Physicochemical Properties And In Vitro Digestibility Of Tartary Buckwheat Starch Modified By Heat Moisture Treatment

In this study Tartary buckwheat(Fagopyrum tataricum Gaertn)has been used as material to study the physicochemical properties of Heat Moisture-Treated starch.As a kind of medicinal and edible crop,Tartary buckwheat has been recognized by people.With the nutritional advantages of Tartary buckwheat,it is considered as raw material for functional foods and medicines.As consumers become more interested in food choices,the awareness of healthy eating food has become very evident.Similarly,the food industry is eager to meet these needs by producing foods and food ingredients that not only maintain nutrition but also promote health and safety.Resistant starch has received much attention for both its potential health benefits and nutritional benefit.Resistant starch positively influences the functioning of the digestive tract,microbial flora,blood cholesterol level,the glycemic index and assists in the control of diabetes.Apart from the potential health benefits of resistant starch,another positive advantage is its lower impact on the food sensory properties compared with traditional starches.With the recent pursuit of a healthy diet,other sources of natural food ingredients are sought to supplement traditional staple foods,which have been used as energy for many years.Tartary Buckwheat is a promising new source of resistant starch because the starch produced has a miscellaneous range of physicochemical structural and thermal properties with a wide range of industrial application prospects.In this study,original starches were isolated from Tartary buckwheat flour to be modified using the Heat Moisture Treatment method.Based on physical and chemical properties as well as the effect of HMT on starch digestibility of Tartary buckwheat starch in contrast to sorghum,broomcorn millet,and common buckwheat resistant starch was prepared and analyzed for the difference.Native and HM-treated starches granular morphology,pasting properties,thermal characteristics,textural characteristics,water solubility,and swelling power were investigated.Besides,in vitro starch digestibility was conducted to study the effect of HMT on starch hydrolysis.The main results were as follows:(1)By comparing the physicochemical properties of original starches,HM-treated starches displayed lower values of water solubility and swelling power.These characteristics providing good handling during processing and providing brittleness,expansion,and upgraded texture in the final product.With the use of heat moisture treatment,peak viscosity,hold viscosity,breakdown,final viscosity,and setback viscosity were also decreased while thermal properties were increased significantly.The analysis showed that HMT could produce starch which is more resistant to heat treatment as well as mechanical shearing.(2)Using a scanning electron microscope(SEM),the structures of the four HM-treated starches were similar.Their original form was disappeared after HMT,forming a three-dimension form and larger size.Their granular structure was destroyed,and they presented an irregular and gravelly shape,with a rough surface and clear coated undulation.(3)Tartary buckwheat modified starch(MTB)granules presented an irregular shape with rough surface which had no significant difference between common buckwheat(MCB),sorghum(MS)and broomcorn millet(MBM).Moreover,there was no significant difference between tartary buckwheat and common buckwheat for their solubility and swelling power,which were higher than that of sorghum and less than for broom corn millet.Compared to common buckwheat and broom corn millet,The pasting viscosity and starch gel hardness of MTB was significantly lower.And finally,there was no significant difference in thermal properties among all tested modified starch.(4)Taking into account starch digestibility,starch hydrolysis has greatly affected HMT.The amount of SDS(Slowly Digestible Starch)and RS(Resistant Starch)were slightly increased in both modified starch which in turn reduced RDS(Rapidly Digestible Starch).Tartary buckwheat displayed the highest amount of RS of 13.56% followed by broomcorn millet(11.31%)and common buckwheat(9.75%)and lastly sorghum 8.4%).