马铃薯果胶流变特性的研究

以马铃薯果胶(potato pectin extracted by chelating agent,PPCH)为研究对象,研究果胶溶液质量分数、剪切速率、温度、pH、金属离子等因素对马铃薯果胶流变学特性的影响.研究表明,PPCH溶液的黏度随溶液质量分数上升而增加.随着剪切速率的增大,PPCH溶液黏度下降,剪切变稀现象随...     

响应面试验优化阿魏酰基脂肪酰基结构酯合成工艺及产物稳定性

利用响应面试验对在溶剂体系中脂肪酶Lipozyme RM IM催化玉米胚芽油与阿魏酸酸解制备阿魏酰基脂肪酰基结构酯的反应条件进行优化。在摇床转速为220 r/min的条件下,选取投料比（阿魏酸与玉米胚芽油质量比）、反应温度、反应时间3 个因素作为考察对象,以阿魏酸转化生成阿魏酰基脂肪酰基结构酯的得率为考察指标,运用Design-Expert软件的星点设计功能进行试验设计并对结果进行分析。结果表明,3 个因素均为影响阿魏酸酯化的显著因素;经响应面分析可确定最优值为投料比8.9∶1（g/g）、反应温度76.0 ℃、反应时间28.1 h。该条件下的平均得率达59.1%,与响应面拟合方程的得率预测值58.8%吻合良好。在煎炸过程中新制备的结构酯产生较低的聚合物,同时其具有较高的贮藏稳定性。     

羊奶脂肪酶特性的研究

对影响羊乳脂肪酶活性的温度、pH以及金属离子进行了研究。结果表明,羊奶中脂肪酶在37℃时活性最高,在40⁵0℃时具有较高的热稳定性;羊奶脂肪酶最适pH为6.5,在pH5.0⁶.5时稳定性较高;Ca2+和Fe2+对脂肪酶具有激活作用,而K+、Zn2+、Cu2+、Mn2+和Mg2+对脂肪酶具有抑制作用,低浓度的Al3+和Fe3+对脂肪酶活性具有抑制作用,而高浓度的Al3+和Fe3+对脂肪酶具有激活作用。      

单甘酯对马铃薯淀粉物化特性的影响

考察分子蒸馏单甘酯(MON)对马铃薯淀粉(PS)糊的流变特性、淀粉凝胶析水特性及其硬度的影响,并借助差示扫描量热仪(DSC)和扫描电子显微镜(SEM)方法,分析PS与PS-MON的热特性和凝胶微结构的变化。结果表明:添加MON可显著提高PS的起始糊化温度、最大黏度值下的温度和糊化过程的焓值;显著降低淀粉糊的最大黏度值和凝胶老化过程的析水率(P<0.05);并增强凝胶内部结构的致密性,提高淀粉老化凝胶的硬度(P<0.05)。     

响应面优化溶剂体系酶催化阿魏酸乙酯与甘二酯酯交换合成阿魏酰基脂肪酰基结构脂

在异辛烷体系中,通过Novozym 435脂肪酶催化阿魏酸乙酯与甘二酯酯交换反应,以得到阿魏酰基脂肪酰基结构脂。利用Design Expert 8.0软件对响应面进行设计,通过对响应面实验优化和分析得出,3个因素对EF转化率影响大小顺序为:反应时间>加酶量>反应温度。并确定在此体系下酶法催化双硬脂酸甘二酯酯交换合成阿魏酰基脂肪酰基结构脂的最佳工艺条件为:反应温度67℃,反应时间18 h,加酶量11%,在此工艺条件下,可得到阿魏酸乙酯转化率为79.4%,亲脂性产品阿魏酰基脂肪酰基结构脂得率为60.0%。     

马铃薯辛烯基琥珀酸淀粉酯的制备研究

以马铃薯淀粉为原料,研究了水相法制备辛烯基琥珀酸淀粉酯的工艺条件。探讨了反应时间、反应温度、酸酐稀释倍数、碱用量、淀粉乳浓度及酸酐用量等因素对产品取代度的影响,并通过正交试验确定了最佳工艺参数,即:OSA用乙醇稀释5倍,淀粉乳含量35%,反应温度35℃,pH8.0,反应时间3h。在此工艺条件下,产品取代度可以达到0.017。用电镜扫描观察了淀粉颗粒形态,初步证明了酯化反应主要发生在颗粒表面的无定形区,并未改变其晶型。     

微波对马铃薯淀粉特性影响的研究

采用DM2500P偏光显微镜、NDJ-5S黏度仪、RVA研究微波处理对马铃薯淀粉的特性的影响。结果表明:原淀粉颗粒呈椭圆形,而微波作用后的淀粉的颗粒结构被破坏,外形为不规则颗粒、纤维状;马铃薯原淀粉糊和微波淀粉的表观黏度随剪切速率的增大而降低,呈剪切稀化现象;微波淀粉的剪切应力和剪切速率的变化呈正相关;马铃薯原淀粉的糊化温度为64.5℃,峰值黏度是11491cp,保持黏度为3105cp,最终黏度是3653cp;微波马铃薯淀粉的RVA糊化黏度曲线中未出现明显的峰值黏度,微波淀粉保持黏度为232.00cp,最终黏度是578.00cp。     

