In Vitro Digestibility Of Waxy Rice Flour

Waxy rice and the food made from glutinous rice have always been popular among our residents,but there are few studies on the digestibility of two major components of starch and protein in waxy rice.Waxy rice was used as experimental material in this study,method for simulating digestion in vitro was used to determine the digestion characteristics of starch and protein in different varieties of waxy rice flour and analyse the influence of milling methods and ozone dry treatment methods on the digestibility of waxy rice powder,the correlation between the properties and digestibility of waxy rice starch was investigated finally.The result of the starch digestion in vitro of different tapes of waxy rice flour: The digestion trend of each sample starch was consistent.The digestibility reached equilibrium at about 90 minutes of enzymatic hydrolysis,and the digestibility of the samples was 69% ~ 81% after 180 min digestion.The digestibility of Anhui japonica waxy was the highest among the six cultivars,while that of Nanning indica waxy rice was the lowest.The result of the protein digestion in vitro of different tapes of waxy rice flour: The enzymatic hydrolysis of protein in waxy rice occurred mainly in the enzymatic hydrolysis phase of pepsin(0 ~120 min).The proportion of soluble nitrogen in the first 30 minutes increased sharply,and then slowly increased to 40% to 50%.In the trypsin digestion stage(120 ~ 240min),the soluble nitrogen content increased slowly,and finally reached 60% ~ 78%.The release amount of nitrogen is the highest in Anhui japonica waxy and Xinyang indica waxy,while the nitrogen release is the lowest in Nanning indica waxy rice and Yuenan indica waxy,which indicated that the protein was more digestible in Anhui japonica waxy and Xinyang indica waxy rice.In all,Comprehensive analysis found that Anhui japonica waxy starch and protein digestibility are relatively high,easy to digest by the human body.Studies on the content of broken starch,gelatinization and digestion of waxy rice flour under different milling conditions shows that the content of broken starch in the dry grinding process was 1.4 times of that in the wet grinding powder.And it was found the dry grinding method had a greater damage to starch granules through scanning electron microscopy.The value of the peak viscosity,final viscosity,setback and breakdown in dry-grinding waxy rice flour was significantly smaller than those of the wet-grinding,which indicated that the milling method could change the gelatinization characteristics of waxy rice flour.The vitro simulated digestion showed that the final digestibility of dry starch was about 9% higher than that of wet grinding,which indicated that the dry-grinding milling method increased the content of damaged starch in waxy rice,decreased the viscosity of the system,and it was easier to digest with digestive enzymes.Studies on the carboxyl content and digestibility of waxy rice under different ozone treatments indicated that with the prolongation of ozone treatment of glutinous rice,the content of carboxyl groups in waxy rice increased,and the oxidation degree of waxy rice increased.The digestibility of starch in waxy rice flour after gelatinization decreased with the increase of oxidation degree.Compared with the original waxy rice flour,the contents of slow digested starch and resistant starch with health function were significantly increased,but the content of fast digested starch deceased after modification.The digestion trend of starch in non-gelatinized waxy rice flour was opposite,and the starch digestibility of gelatinized waxy rice flour was higher than that of non-gelatinized waxy rice flour.So ozone treatment can improve the digestion of gelatinized waxy rice flour.Study on the structure and properties of waxy rice from four different producing areas suggested the short chain is less and the long chain is more in the branch structure of Vietnam indica waxy rice,while opposite situation appeared in the branch structure of Nanning indica waxy.The order of the average chain length is Yuenan indica waxy,Anhui japonica waxy,Xinyang indica waxy and Nanning indica waxy.The digestibility of four kinds of waxy rice was: Anhui japonica waxy> Vietnamese indica waxy > Xinyang indica waxy> Nanning indica waxy,and the digestibility of the waxy rice starch was higher than that of the corresponding waxy rice starch.Nanning indica waxy starch had the largest crystallinity,and the more starch granule crystal area was,the lower amylase digestion ability was.The content of short chain A in amylopectin is higher in the Nanning indica waxy and the average chain length is shorter,the branching degree is high,and there are more ?-1,6 glycosidic bonds.Therefore,?-amylase is more difficult to act on starch,its resistant starch is the highest.RDS content was in the order of Anhui japonica waxy,Vietnamese indica waxy,Nanning indica waxy,Xinyang indica waxy.Anhui japonica waxy had the smallest degree of crystallinity and the largest dispersion.Compared with the other three kinds of starch,its molecular chain length distribution of the branched chain is relatively average,and it is presumed that the molecular structure is loose and easy to be enzymatically hydrolyzed by amylase.Therefore,the digestion experiment of Anhui japonica waxy starch is faster...