Chemical composition, structural and functional properties of soluble dietary fiber obtained from coffee peel using different extraction methods

This study aimed to evaluate the effects of chemical, enzymatic, chemical–enzymatic, ultrasound-assisted enzymatic, and shear emulsifying-assisted enzymatic extraction methods on the physicochemical, structural, and functional properties of soluble dietary fiber from coffee peel. We found that the highest extraction yield of soluble dietary fiber was obtained using the shear emulsifying-assisted enzymatic method, and that similar protein contents were obtained from coffee peel using the enzymatic and shear emulsifying-assisted enzymatic methods. Compared with the other extraction methods, shear emulsifying-assisted enzymatic processing resulted in a higher water-holding capacity (7.05 g/g) and oil-holding capacity (3.61 g/g), but a lower emulsifying capacity (58.50%) when compared with that of chemical, enzymatic, and chemical-enzymatic processings. The soluble dietary fiber obtained from coffee peel using shear emulsifying-assisted enzymatic extraction was also characterized by the highest glucose absorption activity (228.06 mg/g), and enzymatic processing resulted in the highest nitrite ion absorption capacity (10.09 mg/g, pH = 2). These results indicated that shear emulsifying-assisted enzymatic extraction method was the most appropriate extraction method for coffee peel soluble dietary fiber.