Scientific Study

Three extraction methods were used to remove lipid materials from 8 edible nuts and seeds before analysis for their total dietary fiber (TDF) and nonstarch polysaccharide (NSP) contents. Portions of ground materials were extracted by: n-hexane; followed by 80% methanol; n-hexane-acetic acid (95 + 5; v/v); and supercritical carbon dioxide. Defatted samples were gelatinized in water and incubated with amyloglucosidase; 95% ethanol was added to the hydrolyzates; and the residues were collected on tared glass crucibles. TDF was calculated according to a simplified enzymatic-gravimetric method developed in our laboratory; and NSP was determined as described by Englyst and coworkers. Dietary fiber values obtained with any of the extraction methods range from 3.47 g/100 g for cashews to 28.56 g/100 g for sunflower seeds. Nonstarch polysaccharide values range from 2.43 g/100 g for pecans to 5.56 g/100 g for peanuts. With the exception of sunflower seeds; samples extracted with supercritical carbon dioxide had lower TDF contents but similar amounts of NSP compared with samples extracted by the other 2 methods.