枯草杆菌蛋白酶水解大豆分离蛋白的研究

采用枯草杆菌蛋白酶对大豆分离蛋白进行水解工艺条件的研究。通过单因素分析 ,正交试验 ,确定了枯草杆菌蛋白酶酶解大豆分离蛋白的最佳水解条件 ,即 pH7 0、温度45℃、酶浓度2000u/g大豆分离蛋白、底物浓度3 %。在此条件下水解6h ,水解度可达60 %以上     

Protamex蛋白酶水解大豆分离蛋白的研究

以大豆分离蛋白为底物,通过响应面分析,确定了用Protamex蛋白酶水解的最佳条件。最佳酶解条件为:大豆分离蛋白浓度6.0%,加酶量2.4%,酶解温度51℃,酶解时间4h,pH7.0。在最佳条件下,可得到水解度为12.94%的酶解液。     

中性蛋白酶水解大豆分离蛋白的研究

本研究利用大豆分离蛋白为原料，选用枯草杆菌中性蛋白酶As1．398对其进行酶水解，在单因素分析的基础上采用响应面分析方法对大豆分离蛋白酶解条件进行优化，得出的最佳水解条件为：温度52℃，pH值7．5、E／S％。4．5％、S％=3％、水解时间2h，此条件下蛋白质的溶出率为67.2％。     

碱牲蛋白酶水解大豆分离蛋白的研究

采用Alcalase碱性蛋白酶水解大豆分离蛋白,利用扫描电镜观察不同预热温度对大豆分离蛋白结构的影响.研究了温度、pH、底物浓度、酶与底物比和时间对水解度的影响.通过正交实验及验证实验确定了最佳水解条件为:预热温度90℃、pH8.5、温度55℃、底物浓度为5%、酶与底物比为15%、水解时间4h,水解度为25.12%,多肽得率78.85%.     

大豆分离蛋白的酶法水解研究

本试验主要从预处理温度、预处理时间、底物浓度、加酶量、酶解温度、酶解时间等方面系统研究了AS1·398中性蛋白酶对大豆分离蛋白水解的影响,并运用正交试验设计和方差分析得到水解最佳条件。     

大豆分离蛋白水解用酶的筛选研究

研究了不同蛋白酶对大豆分离蛋白的水解情况,筛选出 Protamex酶作为大豆分离蛋白的水解用酶。      

大豆分离蛋白水解用酶的筛选研究

研究了不同蛋白酶对大豆分离蛋白的水解情况,筛选出 Protamex酶作为大豆分离蛋白的水解用酶。     

氨肽酶与中性蛋白酶协同水解大豆分离蛋白的研究

以大豆分离蛋白为底物,游离氨基酸含量、多肽分布、水解度为指标,氨肽酶ProteAXG为对照,开展中性蛋白酶和氨肽酶双酶协同水解的研究。在底物质量浓度6 g/dL,中性蛋白酶添加量5000 U/g,氨肽酶添加量9.75×105U/g,pH 8.5,温度50℃,水解4 h后,水解液中游离氨基酸含量13.6 mg/mL,多肽相对分子质量在1100以下,其中600左右的多肽约占16%,二肽三肽约占75%,水解度达50.8%。氨肽酶与中性蛋白酶优化后,水解度达62%。结果表明:该氨肽酶无论单独或与中性蛋白酶组合水解,都能达到较为深度的水解效果。     

Protamex复合蛋白酶水解大豆分离蛋白的研究

为优化大豆分离蛋白酶水解条件，本试验采用二次回归正交旋转组合设计方法对Protamex复合蛋白酶水解大豆分离蛋白的条件进行研究。建立了水解度(DH)与pH值、反应温度、反应时间、底物浓度、酶与底物浓度比之间的数学模型；并获得最佳水解工艺条件：pH值6．5，温度40℃，水解时间10h，底物浓度14％，酶与底物浓度比4．5％；主成分分析表明，pH对DH的贡献率最大。     

菠萝蛋白酶水解大豆分离蛋白工艺优化研究

以水解度为指标，研究了温度、pH、底物浓度、酶浓度等因素对菠萝蛋白酶水解大豆分离蛋白的影响。影响菠萝蛋白酶水解大豆蛋白的影响因素顺次为酶浓度、温度、底物浓度、pH。最佳参数组合是酶浓度为6％、温度为65℃、底物浓度为5％、pH为8．0。在此条件下，菠萝蛋白酶水解大豆分离蛋白的水解度在半小时内可以达到8．18％。     

不同来源蛋白酶水解对大豆分离蛋白分散性及溶解性的影响

研究了动物(胰蛋白酶)、植物(木瓜蛋白酶与菠萝蛋白酶)、微生物(碱性蛋白酶和中性蛋白酶)三种来源蛋白酶的低限度水解对大豆分离蛋白(SPI)分散性和溶解性的影响。结果表明,三种来源蛋白酶轻度水解可显著提高SPI的分散性,但却使其溶解性有不同程度的降低。三种来源蛋白酶水解产物的分散度大小依次为:植物来源蛋白酶>微生物来源蛋白酶>动物来源蛋白酶,而其溶解性则相反:动物来源蛋白酶>微生物来源蛋白酶>植物来源蛋白酶。本文对采用酶解的方法制备高分散性与高溶解性SPI具有一定的参考价值。通过对木瓜蛋白酶水解沉淀物进行分析,可以推测酶解使SPI溶解度显著下降的原因可能是SPI被水解后通过疏水作用力和氢键相互聚集形成了不溶性的沉淀。     

