Abstract
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 (<0.3%) and a w (<0.03) can be considered favourable to stability. Colour analysis indicated a high colouring strength and the antioxidant capacity suggested that, in addition to representing a source of colour in food products, natural dyes may have an additional function, with possible health benefits.
Highlights
Colour is one of the main sensory attributes that influence the choice and acceptance of food by consumers and is considered an important parameter in quality control
The use of natural dyes is a current market trend, for its colour function and for the potential health benefits attributed to natural pigments, which include antioxidant properties and prevention of cardiovascular diseases and neurological conditions (Pascual-Teresa, 2014; Esatbeyoglu et al, 2015; Rodriguez-Amaya, 2016)
The natural dyes investigated included anthocyanins from grapes, curcumin from turmeric roots and betalains from beetroot, all kindly provided by Christian Hansen Industria e Comércio Ltd (Valinhos, São Paulo, Brazil), in the form of soluble powders and without additional purification
Summary
Colour is one of the main sensory attributes that influence the choice and acceptance of food by consumers and is considered an important parameter in quality control. Some studies evidence adverse reactions associated with the consumption of these food additives, such as the development of some types of cancer, allergic reactions, induction of hyperactivity and behavioural changes in children (McCann et al, 2007; Stevens et al, 2011; Kus & Eroglu, 2015). Their safety has been questioned with increasing intensity, leading to the prohibition of the use of some of these dyes in food. The use of natural dyes is a current market trend, for its colour function and for the potential health benefits attributed to natural pigments, which include antioxidant properties and prevention of cardiovascular diseases and neurological conditions (Pascual-Teresa, 2014; Esatbeyoglu et al, 2015; Rodriguez-Amaya, 2016)
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