FOOD
FLAVOR T h i s excellent likeness of Harvey W . Wiley appeared on the front cover of Gdod Housekeepmg for M a y , 1912. W e are pleased t o reproduce i t here with
the kind permission of .that magazine.
QUALITY CONTROL IN THE DAIRY INDUSTRY C. Ernest
Q
UALITY and quality control in dairy products involve extensive considerations. They encompass various fields of scientific and technological activities. I n this limited paper it is possible to discuss only partially and briefly this broad and complex subject of great importance to the dairy industry. It is opportune to recall briefly Harvey W. Wiley’s direct and indirect influence on the approach of the dairy industry to the important responsibility of quality and quality control. One of his h t problems upon becoming chief of the Chemical Division, Department of Agriculture, in 1883 was the more extensive study of food adulteration. He immediately organized a section for the specific study of food adulteration and continued unceasingly in his efforts to place before the public the danger of such adulteration and to secure legislation for its prohibition. When the Food and Drug Law was finally enacted in 1906,it was, with but slight variation, in the form originally drafted by Wiley, and
Thompson
THE BORDEN COMPANY, 350 MADISON AVENUE NEW YORK 17. N. Y.
thus he may be Fegarded as the father of pure food and drug legislation in the United States. Wiley continued as chief of the Bureau until 1911 when he retired. He was specially emphatic in his protestations against any form of adulteration or the use of chemical preservatives in food products. During those years adulteration and chemical preservation were practiced to a limited extent by the food industry. The use of preservatives was occasionally detected in dairy products. Milk, however, did not lend itself readily to extensive adulteration, but wae limited mainly to skimming and the addition of water. Wiley and his associates vigorously campaigned against such practices. His sound basic principles of quality control as related in particular to adulteration and the use of pmervatives pointed the way to recognizing that all foods should be pure
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INDUSTRIAL AND ENQINEERING CHEMISTRY
and clean, that their keeping qualities should not rest upon the use of preservatives. The dairy industry, as part of the greet food industry, joins in acknowledging Harvey W. Wiley as an outstanding leader and public servant whose staunch adherence to fundamental principles has had a far-reaching beneficial effect. A SAFE MII& SUPPLY
studies indicate that sulfa drugs are highly effective in the destruction of all bacterial types associated with mastitis. The outlook is bright for the further reduction of mastitis in cattle. A healthy cow is a prime requisite to safe milk. It is unquestionable that today we have more healthy cattle in milk-producing herds than any nation in the world, and the dairy industry is organized to maintain the newsary control continuously. The farmer has learned from experience the vital significance of any diseased cattle in the herd; frequent inspections have stimulated his vigilance, and the enforcement of rigid regulations has led him to realize that only healthy cattle pay dividends. Anyone intimately connected with the production or handling of milk should have good health and clean habits. Certain of the serious epidemic diseases such as typhoid fever, paratyphoid fever, streptococcus sore throat, scarlet fever, diphtheria, and dysentery may be carried through milk should it become contaminated as a result of unsanitary handling.' This presented aserious problem some fifty years ago. For a number of years health officials throughout the nation have given continuous attention to bettering sanitary conditions on dairy farms, eliminating diseased cattle, encouraging clean milk production, proper pasteurization, and careful supervision over the health of employees. As a result the problem of a safe milk supply no longer exists. The adoption of pasteurization by milk distributors and those manufacturing dairy products has further guaranteed the safety of the milk supply. More recently the phwphatase test has furnished a control method for determining the thoroughness of pasteurization.
