Effect Of Milling Processes On Quality Of Rice Flour

The research take rice mixture (Vietnamese rice, H518,) mixing in a proportion, as a raw material; studied in the processing methods,(semi-dried milling, wet milling, dry milling) on the influence of physical and chemical properties(particle size distribution, pasting properties, thermal properties, rheological properties) of milled flour and its application in the production of rice flour used to make steamed rice cake. The study has greatly practical significance for making full use of rice and improving its added value.Earlier analysis of rice from different soak conditions, the results showed as follows:1、The moisture content of rice resulted in different rice quality, different soak time, different soak temperature and different ratio of water and rice. At normal temperature, in soak time 2 hours, the ratio of water and rice,1 to 1, the moisture content of rice has reached its saturation point and decreased in damaged starch content. Based on this,So the moisture content of rice should be controlled directly in the target level after soak procession to weaken the effects from other factors.2、Set up different targets of moisture content:16%,20%,24%,28%,30%, watering according to the calculation in addition, in soak time 24 hours, the moisture content of the rice reached its target; the aim to control the moisture content of the material rice was achieved before grinding, and then different rice flours were obtained in different types of grinders. Compare the powder-obtained rate, the damaged starch content, whiteness, acidity, and thermal properties of these rice flours from different machines, the results showed that the omnipotent 28% of semi-dry milling was the finest,so as to the omnipotent 28% and the whirlwind 28% has higher flour rate and lower damaged content.Universal 28% white degree is higher, more stable in the heating process, the thermal characteristics of the two similar,Combined with laboratory conditions, the final choice of rice by conditioning to 28% water by high-speed universal grinder grinding as the best dry powder legal system process.3、Rice are used to obtain the flour in different procession, that is wet milling, dry milling, semi-dry willing and the different powder qualities are compared, including their particle morphology, damaged starch content, whiteness, hydration characteristics, molecular structure, pasting properties, thermal properties, rheological properties, etc. Experimental results show that:the semi-dry rice flour in many properties is close to the wet milling powder Whiteness 73.79Wb wet milling close to the resulting semi-dry rice Whiteness 72.98Wb. Damaged starch content of wet milling is 2.41%, and damaged starch content of semi-dry rice flour is 2.81%, so they are similar; when the temperature is 25 ℃, the absorbent (WAI), water soluble rate (WS) and swelling (SP) of wet milling is the smallest, the corresponding values are 2.98,2.47%,3.18, the corresponding value of semi-dry rice flour after tempering is closer to that of wet milling than dry milling. Through Fourier transform infrared detection, peak wavelengths of three different processes rice flour are substantially the same, that is to say, mechanical forces and different process do not destroy their molecular structure, and there is no other new molecules, the peak of semi-dry and wet are greatly similar, But at the same wavelength, light transmittance of wet is much higher than that of the other two, and the transmittance of semi-dry is similar to dry. Peak viscosity, valley viscosity, attenuation, final viscosity and setback of wet milling are all the lowest; while the values of semi-dried milling are the highest. As a result, peak time and pasting temperature are close to and significantly higher than that of dry milling, which illustrates the different milling processes greatly affect their pasting properties. Starting temperature is of semi-dry rice flour is the highest, but its ending temperature is the lowest. However, enthalpy value is significantly lower than that of the wet milling, which means that wet milling and dry milling are easy pasting, and the degree of crystal ordering wet milling is the highest. The numerical differences illustrate the different milling processes greatly influence its thermal properties. All derived indicators of semi-dry rice flour are close to that of wet milling; both processes are much better than dry powder process as well.4、The applications of the three big rice to rice steamed sponge cake production, rice steamed sponge cake was made by the exquisite lovely appearance, colour and lustre is white and transparent, followed its original colour and lustre, tempting fermentation bouquet, internal cellular but smaller aperture, smooth taste, sweet and sour moderate, good flavor, but a sticky, compared with the market of Hunan Province rice steamed sponge cake still has certain gap, but more joint Jiangsu, Zhejiang provinces and other places.