Abstract
The effects of particle sizes and drying methods of samples on dietary fiber (DF) values were studied. Van Soest's detergent method was used for fiber analyses.
DF values of air dried sample of lettuce or radish greens at 100°C or 60°C was compared with that of freeze-dryed one. As drying at 100°C or 60°C formed brown compounds which were measured as a part of the DF, freezedrying have been applied for sample drying.
The effects of particle sizes on DF values was examined on soybean, wheat bran and cabbage. After dried samples were ground to pass a 1.0 mm screen of a Wiley Mill, they were sifted with stainless steel sieves. The DF value increased with increasing of particle size. The DF values of 3 kinds of samples ground to pass a 0.4 or 0.6 or 1.0mm screen of a Wiley Mill were compared. The DF values of ground samples to pass 0.6mm and 1.0mm screen were identical. These results showed that the difference of DF values among particle sizes was not due to difference of dissolution rate among particle sizes. Therefore ground sample should not be sifted.
Sample with a high starch content had been incubated with bacterial α-amylase at 35°C for 1hr in pH 7 buffer before deterrnination of their neutral detergent fiber (NDF) contents. Samples used wheat bran and azuki bean. The treatment with α-amylase made filtration easy and estimation of NDF low. The treatment with α-amylase was necessary to decompose a starch in samples. However, since crude bacterial α-amylase may contaminate hemicellase, purified α-amylase must be used.
