BORIC ACID OCCURRING NATURALLY IN SOME FOODS. 



Arthur H. Smith. 



Among the common chemical preservatives which have been 

 used in foods and which are prohibited entirely or tolerated 

 under certain restrictions by the Federal Foods and Drugs Act, 

 as now enforced, are benzoic acid, salicylic acid, sulfurous acid, 

 boric acid and formaldehyde. Boric acid is used principally for 

 preserving meats, meat products, fish and dairy products. Its 

 presence can be detected readily by acidifying the ash of the 

 sample with hydrochloric acid and then dipping a piece of 

 turmeric paper into the solution. If boric acid is present the 

 yellow turmeric paper becomes red on drying. 



In the course of some food analyses the writer had occasion 

 to test a sample of datenut butter which was made from dates 

 ground very fine, and peanut butter. The butter has the con- 

 sistency of a stiff jam and is very pleasing to the taste. I 

 obtained a positive but not a very strong test for boric acid. 

 It seemed unlikely that boric acid had been used as an artificial 

 preservative in such small quantities as evidently existed in 

 the material. I then tested some peanuts which had been 

 roasted but found no boric acid in them. Dates, however, gave 

 a test for boric acid when the acidified ash was tested with 

 turmeric paper. It was obvious, then, that the boric acid in 

 the datenut butter must be, in part, at least, naturally occurring 

 in the dates. Several European writers have reported the 

 occurrence of small amounts of boric acid in natural foodstuffs. 

 In the Analyst for 1914 is an abstract of an article by G. Bert- 

 rand and H. Agulhon in Bull. vSoc. Chim. 1913, 13, 824-827, 

 citing the occurrence of boric acid in milk and eggs. In the 

 Analyst for 1912 is an abstract of an article by L. Robin in 

 Eighth Int. Cong. App. Chem. 1912, Vol. 1, 429-432, in which 

 he states that boric acid is a natural constituten of wines. In 

 the Analyst for 1913 is an abstract of an article by V. Villa- 

 vecchia and I. Barboni in Ann. Lab. Chim. Cent, delle Gabelle 

 1912, 6, 27-68, in which the occurrence of boric acid in Italian 

 salt is discussed. In Zeit. Offentl. Chem. 1905, XI, 231-234, 

 is discussed the occurrence of boric acid in common salt. 



The above mentioned facts led to experiments in which a 

 quantitative analysis for boric acid was made in some of our 

 common fruits. Because of the limited time and because of 

 lack of fresh fruits, dried fruits were used. The writer tried at 



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