Acid Hydrothermal Amendment of Grape Wine Pomace: Enhancement of Phenol and Carbohydrate Co-solubilization

Abstract

The byproduct from the winery industry has many bioactive compounds which are considered high value-added compounds. In addition, white grape pomace (GP) is rich in carbohydrates, which consequently can be used as raw material for subsequent bioprocesses. The present study carried out low-temperature hydrothermal treatments using different operational conditions: temperature (65–95°C), operational time (120–240 min), sulfuric acid concentration addition (5–15% v/v). The results show that using 65°C, 120 minutes and 15% (v/v) of H2SO4 it was possible to obtain a liquid phase rich in phenols and carbohydrates. Reaching a total of phenol compounds of 2113 ± 140 mg gallic acid/kg GP, composed mainly of 3-hydroxytyrosol (1330 ± 22 mg/kg GP). On the other hand, the carbohydrate solubilization reached 245 g glucose/kg GP. These results demonstrate the potential of hydrothermally treated grape pomace as raw material for biorefinery processes.