Two prominent accomplishments in quality control stand out in the dairy field today--first, the removal of diseased cattle from milk-producing herds, and second, the education and supervision of personnel in the interest of eliminating individuals who may be suffering with infectious, contagious, or communicable diseases. This work has been done so well that consumers are practically unaware now that a danger of this nature ever existed. Between 1850 and 1910 it was recognized that milk might become the vehicle for the transmission of pathogenic organisms which might endanger human life. Cattle are subject to bovine tuberculosis, brucellosis or undulant fever, Bang'a disease (responsible for contagious abortion), foot and mouth disease, and other diseases infectious to man. Fortunately none have been highly prevalent in the milk-producing herds in the United Staka with the exception of bovine tuberculosis. I n 1910 it was estimated that 10% of the dairy cattle in the United Statea would react positively to the tuberculin test. In that year the D i ~ s i o nof Animal Industry of the United States Department of Agriculture began a series of tests and examinations looking toward the elimination of such infected animals. Reports showed in 1917 that, of 20,101 cattle teated, 3.2% reacted to the tests; in 1922, of 2,384,235 cattle tested, 2.5% reacted; and in 1936, of A CLEAN MILK SUPPLY 22,918,038 cattle teated, 0.7% reacted. In other words, over a period of twenty years, positive reactions of cattle tested deNot only must the production of milk be clean but it must be creased from 3.2 to 0.7% even though the number of cattle teste& maintained in clean condition from the moment it is drawn from the cow until delivery to the consumer, irrespective of what form increased a thousand fold. Mastitis is the general term for the it sasumes or the type of package that serves as the container. bacterial invasion of udder tissue. The udder becomes inflamed A clean milk supply means one in which the milk is free from and the composition of the milk is altered. Inasmuch as a mixed bacterial flora may be present, the presence of pathogens visible dirt and has a low bacterial count. As far as market milk, may exist. Mastitis is readily recognized, and cattle showing any cream, and closely related products are concerned, state and local boards of health have promabnormality with respect to Harvey W. Wiley's important influence on the most the appearance of the udder ulgated detailed regulaimportant activity of the dairy industry-quality and or milk obtained therefrom tions for every phase of is considered as justification quality control-is reviewed. What constitutes a safe and sanitation connected with for their separation from clean milk supply? Important considerations in sanitathe maintenance of clean healthy cows, proper conthe herd and the rejection tion are discussed in connection with the phenomenal of all such milk as unfit growth of the dairy industry. Composition and construction of barns, use of for human consumption. It small mouthed milk pails, sumer-acceptance factors are presented for the major milkingand handling ofmilk was estimated that farmers milk producte-milk and oream, butter, ice cream, by healthy personnel, use of cheese, evaporated and condensed milks, nonfat dry milk lost 3% of their potential milk production due to aolids, and d r y whole milk. Quality control is shown in clean and sterilized utensils, mastitis in 1942. Recent the fieldr of standardization, fortification, and nutrition. properuseandcareofmilking ~~
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machines, prompt and efficient cooling of the milk, and prompt delivery of the milk to its destination. These regulations have included every phase of factory sanitation and have provided for regular and continuous factory inspections. To assist local health officers of smaller communities and serve as a guide to public health officials, the United States Public Health Service has made available through the years a Milk Ordinance Code outlining the minimum requirements of a safe and clean milk supply. Where milk is produced for manufacturing purposes and does not come under the direct supervision of local boards of health, there is a growing tendency toward the adoption of those standards which are recognized as satisfactory for market milk. The American Dry Milk Institute, representing the majority of nonfat dry-milk solids manufacturers, and the Evaporated Milk Association, representing the evaporated milk industry, have developed their own Sanitary and Quality Standards. These include the requirements of a clean milk supply and the maintenance of strict factory sanitation based on the established and recognized requirements for market milk. Section 402 of the new Federal Food, Drug and Cosmetic Act states that a food shall be deemed to be adulterated if it has been prepared, packed, or held under unsanitary conditions whereby it may have become contaminated with filth or whereby it may have been rendered injurious to health. This requirement is mandatory to all producers of milk and milk products which enter interstate commerce, and its effect is far-rcaching. SANITATION
