为了改善马铃薯脱水制品的干燥工艺,该文以薄层干燥试验为基础,研究了不同热风温度(40、50、60、70、80、90℃)、风速(0.5、1.0、1.5、2.5、3.5 m/s)和切丁长度(2.5、5、10、15 mm)对马铃薯全粉的糊化特性的影响.采用扫描电子显微镜和差示扫描量热仪对马铃薯全粉的微观结构和糊化特性进行分析,并测定了其吸水性.研究表明,糊化焓值可以表征马铃薯全粉的糊化水平,焓值越高,糊化水平越低;糊化起始温度的范围为62.31~64.96℃,终止温度的范围为70.16~74.19℃,比纯淀粉制品糊化温度高;高于糊化温度进行干燥时,淀粉不会完全糊化;0.5~2.5 m/s风速干燥的样品糊化焓值没有显著差异(P>0.05),3.5 m/s干燥的样品焓值显著小于其他风速干燥样品;马铃薯全粉焓值随切丁长度增大而显著减小(P<0.05);不糊化样品吸水性没有显著差异(P>0.05),吸水性随糊化程度的增强而显著增强;热风干燥条件为温度70℃,风速1.0 m/s和切丁长度10 mm时,马铃薯全粉的糊化程度较低.研究可为热风干燥制备未糊化的马铃薯全粉提供理论基础.%In early 2015, Ministry of Agriculture put forward the strategy that potato is classified as the fourth staple food and transferred into popular principal food suitable for dietary habit in China. Even though the China's potato production ranks the first in the world, the sustainable development of potato processing and consuming is still extremely restricted due to the following reasons: The percentage of potato deep processing remains low; the processing products of potato are single, and have low nutrition and add value; and the potato products as staple food suitable for our dietary habit are in lack. Potato flour is one of prime products in potato deep-processing, and hot air drying has been widely used in the drying for agricultural products because of its easy operation, low cost and simple requirements for environment, court and equipment. The potato gelatinization characteristics affect the reproducibility of dehydrated products of potato. The more highly gelatinized the potato, the worse the reprocessing property, and the more difficult the application of potato as China's principle cooking food. Therefore, it has an important significance to the research of the effects of the hot air drying conditions on the gelatinization characteristics, the drying technology of dehydrated potato products and China's strategy of potato as staple food. Based on thin-layer drying experiment, the paper researched the influence of different temperature (40, 50, 60, 70, 80, and 90℃), different air velocity (0.5, 1.0, 1.5, 2.5 and 3.5 m/s) and different dicing length of fresh-cut potato (2.5, 5, 10 and 15 mm) on potato flour gelatinization quality. Microstructure and gelatinization quality of potato flour were analyzed with the use of scanning electron microscopy (SEM) and differential scanning calorimeter, and the water-absorbing capacity was measured. The results showed that gelatinization enthalpy could represent the degree of potato gelatinization; the lower the gelatinization enthalpy, the lower the degree of gelatinization; the range of initial gelatinization temperature was 62.31-64.96℃, and the range of termination temperature was 70.16-74.19℃, which was higher than the gelatinization temperature of pure starch product; the starch was not completely gelatinized when drying under the temperature higher than gelatinization temperature; the samples dried under the air velocity of 0.5-2.5 m/s showed no significant difference in gelatinization enthalpy (P>0.05), while the gelatinization enthalpy of the samples dried under the air velocity of 3.5 m/s was significantly smaller than that under other air velocities; the enthalpy of potato flour decreased significantly with the increase in dicing length (P<0.05); ungelatinized samples showed no significant difference in water-absorbing capacity, and water-absorbing capacity was strengthened as the degree of gelatinization got higher; the gelatinization degree of potato dehydrated products was low when the hot air drying was under the temperature of 70℃, the air velocity of 1.0 m/s and the cutting length of 10 mm. This research can provide theoretical basis for the production of ungelatinized potato flours with hot air drying method.
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