Utility of critical fluids in extraction and encapsulation of polyphenolics from by-product of cider production

Efficacy of subcritical water in the recovery of the polyphenolic compounds from the apple pomace using a batch reactor system at 100-bar over a temperature range of 100-200oC for a residence time of 10–30 minutes was investigated. Organic solvent extractions using acetone and ethanol were carried out to serve as a baseline for comparison with the subcritical water extraction. Subcritical water was efficient in solubilising the apple pomace, and extracting polyphenolics with high antioxidant activity. Maximum solubilisation of the apple pomace was achieved at 145oC for 30 minutes and total phenolic content and antioxidant activity at 200oC. Solubilisation, ORAC activity and total phenolic content of subcritical water extract were 28.20g/100g DW, 99285μmol TE/g DW and 49.86mg/g GAE DW of apple pomace respectively, compared to 19.20g/100g DW, 6260.27 μmol TE/g DW and 21.70mg/g GAE DW of acetone extracts of apple pomace respectively. Protocatechuic aldehyde was identified for the first time only in the subcritical water extract and to date has not been identified in solvent extracts of cider apple pomace. Encapsulation of polyphenolic s of subcritical water extract using spray drying was explored. Particles/powders formed were derived from the naturally occurring carbohydrate polymers co-extracted with polyphenols. Addition of HPβ-Cyclodextrins (SWE+ HPβ-CD) to the directly encapsulated powder (SWE) significantly reduced hygroscopicity and improved antioxidant activity.