Physicochemical Properties And Heat-moisture Treatment Of Black Rice Starch

Black rice is rich in nutrients and low in price,and the content of starch in black rice is 78.70%.The anthocyanins in black rice have good anti-oxidation and blood fat-lowering effects.In the industry,anthocyanins are often extracted from black rice as natural pigments,but the remaining black rice is simply processed into products such as black rice porridge and black rice beverage,which limits the application of black rice starch to a certain extent.This article uses the black rice in Guangxi as the raw material.In this paper,the extraction process,physicochemical properties and heat-moisture treatment of black rice starch were studied.The main research results are as follows:Optimum conditions for alkali extraction of black rice starch.The effects of lye concentration,solid-liquid ratio and extraction time on the extraction rate of black rice starch were studied by single factor experiment.On the basis of this,the response surface optimization test was carried out to determine the optimal extraction conditions of black rice starch.The conclusion is that the NaOH concentration is 0.42%,the ratio of material to liquid is 1:4.5(g/mL),the extraction time is 4 hours,and the extraction rate of black rice starch is 76.98%.The comparative study on the physical and chemical properties of black rice starch and rice starch.The amylose content of black rice starch is 18.00±0.19%;the starch particle morphology is irregular polygonal structure,the average particle size of black rice starch is 4.39±0.11?m.The solubility and swelling power of black rice starch are higher than that of japonica rice starch at higher temperature.The enthalpy of black rice starch is similar to that of indica rice starch,but the thermal stability of black rice starch is poor.Black rice starch gel hardness and chewiness are better than japonica rice starch and glutinous rice starch,showing better taste,but poor viscosity.Black rice starch has higher content of RDS,low content of SDS and RS,belonging to high RDS content starch.Effect of heat-moisture treatment(HMT)on physical and chemical properties of black rice starch.The transparency,solubility,swelling power and RDS content of black rice starch decreased with the increase of initial moisture content after HMT treatment.The SDS and RS contents of black rice starch increased with the increase of initial moisture content after HMT treatment,and the thermal stability is improved.The RDS content of starch reached the lowest value of 66.04±0.91%when the moisture content was 25%,and the antidigestibility of black rice starch has been strengthened.When the moisture content is 25%,the RDS content of starch after HMT treatment reaches the minimum value of 66.04±0.91%,while the content of SDS and RS is the highest,the anti-digestibility is strengthened.The modified black rice starch is not easy to cause strong fluctuations in blood sugar,which is beneficial to the consumption of diabetics.