INDUSTRIAL A N D ENGINEERING CHEMISTRY
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confronted the food chemist has been the establishment of chemical means for the detection of decomposition in food products. This has been successfully accomplished in a wide variety of commodities, such, for example, as canned salmon, eggs, and tomato products. New Problems Constantly Arising
As has been said, much progress has been made, but much remains to be done. Today the food chemist is concerned with such questions as the identification of imitation fruit flavors as distinguished from genuine flavors, especially where these occur in mixtures of both genuine and synthetic materials. Much progress has been made along the line of the differentiation of flavors, but problems are still arising. Such an apparently simple question as the detection of added water in food commodities sometimes raises almost insuperable obstacles. Water is the cheapest and most prevalent of adulterants. The hydrant is available to every food adulterator. The normal moisture content of natural food products varies within wide limits. How is the chemist to establish that the moisture content of a particular commodity has not been artificially increased by means of the town water supply? New theories of nutrition involving the vitamin content of foods and that of certain food accessories have
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opened a wide field for the food manufacturer whose enthusiasm in advertising his product exceeds the bounds of propriety. Here the food chemist is confronted with questions calling for the development of novel methods of analysis. Ilustrations might be multiplied but time will not permit. I n conclusion, let me repeat that the problem of the food regulatory chemist is a complex and growing one and that his operations are of the utmost importance to the welfare not only of the consumer but of the honest food manufacturer. There is, moreover, an appeal to the chemist not only because of the public service involved, but because there are presented a great variety of problems of the most absorbing interest that have sufficed to enlist and hold in the regulatory services men of high ability and training. Let me say also that although the food inspection chemist does not ordinarily advertise his activities, knowing full well that to do so would damage the reputation of honest commodities which are in competition with adulterated and misbranded products, and that, although the American consumer may not, in general, be aware that he is protected by the vigilance of municipal, state, and federal food chemists, the network of food-law enforcing agencies of the United States guarantees today to the American table a safer, more honest, and more wholesome food supply than is available in any other country.
The Service of Chemistry to the Milling Industry C. 0. Swanson KANSASSTATEAGRICULTURALCOLLEGE,MANHATTAN, KANS.
HE milling industry has been slower in obtaining the
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full benefits of chemistry than some other industries. As the task of this industry is to convert cereals into food products the chemists employed in it are designated cereal chemists. Two decades ago the cereal chemists in this country numbered only a few dozen. Now these men have an association of several hundred active members, and there are probably as many more whose work is taken up, either exclusively or partially, with problems connected with wheat and flour. Twenty years ago less than a dozen flour mills had chemical laboratories. Now an important flour mill would no more think of dispensing with the chemist than they would with the miller. What are some of the reasons for the entrance of the chemist into this field of service? What are some of the results of his services? And what are some of the problems awaiting solution? Development of New Problems
The soils of the plains area of the United States, the largest wheat section in the world, accumulated nitrogen through countless ages. Abundance of nitrogen in the soil means strong wheat, provided climatic conditions are suitable to this crop. Depletion of nitrogen, with a demand for greater production per acre, means weaker wheat. The present-day miller is facing wheat problems unknown to the past generation. Then there is the change in the baking industry. Formerly most of the flour was used in the home. The housewife relies more on art than on science in baking, and she is able to make a satisfactory product from weaker flours. Her main purpose is to get palatable bread, and the number of loaves from a given quantity of flour is of secondary importance. Today probably more than half of our bread is baked in the commercial bakery, where profit must be a governing consideration. Not only is it necessary to make a bread suit-
able to the public taste, but the amount from any given lot of flour must be such that the shop will show a profit. Recently there have occurred tremendous mergers in the baking industry, It is stated on good authority that 40 flour buyers purchase 40 per cent of all the flour consumed in the United States. This concentration gives them a tremendous advantage in bargaining with mills. They can dictate the quality to be supplied and, within certain limits, the price as well. This forces the mills to standardize their flour to a degree unknown until a few years ago. Some of the larger milling concerns have established brands well known to the public. These flours are not so much better than some other less well-known brands, but they are uniform to a superlative degree. They are the same today, yesterday, and forever. The mills that achieved this distinction were the first to establish chemical laboratories. Without this service, such success would not have been possible. Other mills soon found out that if they were going to stay in the race they also must have the services of chemists. At first the principal duty of the mill chemist was to make what may be called a “post mortem” examination of the flour. The mill ground hundreds and thousands of barrels a day. Several times during the day samples of flour were taken to the laboratory where the chemist determined the ash, moisture, and protein, and in many cases, also made baking tests. Value of Chemical Tests
What is the value of the ash test? The wheat kernel consists of three main parts-the endosperm, the bran coat, and the germ. The work of the mill is to separate the outside bran coat and the germ from the inside endosperm and convert the latter into fine, white flour. As the bran coat contains from twenty to twenty-five times as much ash as the endosperm, the ash determination shows very accurately how successfully the mill performs its work.
