TITLE:
Water Adsorption Isotherms of Amaranth (Amaranthus caudatus) Flour
AUTHORS:
J. Gabriela Peña Balderrama, Sergio C. Carballo Cadima
KEYWORDS:
Amaranth; Water Adsorption Isotherm; GAB Model
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.5 No.2,
January
17,
2014
ABSTRACT: Water sorption isotherms are unique for individual
food materials and can be used directly to predict shelf life and determine
proper storage conditions. In this context, the aim of this study was to
determine the moisture adsorption isotherms of amaranth flour at 15℃, 25℃ and 35℃ in a range
of water activity from 0.1 to 0.9. Experimental data were modeled using five
equations commonly applied in the foods field. The goodness of the fit for each
isotherm model was evaluated through the coefficient of determination, the
variance due to error and the confidence interval of the estimated parameters.
All models can predict the adsorption isotherms of amaranth flour, but the GAB
equation gives a better understanding of the observed sorption behavior.
Estimated adsorption monolayer water contents ranged from 6.4 g to 7.2 g of
water per 100 g of dry material. It was observed by a weak dependence of water
activity with temperature. For ensuring microbiological stability, water
content in amaranth flour should not be higher than 13 g of water per 100 g of
dry material.