Study On The Impacting Factors Of Water Absorption Of Waxy Rice Flour

The purpose of this paper is to study the impacting factors of water absorption of waxy rice flour:studying on the influence of different producing areas of water absorption of waxy rice flour; studying on the influence of different particle size distribution of water absorption of waxy rice flour; studying on the influence of different processing methods of water absorption of waxy rice flour; studying on the influence of damaged starch rate of water absorption of waxy rice flour. It can provide theoretical basis for the production and storage of tangyuan.Firstly, this paper studied the influence of water absorption of waxy rice flour from different producing areas, measured the basic ingredients(moisture, ash. starch, protein, fat) of five varieties of waxy rice flour and consistence thermal and chemical properties(gelatinization peak viscosity, gelatinization starting temperature). Waxy rice flour protein content is about7%(w/w, dry base); Crude fat content is between0.7%～1.1%(w/w, dry base); Starch content is as high as90%(w/w, dry base); Ash content focused on0.18%-0.27%(w/w, dry base). The basic ingredient of different regions have differences. The starch is the major component of waxy rice flour, then, the protein content is higher. Consistence thermal and chemical properties of different varieties of rice is also different, gelatinization peak viscosity is1381CP～1381CP, gelatinization starting temperature from65.2℃to83.1℃, the lowest gelatinization viscosity from372CP to1230CP.Secondly, preparing different granularity of waxy rice flour use different mesh number of standard test sieves. Waxy rice flour was determined by particle size laser particle size distribution, in order to study the effect of particle size to the water absorption of waxy rice flour. The mesh number of standard test sieve is bigger, the granularity of powder is smaller, as the fine particle powder of the transmittance is better. According to particle size distribution, trends are consistent between0～10μm of four kinds of particle size (120,150,180,200) waxy rice flour. Trends increase as the number of standard sieve test between10～200μm, when abscissa of the reach peak increases. Waxy rice flour water absorption rate is negative correlation with the particle size.With the decrease of the particle size, specific surface area of the particles, the corresponding slip angle and the angle of repose increases, lead to better liquidity of the flour. The characteristics of particle’s adsorption and aggregation increased the power of surface convergence.Thirdly, preparing various waxy rice flour in three different ways of processing. Determinate the basic composition of the sample. Electron microscopy is used to observe different samples of waxy rice flour particle morphology, Results showed that the waxy rice flour processing mode has much effect on the protein content. Different processing methods for waxy rice flour have little impact on starch content. Using scanning electron microscopy is to observe microstructure of three processing ways of waxy rice flour. The results show obviously that the damage of waxy rice flour particle after dry grinding is very big. The quality of waxy rice flour which is prepared by wet milling of frozen vacuum drying is superior than other two ways. It shows that wet water absorption of the flour prepared by wet milling frozen vacuum drying is maximum based on the study of water absorption of waxy rice flour prepared in three different processing methods. Considering the economic factors, wet milling drum wind drying is more suitable for industrial production.Lastly, studying the effect of damaged starch rate to the waxy rice flour water absorption. Controling the number of grinding makes samples with different damaged starch content. Determination the water absorption rate of each sample by particle size ratio. Results show that the rate of broken starch waxy rice flour increase with the corresponding water absorption. It may be that water absorption of the damaged starch is higher than the one of intact starch.