Mannane as an Article of Human Food- 
BY 
C. Tsuji, Ndgakushi. 
Since the discovery of mannose by Reiss by treating the 
so-called cellulose of the nut of Phytelephas with sulphuric acid, 
and since its closer description by E. Fischer who obtained it 
as a product of the oxidation of mannite, there have been found 
in many plants slime-like and cellulose-like polyanhydrides that 
yield by hydrolysis mannose. They have been distinguished as 
mannane, para-mannane and manno-cellulose. 1 ) 
Thus far, there is not known, however, any article of human 
food whose nutritive value is due to a polyanhydride of mannose , 
while polyanhydrides of glucose (starch, glycogen, maltose) play 
an important role, especially starch. 1 2) But there are sold in 
this country as an article of food gelatinous colorless tablets, 
apparently consisting of starch paste, called namakonniaku that 
are largely consumed by the people. These tablets, however, 
do not give a blue coloration with iodine, and do not, there¬ 
fore, consist of starch. My investigation has proved that this 
substance is a polyanhydride of mannose. In the following 
lines, I will describe the root from which the konahonniaku is 
made, and the experiments which elucidate the nature of the 
product. 
This tuberous root-stock is derived from Amorphophallus 
Rivieri Durien, var, Konjac Engl., a plant belonging to the 
Aroideae and largely* cultivated in the central part of this 
country. The root resembles in form the taro, has a white 
spongy flesh of a sharp taste and a brown epidermis. The root¬ 
stocks vary in size from that of a potatoe to that of a squash 
and reach sometimes the weight of several kilos. 3) 
1) Compare E. Schulze , Z. Physiol. Chem. 16, 386. 
2) The refuse of the stone-nut, used in manufacture, is utilized now in some 
places as a food for animals with good effect. 
3) The art of preparing a suitable food from this root-stock and of removing 
the sharp taste was introduced into this country about a thousand years ago by 
Chinese. 
