直链淀粉与支链淀粉的分离方法

按照溶解度差异和分子特性差异两种分离原理，直链淀粉与支链淀粉的分离方法分别有温水抽提法、配合剂分离法、盐类分离法、控制结晶法以及色谱法和纤维素吸附法等。对这些方法进行了综述及分析比较。     

葛根直链淀粉和支链淀粉分离纯化的研究

用重结晶的方法对葛根淀粉中直链淀粉和支链淀粉组分进行分离和纯化，并利用碘亲和力测定，凝胶过滤层析，Ｘ－射线衍射等方法对产品的纯度进行了鉴定。结果表明通过重结晶８次可得到完全纯化的葛根直链淀粉；反复３次加入正丁醇去除残留的直链淀粉可得到完全纯化的葛根支链淀粉。     

芋头淀粉的分离和纯化

用重结晶法可以得到纯度较高的芋头直链淀粉和支链淀粉。直、支链淀粉的蓝值分别是1 1 8和 0 2 0 ,λmax分别为 61 4nm和 5 87nm ,芋头淀粉中直链淀粉含量为 1 4 7%。高效液相色谱表明 ,芋头支链淀粉的分子质量具有较宽的分布 ;重均聚合度 ,大米支链淀粉 >芋头直链淀粉 >大米直链淀粉 >芋头支链淀粉 ;分散度 ,芋头支链淀粉 >芋头直链淀粉 >大米直链淀粉 >大米支链淀粉 ;芋头支链淀粉中 ,长支链所占比例 >短支链 ;分散度 ,长支链 >短支链。     

马铃薯直链淀粉与支链淀粉的分离方法

以马铃薯淀粉为原料,运用稀碱溶液对淀粉进行快速分散,采用稀盐溶液沉淀支链淀粉进行初分,再以正丁醇螯合直链淀粉,经四次重结晶,成功地分离了马铃薯的直链淀粉与支链淀粉,产品纯度用其碘络合物的紫外可见扫描图谱与凝胶过滤色谱进行了证实。     

马铃薯直链/支链淀粉的分离

将从新鲜马铃薯中分离出来的淀粉配置成1.33％(m/V)的水溶液,经高压灭菌锅121℃蒸煮180 min后,采用正丁醇螯合直链淀粉.将样品置于泡沫箱中过夜缓慢冷却后,再通过离心(8700g,30 min)实现直链淀粉与支链淀粉的分离.过量的甲醇(两倍于支链淀粉溶液体积)添加到浓缩的支链淀粉溶液中将支链淀粉沉淀,随后通过...     

一种快速分离稻米淀粉主成份的方法

本文选用了７个不同品质的水妥品种为供试材料，探索出一种快速稳定的分离稻米淀粉两种主要组份－直链淀粉和支链淀粉的方法，即用０．１ｍｏｌ／ＬＮａＯＨ溶液处理，分离和Ｉ２－ＫＩ溶液染色。不同水稻品种，其直链淀粉呈现兰色的深浅不一致，与直链淀粉含量呈正相关。     

红薯直链淀粉的分离纯化和检测

以红薯淀粉为原料，在糊化和未糊化条件下采用碱液分散法对原淀粉进行分级，对提纯后的直链淀粉样品进行了分析；采用除去蛋白质和脂类的原淀粉进行浸提，可以大大提高产物的纯度，产品的纯度用其碘络合物的紫外可见光扫描图谱进行了证实。同时测得红薯直链淀粉含量16．12％。     

粉葛直链淀粉与支链淀粉分离工艺研究

以粉葛为原料,对粉葛中直链淀粉和支链淀粉的分离工艺进行了研究。根据直链和支链淀粉的理化特性及结构的不同,采用正丁醇-异戊醇配合物沉淀法对粉葛直链和支链淀粉进行粗分离,再经正丁醇重结晶得到较纯的直链与支链淀粉,讨论了分离前对淀粉进行预处理、纯化次数、分离过程中离心时间对分离效果的影响。通过对淀粉-碘复合物光吸收特性分析和蓝值比较,表征分离得到的直链与支链淀粉的纯度。结果表明:直链淀粉纯化5次、支链淀粉纯化6次、分离前经过预处理、支链淀粉纯化时离心时间和速度为30min,5 000r/min的条件下,光谱分析测得的最大吸收波长和蓝值都落在直链淀粉与支链淀粉文献报道结果的相应数值范围内,表明此时分离效果最佳,正丁醇结晶法分离的直链和支链淀粉纯度较高。     

