IX. OCCURRENCE IN FOOD 457 



In Southeast Asia soybeans are often ferniciitcd liy the mould Aspergillus 

 orijzae. The prothiet is di«rostihle and pahital)le. However, it has lost a eon- 

 sideral)le part of its thiamine. So the fermentation process does not mean 

 an improvement in regard to thiamine (Janseii^). 



c. Nuts 



Xuts are pretty rich in thiamine (300 to 500 y per 100 g.). Coconuts con- 

 tain only traces of thiamine. 



(/. Potatoes 



In countries where potatoes are much in use, as in Western Europe, 

 potatoes may fulfill a large part of the thiamine need of the population be- 

 cause of their high thiamine content. This content does not appear to be 

 very high, i.e., 80 to 100 y of thiamine per 100 g., but potatoes contain 

 about 75 to 80% of water. Thus, in terms of dry matter, the content is 

 four to five times as large. 



Boiling potatoes reduces the thiamine content very little. Boiling peeled 

 potatoes in a large quantity of water produces a slight reduction, but al- 

 most all the thiamine will remain in the potatoes and only traces are found 

 in the water, provided that the boiling ceases w^hen the potatoes are done. 

 If however, the boiling has been prolonged until the potatoes fall apart, 

 then the thiamine is extracted by the water. 



These factors are of consequence for such European countries as the 

 Netherlands where potatoes form a large part of the diet and thus con- 

 stitute* an important source of thiamine. 



On account of the fact that the potato was one of the chief food items 

 in wartime in the Netherlands, an investigation was made into the thiamine 

 content of different varieties of potatoes, raised under different conditions 

 of soil, manure, etc. More than 100 varieties were analyzed. '■' It appeared 

 that the thiamine content of different samples varied from 40 y to 160 7 

 per 100 g. of fresh potato. However, in the \'arieties that were in common 

 use the content amounted to 85 to 100 7 per 100 g. 



e. Meat and Fish 



The vitamin content of the organs, particularly li\'er and kidne}^ is 

 higher than that of the muscles. This is also the case with thiamine. Beef 

 contains about 120 7 of thiamine per 100 g. Since thiamine plays such an 

 important part in muscle activity, however, it is obvious that the thiamine 

 content is highest in those muscles which perform most of the work, as, 

 e.g., the breast muscles in flying ])irds. 



' A. J. Reestman, B. C. P. Jansen, and J. Boumaii, Landhouwkund. Tijdschr. 55, 

 711 (1943). 



