直链淀粉和支链淀粉在性质方面存在着很大差别。直链淀粉不溶于冷水，热水中

Amylose and amylopectin differ greatly in their properties. Amylose is insoluble in cold water and hot water. The hydrogen bonds formed in the starch granules break, so it is soluble in hot water. The amylose aqueous solution is stable and has weak coagulability. Amylopectin is difficult to dissolve in water, absorbs water and gelatinizes in hot water, the aqueous solution is unstable, and has strong coagulability. Amylose can be made into fibers and films with high strength and good flexibility, but amylopectin cannot. Starch granules are insoluble in general organic solvents, and can only be dissolved in a small amount of organic solvents such as dimethyl salazone and dimethyl formamide. Amylose shows a blue color when it encounters iodine. When heated, the iodine molecule enters the inclusion complex formed in the spiral structure of the starch and disintegrates. The blue color disappears and forms an inclusion compound after cooling. The blue color reappears. This reaction is sensitive. Commonly used for starch inspection. Amylopectin is purple-red when it meets iodine. In addition, the amorphous regions in starch granules have higher permeability and higher chemical activity than crystalline regions. <br>When the starch is heated in cold water, the starch granules start to absorb water and swell. At this time, the starch mainly occurs in the amorphous area. The crystalline area has elasticity and can still maintain the granule structure. When heated to a certain temperature, the granules absorb more water and expand in volume. Larger, the crystal structure disappears and becomes a translucent viscous paste. This phenomenon is called gelatinization of starch. The essence of gelatinization is that water molecules enter the starch granules, destroying the hydrogen bonding association state between starch molecules, and then dispersed in water to form a colloidal solution. The temperature at which starch is gelatinized is called the gelatinization temperature, also known as the gelatinization temperature. Generally, the internal structure of small-grain starch is tight, and the gelatinization temperature is higher than that of large-grain starch. The binding force between amylose molecules is stronger, and the gelatinization temperature is higher. The starch granules from different sources have different structures and different gelatinization temperatures. The table lists the gelatinization temperature of different varieties of starch. Many non-aqueous solvents such as liquid ammonia, formaldehyde, formic acid, chloroacetic acid, dimethyl sulfoxide, etc., because they can destroy the hydrogen bonds between the molecules in the starch granules or form soluble complexes with starch, promote starch gelatinization. Certain chemical reagents such as alkali, salt and alcohol can also reduce or increase the temperature of starch gelatinization and affect the degree of gelatinization.<br>After gelatinized starch is placed for a long time, it is easy to regenerate. The essence of retrogradation is that the movement of gelatinized starch molecules slows down when the temperature is lowered. The branches of amylose molecules and amylopectin molecules tend to be arranged in parallel, close to each other, Hydrogen bonding to recombine the mixed crystallite beam. Its structure is very similar to that of the original raw starch granules, but it is not radial, but is randomly combined. At this time, due to the hydrogen bonding effect, the intermolecular association in the starch paste is very strong, and the synthesis and application of low-viscosity quarter-type cationic starch under water solubility are reduced. Starch paste, amylose molecules have no time to rearrange and form a bundle structure, then form a gel.

