fortified soybean oil was obtained. The pig intestinal mucosal protein solution was purified to a specific activity of 2.487 × 10⁻⁴ U mg⁻¹, maximum reaction velocity (V_max) of 8.42 × 10⁻⁹ mol/h and Michaelis constant (K_m) of 2.03 × 10⁻⁵ m . The protein solution had a molecular mass of 156 kDa by gel filtration. The sodium deoxycholate concentrations, optimum pH, Tween 40 amount and enzyme amount for vitamin A production in soybean oil were determined to be 6.0 mm , 8.0, 3.0% (w/v) and 0.2 U/mL enzyme, respectively. Under these conditions, β-carotene 15,15′-monooxygenase produced 14.65 mg/L vitamin A after 20 h, with a conversion yield of β-carotene of 33.29% (w/w). Therefore, the nutrients in soybean oil were improved.     

Enzymolysis reaction kinetics and thermodynamics of rapeseed protein with sequential dual‐frequency ultrasound pretreatment

We evaluated the effect of sequential dual‐frequency ultrasound (SDFU) pretreatments on rapeseed protein enzymolysis, using alcalase as a model enzyme. Hydrolysed protein concentrations, enzymolysis kinetics and thermodynamic parameters were investigated. The results showed that the hydrolysed rapeseed protein concentration following SDFU pretreatments was higher compared to that of the control for up to 75 min of enzymolysis at various substrate concentrations of 5–25 g L^?1; both control and SDFU pretreatment groups showed first‐order reaction kinetics. Compared to the control, the Michaelis–Menten constant (K_M) value decreased remarkably by 17.61%, while an increase in the binding frequency between enzyme and substrate (K_A) by 10.47% was observed. The thermodynamic parameters, enthalpy, entropy and activation energy were reduced in the SDFU pretreatment group compared to the control by 31.78%, 18.0% and 29.56%, respectively. SDFU pretreatment showed little effect on Gibbs free energy at the various temperatures studied.     

旋叶动态膜分离式酶解反应器酶解糊精的实验研究

研究了旋叶动态膜分离式酶解反应器的主轴转速、底物浓度和循环量等操作参数对糖化酶酶解糊精反应的影响 ,测定固定化酶反应的动力学参数 ,并对其适宜操作条件进行了探索     

羊胎水解液类脂物化学组成的研究

羊胎水解液乙醚萃取物经ＫＯＨ－乙醇皂化,乙醚萃取,过醚萃取,过硅胶色谱柱,淋洗物经Ｎ,Ｎ－二（三甲基硅）三氟乙酰胺（ＢＳＴＦＡ）衍生化后进行ＧＣ－ＭＳ分析。结果表明,羊胎水解液乙醚萃取物中主要含有三类物质：饱和脂肪酸,不饱和脂肪酸,甾醇及微量雌性激素。     

膜分离式酶解反应器流体流动特性

讨论了膜分离式酶解反应器进行酶解反应操作时流体流动的特性。导出停留时间分布函数方程式，采用降阶法的阶跃方式进行了实验验证。结果表明：实验值与按分布函数方程式的计算值吻合良好，通过与连续釜式反应器（ＣＳＴＲ）停留时间分布的特征值的比较，显示出这种反应器的优越性。     

纤维素酶法提取天然辣椒素的研究

对酶法提取天然辣椒素的方法进行了研究,通过酶解液初始pH值、酶解时间、酶解温度和酶量的四因素三水平正交实验,得出最佳酶解条件为:在酶解初始pH为5.4,酶解温度55 ℃,酶解时间4 h,用酶量为2.5 mg/g辣椒的下,天然辣椒素产量为7.65 mg/g;与乙醇浸提法提取辣椒素相比,产量比乙醇浸提法提高了33 %.     

马铃薯渣酶法水解液制备单细胞蛋白饲料

对马铃薯渣制备膳食纤维的酶法水解液,制备单细胞蛋白饲料进行了研究.试验结果表明,单细胞蛋白边糖化边发酵的摇瓶培养的较优工艺条件为:底物浓度为8%(添加8%的麸皮水)、初始pH为4.5、接种量为15%、葡萄糖淀粉酶加入量为100U/g(原料中淀粉)、青霉素加量为80 U/g(原料)、培养温度为28℃、培养时间为60h、转速为250r/min.在此条件下,干酵母产量最高为19.920g/l,单细胞蛋白中的蛋白质含量达12.27%.     

Determination of physicochemical properties and degradation kinetics of triamcinolone acetonide palmitate in vitro

Purpose: Triamcinolone acetonide palmitate (TAP) is a lipophilic prodrug of triamcinolone acetonide (TAA) to improve the insoluble TAA physicochemical properties for the preparation of emulsions. Methods: This investigation has focused on the preformulation study of TAP, including its physicochemical properties and hydrolysis kinetics in vitro. Results: The solubility of TAP in medium-chain triglyceride is about twice greater than that in soybean oil (long-chain triglyceride) (19.17 versus 9.55 mg/g) at 25°C, and in all investigated cases, lecithin (80, 160, and 240 mg/g) as solubilizer provided increased solubility of drugs in medium-chain triglyceride and long-chain triglyceride, whereas the maximum water solubility of TAP was 0.10 μg/mL. The partition coefficient (log P) of TAP was 5.79 irrespective of the pH conditions. The hydrolysis of TAP followed pseudo-first-order kinetics in aqueous solutions, and the stable pH range was from pH 5.0 to 9.0. The in vitro enzymolysis kinetics of TAP in rat plasma and liver homogenate was evaluated by measuring the decrease of TAP as well as the increase of TAA at 37°C for 96 hours. The results demonstrated that the TAP may be hydrolyzed mainly by rat plasma esterase and, to a minor extent, by liver esterase, and the hydrolysis half-life of TAP in 100% rat plasma was 17.53 ± 6.85 hours at pH 7.4. Conclusions: All these results indicated that TAP had successfully obtained higher lipid-soluble property for the preparation of intravenous emulsion and may be an effective prodrug for sustained release of TAA in vivo.     

利用菜籽饼粕生产复合氨基酸的研究

众多的研究表明,菜籽蛋白对人具有很高的营养价值,其氨基酸组成和ＷＨＯ／ＴＡＯ推荐的比例很接近。文介绍了以菜籽饼粕为原料,用酶－酸两步水解法生产复合氨基酸的方法,对原料的选择处理、酶解以及酸解条件、沉淀剂的使用等方面进行了研究和探讨,建立了生产氨基酸的工艺路线,并且生产的复合氨基酸的纯度、产品得率、氨基酸组成、安全性能等进行了初步评价。