Physical Properties Of Rice Starch

Among commercial starches, rice starch finds special application because it has a small granule size and its residual protein is non-allergenic,so exploitation and utilization of rice starch have become the hot topic in the world.In order to exploit rice starch production with high value, there is a great urgency to study the physical property of rice starch. Firstly rice starch is isolated by alkalin steeping, alkaline protease, sodium dodecyl sulfate,combination of neutral protease and high-intensity ultrasound, respectively. Viscosity of rice samples with different amylose contents were studied, and correlation between cooked rice texture and rapid visco analyzer were measured. Protein is second composition of rice . The influence of protein on rice starch viscosity were analyzed. The study was undertaken to examine the of cooking of rice starch in the presence of lauric, palmitic, myristic and stearic acid on complexing index,iodine spectra,solubility,pasting and rheological properties.Differential scanning calorimetry(DSC) was used to evaluate phase transitions of rice flour and starch. Alkali is an important additive in the food. The objectives were to observe the effects of sodium carbonate and sodium hydroxide on the viscosity of rice starch. And the effect of single sugar and double sugar on rice starch viscosity were determined. The calibration model of RVA viscosity properties of rice were established by near Infrared transmission spectrum.The following results were obtained.(1)The protein of rice flour was isolated by four methods. The results showed that alkalin steeping was the best to remove protein.But a lot of water was consumed in the rinse. SDS was able to remove some proteins.But protein contents was high in acquired rice starch.Alkaline protease can be used to recover rice starch from wet-milled rice flour.But Time was too long in alkaline protease assimilation. Combination of neutral protease and high-intensity ultrasound for isolation of rice starch was applied, and acquired rice starch can accord the request of commercial starch. The contents of damaged starch was low.(2)The viscosity profile of rice starch with different amylose contents were measured by RVA. The results showed that rice samples with different amylose contents were able to be differentiated according to setback and breakdown. Similar samples with amylose contents were also able to be differentiated.And this discrepancy is correlation with eating quality of rice. So the excellent and inferior of eating quality of rice samples can be differentiated according to RVA. Textural properties of rice flour gels formed after RVA analyses were determined with a textural analyser.Correlation between amylose contents and RVA index and textural index were significantly different. The change of hardness and adhesiveness of rice flour gels were conform with setback and breakdown of RVA. Gels will be rigid and adhesiveness will small when setback is big.(3)The aim of this study is to determine how protein affect the viscosity curve of rice starch.The results showed that the change of brown rice and milled rice was the same with viscosity curves when proteins are removed.In order to determine the effect of disulphide bonding on viscosity of flour from the varieties,Dithiothreitol(DTT) was added to the flour.The addition of DTT to the RVA test aims to disrupt the disulphide bridges and keep them reduced.DTT lowers the curve and has similar effects with protease. In four storage samples, the curve of two samples with low amylose contents drop and the curve of two samples with high amylose contents ascend.100% propanol was the most efficient solvent for the extraction of prolamin from rice flour.Addition of prolamin to rice starch was found to cause a decrease in peak viscosity,final viscosity, setback viscosity but increase in breakdown and decrease in hardness,adhesiveness and gumminess of the starch gel. The higher the rate of N, the higher the protein content,the lower the overall curve,brown rice and milled rice are the same.(4)The influence were examined about cooking of rice starch in the presence of lauric, palmitic,myristic and stearic acid.The results showed that the complexing index progressively increased with the increase in levels of fatty acids and cooking duration. However, the increase was more pronounced with the addition of lauric acid.Theλmax values of cooked rice starch pastes decreased with the increase in levels of all fatty acids and cooking duration. The 630/520 nm ratio of rice starch paste decreased with increase in the levels of fatty acids and cooking duration. Water-solubility decreased with the increase in level of fatty acids. The decrease was more pronounced with the addition of lauric acid inλmax values, 630/520 nm ratio and water-solubility.The addition of both the fatty acids inhibited the swelling of the rice starch granules and consequently, increased the TG′.Addition of both fatty acids decreased the peak G′, while the addition of lauric acid resulted in a more decrease in peak G′in both the starches.The synersis in cooked rice starch paste increased with increase in storage duration and increased with addition of both the fatty acids.(5)DSC was used to evaluate phase transitions of six rice flours and rice starches with different amylose contents in systems with different water content. The To and TG for flours and starches in the presence of excess of water increased with the increase of amylose contents. The total gelatinization enthalpy was found to be low. The△HG increased with the increase of water content in systems. The△HG was found to be higher in starches than in flours. Both△HG were higher in waxy genotypes than in non-waxy genotypes. The To of flours and starches increased with the increase of water content, while TG decreased with the increase of water content.(6)This study is to determine how the alkalin,sugar and anion affect the viscosity curve of rice starch.The results showed that the addition of Na2CO3 and NaOH resulted in significant decrease in the curve.The viscosity curve of rice starches decreased with the increase of Na2CO3.The addition of signal sugar and double sugar made the viscosity curve drop.The law that anion made rice starch paste was that the stronger alkali property of anions were the easier rice starch to become paste. The order that anion made starch paste is OH—>HOC6H4COO—>SCN—>I—>Br—>CL—>SO62—.(7)One hundred and sixty-four samples of small amount of milled rice were scanned by Foss Tecator Infratec 1255, and their amylose contents , gel consistency and RVA viscosity value were determined by chemistry method. With the WINISI calibration maker software, several mathematics treatments to the sample spectra and several different regression methods were adopted to optimize a good calibration equation for determination of amylose content, gel consistency and RVA viscosity value in milled rice.