Extração assistida por ultrassom e encapsulamento de corante da casca de beterraba com potencial para aplicação em iogurte

Abstract

Betalains are natural pigments with high antioxidant power and are associated with health maintenance. However, they are sensitive to factors such as high temperature, light and oxygen presence as well as pH outside the range of 4 to 7. Microencapsulation associated with specific extraction and drying methods has been an alternative to improve pigment stability making it possible to incorporate pigments in different food matrices. Thus, the objective was to extract and characterize a natural dye obtained from the beet co-product was encapsulated for application in food matrices. The extract was obtained by sonication of the bark by means of an Experimental Design (DCCR), based on the Response Surface Methodology (MSR), using amplitude, pH and extraction time as independent variables. Four extracts were chosen and encapsulated by ionic gelation, with alginate as the wall material. The capsules were lyophilized and analyzed by light microscopy, moisture content and water activity (aw), dye retention rate, amount of polyphenols, antioxidant activity, color, dye stability and sensory analysis by acceptability testing. principal component analysis (PCA) by the method Check All That Aplly (CATA) and ideality test. The pH was the most significant independent variable for extraction of bioactive compounds in the extracts, and the treatment with higher values of independent variables (T8), obtained higher amount of polyphenols (689.9 ± 3.1mg / 100g). Already the T3 treatment of pH 4, associated with a shorter extraction time (603.6 seconds) stronger color and more different from the others. After drying, the particles had a size between 697.56 ± 154.18 and 844.83 ± 180.9µm and content below 0.57 ± 0.02 for aw. T8 and T10 with higher pH values and extraction time showed high retention rates for betalain amount and antioxidant activity. Regarding stability, T3 presented lower degradation rate after 15 days in the absence of light. In the sensory analysis, the sample containing T3 was the closest to the ideal characteristics for a natural-colored yogurt. Thus, it can be concluded that the extraction process, associated with the dye microencapsulation method, contributed to obtain and preserve high rates of bioactive compounds and antioxidant activity.