Chandrasiri et al (1987) found that hemicellulose content of soya bean underwent little change during germination, whereas cellulose content decreased signiÐ- cantly. Lignin nearly disappeared at day 3. The reduction in indigestible dietary Ðbres caused by germi- nation is very important, as a diet with high content of indigestible dietary Ðbres a†ects the digestion and the intestinal absorption of nutrients induced by a great faecal loss of energy and in most instances of nitrogen and fat (Southgate and Durnin 1970; Reinhold et al 1976; Bau et al 1983), a point taken up by Weinsotck and Levine (1988). An a-L-arabinofuranosidase (EC 3.2.1.5.5.) was puri- Ðed from cotyledons of 4-day-old soya bean seedlings by Hatanaka et al (1991). This enzyme can degrade both soluble polysaccharide from soya bean seeds and nitrophenyl-a-L-arabinofuranoside. Kaji (1984) reported that some a-L-arabinosidases from various sources can degrade both high-molecular-weight polysaccharides and low-molecular-weight polysaccharides and also low-molecular-weight artiÐcial substrates, like nitrophenyl-a-L-arabinofuranoside. In mature soya bean seeds arabinose is one of the dominant constituents of the polysaccharides in the endosperm. During germination, the content of the water-soluble polysaccharide in the cotyledons decreases greatly as the seedlings develop, suggesting the use of the polysaccharide as an energy source or carbon skeleton for macromolecule biosynthesis (Kasai and Suzuki 1980). These observations could explain the partial degradation of soya bean dietary Ðbre during germination.