Hoover R, Vasanthan T
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada.
Carbohydr Res. 1994 Jan 15;252:33-53. doi: 10.1016/0008-6215(94)90004-3.
Native wheat, oat, lentil, yam, and potato starches were heat treated at 100 degrees C for 16 h at moisture contents between 10 and 30%. The heat treatment did not change granule size and shape. In oat starch, granules were less compactly packed after heat treatment. The X-ray diffraction intensities increased in wheat, oat, and lentil starches, but decreased in potato and yam. The X-ray patterns of wheat and oat starches remained unchanged, while those of lentil, potato, and yam starches became more cereal-like. In all starches, the swelling factor and amylose leaching decreased, being more pronounced in potato. Heat treatment induced complex formation between amylose and native lipids. Differential scanning calorimetry of the heat-treated samples showed a broadening of the gelatinization-temperature range and a shifting of the endothermal transition towards higher temperatures. These changes were more pronounced in potato starch. The gelatinization enthalpy of wheat, oat, and lentil starches remained unchanged, but those of potato and yam starches decreased on heat treatment. Heat treatment increased the 95 degrees C viscosity of wheat starch, but decreased those of oat lentil, potato, and yam starches. In all starches, thermal and shear stability increased after heat treatment. Acid hydrolysis decreased on heat treatment of wheat and lentil starches, but increased in oat, potato, and yam starches. However, in potato and yam starches, the foregoing trend was evident only during the first seven days of hydrolysis. Thereafter, acid hydrolysis was more pronounced in native than in heat-treated starches. The susceptibility towards hydrolysis by porcine pancreatic alpha amylase decreased on heat treatment of wheat and lentil starches, whereas increases were observed for oat, potato, and yam starches. The results indicated that the extent of starch-chain associations within the amorphous regions and the degree of crystalline order are altered during heat-moisture treatment. The magnitude of these changes were found to be dependent upon the moisture content during heat treatment and on the starch source.
将天然小麦、燕麦、小扁豆、山药和马铃薯淀粉在100℃下热处理16小时，水分含量在10%至30%之间。热处理未改变颗粒大小和形状。在燕麦淀粉中，热处理后颗粒堆积不那么紧密。小麦、燕麦和小扁豆淀粉的X射线衍射强度增加，而马铃薯和山药淀粉的X射线衍射强度降低。小麦和燕麦淀粉的X射线图谱保持不变，而小扁豆、马铃薯和山药淀粉的图谱变得更像谷物淀粉。在所有淀粉中，膨胀因子和直链淀粉浸出率均降低，在马铃薯淀粉中更为明显。热处理促使直链淀粉与天然脂质形成复合物。热处理样品的差示扫描量热法显示糊化温度范围变宽，吸热转变向更高温度移动。这些变化在马铃薯淀粉中更为明显。小麦、燕麦和小扁豆淀粉的糊化焓保持不变，但马铃薯和山药淀粉的糊化焓在热处理后降低。热处理提高了小麦淀粉在95℃时的粘度，但降低了燕麦、小扁豆、马铃薯和山药淀粉的粘度。在所有淀粉中，热处理后热稳定性和剪切稳定性均增加。小麦和小扁豆淀粉热处理后酸水解降低，而燕麦、马铃薯和山药淀粉的酸水解增加。然而，在马铃薯和山药淀粉中，上述趋势仅在水解的前七天明显。此后，天然淀粉比热处理淀粉的酸水解更明显。小麦和小扁豆淀粉热处理后对猪胰α淀粉酶水解的敏感性降低，而燕麦、马铃薯和山药淀粉的敏感性增加。结果表明，在湿热处理过程中，无定形区域内淀粉链的缔合程度和结晶有序度发生了改变。发现这些变化的程度取决于热处理过程中的水分含量和淀粉来源。
