Desenvolvimento de um corante alimentar natural à base de antocianinas obtido a partir do epicarpo de frutos de Prunus spinosa L.: otimização da extração e estudo de aplicação

Abstract

Among organoleptic properties, colour plays a very important role in the overall perception of a foodstuff, since sight is usually the first contact that consumers have with the product. In this context, colorants have been widely used as food additives, to supply or intensify food colouring aspects, making them more attractive and pleasant. However, due to consumers’ concerns about the health and adverse effects of some artificial colorants, there is a strong interest in replacing them with safer natural alternatives. Anthocyanins are a group of pigments with red, blue and violet coloration, being present in many flowers and fruits and increasingly considered as potential alternatives to artificial colorants. Prunus spinosa l. is a wild shrub with bitter and astringent fruits that are poorly commercially exploited but have high levels of anthocyanins, more specifically cyanidin 3- rutinoside and peonidin 3-rutinoside, concentrated in the epicarp. The objective of this study was to develop a natural food colorant, from the extraction of anthocyanins from the fruit epicarps of p. spinosa, combining the growing interest of substituting artificial colorants for safer natural alternatives and the valorization of agricultural products from underexploited sources. The conditions that maximize the extraction of anthocyanins from the fruit epicarp of p. spinosa were optimized, comparing two extractive techniques, one conventional heatassisted (hae) and another alternative ultrasound assisted extraction (uae), testing as relevant variables time, temperature (hae) or power (uae), and solvent concentration. For that purpose, a response surface methodology was applied, using a circumscribed central composite design with three variables and five levels, and the anthocyanin compounds were identified and quantified by hplc-dad-esi/ms. Ultrasound assisted extraction was the most efficient method, under optimum conditions of 5.00 ± 0.15 min, 400.00 ± 32.00 w and 47.98 ± 2.88% ethanol, where the extraction yield was 68.60 ± 2.06% (v/v), with a total anthocyanin content of 18.17 ± 1.82 mg/g of dry extract and 11.76 ± 0.82 mg/g of dry epicarp, wich gives rise to a purple-reddish extract. Additionally, these response values were slightly improved when the solid-to-liquid ratio effect at the optimal conditions in a doseresponse format was tested, showing a steady decreasing pattern in the range 5 to 250 g/l. In addition to studying the colorant potential of this natural ingredient, it was also intended to evaluate its functional potential, for which an evaluation of the bioactive properties was determined, and an application study was carried out using a food product incorporated with the extract obtained under optimized conditions the evaluation of the bioativities was carried out through analyzes of the antioxidant, anti-inflammatory, antimicrobial and cytotoxic capacity. The extract presented a considerable antioxidant activity, with ec50 values of 204 ± 2 μg/ml for the tbars assay and ec50 of 296 ± 4 and 509 ± 3 µg/ml for oxhlia method at 60 and 120 min of reaction, respectively. The antimicrobial capacity was tested in 9 strains of bacteria of interest in the health area, in which the extract did not present bactericidal effect, but all had their growth inhibited with an extract concentration between of 2.5 to 20 mg/ml. The anti-inflammatory activity was assessed on raw 264.7 mouse macrophages and cytotoxicity was tested using 4 human tumor cell lines and on a primary culture of non-tumor liver cells, for which the extract showed no activity and no toxicity. The dye extract was incorporated into “beijinhos”, a typical brazilian confectionery product, that has as basic ingredients condensed milk, cream and butter, to evaluate its applicability as a natural colorant ingredient for a food matrix. The color, ph, and texture parameters, nutritional composition, and energetic value of “beijinhos” samples were determined after cooking and after one day of storage. In general, the incorporated optimized extract revealed a good coloring ability without altering the nutritional characteristics of the food product. With this, it was possible to evidence the potential exploitation of p. spinosa fruit epicarp as a source of anthocyanins to be used in the food industry, having as added value to the dye power, its bioactive capacity.