Investigation Of Methods For The Extraction Of Polyphenols From Grape (Vitis vinifera L.) Pomace

Grapes (Vitis vinifera L.) are one of the largest food crops grown in the world, with global production of around 77.8 million tons. They are primarily used for wine production (85%) of which approximately 10 million tons give rise to solid waste "pomace". Pomace or Wine Marc consists of grape skin, seeds, and stalks and their proportion depends on the grape variety. Pomace is an excellent source of bioactive compounds such a polyphenols, flavonoids and dietary fibers, which could be further \nprocessed to yield nutraceuticals that can be used in the food, pharmaceutical and cosmetic industries. Conventional extraction methods such as heat-reflux, Soxhlet and solvent extraction are energy and time intensive and often generate lower yield. Advanced techniques including \nmicrowave-assisted extraction (MBE) and ultrasound can be used to overcome the constraints of conventional processes. The objective of this thesis is to intensify the extraction yield of bioactive components from grape pomace using advance extraction techniques including MBE and ultrasound by evaluating the effect of process parameters including type of solvent, solvent concentration, extraction time and temperature. Total polyphenol concentration was quantified using Folin-Ciocalteau method and antioxidant activity was quantified using free radical scavenging techniques including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Fe3+- tripyridyltraizine (FRAP). It was observed that MBE process yielded high concentration of polyphenols in comparison to ultrasound and convention heat-reflux methods.