Microencapsulation by Spray Drying of Yerba Mate Extract (Ilex paraguariensis)

Yerba mate is a plant that has a variety of chemical compounds that are known to have beneficial effects on the body. Spray drying microencapsulation process is an alternative to improve the stability of the compounds present in the aqueous extract of the leaves (Nunes, 2014).
Toasted matte tea (MT) and Microencapsulated soluble toasted mate tea with maltodextrin (MMT) were analyzed and characterized by SEM (Scanning Electron Microscopy, Hitachi 3000), 1000x e 180x, respectively, vacuum-bonded samples with 15 kV voltage and TG -DTA (Thermogravimetric Analysis - Differential Thermal Analysis, TM 3000 Hitachi), 5 mg sample, under nitrogen and synthetic air atmosphere, whose flow was 100 mL min-1, with heating from 30 to 650 °C, at 10 °C min-1.
In the characterization by SEM, the MT sample presented several breaks, derived from the toasting of the product, besides irregular sizes and shapes and the MMT sample with predominantly rough spherical particle surface of varying sizes, folds, cracks and pores, there is the presence of hollow particles, formation related to the expansion suffered in the final stages of drying. Microcapsules obtained under the selected condition may assist in maintaining nutritional properties and no color modification.
Under the conditions of the study, the TG-DTA thermal degradation curves presented similar profiles for the MT and MMT samples under nitrogen atmosphere, with mass losses of 7.29 and 8.18% (endothermic event) that occurred up to 142.58 and 154.64 ºC, relating to moisture and volatiles; followed by exothermic events with 51.99 and 64.41% losses up to 400.90 and 380.89 °C, which occurred simultaneously and consecutively during the degradation of bioactive compounds and sugars; and due to the inert atmosphere no oxidative decomposition was observed, resulting in a larger amount of residue 28.30 and 39.83% (up to 555.65 and 558.60 °C), respectively. Similarly in synthetic air atmosphere three events were observed with mass losses: 7.16 and 7.87% (up to 142.58 and 154.65 °C); 55.05 and 39.64% (up to 400.9 and 380.89 °C); 30.76 and 40.80% (up to 487.4 and 482.69 °C); and with final mineral residue de 7.05 e 11.69%, respectively. These variations in thermogravimetric curves suggest that there is a slight difference in composition between the herb and the microencapsulated extract and the addition of maltodextrin.

Nunes, G.L. Microencapsulação por spray drying do extrato crioconcentrado de erva mate (Ilex paraguariensis a. st. hill) empregando a maltodextrina como agente encapsulante. Mestrado (Ciências de Alimentos), UFSC, 92p. 2014.