Each can of milk is customarily examined at the receiving station immediately as to temperature, off-odor, off-flavor, and, if necessary, acidity and sediment. These tests are to determine, as far as possible, whether the milk meets established requirements. In addition, all dairies are under constant inspection, and periodic determinations for sediment and bacterial quality are made to ensure a continuously clean mitk supply. Equal in importance to a clean milk supply is the prevention of contamination during processing. Bacteriological cleanliness in contrast to apparent cleanliness is necessary. Thorough washing and cleaning of all equipment immediately after use is important. Alkaline washing compounds such as trisodium phosphate and sodium hydroxide, carbonate, or metasilicate are used scparately or in various combinations. More recently organic acids, formerly considered objectionable on account of their corrosive action, are being used in combination with surface-active agents and corrosive retarders. Their inherent inhibiting effects on objectionable microorganisms give promise of further improvement in the sanitary practices of the industry. Steam sterilization is used whenever possible; otherwise hypochlorite solutions of tested strength of 50 to 250 p.p.m. available chlorine are applied. Bacteriological surveys are made just prior to or during operations where there is evidence of unusual contamination. Water supplies are constantly checked. METHODS OF EXAMINATION
Bacteriological methods used for the examination of raw milk su'pplies and the determination of sediment are published in the 8th revised edition of Standard Methods for the Examination of Dairy Products of the American Public Health Association. These methods are the standard plate count, the direct microscopic method, and the methylene blue reduction method. With the development of efficient single-service strainers for dairy farms and of efficient strainers, clarifiers, and filters for milkreceiving plants, the sediment test is becoming more and more a measure of the efficiency of these sediment-removing devices. The sediment test, which is the measure of visible dirt, compares the sediment disk with photographic standards. Until 1939 the photographic standards were designed for measuring sediment on stirred samples of milk. Since that time there has been a growing tendency to develop standards for sediment when the samples are
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withdrawn from the bottom of the can without stirring. This procedure is more favorable to recognizing contamination. Market milk and market cream are not so acceptable to the consumer when the minimum requirements of pasteurization are exceeded; consequently there is a delicate balance between pasteurization that guarantees thesafety of the milk and that which is detrimental to the flavor or physical quality of the product. It appears that the phosphatase test will solve this important problem. This test is based on the property of the heat-sensitive enzyme phosphatase in milk to liberate phenol from phosphoric phenyl esters. When milk is heated, this enzyme becomes inactivated. During pasteurization at 143" F. for 30 minutes, 96% of the enzyme is destroyed. It is completely inactivated at 145" F. for 30 minutes. By quantitative determination, inadequate pasteurization or subsequent contamination with raw milk is indir cated. The test has been modified considerably since it was first introduced, each development bringing to light its value and application. Milk drinks, ice cream, and frozen desserts are made- from combinations of pasteurized cream, milk, and concentrated milk products to which a variety of other ingredients are added. Bacterial contamination may occur from such added ingredients or from the growth of unfavorable bacteria during processing which may lower the quality of the final product. Modifications in microbiologicalmethods require consideration as to adaptability to the product under examination. I t appears thdt yeast and mold count, predominating bacterial flora, presence of thermophilic, thermoduric, and coliform organisms are important in measuring quality. Products involved are various concentrated, condensed, and dPied milk products, flavoring, sweetening, and stabilizing agents, eggs and egg products, fresh and canned fruits, nuts, etc. In this field there is a real need for better and more rapid methods that will be helpful in further maintaining quality. GROWTH OF THE DAIRY INDUSTRY
The dairy industry has experienced phenomenal growth, A variety of factors have made contributions without which such growth would have been impossible. The cream separator, mechanical refrigeration, Babcock tester, milking machines, pasteurizers, mechanical can and bottle washers, combined butter churn and worker, highly efficient condensing and drying equipment, and modern machinery have made it possible to increase greatly the capacity of plants for efficientiy handling milk and milk products and to improve in a considerable degree the quality of products reaching the consumer. Valuable contributions have been and are still being made by the sciences of bacteriology, chemistry, animal husbandry, and nutrition. Its rapid growth in so many varied fields could never have been accomplished had not the industry as a whole been appreciative of the value of quality control and receptive to the introduction of necessary methods of control and laboratory examination. The cow has also made her contribution. In 1850 the average milk yield per cow waa 1436 pounds; in 1924, 4167; and in 1942, 4739. In 1943, 26,670,000 cows gave a total milk production of 118,235,000,000 pounds. Table I indicates the increased production of the more important dairy products over the past fifty years. Earlier figures are
TABLE I. PRODUCTION OF DAIRY PRODUCT6OVERHALFACENTURY Y E .4R Butter Cheese Evapd. sweetened condensed milks Ice cream and sherbet Malted milk Whole milk powder Nonfat dry milk solids
