菊粉加工性质的研究

本文对菊粉在水中的溶解度、酸性条件下的稳定性、其水溶液黏度和形成凝胶条件、持水力等方面进行了研究。试验发现，室温下菊粉在水中的溶解度很小（21℃溶解度为3．23％），随着温度的升高，其溶解度显著增大，在90℃时达37．62％；pH值在4～7范围内。菊粉基本不水解，当pH值〈4时，菊粉发生水解，其水解度随温度的升高而增大：菊粉水溶液的黏度随其含量的升高而逐渐增加，当菊粉含量为35％、温度为90℃，其溶液开始形成凝胶：在室温下菊粉的持水力为181．8％．     

黑米花色苷热降解动力学研究

黑米花色苷在酸性水溶液和10%乙醇溶液中的热降解性质。通过考察黑米花色苷含量在4℃、25℃、80℃和100℃下随时间的变化,通过计算得到黑米花色苷在两种溶液和不同温度条件下的降解速率k、半衰期t_(1/2)、温度系数Q_(10)、活化能Ea。结果表明:黑米花色苷在pH3去离子水和10%乙醇溶液中的热降解规律符合动力学一级反应规律,其热降解速率随温度升高而增大,黑米花色苷在pH 3去离子水溶液中的稳定性优于10%乙醇溶液。     

活性嫩黄K-6G的水解及醇解动力学研究

 针对活性染料在纤维上染色的动力学性能,研究不同条件下一氯均三嗪型活性染料活性嫩黄K-6G(C.I.Reactive Yellow 2)在甲醇碱性水溶液中的醇解和水解反应动力学,并确定了pH值为10时,不同温度下该染料的醇解与水解反应速率常数。研究表明,在80℃,pH值为9～12之间,醇解效率随时间延长逐渐变少,且pH值越高,醇解效率减少的越快, pH值的升高不利于醇解反应进行,即染料的醇解反应优先性下降;在50～70℃,甲醇化反应占相对优势,其速率为水解速率的2～3倍;80～95℃,甲醇化反应速率常数和水解速率常数基本相等。同时实验中还发现染料的醇解和水解反应都是准一级反应。     

西红花苷-1的稳定性研究

采用化学动力学方法研究pH值、温度、光照、初始质量浓度对西红花苷-1稳定性的影响。结果表明:西红花苷-1在溶液中的降解反应为表观一级反应,pH值、温度、光照、初始质量浓度均能够影响其稳定性,在pH6.0～7.0之间时最稳定,在自然光照射下的反应速率较紫外光更快,对温度极其敏感,但反应速率常数与其初始反应质量浓度无关,其在溶液中降解反应活化能Ea为45.36kJ/mol。     

单偶氮染料AR37的光催化降解动力学研究

探讨光催化技术在水体环境中降解单偶氮染料Acid Red 37(AR37)的可行性,通过单因素实验研究其降解动力学。探讨了TiO_2催化剂用量、温度、底物浓度和pH等对AR37降解动力学的影响。结果表明,单偶氮染料AR37光催化降解符合假一级动力学,动力学速率常数为0.039 4min~(-1);温度较高的反应体系和较低的反应底物浓度有利于单偶氮染料AR37染料的光催化降解;当催化剂用量适中时,降解速率最大;溶液初始pH为9.0时,其降解速率常数达到最大值0.050 62 min~(-1),酸碱性太强都不利于单偶氮染料AR37染料的降解。     

蒜酶对水体中马拉硫磷降解的初步研究

研究了在37℃温度条件下蒜酶时水溶液中马拉硫磷的降解效果,采用气相色谱法测定了马拉硫磷的含量.结果表明,与对照相比,蒜酶对马拉硫磷的降解显著(P<0.05),7d时降解率可达50%,15d时未检出马拉硫磷.动力学分析表明,对照组和加酶组的马拉硫磷的降解均符合一级动力学模型,但对照组的速率常数远低于加酶组.     

