Measurement of degree of starch gelatinization by enzymatic method

DI PAOLA, ROMINA; ASIS, RAMON; ALDAO, MARIO A. J

STARCH/STARKE

WILEY-V C H VERLAG GMBH

Año: 2003 vol. 55 p. 403 - 409

0038-9056

In this work, a new enzymatic method is proposed to evaluate the degree of starch gelatinization in starchy food and feed. The procedure developed is based on the fact that the gelatinization process enhacens the chemical reactivity of inert starch granules towards amylolytic enzymes. Aqueos suspensions of maize starch were treated at different temperatures to obtain different degrees of gelatinization, from 25 °C (control without gelatinization) until 95 °C. Heated samples were then incubated with a glucoamylase. The enzymatic activity was measured by the glucose released during the digestion time by using a standard glucose oxidase method. The initial velocity value of the enzymatic reaction (Vi) was selected as the parameter to quantify the degree of starch gelatinization (DG). Changes in granule morhology and the starch available for hydrolysis were evaluated by photomicrographs. The new method was standarized and compared with DSC and viscosity measurements in order to chek its efficiency, considering the DG calculated by Vi and by DSC (correlation coefficient r=0,97), thus Vi reflect the degree of starch gelatinization as well as DSC. These results show that the developed enzymatic procedure is an effective method to evaluate the DG in starchy foods and feeds.