Publication no. C-1998-0406-05R |  VIEW ARTICLE

Measuring and Modeling Grain Sorption Equilibria of Amaranth Grains.

María Lucía Pollio (1,2), Marcela P. Tolaba (2), and Constantino Suárez (2,3). (1) Comisión de Investigaciones Científicas de la Provincia de Buenos Aires. (2) Departamento de Industrias, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, 1428 - Buenos Aires, Argentina. (3) Corresponding author. E-mail: <suarez@di.fcen.uba.ar> Cereal Chem. 75(3):297-300. Accepted January 8, 1998. Copyright 1998 American Association of Cereal Chemists, Inc.

Water activity (a(w))of Amaranthus cruentus were measured at 35, 45, and 65°C at different moisture contents by means of an electronic water activity meter. Experimental curves were fitted to one three-parameter equation (GAB equation). The equilibrium values and temperature shifts were modeled with a three-parameter equation in the approximate a(w) range of 0.03-0.88. An analytical expression to calculate the isosteric heat of sorption and its moisture content dependence was used, and the results were compared with the isosteric heat calculated from the experimental equilibrium data by means of the Clausius-Clapeyron equation.