1850 1860 Began in 1860 Increase in production began 1900 Began 1889 Began 1909
1919
1000 LE. YEAR 1000 LE.
300,000 1933 2,349,033 100,000 1943 1,109,336
.... , .. . .... 56,000
1942 3,762,219 1942 471 080 1943 1043 1940
(gallbns)
49,000 137,229 826,000
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from cemw records; later o n e from the statistical records of the United States Department of Agriculture. COMPOSITION AND CONSUMER ACCEfTANCE
The federal definitions and stmdards of identity relsting to composition and quality, and similar standards and definitions promulgated by state and loed ordinances, make it necessary to keep B watchful eye over this phase of quality eont,rol. I n 1884 the Association of Official Agrioultural Chemists was arganized in response to sn acute need for stsndardizing the physical and chemical methods of analysis used in regulation arid research in the food industry. Today these methods of analysis represent the ~ecumulatedeffort of eollshorrttive study over sixty yeari. In questions involving legality, only these official msthodz are recognized. In their development tho motive has been solely that of ~ccuraey. They frequently involve highly technical procedures and rue uaually time consuming. For these reasons they are not readily adaptod to direct application in routine quality controlinthedairyindustry. They form the Section of Researah Iaboretory with Milk Dryor in Baekgrouikd central pivot around which morepractied methods of examination are built. Contivo humidity for 8 daya. Failure to drop onti p&it, i s coiisldered siderablc progress has been made in developing such practical sufficient to justify the opinion that it will keep wdl in trade methods, hut they are in further need of improvement. Rapid channels for a period of 6 weeks. Whether the quality in butter and accurate methods of analysis that will permit the continuous is evaluated on the basis of arom&, flavor, body, toxt,ure, color, examination of samples during procersing are necessary. Eleoor wholesomeness, tho consiimcr places emphnsis on uniformity of tried methods of mensurement involving colorimetry show promflavor and keeping qudity. The art of making butter is fast beise in that direction. Microbiological methods disousaod precoming a science. Tochoical methods are being applied to every viously are customarily used in the examinstion of all manufacphasc of the manufacturing operations with the result that more tured dairy products. butter of excellent keeping quality is being produced. B u n m . Bacterial eounte are of little value in judging butter Ice CRMM. The ~onsumerrecognizes certain physical differquality. Most of the butter manufactured in this country is enoes in the texture of ice cream as coarse, icy, snowy, flaky, made from cream produoed by a number of individual farmers. sandy, and buttery, as well as oertain flavor variations resulting "Off-flavors" in bulter are due largely to the setion of microorfrom the nature and amount of ingredients used. T o produce sufganisms on cream used in the manufuture. During the past ficient ice cream for the eonsuming public, the federal definition decade the butter industry, in cooperation with the Food and will probably provide for the uge of all types of milk pmducte. Drug Administration, has given s great deal of attention to the Furthermore, the public domands the addition of a wide variasubject of sanitation and its relation to butter quality control. tion of other ingredients. Qnality control of ice eream therefore Vsndeveer and Wildman's mold count method for evaluating deinvolve-soxmination of the various ingrcdicnt? used. Methods composition in butter has furnished a means whereby the uxe of of examination will depend upon those that are best adapted to unsatisfactory eream may be detected. The Reacnrch Committet: the pmduet under observation. Progressive work is going un in of the American Butter Iiwtitute has, in coopration with other many of the lnbore.tories associated with this industry. Exsminterested parties, led the way to the development of methods of inat.ims are made of raw materials used. The finished products determining mold and sediment in mam whioh csn be used si: a rue subjoctcd to ohemicnl snd microbiological examinations durbasis for judging the quality of this product. As a result the bnting and upon the completion of manufact,ore. Methods availter industry has made considerable progress in eliminating unsat&le st prescnt require further study, and there is need of more isfactory sources of supply. accurate snd improved procedures. Tho physical and mnitary cleanliness of equipment rtnd the CHEESE. The art of manufacturing cheese has came down control of contaminatiori after manufacture is important. Potato through the ages. In tho original methods t h e was much in dextruseagarisusedin detenniningyaast andmoldoount. Modithe way of sanitation to bo desired. I n recent y e a the employfications of the Bbrri smeru culture technique is of considerable incnt of men with oollege training in dairy manufacturing has hnd value. The pH vslue of butter serum is considered a measure of B beneficial influewe on the industry. Methods involving ssnithe active acid in the