大豆分离蛋白的碱性蛋白酶酶解条件研究

碱性蛋白酶酶解大豆分离蛋白可以制备大豆多肽,用茚三酮比色法测定酶解液中氨基氮的含量来判断其酶解效率.影响大豆分离蛋白酶解的主要因素有酶用量、酶解pH值、底物浓度、酶解温度、酶解时间等,通过单因素和优化酶解条件正交试验分析,筛选出碱性蛋白酶酶解的最适试验条件是:在酶用量为7％,pH值为8.5,温度50℃,底物与溶剂的固液比为1∶15,酶解时间5h效果较好.     

The evaluation of proteases as coagulants for soy protein dispersions

The ability of different proteases to induce the gelation of soy protein isolate dispersions (5.33% w/w) was studied. The coagulation time and gel firmness were determined using dynamic viscoelastic measurements. Among the six protease tested, papain was the most effective coagulant in terms of gel strength and coagulation speed; the second was alcalase. Degree of hydrolysis (DH), pH and viscosity profiles of soy proteins were tested during the coagulation with different proteases. The result suggested that strong interactions, other than electrostatic interaction, existed between peptides in papain and alcalase induced coagulation. Thermal and pH stability tests indicated that papain was more stable than alcalase in the temperature (60–90 °C) and pH (5.8–7.0) ranges studied. Higher papain dosages within the range of 5–13.3 U/ml resulted in firmer soy protein gels, but concentrations higher than 13.3 U/ml produced weaker gels. With the addition of 0.625 mM cysteine, the soy protein coagulation ability of papain was improved. A soy protein gel formed with 0.025% papain in the presence of 0.625 mM cysteine had about the same strength as that induced by 0.133% papain without cysteine.     

Antioxidant activities and functional properties of soy protein isolate hydrolysates obtained using microbial proteases

Soy protein isolate (SPI) hydrolysates were prepared using microbial proteases to produce peptides with antioxidant activity. The process parameters (substrate and enzyme concentrations), hydrolysis time, functional properties and the effects of ultrafiltration were further investigated. The results showed that the soy protein isolate exhibited a 7.0‐fold increase in antioxidant activity after hydrolysis. The hydrolysis parameters, defined by the experimental design, were a substrate concentration of 90 mg mL^?1 and the addition of 70.0 U of protease per mL of reaction. The maximum antioxidant activities were observed between 120 and 180 min of hydrolysis, where the degree of hydrolysis was approximately 20.0%. The hydrolysis increased solubility of the soy protein isolate; however, the hydrolysates exhibited a tendency to decrease in the interfacial activities and the heat stability. The SPI hydrolysates fractions obtained by ultrafiltration showed that the enzymatic hydrolysis resulted in samples with homogenous size and strong antioxidant activity.     

预处理方式对酶修饰大豆分离蛋白水解程度的影响

研究微波辐照、加热处理、高速剪切三种预处理方式对大豆分离蛋白酶修饰产物水解程度的影响。以水解度、溶解性为指标进行综合评价,揭示水解度与溶解性的关系。结果显示,与空白对照相比较,三种预处理方式均能提高酶修饰产物的水解度和溶解性,溶解性随水解度的增加而增加。在底物浓度10%,温度50℃,酶添加量0·50%条件下,水解度分别提高了2·43倍、2·87倍和3·19倍,蛋白粉溶解性提高了1·65倍、1·76倍、2·23倍。其中,高速剪切预处理对大豆分离蛋白酶修饰水解度和溶解性增加尤为显著。与传统酶修饰方法相比,本实验将酶修饰时间由4·5h缩减至2·0h,提高了反应效率。      

酶膜反应器中水解大豆分离蛋白的研究

目的:为获得大豆分离蛋白最佳水解工艺务件;方法:使用中性蛋白酶Protease N(IUB 3.4.24.28)在pH 7.0和45℃条件下在截流分子量10 kDa切向流过滤酶膜反应器(EMR)中,对大豆分离蛋白(SPI)进行4h连续化水解,以平均水分通量Javerage和蛋白质回收率Sapparent为指标,通过响应面分析方法对初始水分通量Ji,初始蛋白质浓度[S]和初始蛋白酶浓度[E]/[S]进行优化;结果:3个因素对Javerage和Sapparent的影响显著,并存在显著差异;结论:经优化后的最优工艺条件为:Ji为10 mL/min,[S]为4%(W/V),[E]/[S]为1.5%(W/W),该条件下的Javerage和Sapparent分别为71.20%和42.55%.     

