槲皮素对挤压大米淀粉结构及功能特性的影响

Effects of quercetin on the structure and functional properties of extrusion rice starch

为改善挤压大米淀粉的功能特性,以米粉为主要原料,探究了不同槲皮素(quercetin,Q)添加量(0~10%)在挤压场下对米粉中淀粉的水溶性、吸水性、糊化特性等功能特性的影响。在此基础上,借助扫描电子显微镜(scanning electron microscopy)、X-射线衍射、红外光谱、及紫外可见光分光光度计揭示了Q在挤压场下对淀粉结构的演变规律。试验结果表明:当Q添加量为4%时,样品的吸水指数、碘结合能力均达到了最大值,且自由水弛豫时间提前;挤压体系中Q与淀粉通过氢键结合,颗粒结构变得更加立体、紧凑。与挤压米粉相比,槲皮素的添加延缓了淀粉的回生且提高了淀粉的热稳定性。根据以上结果可知,挤压体系中Q与大米淀粉复合,促进了淀粉分子链重排,进而改变淀粉的结构及功能特性,该研究可为开发抗回生的挤压大米淀粉基产品提供理论依据。

The properties of starch are determined by its own multiscale structure.Appropriate modification has also been adopted to regulate its properties in the multiscale structure of starch.Extrusion processing can be expected to apply in the food manufacturing industry,due to its continuous production,easy operation,green environmental protection,and safety.The mixing,stirring,crushing,shearing,and thermal effects generated by extrusion can be used to destroy the original structure of starch,and then induce the starch molecules for the new structure and properties.Among them,polyphenol has been added into the starch system as small molecules with physiological activity function in recent years.The hydrophilicity of starch molecular,hydrogen bond and van der Waals force interacted to promote the evolution of starch multi-scale structure for better properties.The polyphenol-starch-based foods have also been applied to increase the nutritional properties of foods.New functional foods can be produced to prevent and treat diseases,such as hyperglycemia.The polyphenols can dominate the structure of rice products and the product properties.This study aims to investigate the functional and structural properties of quercetin(Q)on the formation of complexes of rice(R)under the extrusion field.Q was also added(0-10%)into the rice.Scanning electron microscopy(SEM),X-ray diffraction(XRD),infrared spectroscopy(FTIR),rapid viscosity analyzer(RVA),differential scanning calorimeter(DSC),and Ultraviolet visible spectrophotometer were carried out to characterize the structural properties.Furthermore,a systematic investigation was implemented to explore the effects of Q on water solubility index(WSI),water absorption index(WAI),and particle size of the complexes.The experimental results showed that the relaxation time of T23 was advanced significantly when the Q concentration was 4%.The starch crystal structure was damaged by extrusion,compared with the R,thus leading to the WAI and WSI of ER increased significantly(P<0.05).The DSC results showed that the heat absorption peak outstandingly disappeared in the range of 57.88-76.39℃.The crystallinity of starch was destroyed to depolymerise the double-helix orderly arrangement structure.The FTIR results showed that the characteristic absorption bands of benzene ring bond stretching appeared in 1519.59 and 1320.15 cm−1.The XRD results showed that a new crystal structure appeared near 27.4°with the addition of Q,and the relative crystallinity increased from 8.31%to 16.81%.Meanwhile,the smaller particle size of E-QR was obtained,compared with the ER.The morphological results showed that the Q was attached to the surface of the complex,indicating more three-dimensional and compact particles.The iodine binding capacity showed that the Q inhibited the recrystallization of starch,and then delayed the regeneration of amylose,compared with the ER.The setback of E-4%QR decreased by 23.16%.In summary,the hydroxyl group of Q was tightly bound to starch via hydrogen bonding.The recrystallization of starch was inhibited to promote molecular rearrangement,thus leading to the modified structural and functional properties of starch.This finding can provide a theoretical basis for the development of new rice products.