慈菇淀粉分离纯化及其支链淀粉分子结构研究

本研究采用正丁醇法对慈姑支链淀粉与直链淀粉进行分离,Sepharose 2B凝胶层析表明支链淀粉得到纯化。采用酶法分析了慈姑支链淀粉的分子结构,结果表明慈姑支链淀粉的平均链长(CL)为22,其中外链长(ECL)为14,内链长(ICL)为7。异淀粉酶和普鲁兰酶依次作用于慈姑支链淀粉的β-极限糊精,计算得支链淀粉A链与B链比值为1.33:1.0,分支化度为2.33。     

热线法测量食品热导率的实验研究

在食品材料的热导率的测量中,热线法是一种比较理想的方法。本文在介绍热线法的同时,运用自行研制的热线法导热系数测量仪对一些食品材料的热导率进行了测量。并将实验得到的数据同一些经验公式进行了对比,重点研究了食品中的水分对食品材料的热导率的影响,并得到了食品材料的热导率和其含水率关系的经验公式。     

非稳态热线法测定大麦的导热系数

将一根细长的线性热源埋于自然堆积的大麦中 ,通过一套由稳压电源、电位差计、电流表等二次仪表组成的测试装置 ,测定热线的升温速率 ,然后根据非稳态法热线测定的理论模型 ,计算出不同含水率大麦的导热系数。结果显示 ,在常温下 ,含水率在 10 %～ 2 6 .5 3%间的大麦的导热系数在 0 .1344～ 0 .192 1W/m·K之间 ,与其含水率呈现一定的相关性     

Wet Method for Measuring Starch Gelatinization Temperature Using Electrical Conductivity

ABSTRACT:  The objective of the present study was to develop a method for obtaining the gelatinization temperature of starches by using electrical conductivity. Native starches from corn, rice, potato, and wheat were prepared with different proportions of water and heated from room temperature to 90 °C, in a device especially designed for monitoring the electrical conductivity as a function of temperature. The results showed a linear trend of the electrical conductivity with the temperature until it reaches the onset gelatinization temperature. After that point, the electrical conductivity presented an increment or decrement depending on the water content in the sample and it was related to starch swelling and gelatinization phenomena. At the end gelatinization temperature, the conductivity becomes stable and linear, indicating that there are no more changes of phase. The starch gelatinization parameter, which was evaluated in the 4 types of starches using the electrical conductivity, was compared with those obtained by using differential scanning calorimeter (DSC). The onset temperature at which the electrical conductivity increased or decreased was found to be similar to that obtained by DSC. Also, the final temperature at which the electrical conductivity returned to linearity matched the end gelatinization temperature of the DSC. Further, a wet method for measuring the onset, peak, and end gelatinization temperatures as a function of temperature using the electrical conductivity curves is presented for a starch–water suspension.     

Reference Materials for Calibrating Probes Used for Measuring Thermal Conductivity of Frozen Foods

Reference materials which contained either 8% or 10% bentonite pastes and very fine pure copper powder (300 mesh, 30–.55%), provided thermal conductivities ranging from 0.9 to 1.9 W/mK. These materials were used to calibrate probes for measuring thermal conductivity of frozen food materials. Thermal conductivity values measured by the steady-state (parallel plate) method, the unsteady-state heat transfer (heating curve) method, and the probe method agreed within 5%. Although experimental density and heat capacity data of copper-filled bentonite pastes agreed with a mass average value of component properties, measured thermal conductivity values were much lower than the volume fraction average values.     

