【作者】 刘娜；

【导师】 彭强； 王敏；

【作者基本信息】 西北农林科技大学 ， 工程硕士（专业学位）， 2019， 硕士

【摘要】 荞麦（Buckwheat）属蓼科（Polygonaceae）荞麦属（Fagopyrum）假禾谷植物,是一种药食同源的粮食作物。苦荞（Fagopyrum tataricum Gaertner）作为荞麦主要的栽培品种之一,富含芦丁、槲皮素等多酚物质,其突出的抗氧化、降血脂、降血糖等保健功能引起了国内外学者的广泛关注。在苦荞麦加工过程中,苦荞淀粉与黄酮类物质发生的相互作用会影响苦荞麦制品的理化性质和功能特性,但其影响规律及机制尚不清楚。本文以苦荞淀粉和槲皮素为试验材料,探究水热条件下制备苦荞淀粉-槲皮素复合物的最佳工艺,并分别制备槲皮素浓度为2.5%、5.0%、7.5%、10.0%的苦荞淀粉-槲皮素复合物,采用扫描电子显微镜（SEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）等技术分析苦荞淀粉-槲皮素复合物的结构特性,研究不同复合程度对苦荞淀粉的老化特性、流变学特性、消化特性等的影响,探讨不同复合程度的苦荞淀粉-槲皮素复合物的结构特性变化规律,以期为苦荞麦功能性产品的开发与生产提供参考依据。主要研究结果如下:（1）本研究中苦荞淀粉-槲皮素复合物的最佳制备工艺为:糊化温度70℃;料液比1:10;槲皮素浓度10.0%;共糊化时间1.5 h;预糊化时间10 min,该条件下苦荞淀粉与槲皮素复合率可达37.3%。此外,随槲皮素添加量的上升,复合率呈上升趋势,其中槲皮素浓度为2.5%、5.0%和7.5%时,苦荞淀粉-槲皮素的复合率为26.8%、31.4%、和35.1%。（2）在本研究制备的复合淀粉中,槲皮素主要通过氢键与苦荞淀粉的表面结合。SEM结果显示,槲皮素附着在苦荞淀粉颗粒表面,随着槲皮素浓度的增加,更多的槲皮素融合在淀粉颗粒上,并增加了淀粉颗粒间的交联;XRD图中无V型特征峰存在,但在2θ=27.5o处有特殊峰,说明槲皮素并未与苦荞麦直链淀粉的螺旋内腔结合,仅与直链淀粉的螺旋外侧以及部分支链淀粉复合;苦荞淀粉-槲皮素复合物的FT-IR谱图中无新峰出现,但随槲皮素浓度的增加,3500³000 cm^-1处峰的拉伸变得更宽,说明氢键是两者结合的主要作用力。槲皮素浓度从0.0%增加到7.5%时,苦荞淀粉-槲皮素复合物的分解温度从310℃升至318℃,说明槲皮素的添加可以提高淀粉体系结构的稳定性。（3）在本研究中,槲皮素的浓度对苦荞淀粉的理化性质有不同的影响。随着槲皮素添加量的提高,苦荞复合淀粉的透明度持续下降,槲皮素浓度低于5.0%时可加快苦荞淀粉透明度的下降,而槲皮素浓度高于5.0%时结果相反,因此可通过增加槲皮素的浓度来保持苦荞淀粉的透明度。此外苦荞淀粉与槲皮素间的复合还可显著性降低淀粉的溶解度、膨胀度和吸水率,同时增加淀粉的冻融稳定性和吸油率,说明苦荞淀粉与槲皮素间的相互作用可以提高淀粉的加工性能。糊化后的苦荞淀粉是假塑性流体并具有剪切稀化现象,苦荞淀粉与槲皮素间的复合提高了苦荞淀粉的稳定性、抗剪切性、弹性和黏性,其中当槲皮素浓度为10.0%时,苦荞淀粉显示出最高的抗剪切特性。（4）在本研究的实验条件下,苦荞淀粉与槲皮素间的复合会抑制苦荞淀粉的消化,复合率越高抑制作用越明显。其中复合率从26.8%到37.3%（槲皮素浓度从2.5%增加到10.0%）时,与预糊化淀粉相比,苦荞淀粉-槲皮素复合物的消化率降低3.0¹3.4%,快速消化淀粉（RDS）含量降低2.3¹2.7%,抗性淀粉（RS）的含量升高3.1¹3.5%。上述结果说明,苦荞淀粉与槲皮素在共糊化过程中发生了以氢键为主要作用力的复合。其复合程度与淀粉预糊化时间、共糊化时间、温度、槲皮素浓度和料液比都有直接关系,并显著影响苦荞淀粉的加工和消化性质。在本研究的实验条件下,与预糊化淀粉相比,苦荞淀粉-槲皮素复合物的热稳定性、抗老化和抗消化性增强,这为苦荞及其淀粉类食品开发的最佳原料配比提供了参考依据。更多还原

