Extraction of phenolics from Terminalia chebula Retz with water–ethanol and water–propylene glycol and sugaring-out concentration of extracts

In this study, the spherical central composite design (Spherical CCD) was employed to determine the effect of conditions (temperature, solvent composition and extraction time) for extraction of total phenolics from Terminalia chebula fruits with water–EtOH and water–propylene glycol (PG) mixtures. Then the feasibility of sugaring-out concentration to concentrate the extracts was examined. Second order polynomial models on extraction yields of total phenolics as functions of extraction conditions were proposed and the models showed reasonable prediction of the experimental data with R2 of 0.901 and 0.828 for water–EtOH and water–PG, respectively. When glucose was added to water–ethanol (EtOH) and water–propylene glycol (PG) extracts of T. chebula, the mixtures were separated into two phases: (1) the top phase rich in EtOH or PG, into which phenolic compounds were concentrated and (2) the glucose rich aqueous phase. The suitable glucose concentration to induce phase separation in both systems was 200 g/L. The distribution coefficients of total phenolics, gallic acid and ellagic acid in water–EtOH were 1.98, 4.89 and 3.52, respectively, while those for water–PG system were 1.98, 4.34 and 3.22, respectively.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Extraction of phenolics from Terminalia chebula with water–EtOH and water–PG. ▶ Water–EtOH and water–PG extraction requires rather low temperature. ▶ Glucose addition to water–EtOH and water–PG extracts induces phase separation. ▶ High distribution of phenolics in EtOH or PG rich phase supports possibility of sugaring-out concentration.