Effect Of Buckwheat Flavonoids On Wheat Starch Properties And Their Interactions

As a plant extract with a variety of physiological functions,buckwheat flavonoids can influence the nutritional,edible and storage quality of wheat starch.In this paper,the effects of buckwheat rutin and quercetin on the properties of wheat starch were studied: including gelatinization characteristics,gel characteristics,retrogradated and digested characteristics,and the ways of they interaction was discussed.Quality and nutritional quality play an important role in laying the theoretical basis for the utilization of functional ingredients in buckwheat.The main conclusions are as follows:The effects of buckwheat rutin and quercetin on the gelatinization characteristics,retrogradated properties and aging properties of wheat starch were studied.From RVA and electron microscopy,it was found that rutin and quercetin slowed the process of wheat starch gelatinization.From RVA,electron microscopy,DSC and agglutination results,the retrogradated rate of wheat starch after adding rutin and quercetin was accelerated.The results showed that rutin and quercetin reduced the viscosity and elasticity of wheat starch gel,and the effect of rutin on the elasticity was higher.The results showed that rutin and quercetin reduced the viscosity and elasticity of wheat starch gel.The results showed that rutin and quercetin reduced the wheat starch gel hardness,and increased the cohesion which showed the increase of gel strength.The results showed that rutin and quercetin could decrease the hardness of wheat starch,Both quercetin and rutin all make wheat starch granules the water absorption capacity increasing,and the effect of quercetin is more.The solubility and swelling strength of wheat starch increased significantly with the addition of rutin,but only high concentration of quercetin could significantly increase the solubility and swelling force.From the results of freeze-thaw stability,the addition of rutin and quercetin increased the water Precipitation rate of wheat starch during freezing and thawing.The results of the transparency measurement showed that the transparency decreased with the increase of rutin and quercetin concentration.The effects of buckwheat rutin and quercetin on the digestion of wheat starch were studied.In the mixed system of rutin or quercetin and wheat starch,the free rutin and quercetin decreased,increased and decreased again with the increase of?-amylase hydrolysis time.With the increase of glucosidase hydrolysis time,The content of free rutin and quercetin increased with the prolongation of hydrolysis time,and it was found that there was interaction between flavonoids and wheat starch granules.Secondly,rutin and quercetin had inhibitory effects on ?-amylase and glucosidase activity.In 0 to 7 days,the rapid digestion of starch was significantly reduced.In 3-7 days,the slow digestion and anti-digestion of starch was significantly increased.The results showed that rutin and quercetin could inhibit the activity of starch digestive enzymes and interact with wheat starch,which could increase the content of resistant starch,decrease the digestibility and inhibit the absorption of wheat starch.Finally,the interaction mechanism between rutin and quercetin and wheat starch was studied.The free content decreased after the gelatinization of wheat starch.The free content of rutin and quercetin changed with the aging time,and the rutin and quercetin increased the size of wheat starch granules,which indicating that two flavonoids can form hydrogen bonds with wheat starch.Rutin and quercetin significantly reduced the pH of wheat starch,and changed the ion distribution and moisture distribution of the mixed system.Except quercetin making amylose and iodine reaction color absorbance significantly decreased,quercetin on amylopectin,rutin made the amylose or amylopectin and iodine color reaction were not significantly changed,which probably because quercetin into the wheat amylose spiral inner cavity through the hydrophobic interaction.X-ray diffraction results demonstrate the above speculation.Raman infrared spectroscopy analysis showed that there is no covalent bond between rutin or quercetin and wheat starch.Therefore,the combination of rutin and quercetin and wheat starch is hydrogen bond and hydrophobic interaction.In addition,the change of ion distribution and water activity of mixed system is also the reason for the change of wheat starch properties.