Comparative Analysis of Quality Criteria for the Control of Liquefaction at the Obtaining of Starch-Based Hydrolysates

Abstract

Starch hydrolysates production converts starch to different kinds of products using enzymes in two steps, liquefaction and saccharification. This study investigated three types of analysis methods for the assessing and characterization of the liquefaction process: a rheological method (to measure yield stress), a chemical method (for the determination of Dextrose Equivalent DE) and a chromatographic method (HPLC to obtain the Degrees of Polymerization DPs). Potato starch with 13.5% dry substance was liquefied with the enzyme Liquozyme Supra for two hours in optimal conditions of pH and temperature. A comparative analysis between the methods to describe the liquefaction process was realised. Yield stress offered valuable information on the flow behavior of the samples showing that after 15 minutes of liquefaction the product behaves as a fluid without yield point, with a decreasing value of the middle yield stress. DE had an ascending value during liquefaction indicating that the total reducing sugars are increasing in time. After two hours of liquefaction, glucose (DP1) in very small amounts (around 1%), maltotriose (DP3) and maltotetrose (DP4) in much higher amounts were obtained; no maltose was produced. The quantity of DP3 and DP4 was increasing with the liquefaction time whereas the content in oligosaccharides with DP 5 or higher as 5 (DP5+) was decreasing. The comparative analysis of the chemical and the chromatographic method showed that both methods characterize very well the liquefaction process. It was found that there was a strong relationship between the DE values and the total DP3+DP4 as measured from HPLC and also between DE and DP5+.Â