胶态微晶纤维素的流变特性研究

研究了胶态微晶纤维素在水溶液中的浓度、溶液的pH值、温度、金属离子、剪切速率、剪切和静置时间、热处理温度和时间、高压均质处理等对胶态微晶纤维素粘度的影响,结果表明:胶态微晶纤维素在溶液中可形成凝胶,形成的凝胶具有摇溶性,胶态微晶纤维素溶液具有典型的剪切稀变性和良好的时变性,在低酸性条件下具有较好的稳定性,高温和高压处理有利于胶态微晶纤维素在溶液中的分散,二价金属离子会显著影响其粘度。     

多因素交互作用导致烘焙咖啡中绿原酸快速降解

研究烘焙温度、时间及基质pH值对咖啡绿原酸的影响,采用小粒生咖啡豆进行不同程度的烘焙实验,分析不同烘焙温度和时间下pH值、质量损失率、水分质量分数、新绿原酸含量、绿原酸含量、隐绿原酸含量及3 种异绿原酸异构体的变化情况,并建立绿原酸降解动力学模型,采用化学反应模型验证绿原酸单体的降解情况。结果表明,烘焙咖啡中水分质量分数、质量损失率随烘焙温度的升高总体分别呈降低和升高的趋势,随烘焙时间的延长分别呈降低和升高的趋势。绿原酸含量随烘焙温度升高和时间延长显著降低（P＜0.05）,相比生咖啡豆,新绿原酸、隐绿原酸含量随烘焙温度升高先升高后降低,随烘焙时间延长显著降低（P＜0.05）。新绿原酸、隐绿原酸含量与咖啡pH值和烘焙时间呈显著负相关（P＜0.05）,绿原酸含量与烘焙温度、时间呈显著负相关（P＜0.05）,与咖啡水分质量分数呈显著正相关（P＜0.05）。温度和时间的交互作用均对咖啡绿原酸类化合物降解产生高度显著影响（P＜0.001）。绿原酸3 种异构体热降解符合一级反应动力学模型。在化学反应模型中,绿原酸转化为新绿原酸和隐绿原酸两种异构体,3 种异构体质量浓度均随pH值和温度的升高显著降低（P＜0.05）,温度与pH值交互作用对绿原酸降解影响高度显著（P＜0.001）。综上,温度、时间及pH值的协同作用致使烘焙咖啡中绿原酸的快速降解。     

龙葵果花色苷降解动力学

通过研究4种龙葵果花色苷提取物在不同pH值和温度下的降解动力学过程,得出其降解规律。结果显示,龙葵果花色苷的降解符合一级反应动力学模型。相同pH下随着温度的升高,龙葵果花色苷的降解速率常数呈现指数型增长趋势,半衰期呈现指数型下降趋势。60℃和70℃时随着pH的增大,粗提物、一级精制物的降解速率常数呈现对数型增长趋势,而组分1和组分2的降解速率常数则呈现指数型增长趋势,4种提取物的半衰期均呈现指数型下降的趋势。而80℃和90℃时,4种花色苷提取物的降解速率常数和半衰期并未呈现规律性的变化。4种龙葵果花色苷提取物均在60℃、pH 1.0时降解最慢,稳定性最好,其中粗提物的稳定性最强。     

酸化速率对大豆蛋白凝胶结构的调控

为探讨酸化速率对葡萄糖酸内酯诱导的大豆分离蛋白凝胶结构的影响,通过不同的保温温度制备大豆蛋白凝胶样品,将pH值、浊度、凝胶强度、保水性、频率扫描及微观结构作为测定指标,反映葡萄糖酸内酯酸化速率和大豆蛋白凝胶结构的变化情况。结果表明:随着保温温度的不断升高,葡萄糖酸内酯凝固剂的释放速率越来越快,大豆分离蛋白凝胶的pH值下降速率增大;蛋白浊度不断增加,表明蛋白聚集速率的增加,凝胶体系在越来越短的时间达到稳定状态,保温温度与蛋白凝胶的酸化速率呈正比。随着酸化速率的增加,大豆分离蛋白凝胶的凝胶强度和刚性不断提高;保水性在60℃时达到最大值;微观结构的测定结果显示,在60℃保温的大豆分离蛋白凝胶结构更均匀致密。综上,酸化速率显著影响大豆分离蛋白凝胶结构,60℃保温时的酸化速率形成最致密均匀的凝胶结构。     

Acid thinned jicama and maize starches as fat substitute in stirred yogurt

Jicama and maize starches were hydrolyzed with HCl (1.5, 3.0 or 4.5 g/100 g of starch), at a temperature of 40 °C using two hydrolysis times (3 and 6 h). The acid degradation of both starches was not excessive as revealed by the positive blue value, amylose content, gel formation and gel thermo-reversibility. Jicama starches were more susceptible to acid hydrolysis than maize starches. Hydrolyzed jicama starches showed low values of gel strength and water solubility index, and high values of damaged starch, total sugar content and water absorption index. Stirred yogurt formulated with hydrolyzed starches showed different properties of syneresis index according to the starch type and hydrolysis conditions. Yogurt samples with hydrolyzed jicama starches added did not show significant differences in pH and viscosity. Sensorial testing showed that it is possible to produce yogurt with good functional and sensorial properties using hydrolyzed jicama starches as a fat substitute.     