直链淀粉和支链淀粉在性质方面存在着很大差别。直链淀粉不溶于冷水，热水中，淀粉颗粒内形成的氢键断裂，因此溶于热水。直链淀粉水溶液稳定，凝沉性弱。支链淀粉难溶于水，在热水中吸水糊化，水溶液不稳定，凝沉性强。直链淀粉能制成强度高、柔软性好的纤维和薄膜，支链淀粉却不能。淀粉颗粒不溶于一般有机溶剂，仅能溶于二甲基亚飒和二甲基甲酞胺等少量有机溶剂。直链淀粉遇碘显蓝色，当受热时，碘分子进入淀粉的螺旋结构中所形成的包合物解体，蓝色消失，冷却后又形成包合物，蓝色重新出现，此反应灵敏，常用于淀粉的检验。支链淀粉遇碘则呈紫红色。此外，淀粉颗粒中的无定形区具有较高渗透性，化学活性较结晶区高。<br>将淀粉置于冷水中加热，淀粉颗粒开始吸水膨胀，此时主要发生在无定形区，结晶区具有弹性，仍能保持颗粒结构，当加热至某一温度时，颗粒吸收水分更多，体积膨胀更大，晶体结构消失，变成半透明粘稠的糊，这种现象称为淀粉的糊化。糊化的本质就是水分子进入淀粉颗粒中，破坏了淀粉分子间的氢键缔合状态，进而分散在水中形成胶体溶液。淀粉发生糊化时的温度称为糊化温度，也称胶化温度。一般小颗粒淀粉内部结构紧密，糊化温度比大颗粒高直链淀粉分子间结合力较强，糊化温度较高。不同来源的淀粉颗粒结构不同，糊化温度不同。表列举了不同品种淀粉的糊化温度川。许多非水溶剂如液态氨、甲醛、甲酸、氯乙酸、二甲基亚讽等，由于它们能破坏淀粉颗粒中分子间的氢键或与淀粉形成可溶性配合物，促进淀粉发生糊化。某些化学试剂如碱、盐和醇等也能降低或提高淀粉糊化的温度以及影响糊化进行的程度。<br>糊化后的淀粉长时间放置容易回生，回生实质就是糊化的淀粉分子在温度降低时分子运动减慢，直链淀粉分子和支链淀粉分子的分支都趋向于平行排列，互相靠拢，彼此以氢键结合，重新组成混合微晶束。其结构与原来的生淀粉粒的结构很相似，但不呈放射状，而是零乱地组合。此时的淀粉糊中由于氢键作用分子间缔合很牢固，水溶解性下低粘度季按型阳离子淀粉的合成与应用研究降，如果淀粉糊的冷却速度很快，特别是较高浓度的淀粉糊，直链淀粉分子来不及重新排列结成束状结构，便形成凝胶体。

There are great differences between amylopectin and amylopectin in properties. Amylose is insoluble in cold water and hot water, and the hydrogen bond formed in starch granules breaks, so it is soluble in hot water. Amylose was stable in aqueous solution and weak in coagulability. Amylopectin is difficult to dissolve in water, and it can absorb water and gelatinize in hot water. Amylose can make fibers and films with high strength and good softness, but amylopectin can't. Starch granules are insoluble in general organic solvents, but only in a small amount of organic solvents such as dimethylsulfoxide and dimethylformamide. When amylose encounters iodine, it appears blue. When heated, the inclusion compound formed when iodine molecules enter into the spiral structure of starch disintegrates, and the blue disappears. After cooling, the inclusion compound forms again, and the blue reappears. This reaction is sensitive and commonly used for starch inspection. Amylopectin is purple red when it meets iodine. In addition, the amorphous area of starch granules has higher permeability and higher chemical activity than the crystalline area.<br>When the starch is heated in cold water, the starch granules start to absorb water and expand. At this time, it mainly occurs in the amorphous area. The crystalline area is elastic and can still maintain the particle structure. When the starch is heated to a certain temperature, the particles absorb more water, expand more in volume, and the crystal structure disappears into a translucent and sticky paste. This phenomenon is called starch gelatinization. The essence of gelatinization is that water molecules enter into starch granules, destroy the hydrogen bond association state between starch molecules, and then disperse in water to form colloidal solution. The gelatinization temperature of starch is also called gelatinization temperature. Generally, the internal structure of small starch granules is compact, and the gelatinization temperature is higher than that of large starch granules. The gelatinization temperature of starch granules from different sources is different. The gelatinization temperature of different kinds of starch is listed in the table. Many non-aqueous solvents, such as liquid ammonia, formaldehyde, formic acid, chloroacetic acid, dimethyl sulfoxide and so on, can destroy the hydrogen bond between molecules in starch granules or form soluble complexes with starch, thus promoting starch gelatinization. Some chemical agents such as alkali, salt and alcohol can also reduce or increase the gelatinization temperature of starch and affect the degree of gelatinization.<br>The gelatinized starch is easy to regenerate after a long time. The essence of retrogradation is that the gelatinized starch molecules slow down when the temperature drops. The branches of amylose molecules and amylopectin molecules tend to be arranged in parallel, close to each other, and combine with each other by hydrogen bond to form a mixed microcrystalline bundle. Its structure is very similar to the original raw starch grain, but it is not radiated, but randomly combined. At this time, the hydrogen bonding interaction is very strong in the starch paste. The study on the synthesis and application of cationic starch based on the water solubility and low viscosity season decreases. If the starch paste is cooled very fast, especially the starch paste with high concentration, the amylose molecules will not be rearranged to form a bundle structure, which will form a gel.<br>