December, 1928
I N D U S T R I A L A N D ENGINEERIXG CHEMISTRY
What is the importance of the moisture determination? The whole process of milling is based on the single fact that the three parts of the wheat kernel differ from one another in relative toughness or friability. This difference is increased by adding a little water to the wheat as a part of the preparation for milling-a process known as tempering. Enough water must he added to accomplish the desired result, but too much will not only make the wheat mill unsatisfactorily, hut will make the moisture content of the flour and feed too high. A product with too high a moisture content is undesirable for storage. Furthermore, the Government has fixed legal limits for moisture in flour.
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wheat. The quality sought in the flour must be in the wheat. Formerly the quality of the wheat obtained by the mills was judged only by the buyer. Now the buyer uses his best judgment on quality and, in addition, the chemist tests all the wheat, which is then binned on the results of his tests. The blending is no longer made on the judgment of the elevator man, but on the records obtained in the laboratory. An order comes to the office for a flour of a certain quality. The quality of the wheat in the different bins being known, the chemist calculates what percentage shall be drawn from each bin in order to produce flour of the quality desired. In an up-to-date mill there is no guesswork about the quality that will be obtained in a day's run. Using a required mill mix rives the desired flour. I n the better mills the chemist
Need for New Tests The strides made by the chemists in the milling industry have been notable, but new worlds to conquer remain. The premiums often paid for protein in wheat places an unusual importance on this determination. It is not uncommon t o have a difference of 8 cents a bushel premium for each percentage of protein above a certain point, which means that 0.25 per cent niakes a differelice of 2 cents a bushel. Any cereal chemist knows that this comes close to the experimental error in the laboratory, not to speak of the errors due to difficulties in ohtainine a true and reoresentative sarn~leand Flgure 1-Students on the Roll Ftoorof fheMlllst Kansas State Ag.rlcult(lra1 College, Manhattan, Kans.
The protein in wheat flour differs from that in the fine meal of all other grains. When water is added to wheat flour gluten forms, and when the mixture is worked we get the well-known dough. m e n yeast grows in this dougli it expands, and when placed in a hot oven the dough becomes bread. The weater the quantity of vrotein, the greater the
the times. The escape of moisture possible through the outer covering of g a i n is so slow that before ordinary drying methods are used i t is necessary to crush the grain, which usu-
glutenin. There are two or possibly three other proteins in flour. Percentage of dry gluten as determined has a numerical value approximately equal to the percent.age of protein. This is because of the inclusion of non-protein material in gluten as obtained. The big commercial baker desires a high-protein flour because i t lends itself best to liis purposes. High-protein flour is possible only from high-protein wheat and the quantity of high-protein wheat is limited. Low-protein wheat makes a better flour if blended with wbeat of a higher protein content. For these reasons protein has in recent years assumed a commandine imDortance in the evaluation of wheat. and every carload of &e& is tested for protein. AS the quality is imnor. . as well as the ouantitv" of Drotein . tant, various methods are in &e to measure the qualicy of protein in flour. At the present time. the hakine test is the
FIBure 2--Raru of Grlndlng Rolls In a Butfalo, N. Y., Flour Mill
For this redson baking tests are made daily in the well-manned flour mill laboratory. The ash. moisture. Drotein. and bakine tests tell the storv of the quality of flour produced. It was soon discoverez, however, that such examination was not sufficient. For what avail is i t to find that a given lot of flour is not up to standard when this flour has already been loaded into cars, and is perhaps hundreds of miles away from the mill? The quality of the wheat must be known before it is milled. The miller knows that good flour can be made only from good
ally causes loss of moisture, with corresponding errors in the results. The method of heating grain in mineral oil, or the well-known Brown-Duvel method, is a t present a very rapid method, but i t has several faults known to the chemist. The times demand a method which shall be as far in advance of anything now existing as the Brown-Duvel method was when first introduced. Protein determinations are now made on the air-dry basis, so that variation io moisture is one uf the sources of error. If a sufficientlvrmid and accurate moisture determination were available it would not he long before grain would he handled on a constant-moisture basis.
