Study of adsorption isotherms and physicochemical characterization of natural food colourants

• Published in: Ciência e tecnologia de alimentos 2019-06, Vol.39 (suppl 1), p.74-80
• Main Authors: VIANA, Kéllen Wanessa Coutinho, OLIVEIRA, Isadora Rebouças Nolasco de, ROCHA, Juliana de Cássia Gomes, BARROS, Frederico Augusto Ribeiro de, STRINGHETA, Paulo César
• Format: Article
• Language: English
• Subjects: FOOD SCIENCE & TECHNOLOGY
• ISSN: 0101-2061; 1678-457X; 1678-457X
• DOI: 10.1590/fst.37217

Abstract Synthetic colourants are widely used for colouring foods. However, their safety has been questioned. Due to this limitation and the global trend of consuming healthy foods, the industry is faced with the need to replace artificial colourings, which has given rise to a growing interest in colourants from natural sources. Thus, this work obtained the moisture adsorption isotherms of the natural food dyes of anthocyanins, betalains and curcumin and evaluated the humidity, water activity (aw), hygroscopicity, colour and antioxidant capacity in vitro. Isotherms were determined by the static gravimetric method with saturated salt solutions (LiCl. H2O, MgCl2.6H 2O, Mg(NO3)2.6H2O, NaCl, KCl and K2 SO4) at 25 °C. Experimental data were adjusted by GAB, BET, Halsey, Oswin and Henderson models. All models, except Henderson's for Curcumin, fitted the data and BET was used to represent the moisture adsorption isotherm. All the isotherms were type sigmoidal, characteristic of most foods. The observed water content (