Obtenção e estabilidade de corante de antocianinas extraídas do repolho roxo (Brassica oleracea).

Abstract

The search for alternative sources of natural pigments has increased interest in the developmentof research on different raw materials, including purple cabbage (Brassica oleracea). Besides the ability to confer color, being rich in anthocyanins, this vegetable has antioxidant capacity in capturing free radicals. Thus, this work was aimed at the development of dye formulations based on purple cabbage, evaluating their stability during storage, as well as the action of organic acids as copigmentation agents of anthocyanins. Physical-chemical characterization, colorimetric analysis of anthocyanins from fresh purple cabbage, pure and formulated anthocyanins extracts and lyophilized dyes were carried out; alcoholic extraction of anthocyanins; the study of the stability of the pigments of the extracts during the storage; the influence of copigmentation of anthocyanins; the formulation of lyophilized dyes from the anthocyanin extracts; and the behavior of the pigments present in the powdered dyes during storage of 15 days at different temperatures. For this the anthocyanins were extracted with solvent consisting of ethanol + HCl, the action of copigmentation of the extracts was induced by acids, tannic and gallic, in the proportions of 0.4; 0.6; 0.8 and 1% and evaluation of pigment stability was analyzed for a period of 15 days. To obtain lyophilized dyes, three formulations were prepared (F1 - Pure extract; F2 - Extract with 1% of gallic acid; F3 - Extract with 1% of tannic acid). All formulations were added with 15% maltodextrin 10 (DE). Physicochemical, colorimetric and anthocyanin analyzes were performed, the latter two being every 3 days for a period of 15 days at two temperatures, (25 and 10 ºC). The extracts formulated with gallic and tannic acid, both in the 1% concentration, were the best performers at the end of storage, showing a good stability of the anthocyanins besides the color intensity. The lyophilized dyes with acids in their formulation showed an anthocyanin degradation around 1% at the end of the storage, while the formulation of the pure showed values of 7.78 and 7.39%, at ambient and refrigerated temperatures, respectively. However, the dye with 1% gallic acid, stored at 10 ° C, showed the best behavior at the end of the analyzed period, a more intense staining and a low degradation of anthocyanins. It has been observed that copigmentation is a viable and efficient alternative to the stability of anthocyanins. In this way, the natural dyes of purple cabbage can be an alternative for the application in the food, pharmaceutical and cosmetic industry.