Abstract: In this study, dietary fiber was extracted from the residue left after the removal of starch from 6 varieties of potato, namely, Shepody, White Rose, Black Rose, Kexin No. 1, Favorita, and Jizhangshu No. 8, by sequential hydrolysis with medium-temperature α-amylase, alkaline protease and glucoamylase. The chemical composition, microstructure, and physicochemical properties of dried potato residue (DPR) and potato dietary fiber (PDF) were studied. The results showed that the chemical compositions of DPR from different varieties were significantly different (P < 0.05). The contents of total dietary fiber (TDF) in Shepody and Black Rose were 43.16% and 31.87%, respectively. The highest yield of PDF was extracted from Shepody (62.19%), and the yield of PDF extracted from White Rose was the lowest (42.99%). The extraction yield of PDF from Black Rose was 51.27%. Compared with DPR, the contents of starch and pectin in PDF decreased due to the enzymatic hydrolysis, and the contents of protein, cellulose, hemicelluloses, and lignin increased. The structure of DPR was compact while the structure of PDF was loose with some wrinkles and microholes. The content of starch in dietary fiber from Black Rose was the lowest; the content of protein was 7.69%, which was significantly lower than that in White Rose (P < 0.05); and the content of cellulose was 21.30%. There was no significant difference (P > 0.05) in lignin between Black Rose and White Rose, which were richer in lignin than other varieties (P < 0.05). Generally, dietary fiber from Black Rose is superior to that from other varieties in terms of water holding capacity (WHC), oil holding capacity (OHC), swelling capacity (SC), and glucose binding capacity (GAC). So Black Rose is a suitable potato variety for the extraction of PDF.

Key words: variety, potato residue, dietary fiber, chemical composition, physicochemical properties