SULPHUR BLEACHING OF COMMERCIAL OATS AND BARLEY. 9 



odor when the oats are freshly bleached. The odor of sulphurous acid 

 has a tendency to disappear, especially as the oats become drier. The 

 absence of the odors commonly found in natural oats usually arouses 

 suspicion that they have been bleached; therefore, in order to supply 

 the desired odor and to make the detection of sulphur-bleached oats 

 difficult or impossible by physical examination, it is a common practice 

 to mix unbleached oats with bleached oats. The mixed grain is seldom 

 questioned as having been bleached; nevertheless, a trace of sulphurous 

 acid remains and may be detected by subjecting the grain to a simple, 

 qualitative, chemical test recommended by Carroll,'^ 



GROWTH OF FUNGI RETARDED BY BLEACHING. 



Mrs. Flora W. Patterson, Mycologist in Charge of Pathological Col- 

 lections, Bureau of Plant Industry, made tests of samples taken from 

 six lots of oats and barley, before and after bleaching, in order to 

 ascertain how the bleaching process affects the fungi commonly found 

 on the grain, of which the following is a partial report: 



The contents of all tubes were agitated in water, which was then added to steril- 

 ized culture media in petri dishes, 8 dishes being prepared from each number. 

 These cultures now clearly demonstrate the fact that the process of bleaching inhib- 

 its the development of fungi, as the number of species is greatly reduced. Their 

 growth is not only greatly retarded, but it is in no instance so luxuriant, even with 

 the same species, as in the cultures made from the unbleached grain. 



Unless the grain is properly cooled and dried after having been 

 bleached it will contain an excess of heat and moisture, two factors 

 favorable for the growth of fungi, which may result in the deteriora- 

 tion of the grain. On the other hand, since the fungi are partly 

 destroyed and their growth retarded by the sulphur-bleaching process, 

 it is probable that bleached grain will carry a higher percentage of 

 moisture without danger of deterioration than unbleached grain of the 

 same quality. Observations on grain in commerce seem to indicate 

 that this is true. 



GERMINATION REDUCED BY BLEACHING. 



As bleached oats and barley are frequently selected for seeding 

 purposes because of their exceptionally bright appearance, germina- 

 tion tests were made of both grains before and after bleaching in order 

 to ascertain whether or not the vitality is affected by the bleaching 

 process. The results of these tests are given in Table II. 



o Carroll, W. P. A Simple Method of Detecting Sulphured Barley and Oats. Cir- 

 cular 40, Bureau of Plant Industry, U. S. Dept. of Agriculture, 1909. 

 [Cir. 74] 



