Grape seed pomace as a valuable source of antioxidant fibers

BACKGROUND Grape seed pomace is a valuable by-product from winery/oil extraction industries and a potential source of bioactive compounds. Hot water extraction is the most widely used technology for polysaccharide recovery from plant and seed sources. To obtain an antioxidant fiber-rich extract (AFE) from defatted grape seed pomace, seed:water ratio (1:10-1:20) and extraction temperature (70-90 degrees C) effects on extraction yield, total sugars, total phenolic compounds and condensed tannins were investigated. RESULTS The best extraction results were achieved at the highest seed:water ratio and temperature. At these conditions, the extraction yield and total sugar content of the freeze-dried AFE were 100.1 g kg(-1) and 725.3 g kg(-1), respectively. The AFE presented high total phenolic content (16.2 g GAE kg(-1)), condensed tannins (515.1 mg CAT kg(-1)), soluble (219.1 g kg(-1)) and insoluble fibers (132.4 g kg(-1)), besides protein (171.1 g kg(-1)) and ash (152.6 g kg(-1)). The antioxidant capacity of the AFE was 382.7, 823.7 and 1439.4 mu mol Trolox g(-1) for DPPH, ABTS and ORAC methods. CONCLUSION The AFE was shown to be not only an interesting source of fiber with antioxidant capacity, which could become a potential foodstuff, but also an ecofriendly and sustainable alternative to use grape seed pomace. (c) 2019 Society of Chemical Industry