Pentosan and (1 → 3),(1 → 4)-β-Glucan concentrations in endosperm and wholegrain of wheat, barley, oats and rye

Abstract

The major cereal dietary fibre components, pentosans and (1 → 3),(1 → 4)-β-glucans were measured in whole grains of two varieties each of wheat, barley, oats and rye and in the endosperms from these grains. These analyses were applied directly to the grain without prior isolation of a fibre fraction. Pentosan and β-glucan levels were much higher in the whole grain than in the endosperm except in barley in which the β-glucan was present in similar concentrations in whole grain and endosperm. Mean whole grain pentosan levels (dry weight basis) for the two varieties of each grain type analysed in this study were: wheat, 6·6%; barley, 6·6% ; oats, 5·8% and rye, 9·0%. Corresponding values for the endosperm were 2·3%, 1·4%, 0·7% and 3·9%, respectively. β-Glucan content of whole wheat was 0·6%; barley, 4·2%; oats, 3·9 and rye, 2·5%. The respective endosperm values were 0·3, 4·1, 1·8 and 1·7%. The pentosan from the whole grain contained more xylose than that from the endosperm. The differences between these dietary fibre components in whole grain and endosperm represent the maximum potential differences between the whole grain and milled products containing only endosperm.