Starch is a major source of energy in the human diet. Starch granules are mainly composed of glucose-based molecules: amylose (AM) and amylopectin (AP), and some minor components (protein, phosphorus and lipid). Besides being a major source of calories, starch is also one of the most multifunctional raw food ingredients in industry, being used as a product thickener; texture improvement agent, fat replacer, and mouth feel enhancer. The qualities that determine native starch functionality depend on their specific physicochemical properties. A model that could predict product viscosity during processing will benefit industry for quality control and process design purposes. In this study, the kinetic parameters in a modified starch viscosity model were estimated for different amylose to amylopectin ratios. A total of 24 samples of corn starch blends were prepared from base corn starches (waxy, normal, and high amylose) at different different amylosecontents, by calculating the starch amylose content (adding high amylose corn starch to low amylose corn starch) and assuming the remainder was amylopectin. The actual amylose content of the starch samples was analyzed using Concanavalin A (Megazyme procedure). An empirical correlation of calculated and experimental amylose contents in the samples was presented in this study. The rheological properties of the corn starch blends were determined by collecting fundamental rheological data on 6% concentration (starch: water system) by applying the mixer viscometry approach using a modified Brookfield viscometer equipped with a flag mixer impeller. Pasting curve results showed that the starch rheological properties were a function of AM/AP. An empirical equation was proposed for peak viscosity, holding strength, and set back viscosity as function of AM/AP ratios. The peak viscosity, holding strength, and the setback viscosity increased as the starch amylose content decreased. Thermal properties of the corn starch blends were evaluated using a differential scanning calorimeter (DSC). Enthalpies of gelatinization were found to increase as the amylose content of the starch blends decreased.Kinetic parameters of a starch viscosity model were estimated simultaneously, and sequentially, using mixer viscometer data. The estimated parameters contained narrow confidence intervals, and small relative standard errors under 12%. A comprehensive starch viscosity model for two common corn starches: waxy and normal corn starch was proposed and tested on an independent set of data collected from a different measuring system, the Rapid Visco Analyzer (RVA). The model with the estimated parameters predicted the observed data well for the overall pasting curve having a RMSE < 10% for the total testing period. Correlation between the rate constant and activation energy (kinetic parameters in the Arrhenius model) was found to be a strong function of the reference temperature. The gelatinization rate constant kg and activation energy of gelatinization (Eg) increased as power-law functions with decreasing amylose levels.
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