Analytical time series alignment liquefaction number of corn starch mixture

Abstract

The statistical description of the development of dynamic processes in time is carried out using time series. To eliminate random fluctuations and build an analytical function of the trend of the time series, an analytical alignment procedure is used. The choice of the type of the trend function is carried out by the method of finite differences, the calculation of the trend parameters ‒ by the method of least squares. The purpose of this work was the analytical alignment of the time series of the liquefaction number of the corn starch mixture obtained in the experiment on the PChP-99 device. The mechanism of starch gelatinization with a given liquefaction rate under such conditions requires additional theoretical and experimental study. Calculations have shown that the process of liquefaction of starch gel corresponds to the exponential trend equation: y = a • ebt, which is a particular case of an exponential trend. It has been experimentally established that an increase in the proportion of amylopectin starch in a corn starch mixture leads to an increase in the maximum viscosity of the resulting gel when the swelling water-starch suspension is heated. In the process of further gelatinization of corn starch mixture with an increase in the proportion of amylopectin starch, the strength of the gel decreases due to the preservation of the mobility of water molecules during the transition in the sol-gel system, which contributes to an increase in liquefaction number. Experimental data do not contain anomalous values; the error in approximating the regression equation for the trend of the time series is less than 5 %. The statistical significance of the coefficients of the linearized trend equation is proved in favor of the hypothesis of the existence of a time series. The obtained estimates of the regression equation make it possible to use it for predictive purposes, providing an accuracy of up to 95.42 % of the total variability of the liquefaction number in the absence of autocorrelation of first-order residues. Checking the normality of the distribution of the residual component according to the RS test showed the adequacy of the trend model, the hypothesis of the absence of heteroscedasticity according to the Spearman and Goldfeld-Quandt tests is accepted.