辛烯基琥珀酸马铃薯淀粉酯的制备条件研究

以马铃薯淀粉为原料,采用单因素和正交实验方法研究湿法工艺制备马铃薯辛烯基琥珀酸淀粉酯,从淀粉乳的初始浓度、反应温度、酸酐浓度、pH和时间五个方面研究马铃薯辛烯基琥珀酸淀粉酯最佳制备工艺。其结果为:淀粉乳浓度40%、温度30℃、pH7.5~8.0、酸酐浓度5%。      

胆盐水解酶的研究现状

阐述了胆盐水解酶(BSH)的功能、特性以及对宿主微生物产生的影响;介绍了胆盐水解酶基因、基因调节及同系物;讨论了胆盐水解酶未来研究方向和应用的前景。     

胆盐水解酶的分离纯化与部分特性研究

为了给胆盐水解酶结构分析及降低血液胆固醇的机理研究提供理论基础,采用硫酸铵分级沉淀、透析、阴离子交换树脂层析等方法对分离自我国传统开菲尔粒中的1株干酪乳杆菌KTx(lactobillus casei KTx)产生的胆盐水解酶进行了纯化,并对其部分特性进行了研究.结果表明在70%的硫酸铵条件下酶蛋白能最大程度地沉淀.采用DEAE-Sepharose Fast Flow阴离子交换树脂层析,流速1.0 mL/min,用0.1 mol/L NaCl-50 mmol/L磷酸缓冲液(pH 6.5)洗脱,比活力可达到115(AU/mg),是原粗酶液的17倍.纯化后的样品经SDS-PAGE电泳,初步确定了胆盐水解酶的分子质量约30 kDa.该酶的最适反应温度35℃,最适pH 6.0,最适反应底物浓度6mmol/L,酶促反应动力学常数4.57 mmol/L.抑制剂对此酶的抑制作用强弱顺序依次为尿素＞SDS＞EDTA.Al3 对此酶的激活能力最强,其次是Fe3 ,Zn2 对酶活无激活作用.     

Effects of trypsin inhibitor on plasma antioxidant activity and lipid levels in mice from sweet potato roots

BACKGROUND: Several inflammatory diseases are thought to be related to oxidative injury and reactive oxygen species have been proposed as important causative agents of heart disease and ageing. This study was designed to investigate the effects of sweet potato trypsin inhibitor (SPTI) on antioxidant enzymes, lipid peroxidation and lipid profiles in mice. RESULTS: Twenty mice were randomly divided into four groups and fed with TI (10, 50 and 100 mg kg^?1 BW) as treatment and with saline as a control in addition to regular diets. After 35 days, Trolox equivalent antioxidant capacity (TEAC), triglyceride (TG) and cholesterol levels in plasma and superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx), thiobarbituric acid reactive substances (TBARS) in liver were measured. Serum from the group that had received the the highest oral dose of SPTI (100 mg kg^?1 BW) had the highest total antioxidant activity (expressed as 3.59 ± 0.237 mmol L^?1 TEAC). The SOD, catalase and GPx activity of SPTI groups were significantly increased compared with the control group. Malondialdehyde (MDA) was significantly lower in all experimental groups compared with the control one. No significant differences in the concentration of low‐density lipoprotein (LDL)‐cholesterol was found, but high density lipoprotein (HDL)‐cholesterol, triglyceride (TG) and total cholesterol tended to decrease. CONCLUSION: This study showed that the oral intake of SPTI in mice may trigger inflammatory responses which result in an increase in antioxidant enzyme activities, and a decrease in MDA, TG and total cholesterol, which are known risk factors of inflammatory and heart disease. Copyright © 2008 Society of Chemical Industry     

Measurement of antioxidative activity in metal ion‐induced lipid peroxidation systems

This study aims to investigate the acceleration effects of various prooxidants on linoleic acid peroxidation and to assess the feasibility of applying these model systems by measuring the antioxidant activities of butylated hydroxyanisole (BHA), α‐tocopherol and rosemary extracts. According to our results, Fe²⁺ and Fe³⁺ exhibited more stimulatory effects than other prooxidants on the peroxidation of linoleic acid. An additional amount of ascorbic acid can reduce Fe³⁺ to Fe²⁺, resulting in more severe peroxidation. However, ascorbic acid displays antioxidant activity with increasing concentration. The peroxidation of linoleic acid induced by Fenton reaction is less than that induced by iron ions and was increased by addition of ascorbic acid to the system to maintain the regeneration of Fe²⁺ and the production of hydroxyl radicals. BHA shows the strongest inhibitory effects on the peroxidation of linoleic acid in all systems. The antioxidant activity of α‐tocopherol is less than that of rosemary extracts in the iron ion‐induced peroxidation systems. However, α‐tocopherol shows stronger inhibitory effects than rosemary extracts in the Fenton reaction‐induced peroxidation system at a concentration less 100 mg kg⁻¹. These systems can be useful in screening antioxidants from natural sources because of the short reaction time and clear difference between each antioxidant. © 1999 Society of Chemical Industry     

