Physicochemical characterization of sangorache natural colorant extracts (Amaranthus quitensis L.) prepared via spray- and freeze-drying

Abstract

In this study, we sought to prepare sangorache encapsulate (Amaranthus quitensis L.) by spray- and freeze-drying, using three different concentrations (3, 5 and 7%) of the encapsulating agent, maltodextrin. To atomize the powder, we used a Buchi mini spray-dryer B-290 with three inlet temperatures (140, 160 and 180 ℃) and a laboratory freeze dryer with a −0.8 bar pressure for 4 days. During atomization, the powders presented lower moisture content and water activity with the addition of maltodextrin; however, there were no significant changes in the moisture of the freeze-dried powders. Colorimetric analysis revealed that the luminosity (L) and chroma (C) values changed as maltodextrin concentration increased. The structures of particles were examined by scanning electron microscopy (SEM) SEM, and very different morphological characteristics resulted from the two drying methods. Also, apparent density, hygroscopy and dissolution testing revealed significant differences between the powders. Sangorache antioxidant compounds were preserved to a greater extent by applying low concentrations of the encapsulating agent and by the freeze-drying technique. The natural colorant from sangorache inflorescences could serve as an additive to improve food color in the industry.