Green Extraction Methods and Microencapsulation Technologies of Phenolic Compounds From Grape Pomace: A Review

Grape pomace, the main winemaking by-product of the wine chain generated after the pressing of grapes in the production of white wine and/or after the fermentation stage in red winemaking. Grape pomace is rich in phenolic compounds, which possess several physiological effects, directly linked to their pharmacological, technological, antioxidant and antimicrobial properties. Here we address the most relevant techniques to extract and conserve phenolic compounds and reuse grape pomace. Specifically, in this review we discuss the importance of the extractive technologies applied to grape pomace that make up the principles of green chemistry such as supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), microwave hydrodiffusion and gravity (MHG), ultrasound-assisted extraction (UAE), pulsed electric field (PEF), and ohmic heating (OH) for food industry as they are environmental-friendly processes more ecologic, economic and innovative. These techniques show benefits like reduction at the extraction time, number of unit operations, energy consumption, environmental impacts, economical costs, quantity of solvent and waste production, aiming to guarantee safe and quality extracts and/or products. Summed to the green extraction methods the microencapsulation technologies spray drying, spray cooling, lyophilization, extrusion, and coacervation can be applied to the obtained extracts to improve their shelf life, giving a wider and more sustainable use of them. Therefore, here we address the importance of reusing and valuing grape pomace, as well as describing extractive technologies that make up the principles of green chemistry and show a wide range of alternatives for preserving these compounds, sensitive to heat, light and oxygen through microencapsulation techniques.