| Quinoa has high and comprehensive nutrition,is rich in amino acids,high-quality proteins and bioactive substances such as polyphenols,flavonoids,saponins,and has physiological functions such as promoting intestinal health,preventing diabetes,and anti-inflammatory.The varieties and output of Quinoa are increasing substantially due to the rapid development of the quinoa industry.Quinoa starch is the main carbohydrate in quinoa.Studying the properties of quinoa starch is conducive to the development of the quinoa starch industry,and then increasing the added value of quinoa products.In this study,four kinds of quinoa grains such as Haili,Geermu,Gannan and Jingle were used as test materials.Wet grinding method was used to extract quinoa starch,and maize starch and potato starch were used as controls.The structural and physicochemical properties of starches were analyzed,and the relationship between structural and physicochemical properties of different starches were systematically expounded.To optimize the nano-modification conditions of quinoa starch granules and to analyze the characteristics of starch nanoparticles.The main conclusions are as follows:(1)Quinoa starch granules were irregular polygons with uniform size distribution,and the average particle size was 1.21～1.95μm,which belonged to small granular starch.The amylose content was 9.43%～10.90%,which contained a large amount of short amylopectin.Quinoa starch has an A-type crystal structure with the crystallinity of 21.00%～29.67%.The crystal order and the content of double helix structure were lower than those of maize starch and potato starch.(2)Solubility of quinoa starch was lower than that of maize starch and potato starch,and the swelling power was lower than that of potato starch and slightly higher than that of maize starch.The degree of shear-diluted of quinoa starch paste was lower than that of maize starch and potato starch.It was easier for quinoa starch paste to restore the original structure after shearing.Quinoa starch paste had better springiness,cohesiveness,resilience and lower hardness,and quinoa starch paste had better gumminess and chewiness than maize starch but worse than potato starch.The freeze-thaw stability of quinoa starch paste was higher than maize starch but not as good as potato starch.The light transmittance of quinoa starch paste was obviously lower than that of maize starch and potato starch,and it was not easy to retrogradation.The enzymatic hydrolysis rate and was RDS content of quinoa starch were significantly higher than maize starch and potato starch,and in vitro digestibility is high.(3)The concentration of DMSO solvent,dosage of ethanol,the mode of dispersion and interaction significantly all affected the average particle size and PDI of quinoa starch nanoparticles(QS-NPs).The optimal preparation condition was 90% solvent concentration,10 times the volume of ethanol,and ultrasonic vibration dispersion mode,the average particle size of QS-NPs was significantly smaller than that of maize starch nanoparticles(MS-NPs)and potato starch nanoparticles(PS-NPs).The morphology of QS-NPs particles were round and spherical,with smooth surface and uniform distribution.QS-NPs had a V-type starch crystal structure.The crystallinity is lower than that of the original starch,the crystal structure was enhanced.The solubility and swelling power,water absorption and oil absorption of QS-NPs are obviously higher than that of original starch,and higher than that of MS-NPs and PS-NPs.(4)The loading rate of quercetin by QS-NPs was significantly higher than that by PS-NPs and MS-NPs,which was suitable for adsorbing active substances.The average particle size of quinoa starch nanoparticles loaded with quercetin(QS-NPs-Q)was relatively uniform with 855 nm.The original V-type crystal structure of starch nanoparticles loaded with quercetin was disappeared,and the crystallinity was increased,the solubility and swelling power were significantly reduced,the enzymatic hydrolysis rate decreased and the growth was slow.The degree of shear-diluted of starch nanoparticles loaded with quercetin were higher than that starch nanoparticles.The degree of QS-NPs-Q was the most obvious,and the original structure was not easy to recover after high-speed shearing.QS-NPs-Q prolonged the time of DPPH · free radical scavenging,which can effectively hinder the contact of quercetin with free radicals to protect quercetin’s biological activity. |
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