Anthocyanins are used for food coloring due their low toxicity and health benefits. They are extracted from different sources, but black carrot has higher anthocyanin content compared with common fruits and vegetables. Here, we study alcoholic anthocyanin extracts from black carrot to enhance their stability. The objective of our research is to determine if microencapsulation with tetraethyl orthosilicate (TEOS) is a feasible option for preventing black carrot anthocyanin degradation. Extraction solvents were solutions of (1) ethanol/acetic acid and (2) ethanol/citric acid. Samples were purified through a resin column and microencapsulated using TEOS. Fourier Transformed Infrared Spectroscopy (FTIR) spectra of samples were obtained, and degradation studies were performed under different conditions of UV radiation, pH and temperature. Antioxidant activity was evaluated with radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and electrochemical cupric reducing antioxidant capacity (CUPRAC). Color evaluation on food models were performed with CIE Lab at the beginning of experiments and after 25 days of storage. Results indicate that the more stable extracts against pH media changes are samples obtained with ethanol/acetic acid solution as extraction solvent. Extract purification through resin and TEOS microencapsulation had no significant effect on extract stability. In conclusion, although TEOS microencapsulation has proven to be effective for some dried materials from natural extracts in our previous research, we do not recommend its use for black carrot extracts considering our results in this particular case.

Anthocyanins are used for food coloring due to their low toxicity and health benefits. They are extracted from different sources, but black carrot has higher anthocyanin content compared with common fruits and vegetables. Here, we study anthocyanin extracts from black carrot to enhance their performance as food ingredient. Extracts were obtained by ethanol/citric acid and ethanol/acetic acid. Samples were purified through to a packed column and microencapsulated using tetraethylorthosilicate (TEOS). Degradation studies were performed by UV radiation, and pH and temperature media changes. Antioxidant activity was evaluated with radical DPPH scavenging and cupric reducing antioxidant capacity (CUPRAC). Color evaluations were performed with CIE Lab at the beginning and after 25 days of storage. Samples extracted with ethanol/citric acid had higher anthocyanin content. After purification, there was evidence that 3-glucoside cyanidins were trapped into resin. Results indicate that the purest acetylated 3-glucoside derivatives are more stable than the citric acid non-purified extraction. The antiradical activity of black carrots extracts was higher than other reported values, when anthocyanin content is higher, antioxidant effect increases. In conclusion, acylation of anthocyanins provides them more stability against pH media changes, purification with resin and TEOS microencapsulation not necessary benefit stability of the black carrot extracts.