Encapsulamento de chá verde (camellia sinensis var assamica) por “spray dryer” com goma de cajueiro/maltodextrina

Abstract

Among the constituents of green tea (Camellia sinensis), phenolic compounds such as catechins and caffeine, which have been related to some biological activities in the body, stand out. Microencapsulation has been widely used to protect sensitive compounds, as well as helping to remove unwanted flavors and odors, among others. The objective of this work was to obtain and characterize an extract of the leaves of green tea (Camellia sinensis) containing high levels of catechins and caffeine, as well as the protection of these bioactive compounds from the microencapsulation process with cashew gum and maltodextrin used as wall material. From the extract obtained from dried leaves of green tea with ethanol solution (75%), cytotoxicity analysis was performed, as well as evaluation of catechins and caffeine concentrations, antioxidant activity, amount of phenolic compounds and flavonoids. The extract did not present cytotoxic action, with considerable concentrations of catechins and caffeine being quantified, as well as high levels of antioxidant capacity, phenolic compounds and flavonoids. Three formulations of wall material, as well as cashew gum and pure maltodextrin, were characterized: MPA (wall material A) = 10% cashew gum + 20% maltodextrin; MPB (wall material B) = 15% cashew gum + 15% maltodextrin; MPC (wall material C) = 20% cashew gum + 10% matodextrin; GC (cashew gum) and M (maltodextrin). It was verified from the thermal analyzes that the mixture of GC and M improved the characteristics of the wall material used, increasing its thermal stability at temperatures above 100 ° C. Thus, different formulations of wall materials were able to encapsulate the green tea extract, making it feasible to replace part of the maltodextrin used by cashew gum. Three formulations of microcapsules were prepared: A (10% cashew gum + 20% maltodextrin + 7,5% dry green tea extract); B (15% cashew gum + 15% maltodextrin + 7,5% dry green tea extract) and C (20% cashew gum + 10% maltodextrin + 7,5% dry green tea extract). Microcapsules were characterized by SEM, particle size and distribution, water solubility, microencapsulation efficiency, dissolution profile, FT-IR analysis, X-ray diffractometry (XRD) and thermal analysis (DSC and TGA). The microcapsules obtained showed irregular shapes with circular predominance and dentate surface, presenting average diameters equal to 2,50, 2,55 and 3,64 μm, respectively for A, B and C. For the solubility in water, the microcapsule samples presented Values ranging from 63% to 72,66%. The microcapsules A, B and C presented low values of microencapsulation efficiency (33%, 30,75% and 28,25%, respectively.) and dissolution profile ranging from 81,44% to 103,81%. In order to evaluate the use of green tea microcapsules as a promoter of antioxidant capacity and bioactive compounds in conventional foods, the cashew nectar was used as a model system and two formulations were elaborated: cajá nectar with microencapsulated green tea extract (NCEM) and cashew nectar (NC). The formulations were characterized by physical-chemical analysis, functional compounds, microbiological and sensory analysis. The analyzes showed that the addition of microcapsules of green tea to cajá nectar increased considerably the contents of antioxidant compounds and that of phenolic compounds. The analyzes also showed that the nectars presented within the recommended physical-chemical, microbiological and sensorial standards, obtaining sensorial means within the region of acceptance. In this way, the potential for the microparticle employment industry is verified, based on the green tea extract as a food ingredient.