牛蒡菊糖酶法提取

采用固定化酶法提取牛蒡菊糖。结果表明酶水解提取牛蒡菊糖的最佳工艺为：13.5g/100mL 中性蛋白酶、pH 7、固液比1:15、50℃、酶水解6h,菊糖提取率为14.57%;固定化酶制备最佳工艺为：以甲醛(40%):NaOH(2mol/L)=2:3 为凝结液、pH7.5、壳聚糖2.5g/100mL、60℃、加酶量7.5mg/mL,固定8h,酶活力回收率可达到39.13%;固定化酶提取牛蒡菊糖最适条件为：pH7、固液比1:15、60℃、固定化酶加入量13. 5 g/100mL、酶解5h,在此条件下菊糖提取率达到12.89%。固定化酶的稳定性与游离酶相比有显著的提高,连续反应10 次后,固定化酶仍然具有良好的使用性能,此时牛蒡菊糖的提取率为9.42%。     

Cereal fructosans: Part 1—Isolation and characterization of fructosans from wheat flour

Wheat fructosans were isolated by two different methods—One, described earlier by Montgomery & Smith (1957), and one new, simpler method.The preparations were characterized by chemical analysis and by gel filtration chromatography. Their carbohydrate composition was practically identical. The ash content was lower in fructosans prepared by Montgomery and Smith's method, since it involves an ion exchange treatment. The yield of total fructose was higher with our method (68% compared with 32%).Acid hydrolysis was performed with wheat fructosans and, for comparison with inulin, to investigate the possibility of degradation of fructosans in the stomach. The results indicated very slow breakdown at physiological conditions. Wheat fructosans were slightly more acid resistant than inulin.     

Kinetic Study of Thermally Induced Inulin Gel

ABSTRACT: Heated inulin solution undergoes a sol-gel transition during cooling and forms a white smooth gel under optimized conditions. The degree of gel formation is negatively related to hydrolysis of inulin during heating. Heating makes inulin soluble; overheating causes hydrolysis of dissolved inulin into smaller molecules. Using a 2-step model including a solubilization step and a hydrolysis of inulin step, we found that both steps follow pseudo first-order kinetics. Separate studies on initial rates of the solubilization and hydrolysis of inulin steps at constant temperatures show that the solubilization rate of inulin is much faster than that of the hydrolysis of inulin. Gel formation of inulin may be related to the average chain length of inulin after heating.     

无机盐对短链菊粉凝胶性能影响的研究

目的研究无机盐对短链菊粉凝胶指数和保水性的影响,为其实际应用提供理论指导。方法添加不同量的NaCl和CaCl2,测定短链菊粉水溶液凝胶体系的凝胶指数和保水性的变化规律。结果当无机盐添加量一定时,短链菊粉含量越高越有利于凝胶的形成;当菊粉添加量一定时,随无机盐添加量的增加,菊粉的凝胶指数和保水性都呈先增大后减小的趋势,NaCl和CaCl2的添加量分别在4%和5%时达最大值,此时凝胶指数分别为86.68%和94.58%,保水性分别为200.14%和274.86%;在无机盐的添加量相同时,CaCl2对菊粉凝胶性能的影响比NaCl更显著;当菊粉添加量为35%时差异最显著,添加1%CaCl2的凝胶指数和保水性分别比1%NaCl高11.24%和42.85%。结论无机盐能促进短链菊粉凝胶的形成,增加菊粉凝胶的凝胶指数和保水性,CaCl2比NaCl的这种作用更明显。     

