126 



[August, 1908. 



EDIBLE PRODUCTS. 



HYDROCYANIC ACID CONTENT OF 

 CASSAVA. 



The question of the danger of poison- 

 ing arising from the consumption of im- 

 perfectly cooked cassava has formed the 

 subject of several notes and articles in 

 the Agricultural News (Vols. I, p. 5; 

 II, p. 102 ; and III, p. 423), and a leaflet 

 {Hints and Information %n regard to 

 Lassava Poisoning) dealing with the 

 subject was issued some two or three 

 years ago. 



Some investigations in connection with 

 the amount of hydrocyanic acid and 

 starch present in cassava have recently 

 been carried out by the Bureau of 

 Chemistry of the U. S, Department of 

 Agriculture, and the results are pub- 

 lished in Bidletin No. 106 of the Bureau. 

 The previous work that has been done in 

 relation to this question has chiefly been 

 undertaken in Trinidad by Professor 

 Carmody and his predecessor in the 

 office of Government Analyst, and by 

 the Hon. H. H. Cousins in Jamaica. 



Cassava has been divided into sweet 

 and bitter varieties, and although sweet 

 cassavas are considered to be less poison- 

 ous than the bitter varieties, yet it 

 appears that the sweet or bitter 

 character of cassava is not directly con- 

 nected with its content of hydrocyanic 

 acid, but is dependent upon the absence 

 or presence of some bitter principle. As 

 the result of his investigations, made 

 some five years ago, Professor Carmody 

 reported the mean percentage of hydro- 

 cyanic acid in the sweet varieties 

 examined as 0-010, and in the bitter 

 varieties as 022. It is usually held that 

 sweet varieties contain only half as 

 much prussic acid as those known to 

 have been fatal. 



Varieties of cassava grown in Colum- 

 bia, and analysed by the Government 

 Analyst of Jamaica showed a mean 

 percentage of only 0*001 of hydrocyanic 

 acid, the maximum being only 003. 

 From this it appears that all the 

 Columbian cassavas may be practically 

 classed as sweet. 



On the other hand, analyses of native 

 bitter cassavas made by the same officer 

 show percentages of hydrocyanic acid of 

 from 0-036 to 0-077. 



Professor Carmody suggets that the 

 difference between the two kinds con- 

 sists in the hydrocyanic acid being dis- 



tributed throughout in the bitter kind, 

 whereas in the sweet varieties it exists 

 chiefly in the cortex. 



In regard to the proportion of hydro- 

 cyanic acid present, this is certainly 

 influenced by environment, and the ex- 

 periments with cassava that have been in 

 progress in Jamaica for some years past 

 {Agricultural News, Vol. VI, p. 261) 

 would appear to indicate that when a 

 variety — usually cultivated in elevated 

 districts — is transferred to lower levels 

 of country, the proportion of hydro- 

 cyanic acid tends to increase. Mr. 

 Cousins reports that fourteen varieties 

 of cassava, stated to be quite non-poison- 

 ous in Columbia, were tested after a 

 year's growth in the Liguanea plains of 

 Jamaica, and were found to contain, on 

 the average, 0031 per cent, of hydro- 

 cyanic acid. After a further period of 

 four years' growth in the same changed 

 locality the hydrocyanic acid content 

 rose to 0'0124 per cent., or practically 

 four-fold. On the other hand, a report 

 from Trinidad, dealing with this ques- 

 tion, notes that residents of Columbia, 

 who have imported bitter varieties from 

 Jamaica, find they have become sweet. 



The work referred to as having been 

 carried out in the United States was con- 

 ducted at Biloni, Mississippi, and at 

 Miami, Florida, in 1904 and 1905. Cassava 

 is a crop that may be grown in any of 

 the Gulf States, and it was felt that the 

 great feeding value of the roots, could 

 the danger of poisoning be eliminated, 

 justified investigation of the hydro- 

 cyanic and starch contents of different 

 varieties, and the conditions which 

 influenced variation in these constituents. 



Thirty-nine varieties were under trial 

 at Biloni and twenty-eight at Miami. 

 The whole of those raised at Miami were 

 originally obtained from Jamaica, while 

 at Biloni twelve varieties from Porto 

 Rico were grown in addition to the 

 Jamaica kinds. At Biloni, a common 

 native variety, Florida Sweet, was also 

 grown. 



It is curious to note that none of the 

 imported varieties gave so low a percen- 

 tage of hydrocyanic acid as 'Florida 

 Sweet,' which contained only 0'002 per 

 cent. Pie de Perdiz and Cenaguera 

 approached nearly, however, with an 

 average content of 0-003. Of the cas- 

 savas grown at Biloni, Porto Rico, 

 White top contained the highest pro- 

 portion of hydrocyanic acid, 0'030 per 

 cent. This was closely followed by 



