April, 1922. 



SCIENTIFIC AGRICULTURE. 



273 



it goes to tlie second small tank Avhore 

 it -will remain only a short time. The 

 tempered corn goes by gravity to the de- 

 germinator where the kernels are split 

 open, the bran knocked off and the germ 

 loosened from the hominy part of the ker- 

 nel. This mixture of broken material 

 descends to a dryer consisting of revolving 

 horizontal cylinders equipped with steam 

 coils and a suction flue to remove the 

 moist air. The hot material then passes 

 through the coolers, an apparatus some- 

 what similar to the dryer but minus the 

 steam coils. From it the cooled mixture 

 is elevated to the sizing reels which remove 

 the large flinty portions, that are known 

 as pearl hominy or grits. The grits are 

 cleaned in aspirators and all adhering 

 dust, bran and bits of germ are removed 

 and returned to the stream containing the 

 smaller portions. The grits are again 

 sized to remove any kernels which escaped 

 being in the degerminator and finally 

 dried and cooled again in a special dryer 

 and cooler. This is necessary for safe 

 keeping since the grits owing to their size, 

 dr3' slowly in the firs.t dryer. The re- 

 maining stock, consisting of small grits, 

 germ and bran, is passed through a se- 

 ries of break rolls and thoroughly screen- 

 ed and aspirated after each break. The 

 germ flattens out on the rolls and is re- 

 moved either by the screen or the aspira- 

 tor. The final product of the second and 

 third rolls is a f ancj^ table meal ; that 

 from the last roll is corn flour, a commo- 

 dity used in pancake flour, for dustiiig 

 bread pans in bakeries and for filler in 

 sausages. The germ. bran and dust from the 

 aspirators and the shrunken and foreign 

 kernels from the separators, all go into 

 the feed stream and are ground prod- 

 ucing a material called homim^ feed, 

 which is particularly valuable for its high 

 fat and low crude fibre content. The per- 

 centage of fat varies in different mills and 

 with different corn but it usually runs 

 from 7.5 to 9.0 p.c. 



The process as outlined sounds simple 

 but a modern corn mill with its conveyors, 

 elevators, tempering devices, degermina- 

 tors, dryers, coolers, sizing reels, both 

 wire and silk, aspirators, dust collectors, 

 break rolls and grinders is (juite compli- 

 cated and requires skilled millers to oper- 

 ate as well as a chemist to analvse the 



I)ro(lucts and see tliat the composition of 

 the feed is equal to the quarantee and that 

 nothing which is liable to spoil on account 

 of excessive moisture, fat or acidity is 

 shipped out. As the finished products are 

 nearly always lower in moisture than the 

 raw corn, it is necessary for the chemist 

 to obtain as high a percentage of moisture 

 as is consistent Avith good keeping qua- 

 lities to prevent high milling loss. 



Moisture, Acidity and Fat. 



Until recently the amount of corn prod- 

 ucts manufactured has been gradually de- 

 creasing from year to year. The chief 

 reason for this was inefficient or unscien- 

 tific methods of manufacture, which re- 

 sulted in products that were of poor keep- 

 ing quality. From research work carried 

 on by the Bureau of Chemistrj' of the 

 U.S.Dept. of Agriculture, it has been found 

 that corn products, which rival wheat 

 compounds in value as human food, can 

 be made and handled with very little 

 danger of spoilage. There are many fac- 

 tors influencing the keeping qualities of 

 corn and corn products but from a che- 

 mical standpoint the most important ones 

 are Moisture, Acidity and Fat. Of these 

 three variables, the degree of acidity is the 

 most important criterion in judging the 

 quality, as it is the only chemical factor 

 showing a decided eliange as the material 

 deteriorates, but numerous analyses in our 

 laboratory and government investigations 

 show that these three factors are closely 

 related. With uniform moisture the in- 

 crease in acidity varies more or less di- 

 rectly with the fat content and with uni- 

 form fat ; the acidity increases more ra- 

 pidly- as the percent of moisture increases. 

 For instance a sample of homin}' feed 

 containing 8.5 p.c. fat and 12.7 p.c. water 

 showed an acidity of 20.2. After two 

 weeks in a warm place the acidity was 

 38.6. Another feed sample with 10.5 p.c. 

 moisture and 8.6 p.c. fat increased from 

 21.0 to 28.4 in the same length of time. 

 A sample of corn meal with 16.4 p.c. of 

 water and 1.0 p.c', fat increased from 9.5 

 to 16.8 in two weeks while another sample 

 with 13.0 p.c. water only increased from 

 11.0 to 20.4 in six months. 



In commercial grading of new corn the 

 percentage of moisture is of primary" im- 

 portance, since it influences the rate of 



