RESISTANT STARCH IN DIETARY FIBER VALUES MEASURED BY THE AOAC METHOD IN DIFFERENT CEREALS

Total dietary fiber (TDF) was measured by the AOAC method 985.29 using 30 and 60 min of amyloglucosidase incubation. Resistant starch was de termined in the TDF residues after gelatinization, dissolution with 2M KOH, and hydrolysis with amyloglucosidase. The cereals analyzed were: commercial samples of rice (white, parboiled, precooked, and brown pa rboiled); oat (rolled); maize (grits); and wheat (crackers with bran). Varietal samples of white rice with 1, 18, 24, and 30% amylose also w ere analyzed. The results showed that cereal starches have different r esistances to hydrolysis. Oat and wheat starch were completely hydroly zed after 30 min, while rice and maize starch remained approximate to 42 and 50%, respectively, of TDF values after 60 min. As expected in t he varietal rices, when amylose content increases from 18 to 30%, TDF values were significantly higher because of resistant starch. After su btracting the starch content from the TDF values in white rice, result s were similar to values obtained by a chemical method that included l ignin. Therefore, it is suggested that corrections are necessary not o nly for protein and ash, but also for starch, especially on starchy fo ods.