serum. Acidity represented by pH values tntion have been impmved. The cheese industry recogniaes that betmen 6.4 and 6.8 ten& to prevent spoilage during storage. good-quality cheese cannot be made from poor-quality raw maThe phwphatase test gives promiw of boing valuable in indieatterials. Combined effort on the part of tho industry will nccomiiig the degrw of pasteurization reccived by the enam used in plish the desired rwults, and pmgrm is boing made in this direcbutter msnufacture. .4 satisfactory method of judging butter {.ion. The indiwtry needs tho tools of scionee to imfirnte the way. quality involvesscoring huttrr boforc :urd sfter irreuhstion. Cosrrh C o e i m i t t c ~ iof ~ $,lw Xnliotu~l < ' h w ~ cInsLit.tite is s u m w pmkagcd butter is iriciibnted :rt 70* I?. with X S - ~ l o O % rela-
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coUaborlitiiig with several of the leading state universities, with the Bureau of Dairy Industry in Washington, and with the Food snd Drug Administration with the objective of developing more technics1 information relating to cheese manufacture. This program includes methods of cheese analysis, determination of extraoeous matter, relation of m w milk quatity to oheese msnufacture, effect of pasteurization an ehw:e quality, and chemistry and bacteriology of cheese ripening. Stepa are being taken to educate cheese milk producers further as to what constitutes satisfactory sanitation. These accomplishments point toward continued improvement of quality in this industry. From the consumer angle, uniformity of body and flavor are mast important. Science has given little help in this direction up to the present time. In cheese fermentations we are stiU compelled to let nature take its course; a broad field of opportunity awaits the future eceompliahments of the researcI* chemist in this field. Soft products such as cream cheese, creamed cottage cheese, cottage choese, Licderkranz, Camembert, and similarproduetsrequire B milk supply of higli quality if they are to passegs the deliestely fine flavor and aroms required. Microbiological methods ase valusble in determining quality. The quality of the raw milk and failure to hold these products in storage at low temperatures may be responsible for the development of off-flavors. E V A P O ~ TMILK. ED The Federsl Standard of Identity for Evaporated Milk limits the fat and moisture oantent, and permits the addition of certain stsbilising agents and fortifiestion with vitamin D by irradiation or addition of vitamin D coneentrate. Butter fat tend9 to separate and form B eream layer at the top of the an, and salts, principally in the farm ofcalcium citrate, tend to preoipitate when evaporated milk is held at s warm temperature on continued storage. The food value of the product is not materially sffeeted, but consumem take objection on account of the ohange in phpical appemnca of the product. The viscosity of evaporated milk hsr B direct bearing on ita ability to hold the butterfat in euspension and prevent ita separation. On Baaterioloaid Platinn LBboratorr for Market milk
Vd. 37, No. 3
account of the seasonal variation in the composition of milk, the definition of evaporated milk permits the addition of B stabilieer not in exm of 0.10%. The reason for such addition is ~olelyto maintain the necessary chemical equilibrium between the mineral nslts and casein. It permits adequate sterilizstion without coagulation of the casein. Although evaporated milk is a sterile produet, individual cans occasionally become contaminated. This is usually the result of damage due to rough handling in tramit. in which minute cracks develop in the seams of the can where b a o teria gain entrance. Such contamination is readily recognized. The 0808 are swollen, and the milk is coagulated. BWEETENED CONDENSED MILK. Federal definition limits this produet with respect to fat and total milk solids. The bacterial count is usually less than 1wO per gram. The growth of certain bacteria is not necessarily inhibited by the presence of cane sugar even at B concentration of 42 to 45%. When held st warm tomperstures for a considerable time, the bacterial count may inwease. Within reasonable limitations this increase does not appear to be detrimental to the product. Yeast in sweetened condensed milk constitutes a contamination; resultant fermentation tends to make the product unmarketable. Molds 8se objeotionable beoause they tend to form (‘buttons”, so-called by the industry because of their appearance in the form of brown spots. Thiokening of sweetened condensed milk frequently o e c m on continued storage, especially at wtemperatures. This may be the result of bacterial fermentation or of chemical action. This chemical action is believed by some to be B result of interaction between the proteins and sugars. Lactose is p e n t in a state of supereaturation. Should excessive separation of Iactaee cryst& occur, they may settle at the bottom of the om and form whet is termed “sugar separation”. Quality control in this product coneists of microbiological and physical examination before and after incubation. NONFAT DRYMILKSOLIDS.Defatted or nonfat dry milk solids is the name recently given by Act of Congress