成熟度对渝甜糯玉米淀粉颗粒形态及理化特性的影响

Effect of Maturity on Structure and Physical and Chemical Properties of Yutian Waxy Corn Starch

以不同成熟度渝甜糯玉米为材料,采用扫描电子显微镜、X射线衍射仪、傅里叶红外光谱仪、差示扫描量热仪、布拉班德黏度仪等考察成熟度对渝甜糯玉米淀粉颗粒形态和理化特性的影响。结果表明:渝甜糯玉米淀粉颗粒形状为圆形和多角形,随着成熟度的增加,多角形颗粒的数量逐渐增多;渝甜糯淀粉为A-型结晶淀粉,其2θ在15.15°、17.50°、23.00°附近,随着成熟度增加,淀粉结晶晶粒的X衍射强度增大,淀粉结构由吡喃型α-型葡萄糖构成;成熟度对渝甜糯玉米淀粉相变起始温度(To)、相变高峰温度(Tp)、相变终止温度(Tc)和相变热焓(ΔH)的影响不大,To在70.00～72.00℃范围内,Tp在74.90～76.80℃范围内,Tc在80.90～83.40℃范围内;布拉班德黏度曲线显示,授粉后25d采收的渝甜糯玉米淀粉峰值黏度最大,授粉后23d采收的渝甜糯玉米淀粉糊的热稳定性较好,以授粉后30d采收的渝甜糯玉米淀粉的冷稳定性最好。

The structure, physical and chemical properties of Yutian waxy corn with different degrees of maturity were determined by scanning electron microscope, X-ray diffraction, Fourier transform infrared spectrometer, differential scanning calorimeter and Brabender Viscometer. The results showed that the granules of Yutian waxy corn starch had a round or polygonal shape, and the number of polygonal particles increased with the elevated maturity. Yutian waxy starch presented A-type crystalline structure and the 2θ values were around 15.15°, 17.50° and 23.00°. With rising maturity, the diffraction intensity of starch granule crystalline increased. The structure of Yutian waxy corn starch consisted of pyrantype α-type glucose. Thermal properties showed minimum differences in To, Tp, Tc and ΔH among the 5 degrees of maturity. To ranged from 70.00 to 72.00 ℃, Tp from 74.90 to 76.80 ℃ and Tc from 80.90 to 83.40 ℃. Brabender viscosity curves showed that the starch from waxy corn collected 30 d after pollination contained the highest content of amylopectin while the starch from waxy corn collected 25 d after pollination had peak viscosity. The starch from waxy corn collected 23 d after pollination had good thermal stability whereas the best cold stability of waxy corn starch was obtained 30 d after pollination.