甘薯淀粉性质及所制粉丝品质的研究

采用差示扫描量热仪（DSC）、动态流变仪、物性测试仪研究了不同甘薯淀粉的理化性质、糊化温度及流变特性等,并比较了不同甘薯淀粉所制粉丝的品质。     

造纸系统环境对胶黏物沉积性能的影响

通过检测添加胶黏物模型物的纸浆中大胶黏物含量、个数、平均面积以及分析其滤液的阳离子需求量、浊度和纸浆滤水性来确定造纸系统环境的变化对胶黏物沉积性能的影响。实验结果表明,随着温度的升高,纸浆中大胶黏物含量、个数、平均面积均呈上升趋势,单位时间滤水量下降即纸浆滤水性下降,滤液的浊度和阳离子需求量增加;在酸性或碱性环境下胶黏物易于失稳沉积,纸浆滤水性及滤液性能也相对较差。在添加模型物后的纸浆中加入不同的金属离子后,与Al3+和Na+相比,添加Mg2+和Ca2+对胶黏物的絮聚和沉积影响较大,而金属离子对纸浆滤水性及滤液性能影响相对较小。     

pH对紫甘薯色素呈色及紫外可见吸收光谱的影响

研究了常用食品酸碱度范围内,pH对紫甘薯色素呈色及紫外可见吸收光谱的影响。结果表明,在不同pH下,紫甘薯色素呈现不同的色调、不同的紫外可见吸收光谱,两者变化显著并表现出类似的趋势。在pH2.0~8.0范围内,随着pH的升高,色素溶液的颜色由红色逐渐过渡到紫色,最后变成蓝色。在紫外可见光区域,随着pH的升高,紫甘薯色素在237、530nm附近的特征吸收峰逐渐向长波方向移动。      

马铃薯淀粉的物化性质研究

研究马铃薯淀粉的组成、颗粒形貌、粒径大小及溶解度与膨润力、透明度、凝沉性、糊化方面的性质,并与绿豆、玉米淀粉进行比较.结果表明,马铃薯淀粉的蛋白质含量为0.27%, 直链淀粉含量为20.4%,颗粒为椭圆形,平均粒径为40 μm;马铃薯淀粉的溶解度与膨润力较高;马铃薯淀粉的透明度为66.8%,凝沉性高于豆类淀粉,峰值黏度为2 000 BU.     

Effect of temperature on lipid‐derived volatile compounds in boiled potato during storage

BACKGROUND: The aroma of boiled potatoes is greatly appreciated by consumers. Although it is formed by 150 volatile compounds, only a few seem to actually contribute to the characteristic aroma. In addition, potatoes have to be stored at a low temperature after harvest to guarantee a year‐round supply. However, even at low temperatures, tuber volatile composition is modified during storage. The aim of the present study was to investigate the effect of storage temperature on boiled potato volatile constituents, mainly focused on lipid‐derived components, by considering different varieties stored at 4 °C and 8 °C. RESULTS: It was found that fewer lipid‐derived components were obtained when the potato tubers were stored at 4 °C rather than 8 °C. Specifically, the amounts of 2,4‐decadienal isomers and hexanal increased with the storage time, particularly at 8 °C. Similarly, pentanal and nonanal, which are autoxidation products, occurred to a greater extent at higher temperatures. In contrast, the levels of sugar‐derived compounds, in general, increased during storage at 4 °C rather than 8 °C as a result of higher content of sugars at low temperature. CONCLUSION: The effect of storage temperature on lipid‐derived volatile components in boiled potato appears to depend on the variety studied. Generally speaking, lower temperatures during storage promote sugar content and, as a consequence, sugar‐derived products. At the same time, lower temperatures result in less lipid oxidation and, therefore, a fewer lipid‐derived compounds. Copyright © 2009 Society of Chemical Industry     

脂肪酰基氨基酸钠表面活性剂的表面活性及与高分子化合物的相互作用

对自制脂肪酰基氨基酸钠系列表面活性剂的表面性能、泡沫性能进行了测试,研究了高分子化合物对月桂酰基甘氨酸钠溶液性能的影响.结果表明:此类表面活性剂具有较好的表面活性和优良的起泡稳泡性能.非离子型的高分子化合物与表面活性剂之间存在相互作用,非离子型高分子化合物PVA或PEG的加入使表面活性剂溶液的cmc有所增大,但高分子电解质CMC加入使其略有下降.高分子化合物对表面活性剂溶液表面张力的影响不明显.