Microencapsulation of Malva sylvestris anthocyanins using maltodextrin and inulin as two alternative coating materials: characterization, stability and release

Abstract

The aim of this study was to investigate the effect of maltodextrin and inulin as a wall material in five different ratios (MD/IN: 1:0, 0.75:0.25, 0.5:0.5, 0.25:0.75, 0:1, %w/w) on the stability of encapsulated Malva’s anthocyanins. The encapsulation efficiency for the prepared microcapsules was between 84.32% and 98.53%. Analyses of microcapsule properties including moisture content, hygroscopicity, ANCs content (measured by UV and HPLC techniques), antioxidant activity, stability during storage, morphology, and the anthocyanin release in simulated gastrointestinal conditions were considered. Among the five treatments, the F4 (MD/IN: 0.25:0.75) had optimal conditions with the highest ANCs content (1.94 mg g− 1), and encapsulation efficiency (98.53%). An accelerated stability test was performed at 5 °C and 40 °C on formulated microparticles for four weeks. F4 indicated superior stability in comparison to other formulations, which retained 95.3% of their load at 40 °C after four weeks. The obtained results of Fourier transform infrared spectroscopy (FT-IR) and DSC analysis proved that the encapsulation was carried out successfully. In addition, antioxidant activity results revealed that the mentioned ratio retained 64.6% of its antioxidant capacity. Scanning electron microscopy (SEM) analysis identified that the size of the microcapsules ranged from 5 to 200 micrometers. Eventually, the in vitro encapsulated ANCs release profile was observed in response to gastric environment with satisfactory controlled release. As a result, MD and IN combinations (ratio 0.25:0.75) microencapsulation can be a suitable method for stabilizing Malva’s anthocyanins. It can also have significant potential as a natural food coloring agent and herbal medicine.