Production of larch [Larix] arabinogalactan, 3: Comparison of cold water extracts from larch sawdust and different kinds of conifers

When the sawdust of different kinds of conifers was mixed with larch sawdust, there is the possibility that it has an influence on the refining efficiency and the quality of products as well as the yield of larch arabinogalactan. Therefore, regarding the sawdust of different kinds of trees which are feared to be mixed, that is, spruce, Scotch pine grown in Siberia, and Douglas fir grown in North America, the content of the cold water extracts, and the chemical composition in these extracts were measured, and examined by comparing them with those of larch grown in Siberia. The results are summarized as follows. 1) The cold water extracts obtained from the sawdust of different kinds of trees, spruce, Scotch pine and Douglas fir, were as low as 1.1-2.2% when compared with 10.1% for larch sawdust. In addition, the total sugar content contained in the extracts of the sawdust of these different kinds of trees was 28.4-53.0%, and it was very low compared with 85.8% for larch. 2) The total phenol content of the coloring impurities contained in the cold water extracts was especially high in the case of spruce and Douglas fir, being about 20%. This amount is equivalent to about 12 and 15 times of that for larch. 3) The saccharide in the cold water extracts obtained from the sawdust of the different kinds of trees consisted of all six kinds of the composition sugar of wood hemicellulose, and their weight-averaged molecular weight was distributed over a wide range from polymers of about one million to monomers of 180. This fact is different from the saccharide of larch, which consists of one component, and it is suggested that these of different kinds of trees are a mixture of several kinds of polysaccharides. 4) When the sawdust of respective different kinds of trees is mixed by 20% in larch sawdust, it is forecasted that the yield of arabinogalactan decreases to about 6.5% from 8.7% when the whole amount is larch sawdust. Moreover, it is forecasted that the amount of phenol of the coloring impurities which become the decoloring load, increases the time for refining to 1.2-3.2 times similarly.