to what was former% known as dry skim milk. By federal definition it must contain not more than 5% of mo@ure. In 1829 the American Dry Milk Institute, r e p e n t i n g the majority of nonfat dry milk solids manufacturers, &bl&hed standards for this product. This action was stimulated by B growing need for some means to PItect the consumer from inferior grad- on the competitive market. These standards have been of inestimable value in bringing about a general improvement in the quality of this product throughout the United States in the short span of fifteen years. These stsndards d d n e the general and specific requirements for extra grade and standard grade nonfat dry milk solids. They require compliance with fedeisl and state regulations. Limitations regarding physics1 characteristics and limits for each grade are given with respect to butterfat, moisture, titratable acidity, sediment, bacterial account, and solubility. The grading pamphlet of the Institute ineludes the melhods of analysis to he used. Titratable acidity, baoterial count, and solubility index are expremed on the reconstituted basis. Those figures enable the producer to make B ready comparison with corresponding figures of fluid milk with which he is f-liar. I n routine plant control, rnohture is determined by the toluene distillation method. For practical purpanea this method compBsea favorably with the officialmethods. I t ie reasonably rapid and can bo applied during the drying operation. Solubility index is an empirical procedure and -e to measure the approximate insolubility of the pmduot. In vacuum-b-roller and s p r s y - p r o d nonfat dry milk solids this is important. It indicates any denaturing of the proteins through overheating during condensing or drying operations. Sediment tests are made by obtaining sediment did& from reconstituted material and compsring with standard photographic sediment dish. DXYWHOLEMI=. A high-quslity raw milk supply is necesin the production of goodquality whole milk powder. The presenoe of butterfat at 26% mak- it particularly sensitive to
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INDUSTRIAL AND ENGINEERING CHEMIS.TRY
those factors which affect milk quality as related to butterfat. The use of copper, copper alloys, and iron in plant equipment is detrimental to the quality of whole milk powder in that it favors the rapid development of tallowiness and rancidity, and thereby makes the product unacceptable for human consumption. Such equipment has been replaced with stainless steel and glass-lined materials. Recent army specifications have required that whole milk powder shall not contain more than 1.50 p.p.m. of copper and not more than 10.0 p.p.m. of iron. A good grade of sprayprocess whole milk powder should meet the following specifications: moisture not more than 2.50%, fat not less than Z6%, acidity not more than 0.15%, bacterial count not more than 6000 per cc. (equivalent to 50,000 per gram), sediment disk not in exress of No. 3, solubility index not more than 0.50 w. Bacterial rount, acidity, and solubility index are customarily determined on a reconstituted basis using 13 grams of powder in 100 cc. of water. This has the advantage of direct comparison with milk from which it is made. Laboratory methods are similar to those outlined by the American Dry Milk Institute for nonfat dry milk solids. The packaging of whole niilk powder is an important factor in quality control. The prevention of moisture absorption and changes in butterfat is necessary if the product is to keep beyond 3 to 6 months. The use of antioxidants in whole milk powder has met with limited success. For satisfactory storage this product is customarily packed under nitrogen or carbon dioxide gas in which the oxygen content is reduced to a n absolute minimum. With satisfactory gas packing, whole milk powder will keep from one to two years. STANDARDIZATION
Only when reasonably accurate methods of analysis were developed did standardization in the dairy industry become possible. Standardization involves making those necessary adjustments in raw materials whereby the product manufactured will adequately meet the requirements of a given standard of identity, a given legal definition, or a specific declaration on the label. Under the new Food, Drug and Cosmetic Act provision is made for the establishment of standards of identity. There is a definite tendency on the part of many states to adopt similar standards, which indicates a continued trend toward further standardization in dairy products. Progress in this direction will be delayed only by the lack of accurate and dependable methods of analysis. On account of the perishability of raw materials, standardization must be carried out rapidly. Continuous processing makes for economy and improved quality, but requires methods of quality control that can be applied during the operation. Such methods must have a reasonable degree of accuracy, as results have a direct bearing on operating efficiency. As standards of identity are increased or more rigid standards developed, a greater demand will be made for standardizing efficiency which will require new, rapid, accurate, and practical methods of laboratory control.
