274 



SCIENTIFIC AGRICULTURE. 



April, 1922. 



acid development and the sul)sequent keep- 

 ing (pialities. From the time of harvest 

 until along in the following May, the corn 

 arrives at the terminal markets with a per- 

 cent of water above normal and is graded 

 No. 2 or 3. After a time the moisture be- 

 comes more uniform and approximates 

 13.5 p.c. or lower. The corn tlien grades 

 No. 1 unless it contains numerous unsound 

 or damaged kernels in which case the 

 grade is lowered. The writer has found 

 that the percent of moisture as determined 

 l)y the grain inspectors averages around 

 1.0 p.c. too low and in some case.s reaches 

 2.0 p.c. In only rare instances do they 

 show a higher moisture than that deter- 

 mined in our laboratory. 



In grading old corn the degree of acid- 

 ity is most important. Corn with a higli 

 moisture contei^t is sometimes artifically 

 dried at a later date to prevent spoilage. 

 Tsing the moisture test to gi-ade this class 

 of corn would give misleading results since 

 the quality would be lowered during the 

 period the corn was high in moisture. The 

 Bureau of Chemistry has found that the 

 "degree of acidity"' of tlie corn is in 

 direct relation to the factors of moisture, 

 (juality, soundness, and percent of dam- 

 aged kernels. All corn, even when har- 

 vested, shoAvs some acidity and as the com 

 become.s older this increases, oAving almost 

 entirely to the changes taking place in the 

 germ. Damaged and broken kernels ad- 

 mit tlie air and hasten the reactions. 



In order to classify corn as to quality 

 by means of tlie acidity test, it is neces- 

 sary to fix certain liuiits. l)ut as in all em- 

 ])irical standards a certain amount of va- 

 i-iation must be allowed. As a result of 

 numerous tests and careful inspection, the 

 following standards have been chosen. 

 Corn with an acidity above 50 degrees is 

 always very poor and has reached sucli an 

 advanced stage of deterioration that a 

 gbince at it would l)e sufficient. Any 

 corn over 30 is very low quality. Between 

 26 and 30 it has deteriorated eiiougli to be 

 considered unsound although it may ap- 

 l)ear of fair (puUity to tlie eye. Between 

 22 and 26 it is in fair condition while corn 

 iielow 22 is of first class quality from a 

 commercial standpoint. 



One car of corn received by this firm 

 was billed 14.80 p.c. moisture and graded 



No. 2. An analysis showed an acidity of 

 30.5. JHominy feed made from it showed 

 46 degrees of acidity. If this corn, all of 

 which was used for feed, had been graded 

 according to the acidity, it probably would 

 have been No. 4. 



ISince the acidity of corn is highest in 

 the germ and nearly all the increase is due 

 to it in the presence of moisture, the tw(» 

 important factors in the manufacture of 

 corn products with good keeping qualities, 

 are the proper removal of fat and the ab- 

 sence of excessive moistui'e. In hominy 

 feeds for livestock, an acidity higher than 

 that permissable for human beings is not 

 objectionable but in these feeds the mois- 

 ture must be lowered to compensate for 

 the increased fat. While the maximum 

 amount of water consistent with proper 

 keeping rpialities has never been definite- 

 ly settled we have found that corn Avith 

 14 p.c. moisture or less, corn meal or 

 flour Avith 14 p.c. oi- less and hominy feed 

 Avith 10.5 p.c. or^ess, are secure from un- 

 due deterioration if kept in a dry, ven- 

 tilated place. It niight be supposed that 

 corn flour AA'Ould require a loAver moisture 

 content than meal oAving to its finer na- 

 ture but it contains considerably less fat. 



With the percentage of moisture so im- 

 portant a proper method of drying the 

 products is necessary as Avell as a rapid 

 method of determining the extent of the 

 drying. For control AA'ork the ordinary 

 method of drying in an oA'en is too sIoav. 

 BroAvn and DuA'el have made a tester suit- 

 able for the rapid determination of mois- 

 tui'c in grains and other substances. The 

 method consists of heating a known Aveight 

 of the sample in a suitable flask Avith a 

 good grade of mineral oil that has a flash- 

 ing point arduiid 200 degrees C, and in 

 condensing, collecting and measuring the 

 distillate. The apparatus has been stand- 

 ardized i)y the inventors, although every 

 chemist Avould test the recommended tem- 

 peratures carefully before accei)ting any 

 results as correct. The a|)paratus is a 

 great boon to millers as they can have the 

 repoi't from the chemist in little more than 

 half an hour after the sample it taken. 



The Canada Corn Products Co. has made 

 imiiierous large shipments of corn meal to 



