温度对支链淀粉脱支重结晶特性的影响

Effect of Temperature on the Recrystallization Characteristics of Branched Amylopectin

DOI：10.3969/j.issn.1673-1689.2020.01.004

中文关键词: 支链淀粉 普鲁兰酶 重结晶 相对分子质量分布

英文关键词: amylopectin,pullulanase,recrystallization,molecular weight distribution

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中文摘要:

利用普鲁兰酶对完全糊化的支链淀粉酶解脱支12 h再经过湿热处理（101 kPa，121 ℃）2 h，分别在4、25 （常温）、30、40 ℃重结晶2 d。通过将重结晶液离心分离的上清和沉淀两组分进行多方面表征和综合分析，从而认识温度对支链淀粉脱支后在水溶液自组装过程的影响。采用扫描电镜（SEM）、动态光散射、高效液相色谱法、X-射线衍射法、傅立叶红外光谱仪、热重分析仪，分析不同温度对重结晶上清和沉淀的形貌、相对分子质量分布、结晶结构、热性质等方面的影响。结果显示：重结晶沉淀得率随着温度升高呈降低趋势；扫描电镜照片显示上清存在淀粉分子且颗粒比沉淀的大，低温上清液形态为特殊片状和少量圆棒状；X-射线衍射表明所有的样品显示相似的强衍射峰，在经过脱支、凝沉处理之后显示 B 型结晶，40 ℃则转化为B+V 型混合结晶结构。热重分析可知，沉淀和上清的失重最快温度比原淀粉降低，热稳定性降低；从相对分子质量分布图谱可以看出，重结晶完成后上清和沉淀中淀粉分子相对分子相对分子质量均变大，且随温度升高不同组分含量升高。

英文摘要:

In this paper，the pullulanase was applied to hydrolyze and debranch the amylopectin samples that fully gelatinized for 12 hours，then，the resulting samples underwent heat-moisture treatment（101 kPa，121 ℃） for 2 hours. After these procedures the products were kept static for recrystallization for 2 days at 4，25(room temperature），30，40 ℃，respectively. For each sample，two parts of the supernatant and the precipitate were obtained by centrifugation，and then characterized and comprehensively analysed for the effect of the temperatures on the self-assembly processes of debranched amylopectin in aqueous solution. The effects of the temperatures on the morphologies，molecular weight distributions，crystalline structures，thermal properties of supernatant and precipitation samples with different temperature treatments were studied using Scanning electron microscopy（SEM），dynamic light scattering（DLS），high performance liquid chromatography（HPLC），X-ray diffraction，Fourier transform infrared spectroscopy（FTIR） and thermogravimetric analyzer（TGA），respectively. Results showed that the yield of recrystallization precipitation decreased as the temperature increased. SEM indicated that the starch molecules in the supernatant were larger than that in the precipitates. The morphology of the particle in the low temperature supernatant was flaky and a part of them were in a state of round bars. X-ray diffraction results demostrated that all the crystals of the precipitate had similar and strong diffraction peak. After debranching and recrystallization treatments，the B-type crystal was transformed into the B-V-type one at 40 ℃. TGA analysis suggested that the fastest temperature of weightlessness from precipitation and supernatant were lower than that from the native starch，and the thermal stability decreased accordingly. As displayed in distribution curves，the molecular weight of the starch molecules in both the supernatant and the precipitate increased after recrystallization，and the content of different components increased with the increase of temperature.

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