213.
sirable, fortification beyond the limits of restoration will better mrve the nutritional welfare of the Nation. Whether it be ,restoration or fortification, qudlity and quality control considerations become highly important. The official methods of vitamin assay are biochemical. They are time consuming. This has led to the development of a number of physicochemical methods which are reasonably satisfactoly for routine quality control. These are being applied to the determinations of vitamins A, BI, 332, C, and niacin. Vitamin D is always det,ermined by animal assay. When these methods are further perfected, it would be advantageous to the industry and regnlatory agencies to make them official. Until such time, quality control will require a satisfactory interpretation of physicochemical measurements in terms of official procedure. With restoration and fortification goes the responsibility of maintaining those intrinsic values in food products until they are used by the consumer. Quality control must extend its supervision to considerations of correct packaging, transit, and storage; it must be kept in mind that the consumer accepts such foods solely in the interest of improved health through nutrition. NUTRITION
The first essentials of nutrition require that food be safe and clean and possess the maximum of original nutritional values. Over the years regulatory officials have contended that many food products are served to the consuming public in a state of incipient decomposition. Until recently such statements could be substantiated only by visible evidence of decomposition, off-odors and -flavors, or special chemical and animal tests. More recently progress has been made in methods of chemical examination which conclusively establish the degree of decomposition. Unfortunately, like most original and dependable analytical methods they are complicated and time consuming. I t appears that quality control in this field will simplify the complexity of present methods and lead to a further utilizat,iionof more rapid microanalytical methods. During the past quarter of a century leaders in the field of nutrition have taught that there are important differences between the merely adequate and optimal in nutrition. Health means not merely freedom from disease but rather a positive quality of life and an ability to resist disease. To nutritional research goes the credit for the advancement of this ideal. I n the interest of the public health, nutrition has become as essential as sanitation. Our newer knowledge of nutrition is fast becoming a source of information by which each individual may constructively develop his own life history involving positive health and longevity. These considerations directly affect our agricultural and industrial programs and the efficiency of the nation as a whole. I n this field of human nutrition, quality control is destined to accept further responsibilities. Methods of analysis will be necessary whereby nutritional values may be measured in terms of ultimate satisfactory nutritional utilization of such foods by the consumer. CONCLUSION
FORTIFICATION
Although milk is a highly variable product with respect to composition, there is a consumer tendency to expect milk and milk products to be of constant composition. The minerals and vitamim in milk vary with the type of feed and environmental conditions. The vitamins are detrimentally affected by exposure to heat, light, and air. I n the interest of improved nutrition there is a growing tendency to restore to milk and milk products those lost values which result from production and manufacture conditions beyond our control. The science of nutrition is continuing to bring to light the dietary necessities of mankind considered individually and collectively. The relation of vitamin D to calcium and phosphorus and of vitamin B1 to carbohydrate metabolism have been established. Current research is indicating similar relations between the vitamins and food intake. One ichool of thought concludes that, where restoration is highly de-
Some readers may feel that I have given too much credit to the dairy industry for what has been accomplished during the past fifty years. Though their local activities and interests may have indicated many undesirable conditions and unsatisfactory practices, I contend that such is not true of the dairy industry as a whole. There is no food product that requires so high a degree of quality control as do milk and milk products. Progressive application through t,he years has led to such marked improvement that the dairy industry today stands as a n outstanding example of accomplishment in this field. To this program its leaders have given their fullest cooperation. This industry is indebted to thousands of scientists throughout the nation who collectively have made this possible. A sound foundation in the field of quality and quality control has been established on which the dairy industry may continue to build with credit to itself and service to the Nation.