Enzymatic hydrolysis of hemp (Cannabis sativa L.) protein isolate by various proteases and antioxidant properties of the resulting hydrolysates

Enzymatic hydrolysis of hemp protein isolate (HPI) by six proteases (alcalase, flavourzyme, neutrase, protamex, pepsin and trypsin) and antioxidant activities of the resulting hydrolysates, obtained for 2 and 4 h were investigated. The yield of trichloroacetic acid (TCA)-soluble peptides (Y_sp), protein composition and surface hydrophobicity (H_o) of the hydrolysates were evaluated. The results showed that the hydrolysates exhibited varying DPPH radical scavenging (with lowest IC₅₀, ∼2.3 mg/mL) and Fe²⁺⁺ chelating (with lowest IC₅₀ of 1.6–1.7 mg/mL) abilities and reducing power (with highest absorbance at 700 nm of 0.31–0.35), depending on their Y_sp and H_o values. The DPPH radical scavenging and Fe²⁺⁺ chelating abilities of the hydrolysates were positively correlated with their Y_sp or H_o values. The results suggest that enzymatic hydrolysis can be used as an effective technique to produce high value-added products of hemp proteins.     

Use of response surface methodology to optimise the hydrolysis of whey protein isolate in a tangential flow filter membrane reactor

Response surface methodology (RSM) was used to investigate the effects of substrate concentration (S), enzyme concentration (E) and initial permeate flow rate, (J_i), on permeate flux behaviour in a 10 kDa nominal molecular weight cut-off (NMWCO) tangential flow filter (TFF) enzyme membrane reactor (EMR) during 3 h hydrolysis of whey protein isolate (WPI) using Protease N Amano (IUB 3.4.24.28, Bacillus subtilis) at pH 7.0 and 45 °C. The average residual permeate flow rate (J_residual), residual enzyme activity (A_residual) and product recovered in permeate designated as apparent sieving (S_apparent) were monitored. The quadratic model regression equations obtained revealed that all the three factors had significant but dissimilar influences on permeate flux behaviour. J_residual, S_apparent and A_residual increased with increasing E, A_residual decreased with increasing J_i and there was substrate inhibition at low E. The optimised factors were S = 4.72% (w/v), E = 0.055% (w/v; hence E/S ≈ 1% w/w) and J_i = 6.91 mL/min (approximately 0.7% reactor volume per minute). The optimised values were 87.24%, 52.37% and 35.08% for J_residual, A_residual and S_apparent, respectively. The actual values for the responses agreed well with the predicted values implying that RSM is suitable for EMR optimisation. Covariance values showed that J_residual and S_apparent increased concomitantly while A_residual decreased with increasing S_apparent and J_residual.     

大豆分离蛋白膜研究

以大豆分离蛋白(SPI)和甘油为成膜基质,研究多聚磷酸钠、羧甲基纤维素钠(CMC–Na)、微波及磷酸化对大豆分离蛋白膜性质影响。结果表明,多聚磷酸钠可显著提高膜的水溶性(ρ0.01)和抗拉伸强度(ρ0.05),显著降低膜的氧气透过性(ρ0.01)和水蒸气透过性(ρ0.05);CMC–Na能显著提高膜抗拉伸强度(ρ0.01)和氧气透过性(ρ0.05),显著降低膜的水溶性、透光率及水蒸气透过性(ρ0.01);微波处理可显著提高膜的抗拉伸强度(ρ0.05),降低膜的水溶性(ρ0.05);磷酸化可显著降低膜的氧气透过性(ρ0.05)、透光率及抗拉伸强度(ρ0.01)。     

Immobilized alcalase alkaline protease on the magnetic chitosan nanoparticles used for soy protein isolate hydrolysis

An efficient immobilization of Alcalase 2.4L alkaline protease has been developed by using chitosan-coated magnetic nanoparticles as support via glutaraldehyde cross-linking reaction. The Fe₃O₄ nanoparticles, Fe₃O₄-chitosan, and immobilized Alcalase 2.4L alkaline protease were characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectroscopy, electron spin resonance, and vibrating sample magnetometry. Results showed that the binding of chitosan and Alcalase 2.4L alkaline protease on Fe₃O₄ through cross-linking was successful. In addition, the Alcalase 2.4L alkaline protease immobilized with chitosan-coated magnetic nanoparticles enhanced the activity, the optimum reaction temperature and pH value for the immobilized enzyme were 55 °C and 10, respectively, compared with the free enzyme, and the optimal temperature and pH profile range were considerably broadened. Similarly, the thermal stability was enhanced by immobilization, and the kinetic parameters of free and immobilized Alcalase 2.4L alkaline protease were determined. Then, from our hydrolysis experiments, we found that immobilized Alcalase 2.4L alkaline protease uses Fe₃O₄-chitosan had a greatest hydrolytic activity, and the DH of soy protein isolate (SPI) can reach to 18.38 %, against 17.50 % with the free enzyme after 140 min. Furthermore, the immobilized Alcalase 2.4L alkaline protease could maintain about 86 % of its original activity after ten consecutive operations. Thus, Fe₃O₄-chitosan immobilized Alcalase 2.4L alkaline protease a good candidate for the continuous hydrolysis of SPI.