菊粉在乙醇溶液中成胶行为规律的研究

为探索菊粉在乙醇溶液中成胶行为及凝胶质构变化规律,采用加热/冷藏的方法制配制菊粉凝胶,考察质量分数35%、45%和55%的菊粉溶液在体积分数0-40%乙醇溶液中的成胶行为,利用质构仪分析不同条件下凝胶的质构特性。试验发现随菊粉质量分数的增加其在乙醇溶液中的成胶能力增强;乙醇体积分数对菊粉成胶能力影响显著,当乙醇体积分数低于30%时,随着其体积分数的增加菊粉的成胶能力和持水性显著提高;当乙醇体积分数高于30%时,随着其体积分数的提高菊粉的成胶能力和持水性呈下降的趋势。质构仪分析表明,增加菊粉含量可显著提高凝胶的质构特性,而乙醇对凝胶质构有双向作用,随乙醇体积分数的增加,凝胶质构特性呈现先增大后减少的趋势,对硬度、强度、黏附力及黏着性的影响拐点为20%,而对凝聚性和咀嚼性的影响拐点为10%。     

固体酸水解法制备牛蒡果糖工艺的研究

以牛蒡为原料,对以强酸型阳离子交换树脂D061为固体酸水解牛蒡制备果糖的工艺进行研究。考察固体酸与牛蒡浸提液的体积比、水解温度、水解时间、固体酸重复使用次数4 个影响制备果糖工艺条件的主要因素。结果表明：固体酸法可以水解牛蒡制备出高质量的果糖,最佳水解工艺条件为水解时间120min、水解温度75℃、固体酸与牛蒡浸提液的体积比为1:2,重复使用固体酸水解3 次后,水解率为76.7%,还原糖含量为145.8g/L。     

Proteolysis characteristics of Actinomucor elegans and Rhizopus oligosporus extracellular proteases under acidic conditions

Enzymatic hydrolysis of soybean protein isolate by the extracellular proteases from Actinomucor elegans and Rhizopus oligosporus at pH 3.0, 3.5, 5.0, 5.5 and 6.0 was investigated. The activity of the A. elegans protease is lower than that of R. oligosporus, but both proteases exhibit considerable degradation of soybean protein at pH 5.5 and 6.0. The water‐soluble protein content and the degree of hydrolysis of the hydrolysates are increased significantly, and bitterness values are very low. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) reveals that these proteases have different cutting sites on peptide polymers. At pH 5.5, there is a lower content of total free amino acids (39.20 mg per 100 mL; 62.68% hydrophobic amino acids) in the R. oligosporus protease hydrolysate. In conclusion, treatment with R. oligosporus protease at pH 5.5 achieves efficient degradation of soybean protein, suggesting a promising industrial process for making bitterless protein hydrolysates.     

菊粉改善酥性饼干的品质及降低消化速率

可溶性膳食纤维可以抑制淀粉的水解消化,为研究菊粉对饼干品质的影响,通过均匀设计法优化菊粉饼干的配方工艺,并通过模拟人体胃肠道消化过程研究菊粉对饼干消化的影响。结果表明;最佳配方为低筋粉100 g,水20 g,木糖醇15.05 g,菊粉12.60g,油脂(黄油:玉米油=1:1)31 g,小苏打0.5 g,食盐0.5 g。另外,测得菊粉饼干脂肪含量为16.54%,蛋白质3.33%,膳食纤维6.87%,碳水化合物56.63%。通过体外消化模拟结果表明加入菊粉之后,饼干的快消化淀粉含量从14.51%下降到3.06%,慢消化淀粉和抗性淀粉的含量分别增加了3.67%和0.20%,且菊粉饼干的体外消化率低于空白饼干,预测菊粉饼干血糖指数为68.36,属于中等血糖指数食品。故对于高油脂饼干而言,菊粉可以抑制其淀粉的水解消化,降低其血糖指数,菊粉的应用对于开发中低血糖指数产品具有重要意义。     

Heat-induced degradation of inulin

Dry heating of inulin from chicory for up to 60 min at temperatures between 135 and 195 °C resulted in a significant degradation of the fructan ranging from 20 to 100%. The choice of the analytical method has a significant influence on inulin quantification especially in heat-treated samples. The amount of inulin found after thermal treatment measured as fructose after acidic hydrolysis was significantly higher compared with corresponding data obtained with a method based on enzymatic hydrolysis. Using high-performance anion-exchange chromatography with pulsed amperometric detection as well as high-performance thin-layer chromatography, it was found that thermal treatment of inulin leads to a degradation of the long fructose chains and formation of new products, most likely di-D-fructose dianhydrides. These degradation products of inulin are cleavable by acid to fructose monomers, but their glycosidic bonds are no longer accessible for -fructosidase, thus explaining the discrepancies in inulin quantification with respect to the method used. Inulin degradation must be taken into account when fructan is used as a prebiotic ingredient in thermally treated foods like bakery products.