Physicochemical properties and thermal stability of Hibiscus rosa-sinensis flower dye with potential as a functional ingredient in foods

Résumé fourni par la source

Natural plant-based dyes offer sustainable and functional alternatives to synthetic dyes. This study evaluated the stability and functional properties of a powdered dye derived from Hibiscus rosa-sinensis L., obtained by spray drying, using maltodextrin and xanthan gum. Flow properties and thermal stability were determined. The powder demonstrated efficient retention of bioactive compounds, with 672,6 mg GAE/100 g of total polyphenols, 400 mg QE/100 g of flavonoids, 380,9 mg C3G/100 g of anthocyanins, and an antioxidant capacity of 837,5 mM AAE/g. It had a moisture content of 7,64 % and high hygroscopicity (22,9 %), solubility of 87,8 %, and a fast dissolution time (47,3 s). The porosity (74,3 %) and the Carr (24 %) and Hausner (1,33) indices indicated acceptable flowability and low cohesiveness, suitable for industrial applications. The thermal degradation of anthocyanins followed first-order kinet- ics, with a rate constant ranging from 0,0143 d⁻¹ at 25 °C to 0,0788 d⁻¹ at 55 °C and an activation energy of 50,01 kJ/mol. The half-lives (t₁/₂) and t₉₀% decreased with temperature, and the Q₁₀ coefficient showed greater sensitivity between 25–35 °C. The combination of encapsulants stabilized the anthocyanins, preserving color and antioxidant activity. The powder has high technological and nutraceutical value as a functional natural colorant in foods, requiring controlled temperature and humidity during storage.

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