Soluble and insoluble plant fiber in selected cereals and vegetables.

Certain soluble plant fibers have hypocholesterolemic effects. However, information about soluble fibers of most foods is not available. A modification of Southgate's method was used to separate plant fiber into soluble and insoluble fractions. Both fractions were hydrolyzed with dilute sulfuric acid or trifluoracetic acid. Comparison of these two hydrolysis methods was discussed. The hydrolyzed sugars were measured by gas-liquid chromatography. Fiber content of selected cereals and vegetables were examined. Oat, corn, and cooked beans have greater proportions of soluble fiber than wheat and green vegetables. Soluble fractions of cereals and beans were mainly glucose whereas in green vegetables uronic acids were the major components. The differing fiber composition of various plant food sources probably is important in determining their physiological effects.