【Abstract】 Buckwheat is a pseudo-grass plant of genus Fagopyrum in the buckwheat family,belongingtograincrop.InChinese medicinedictionary,it’s calledas“drug homologous food”.Fagopyrum tataricum Gaertner is one of the main cultivars of buckwheat and rich in polyphenols such as rutin and quercetin.It attracts wide attention due to its health functions such as antioxidant,hypolipidemic and hypoglycemic.During the processing of Tartary Buckwheat,the interaction between Tartary buckwheat starch and flavonoids can affect its physicochemical property and functional characteristics,while the mechanism is still unclear.In this thesis,Tartary buckwheat starch and quercetin were used as experimental materials,so as to explore the optimum hydrothermal conditions for the preparation of Tartary Buckwheat starch-quercetin composite.In order to provide reference for the development and production of functional products of Tartary buckwheat,Tartary Buckwheat Starch-Quercetin composite with quercetin concentration of 2.5%,5.0%,7.5%and 10.0%were prepared,its structural characteristics were analyzed via scanning electron microscopy（SEM）,X-ray diffraction（XRD）,Fourier near infrared spectroscopy（FT-IR）,and the effects of different compound degree on the aging,rheological and digestive characteristicsofTartarybuckwheatstarchweredetermined.The main contributions of this work were as follows:（1）The optimum preparation process of Tartary Buckwheat starch-quercetin composite was as follows:reaction temperature was 70℃;the solid-liquid ratio was 1:10;concentration of quercetin 10.0%;water bath time was 1.5 h;pre-gelatinization time was 10 min.Under above condition,the composite rate of Tartary buckwheat starch and quercetin was 37.3%.In addition,with the addition rate of quercetin increased the recombination rate increased.Among them,the complex ratio of quercetin to tartary buckwheat starch-quercetin was26.8%,31.4%and 35.1%,when quercetin concentration was 2.5%,5.0%and 7.5%.（2）In this study,quercetin bound to the surface of Tartary buckwheat starch through hydrogen bond.The SEM results showed that quercetin attached to the surface of Tartary buckwheat starch granules.With the increase of quercetin concentration,more quercetin fused with starch granules,which increased the cross-linking between starch granules.There was no V-type characteristic peak in XRD,but there was a special peak at 2θ=27.5o,indicating that quercetin did not combine to the inner helix of amylose from Tartary buckwheat,but only recombine to the outer helix of amylose and some amylopectin.In FT-IR spectra,no new peaks appeared in Tartary Buckwheat starch-quercetin composite,but with the increase of quercetin concentration,the stretching of peaks at 3500³000 cm^-1became wider,indicating that hydrogen bond was the main interacting force.When the quercetin concentration increased from 0.0%to 7.5%,the decomposition temperature of the Tartary buckwheat starch-quercetin composite increased from 310℃to 318℃,suggesting that the addition of quercetin could improve the stability of starch structure.（3）During processing,the transparency of Tartary buckwheat starch continued to decline.When the concentration of quercetin was lower than 5.0%,the decrease of transparency of Tartary buckwheat starch was accelerated.When the concentration of quercetin was higher than 5.0%,the result was opposite.Therefore,the transparency of Tartary buckwheat starch could be maintained by increasing the concentration of quercetin.In addition,the combination of Tartary buckwheat starch and quercetin could significantly reduce the solubility,swelling and water absorption of starch,and increased the freeze-thaw stability and oil absorption of starch,indicating that the interaction between Tartary buckwheat starch and quercetin could inhibit the aging,dissolution and expansion of Tartary buckwheat starch.The Tartary buckwheat starch after gelatinized was pseudoplastic fluid with the shear-thinning nature.The compound of tartary buckwheat starch and quercetin improved the stability,shearing resistance,elasticity and viscosity of Tartary Buckwheat starch.When the concentration of quercetin was 10.0%,Tartary buckwheat starch showed the highest shearing resistance.（4）In this study,the compound of Tartary buckwheat starch and quercetin could inhibit the digestive characteristics of Tartary Buckwheat starch,and the higher the degree of compound,the more obvious for the inhibition.When quercetin concentration increased from2.5%to 10.0%,compared with pre-gelatinized starch,the digestibility of Tartary Buckwheat starch-quercetin composite was decreased by 3.0-13.4%,rapidly digestible starch（RDS）content was decreased by 2.3-12.7%,and resistant starch content was increased by3.1-13.5%.The above results indicate that hydrogen bond was the main acting force between co-gelatinization of Tartary buckwheat starch and quercetin during.The degree of compounding was directly related with time,temperature,quercetin concentration and pre-gelatinization time,and significantly affected the processing and digestive characteristics of Tartary Buckwheat starch.Compared with the pre-gelatinized starch,the Tartary buckwheat starch and quercetin composite had higher thermal stability and non-aging,which was difficult to digest.This provided basic support for development of Tartary Buckwheat food.更多还原