【作者】 钟耕；

【导师】 陈宗道； Romeo Toledo；

【作者基本信息】 西南农业大学 ， 农产品加工与贮藏， 2003， 博士

【摘要】 本文选择葛根淀粉、藕淀粉、木薯淀粉、马铃薯淀粉和玉米淀粉为测试材料，采用现代分析仪器和设备，对淀粉的理化性质和功能特性进行了深入研究，并对当今碳水化合物的研究热点和难点问题，即碳水化合物食品血糖指数的研究，以期在国内开创血糖指数体外测定的操作平台。通过实验表明： （1）在淀粉的颗粒性质方面，藕淀粉具有最大的颗粒度，马铃薯淀粉次之，然后是玉米淀粉和木薯淀粉，葛根淀粉粒的粒度最小。而在淀粉粒粒度分布上，藕淀粉的最宽，而且呈双峰曲线，这对藕淀粉的分离提纯带来一定的难度。马铃薯淀粉粒粒度虽然较大，但粒度分布窄，其它的几种淀粉粒粒度分布呈单峰曲线；各种淀粉粒的偏光十字和形状都表现出其特征性。淀粉粒的表面结构，以马铃薯淀粉和藕淀粉的最为光滑，在木薯、玉米和葛根淀粉表面都存在凹陷点；玉米淀粉和木薯淀粉的晶型为A型，结晶度为37％和36％。马铃薯淀粉和藕淀粉为B型，结晶度分别为25％和23％。葛根淀粉为C_A型，结晶度为18％；马铃薯淀粉糊的透光率最好，有较好的冷稳定性。木薯淀粉糊的透光率次之，而冷稳定性是几种淀粉中最好的。葛根淀粉糊的透光率最差，但在淀粉糊的热、冷稳定性方面都表现的较好；藕原淀粉和马铃薯原淀粉具有较强的抗酶解能力，而木薯和玉米淀粉较差，而葛根淀粉对α-淀粉酶的作用高度敏感；葛根淀粉所需的糊化温度及范围最大，但糊化的热焓较小。而藕淀粉和马铃薯淀粉则相反，糊化的温度和范围较低，但热焓较大。 （2）采用略为改进的Schoch法，能将藕淀粉和葛根淀粉的支、直链淀粉分离分级，得到的组分经SepharoseCL-2B柱层析和碘亲和力测定，纯度高。藕淀粉的支链淀粉分子量较大，且分布比葛根淀粉的宽。藕淀粉的直链和支链淀粉的重均分子量为4.54×10⁶Da和130×10⁶Da，而葛根淀粉的则分别为1.89×10⁶Da和60×10⁶Da。 （3）从分布指数曲线可看出，淀粉凝胶存在着两个明显不同的T₂值域，即所谓的固相和液相；淀粉凝胶的浓度、水分含量不同，其T₂有显著差异（p＞0.05），表明淀粉粒子受热糊化吸水，与淀粉结 西南农业大学二＊＊三届博士学位论文 合的水分子的流动性急剧降低；相同浓度的藕淀粉凝胶的TZ值要大 于葛根淀粉的，即相同浓度的葛根淀粉的老化速度要快于藕淀粉。水 分含量对淀粉凝胶的老化进程有显著的影响。 （4）淀粉受热作用，产生糊化，其中的抗酶解淀粉含量大大降 低，可消化淀粉含量增加。采用蛋自酶和淀粉酶混合作用，水解淀粉， 淀粉在90min内的水解百分率快速升高，而在90－180min则呈缓慢上 升趋势。通过淀粉在 90m i n时的水解百分率和水解指数推算的血糖指 数值表明，不论采用何种热处理方式，颗粒度细小的淀粉食品糊化后 都属于高血糖指数食品。 本论文的创新之处在于：使用了藕淀粉和葛根淀粉为原料，以开 发其在食品业、工业的应用为目的，应用现代分析技术对其理化性质 和功能特性进行了系统的研究。为探讨淀粉在老化速率的表现，在国 厂 内首次采用了CPMG研究淀粉的凝沉，为缓释葡萄糖淀粉的开发进行 了尝试。采用血糖指数体外测定方法，对淀粉在不同处理方式下的体 外消化进行了研究，以期在国内建立碳水化合物食品血糖指数体外测 定操作平台。更多还原

【Abstract】 The physicochemical properties and functional charactrization were determined with the modern analytical techniques for the wild starches from kudzu vine (Puerariu D. C.) and lotus (Nelumbo nucifera Gaertn), and cassava starch, potato starch, and maize starch. And the glycemic index of carbohydrate foods in vitro was estimated also, trying to start the research in this field domestically. The results showed :The average particle size of the lotus starch was much bigger, and the potato starch was the next, but the k.udzu starch was the smallest; there existed some pores on the surfaces of the maize, tapioca, and kudzu starches through the SEM, but lotus and potato starches were with the smooth surface. The lotus and potato starches displayed a B-type X-ray diffraction pattern, C-type for kudzu starch, and A-type for maize and tapioca starches. The kudzu starch was much difficult to be gelatinizated compared to the others, and the potato starch was the easiest one. The cooling stability of the kudzu starch pasta was much better. Lotus and potato starches were more resistant to pancreatic a -amylase hydrolysis than the others, and kudzu exhibited much higher susceptibility to enzymatic hydrolysis.Modified Schoch method was used to fractionation the kudzu starch and lotus starch, and highly purified amylose and amylopectin from starches were obtained. Light scatter was used to investigate the weight average molecular weights (Mw) for both amyloses and amylopectins of starches. Results from the gel permeation chromatography (GPC) showed the molecular weights for lotus amylose and amylopectin was found to be larger than those of kudzu and maize starches, and the amylopectin molecular weight had a wider distribution in the GPC profile. The similar results for kudzu starch were gained compared tomaize starch, but had a narrow amylopectin molecular weight distribution in the GPC profile. The amylose weight average molecular weights for lotus and kudzu were 4.54 × 106Da and 1.89 × 106Da,separately, while for amylopectins were 130 × 106Da and 60 × 106Da.The effect of water on kudzu and lotus starches retrogradation at 5℃ was studied using *H NMR relaxometry. Gels were made from starches at 25%, 33%, and 40%. Changes in the transverse relaxation time constant (T2) were related to water mobility. Mono-exponential studies showed that, in general, more water retarded starch retrogradation. Distributed exponential studies showed that two distinct regions of T2 were observed in all samples. During aging, the peak values of both regions shifted to lower values for all the gels. Kudzu starch samples showed the most significant shift, and lotus showed the less. For all the samples, the signal intensity of the less mobile region decreased more dramatically than that of the more mobile region during storage.A direct method to quantify the change of resistant starch and an in vitro method to estimate the changes of hydrolysis rate (H), hydrolysis index (HI), and reckoned glycemic index were used in the experiment. The results shown the contents of digestible starches went up apparently, and the resistant starches reduced significantly after heat treatments. The hydrolysis rate for all the starches including lotus starch, kudzu starch, potato starch, tapioca starch, and maize starch, increased under three kinds of heat treatments, that is cooking, microwaving, and heat-pressuring, especially for the microwave. The glycemic index for the heat-treated starches were bigger than 100, and these starch foods were in the range of high glycemic index.Some innovations in the dissertation were as follow: In order to fully utilize the wild starches in food and other industries, that is, lotus starch and kudzu starch from Chongqing, China which were studied firstly, the modern analytical techniques exclusively in starch wereused to investigate the physicochemical and functional properties systematically. CPMG was used domestically to estimate the retrogradation property of starch, and to explore the slow glucose-releas更多还原