温度和纤维状态对热线法导热系数测试的影响

探讨采用热线法测量纤维材料的导热系数时,测试温度和纤维状态对导热系数的影响。在纤维排列方向与热线方向平行和垂直状态下,测试了不同温度时碳纤维、玄武岩纤维、芳纶纤维、芳砜纶纤维的导热系数以及碳纤维织物的导热系数。结果表明:在测试温度范围内,纤维导热系数随温度升高而升高;纤维排列方向显著影响导热系数,垂直时测得的导热系数大于平行时的值;当热线与经纱平行时,在一定温度范围内,纬向紧度显著影响碳纤维织物的导热系数。认为采用热线法测得的导热系数与温度和织物紧度有关。     

Physical Basis for Separation of Rice Starch using Various Density Gradient Systems and its Effect on Starch Recovery,Purity, and Pasting Properties

A 32% waxy and non waxy rice flour slurry containing starch‐protein agglomerates was physically disrupted in presence of water by use of high pressure homogenizer called Microfluidizer®. Microfluidized rice flour slurry from passes 2 and 4 was collected followed by isolation of starch using three different density gradient solutions/systems (CeCl, NaCl/sucrose and ZnSO₄·7H₂ O). Complete deagglomeration was obtained after passing the rice flour slurry four times through the Microfluidizer®. The recovery of isolated starch varied from 76.28% to 91.20% for different density gradient systems. The degree of deagglomeration did not seem to affect recovery but affected the purity of the isolated starches. All starches produced from pass 4 rice slurry resulted in starches with residual protein below 0.5%. Higher density of the gradient solution resulted in higher recovery and purity of starch. The isolation method had a significant effect on the pasting properties of the isolated starch. Residual protein in isolated starch had a negative correlation with peak viscosity and setback of pass 2 waxy and nonwaxy starches. The salts were retained in purified starch despite rigorous washing (at least 75 times greater than the control) and could affect starch properties.     

自然发酵对淀粉凝胶的改性机理及发酵菌株的筛选

采用凝胶过滤层析法研究整粒大米自然发酵后淀粉分子质量分布的变化 ,探讨发酵对淀粉凝胶改性的机理。发现发酵后淀粉大分子降解 ,中等及小分子质量淀粉比例增加 ,分子质量大小趋于均匀 ,从而使淀粉分子易于接近聚合而增强了淀粉凝胶性能。对发酵样品的显微观察发现 ,淀粉粒结构并未破坏 ,因而淀粉溶出损失很小 ,初步认为是微生物所产酶和酸渗入颗粒内部作用的结果。通过对自然发酵菌株的分离筛选获得 3株酵母、5株细菌、2株霉菌。经过工艺试验认为 ,自然发酵主要是酵母菌作用的结果。研究结果可为进一步提高传统发酵类淀粉凝胶食品如馒头、发酵型米粉的品质、改良产品工艺开拓新的途径。     

Intrinsic Thermal Conductivity of Starch: A Model-independent Determination

Effective thermal conductivities of two-phase mixtures of potato or soluble starch granules with pure liquids or aqueous solutions (thermal conductivities in the range 0.169–0.602 W.m^?1.K^?1) were measured at 18.5±2.2°C using the steady state method. Measured values were compared with the thermal conductivities of the liquids and the results indicated a range of 0.38–0.40 W.m^?1K^?l for intrinsic thermal conductivity. Similar measurements, at temperatures up to 50°C for soluble starch (to assess the temperature dependence of the intrinsic thermal conductivity) indicated no significant change over the range of temperature studied for mixtures with pure liquids.     

食用型化学变性淀粉性质研究

该文综述常见化学变性如乙酰化、羟丙基化和交联处理对淀粉物理化学、形态学、热力学等性质影响;且探讨影响淀粉变性效率因素,如淀粉种类、颗粒结构、变性试剂类型和用量等,通过选择合适变性试剂和淀粉原料可生产出具有良好应用效果食品用变性淀粉。     

Thermal Conductivity of Liquid Foods by the Thermal Comparator Method

The thermal comparator is shown to be a rapid, accurate method for determining the thermal conductivity of liquid foods. Increasing solids content decreased thermal conductivity for apple juice concentrate, orange juice concentrate, and milk samples. Equations for predicting the thermal conductivity of apple juice, orange juice, and milk are shown to be specific for each commodity. A comparison of apple juice and orange juice suggests that qualitative attributes of the solids fraction as well as the quantity present are important in determining thermal conductivity.