Microwave-assisted deep eutectic solvent extraction and macroporous resin purification of anthocyanins from Purple-heart Radish: Process optimization, structural characterization and quantitative analysis

A novel approach for extraction and purification of the anthocyanins from Purple-heart Radish was developed by microwave-assisted deep eutectic solvent extraction (MAE-DES) coupled to macroporous resin separation (MRS). Citric acid-based DES as the extractant was screened and characterized from 13 synthesized deep eutectic solvents due to the excellent performance. Through RSM optimization of MAE-DES process, the anthocyanin yield reached 6.442 ± 0.135 mg/g, demonstrating that MAE-DES significantly superior to that of conventional methods. With AB-8 MRS purification, the anthocyanin purity was increased by 63-fold. By UHPLC-Q-TOF-MS/MS, the anthocyanins obtained from Purple-heart Radish were dominantly composed of pelargonins. Based on composition analysis, pH differential method was first modified by introducing weighting factors, avoiding serious underestimation of the anthocyanins content in Purple-heart Radish. MAE-DES and the modified spectrophotometry were successfully applied for assessment of anthocyanin extraction and sample drying methods, providing an efficient alternative to development and application of the anthocyanins from Purple-heart Radish.