Comparative study of the effect of auxiliary energies on the extraction of Citrus fruit components.

A comparative study of methods for ultrasound-assisted extraction (USAE), microwave-assisted extraction (MAE) and superheated liquid extraction (SHLE) of compounds from citrus has been performed. The suited conditions for each method were evaluated to maximize the concentration of 10 representative compounds (sugars, carboxylic acids, phenolic acids and flavonoids) by a desirability function approach based on the chromatographic peaks obtained by LC-DAD. Extracts obtained under the suited conditions were analyzed by LC-QTOF MS/MS. The ANOVA on the molecular entities showed 232 significant entities (p<0.01), and pairwise comparison revealed that USAE and MAE methods are the most similar (50 different entities), and USAE and SHLE the most dissimilar (224 different entities). A discrimination test by PCA showed a clear discrimination among the extraction methods, explaining 78.51% of the total variability. Similarities in the abundance of the monitored compounds was tested by ANOVA showing that the extraction of carboxylic acids (malic and citric acids) was equal by all methods; while for each of the other eight compounds, at least one extraction method is different from the others. Under the evaluated conditions the SHLE method is the less favorable to extract metabolites from citrus, being the best the USAE method.