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1-k-DCSTRIAL AiYD ENGINEERILVG CHE-MISTRY
Probably the greatest problem facing the cereal chemist today is to measure quality of protein in flour. The Kjeldahl method measures the quantity of protein fairly satisfactorily. The trade has learned that there is ordinarily a relation between quantity and quality; that is, within certain limits high-protein flour means a certain degree of strength. But there are very important exceptions. In the spring of 1928, I submitted samples of flour made from a certain variety of wheat to twelve cereal chemists. After making careful tests, eleven of these chemists stated that the flour would not be satisfactory to their trade. Barrel lots were also submitted t o looal bakeries. One, by taking special precautions, succeeded in making a satisfactory bread, but he stated that such flour would not be acceptable in the shop. The other bakery failed to make a satisfactory bread. Yet this wheat was graded No. 1 Hard Winter on a leading commercial market, and carried a 12-cent premium for its excess protein. What happens when water is added to flour to form dough? We know in a general way that about as much mater is bound by the protein in forming gluten as that which is absorbed by the starch. We also know that some of the water is in a free condition. How is gluten formed? How do these protein complexes unite to form the yellowish rubbery substance known as gluten? HOE do the protein complexes in a goodquality flour differ from those in a poor-quality flour? What happens when wheat or flour deteriorates? We know that if wheat iB stored with an excess of moisture it will soon lose its quality for bread-making. The quantity of protein has not materially changed, but the change in quality is profound. Wheat improves to a certain degree when stored under good conditions. What happens t o the proteins when they become more satisfactory for bread-making? The study of surface tension has opened up to physical chemists wide vistas of knowledge, of the secrets of chemical phenomena. It was mentioned above that part of the mater in dough is free. Every flour mill chemist who has made baking tests knows the importance of having the correct quantity of water. There is no doubt that surface tension phenomena are of great importance in determining the quality of the dough. Dough possesses property of resiliency and also of slippage. Recovery in form does not take place if the deformation goes beyond a certain limit. That means that the protein complexes which form the gluten are united into strands which will spring back like rubber, and also that these complexes seem to slip on each other and on the starch granules. The materials that have a strong effect on surface tension, known as capillary action, have a profound effect on the quality of dough and the resulting bread. To these belong alcohol and acids, as well as other substances produced during yeast fermentation. These affect the surface tension and no doubt play an important part in dough development. Phosphatides, liberated during fermentation, most powerfully affect surface tension. This is a field in which practically no research has been done. The methods of the physical chemist should be made more available to the cereal chemist. We know in a general way what happens during fermentation of dough. Fermentation tolerance is considered one of the factors of flour quality. That is, a flour which must be handled on a more exact fermentation schedule is not as desirable as one which will still make good bread if the fermentation period is unavoidably delayed. What are the reasons? The sugar naturally present in flour or that which is added in dough-mixing is consumed by the yeast during growth. If needed, more sugar can be added to replace this. A flour of greater diastatic activity is supposed to have greater fermentation tolerance, as more sugar is made to replace that used by the yeast. The gluten is altered, but no chemical changes seem to occur, at least none large enough to be measured. It
VOl. 20, No. 12
would be very desirable if we could determine more exactly what takes place. Cereal chemists hail with delight any new method which promises to help them in their problems. Some years ago the hydrogen-ion determination was used a great deal. Later the viscosity measurement, which has been found very valuable by many cereal chemists, came upon the stage. The results obtained by this determination correlate with the baking test in about 85 per cent of the cases. But why the exceptions? If we could find a satisfactory answer to this, there would be available a quick method for testing the quality of protein in flour. The ash determination is valuable chiefly because it tells the purity of flour with reference to the extraction. But why does so small an increment of ash as 0.10 per cent have such a profound effect on quality? The effect of this ash seems to be all out of proportion to its amount. Is the high-ash flour poorer because of less uniformity in granulation? Have some of the protein complexes been injured in the grinding? We know that mechanical injury is possible in overgrinding. We also know that the gluten may be severely injured by overmixing the dough, as no gluten can be washed from such dough. What has happened to the protein complexes? No chemical change that can be measured has taken place. What happens when flour is bleached? The coloring matter carotin is destroyed, and some bleaching agents change the hydrogenion concentration. But the maturing effect is not altogether due to this. The oxidizing effects of the bleaching agents seem to have affected also the substances that influence surface tension. These are some of the questions facing the cereal chemist which show that there is still room for investigation in this field. The rewards of such research are alluring. Summary
Only recently have chemists been active in the milling industry. The tremendous development in the baking industry makes it essential that flour shall be both higher and more uniform in quality. At first the flour mill chemist spent most of his time examining the products made by the mill. Now the quality of wheat is known before it is milled, and the mill mixture is made on the basis of the chemist’s determination. il. correct wheat mill blend is the absolute requirement for a satisfactory flour. A man who is well trained in chemistry and also has a wide knowledge of wheat and flour as well as of the requirements of the bakers is necessary in making such a blend. The cereal chemist has a large field for research, both in practical quantitative methods and in theoretical considerations. The times demand that the ash, moisture, protein, and baking tests which are used most by chemists, shall be performed more rapidly and also more accurately. There is no satisfactory rapid method of measuring the quality of protein in flour, and very little is known about the factors that determine quality. Studies in surface tension and other methods of the physical chemist would give us more insight into the chemical phenomena of flour and lay the ba5is for a more exact knowledge. Standards for Ginger Ale, Sarsaparilla, and Cinnamon Extracts -Revised and amended definitions and standards for ginger ale and ginger ale flavor, sarsaparilla and sarsaparilla flavor, and for cinnamon extracts have been adopted by the Secretary of Agriculture a t the recommendation of the Food Standards Committee. These definitions and standards are adopted, not only for the guidance of officials of the Department of Agriculture in the enforcement of the Federal food and drugs act, but by many states in the enforcement of state laws.
