Mannane as an Article of Human Food- 



BY 



C Tsuji, Nvgakushi. 



Since the discovery of mannose by Rciss 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. 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. 



