Extraction, Identification and Thermal Stability of Anthocyanins from Eggplant Peel as a Natural Colorant

The aim of this research is to evaluate the anthocyanin content of local eggplant peels and its potential as a food colorant. In the present study, various mixtures of aqueous ethanol and acetone solutions were utilized to extract anthocyanins from eggplant peel by a discontinuous process to obtain a natural red-purple colorant. First, the most appropriate combination for extraction solvent was selected as 70 (v/v) % ethanol in water acidified with 3 (v/v) % acetic acid, which was determined by analysis of extraction yields and total anthocyanins content of extracts utilizing UV-Vis spectrophotometer. Then, the extracted anthocyanins were identified and quantified by high performance liquid chromatography with diode array detector and characterized by high performance liquid chromatography equipped with three-dimensional mass spectrometry measurements. According to data analyses the major anthocyanin in eggplant skin was delphinidin-3-rutinoside (91.43%). Eventually, the thermal stability of extracted anthocyanins was evaluated during 15 days at different temperatures. Results demonstrated that the amount of anthocyanins decreased further with increasing of storage period and temperature.