Microencapsulação do extrato das flores de hibisco vermelho (Hibiscus rosa-sinensis) por spray chilling

Abstract

The flowers of the red hibiscus (Hibiscus rosa-sinensis) have vitamins, flavonoids, ascorbic acid, niacin, riboflavin, thiamin and anthocyanins, such as cyanidin-3 soforoside. Due to the instability of anthocyanins after extraction, in this work, microparticles of anthocyanins from red hibiscus flower extract were produced by spray chilling and studied through characterization, stability study and gastrointestinal release profile. The ratio of wall material and hibiscus extract was 70:30, using binary lipid formulations, containing fully hydrogenated palm oil (OPTH) and cocoa butter (MC), homogenized in the ultrasound-assisted at the ratios 100 OPTH: 0 MC (Control), 75:25, 50:50, 60:40 and 40:60. The emulsions were homogenized in the ultrasound-assisted for 240 seconds at 200 W. The microparticles were characterized for thermal and polymorphic behavior, presence of functional groups, particle size, polydispersity index, morphology, bulk and compact density, Carr's index and Hausner's ratio, water activity, anthocyanin content, encapsulation retention, antioxidant capacity and color parameters. The storage stability of the microparticles at 35 °C in the presence and absence of light was evaluated. Also, the release profile of these anthocyanins in the simulated gastrointestinal tract in vitro was defined. The increase in MC content reduces the melting temperature and the polymorphic behavior becomes more unstable, with amorphous characteristics in the microparticles, increased viscosity and particle agglomerations, with the appearance of holes, presenting higher values for average diameters, which may affect the sensory and nutritional characteristics of food products. The peaks of the hibiscus flower extract are visualized in the spectra of the microparticles produced by spray chilling. Thus, the anthocyanins were not degraded during microencapsulation. The antioxidant capacity ranged from 75 to 79 %, with the best result for PLM_75:25. MC, when it is used in low proportions in lipid mixture with the fully hydrogenated palm oil, as in PLM_75:25 treatment, improves the characteristics of the microparticles, increasing the antioxidant activity and improving the release profile of anthocyanins in the simulated gastrointestinal system in vitro, with controlled and reduced release in the gastric tract and intense in the intestinal tract for absorption of the antioxidant compounds in the small intestine. Also, in the stability study, the PLM_75:25 treatment had the highest encapsulation retention and reduced total color difference. It appears that the microparticles obtained for all treatments are sensitive to light and the temperature of 35 °C. Ideally, the microparticles should be stored below 35 °C and without light.