Effect of Extraction Conditions for Recovery of Chlorogenic Acid and Flavonoids from Wet Cider Apple Pomace under Subcritical Water

Industrial wet cider apple pomace was subjected to subcritical water mediated hydrolysis in a batch reactor with varying experimental conditions such as solid-to- solvent ratio (1-8 % w/v), temperature (100- 200 oC) and a residency time (10-30 min) to understand the effects of the experimental conditions on overall recovery of polyphenolic compounds. Chlorogenic acid and some flavonoids were identified and quantified by high performance liquid chromatography (HPLC-DAD). Higher yields of chlorogenic acid and the flavonoids were obtained between 100- 150 oC for residence time of 20 minutes. Solid-to solvent ratio and temperature played a significant role in the recovery of the polyphenolic compounds (p< 0.05). The results demonstrated that, residence time at a fixed extraction condition was less significant (p> 0.05). However, it was significant for yield of degradation compounds such as protocatechuic aldehyde, 5- HMF and furfural. Subcritical water selectively influenced the chemical structure of the polyphenolic compounds.