Edible Products. 



584 



[June 1908. 



merce. The former when ground and 

 placed in water develop prussie 

 acid immediately, but no prussie acid is 

 formed when ground linseed cake is 

 placed in water. This difference appears 

 to be due to the fact that linseed cake 

 is now made by hot expression of the 

 oil, and the heat applied in this process 

 is sufficient to destroy the activity of 

 the ferment, to the effect of which on the 

 glucoside contained in the linseed, the 

 liberation of prussie acid is due. There 

 is, however, always the possibility that 

 the prussie acid-yielding glucoside may 

 be decomposed by ferments present in 

 other feeding stuffs used along with 

 the linseed cake, even if it is not acted 

 on by the intestinal ferments after in- 

 gestion. 



In connection with this subject it may 

 be of interest to mention what is known 

 regarding the use of cassava in tropical 

 countries. Two varieties of this plant, 

 the bitter and the sweet, are known, and 

 it was long supposed that only the roots 

 of the bitter sort yielded prussie acid and 

 were toxic. Recent investigations have, 

 however, shown that at least in the 

 West Indies both the sweet and bitter 

 varieties yield similar amounts of 

 prussie acid. Our investigations have 

 shown that the origin of prussie acid in 

 cassava is the same as in the beans of 

 Phaseolus lunatus and linseed, viz., the 

 interaction of phaseolunatin and a 

 ferment. (Proc. Roy. Soc,, 1908, B. 

 LXXVII, 152). In preparing meal from 

 cassava roots these are usually rasped 

 iutoa coarse powder and the latter 

 thoroughly washed. In this process the 

 glucoside is brought into coutact with 

 the ferment and completely decomposed, 

 the prussie acid formed being washed 

 away by the water, so that it can be 

 understood readily enough that meal 

 so prepared is innocuous. Large quanti- 

 ties of cassava are also used as a vege- 

 table, being boiled or baked in the same 

 manner as potatoes. Treatment of 

 this kind will destroy the activity of 

 the ferment, but will not necessarily 

 affect the glucoside, so that boiled or 

 baked cassava is in much the same 

 position as hot-pressed linseed cake, i.e., 

 it contains a glucoside, capable of yield- 

 ing prussie acid, but is harmless so long 

 as it is not in contact with a ferment 

 capable of decomposing the glucoside. 



Numerous cases of poisoning by cassava 

 are on record, but these seemed to have 

 been caused invariably by the consump- 

 tion of raw cassava. It would seenij 

 therefore, that in the cases of linseed 

 and cassava, the application of enough 

 heat to destroy the activity of the 

 enzyme present renders these materials 

 harmless, and the question arises aa tQ 



whether similar treatment would not 

 be efficacious in the case of Rangoon 

 beans. 



The statement has been made by ex- 

 porters of Java beans that the latter 

 become safe to use after being boiled in 

 water, and Messrs. Tatlock and Thomson 

 have stated (loc. cit.) that when Java 

 beans are steeped in water and after- 

 wards boiled, a considerable proportion 

 of the prussie acid-yielding glucoside 

 is removed. Experiments made at the 

 Imperial Institute with Java beans 

 have shown, however, that practically 

 no change in the quantity of glucoside 

 present is effected by this means, but as 

 the activity of the enzyme is destroyed, 

 the ground boiled beans no longer 

 liberate prussie acid when mixed with 

 water. 



There is on record one case which 

 seems to indicate that this treatment 

 of Java beans is insufficient as a pre- 

 caution against poisoning. Thus Robert- 

 son and Wynne state (Zeit. Anal. Chim., 

 1905, XLIV, 735) tliat four persons out 

 of seven who had made a meal of cooked 

 "Kratok" beans (Kratok is a vernacular 

 name for Java beans in use in Holland 

 and Germany), died, and in each case 

 clear proof of poisoning by prussie acid 

 was obtained. 



In view of the large interests concerned 

 in the trade in Rangoon beans, and as, 

 apart from the prussie acid they yield, 

 they appear to be a useful and nutri- 

 tious feeding stuff, it seems desirable 

 that the question of their suitability for 

 use as a feeding material should be 

 definitely settled. This is all the more 

 important, as there is reason to believe 

 that the white may come into use as a 

 human food, siuce they closely resemble 

 small haricot beans in appearance. 



Until this question has been investi- 

 gated it is undesirable that any further 

 definite advice should be given to dis- 

 continue the use of Rangoon beans, 

 since in spite of the fact that both the 

 red and white varieties have now been 

 shown to yield prussie acid, there is at 

 present no evidence that this is formed 

 in quantity sufficient to be injurious, 

 and although these beans have been used 

 as a feeding stuff now for some years, 

 no poisoning cases have been traced to 

 them so far as is known. At the same 

 time, since the beans yield prussie acid 

 in varying quantity, it is clearly not 

 permissible to recommend them for use 

 as a feeding material. All that can 

 fairly be done at the moment is to 

 place the facts on record.— Journal of 

 the Board of Agriculture* March, 190bi 

 Yol. XIV, No, 13, 



