V. Conditions and Trends of Consumption
IN THE arts, fats and oils are consumed in a multitude of ways but practically always as such -- not as a constituent of some other raw material. In feeding stuffs very great quantities of fats disappear but, with a few unimportant exceptions, they always do so as a constituent of some element of the feed and not as such. Thus the amounts of fat that disappear with grain and legumes fed to animals are truly enormous. In food, as in feeding stuffs, very large quantities of fats are consumed incidentally in the ingestion of meats, fish, poultry, milk, and other animal products and in the form of fats and oils naturally contained in cereals, legumes, fruits, vegetables, and other plant products. However, in the human dietary fats and oils are also consumed practically as such, for example as butter, salad oils, and cooking fats.
Quantitative Data Unsatisfactory
Not only because fats and oils disappear both in the arts and in the dietary in a vast variety of ways, but for other important reasons, the quantitative study of the consumption of fats and oils encounters great difficulties.
In the first place, the very concept of consumption is elusive. Presumably one should exclude, in spite of its potential significance, the fat content of large numbers of meat animals that perish from natural causes and from which no attempt is made to recover the fats. Commercial consumption is a significant concept, but it excludes a large amount of fats in products that do not enter into trade, and a large amount that are incidental components of meats and other products that do enter into trade, for example, tankage and garbage. Wastes in the process of recovery are considerable; hence the fat content of the product treated may be considerably greater than the fats recovered as such plus those incidentally retained. The amounts ingested by animals and by human beings would be worth knowing, but they would exclude large quantities that are wasted in various ways on the farms and in households and public eating places. Furthermore, a distinction may be drawn between intermediate and final consumption. Large amounts of fats are contained in cereals, nuts, milk, oil cake, and other products fed to animals; these are in part used up by the animals, and in part are converted or stored up and appear in dairy products or slaughtered animals. Hence a total of the fats consumed by animals and those derived from animals would contain, in effect, considerable duplication. The difficulties are enhanced by the fact that our statistical information is defective especially in respect to the data on animal fats. For the United States, the number of animals killed in inspected slaughterhouses is known; the total slaughter at wholesale is reported by the census of manufactures (biennial since 1919); but only a guess can be made at the number of animals in other uninspected, principally rural, slaughter. Moreover, there is no clear-cut idea of the fat content per average animal slaughtered; the long-time trend seems to be downward, because younger and lighter animals are coming to slaughter in response to the increasing demand for lamb instead of for mutton, for bacon-type hogs instead of for the lard type, and for baby beef instead of for three- to four-year-old steers. To take even the best ratios derived from packing-house practice and apply them to the total wholesale slaughter of cattle, calves, sheep, and hogs as reported in the biennial censuses, and also to the farm and retail slaughter for which the data are officially admitted to be crude estimates, would be little better than intelligent guessing. There is fairly reliable information on the number of dairy cows and other cows, and it is known that the annual production of milk per animal is rising; but the actual figure of average production is conjectural and the rapidity of increase of outturn indeterminable. Only an intelligent guess at the amount and proportion of total milk fat converted into butter is possible. There are fairly reliable quarterly and annual figures upon the production of vegetable oils. The figures for imports and exports of fats and oils are the best figures available. If, then, one combined the best data and estimates for all forms of fats and oils, the result could hardly be relied upon to give more than a very rough approximation to the total volume available for use (with uncertain allowances for the heavy wastes that are known to occur) and only a rough indication of trend of production.
One might, perhaps, work at the matter backwards. This would mean collecting figures for butter, lard, tallow, packing-house grease, oleo oil, lard oil, stearin, corn oil, peanut oil, soy bean oil, olive oil, cottonseed oil, coconut oil, palm oil, and palm kernel oil as products of specialized industries. Some of these are produced in only a few plants and the figures are accurately reported. The more centralized the production, the fewer the plants; the more perfected the methods, the better the figures. On the other hand, butter production in creameries is less easily measured and farm production of butter is merely a guess.
At the best, there are gaps in the information so large as to make statistical conclusions on several important components, and on fats and oils as a whole, exceedingly unreliable.
It would be of interest to know, for each of the several sources of fats, (1) the amount wasted for lack of any attempt at recovery; (2) the amount ingested; (3) the amount wasted in households and public eating places; (4) the amount fed to animals; and (5) the amount used in industrial production other than food. We should like these data for fats produced, fats imported, and fats exported. We should like to distinguish between gross and net consumption. Unfortunately, for many of the sources of fats the statistical information is exceedingly defective and it is difficult to reach reliable bases upon which to make the estimates necessary for arriving at supplementary data.
We have made attempts to reach a rough approximation to the amounts of fats and oils available for human consumption or industrial use in the United States in recent years, but at several points gaps are so wide and the procedure is so open to objection that we do not feel justified in presenting here even a preliminary approximation, lest in spite of reservations and qualifications it should be taken for more than it would be worth. In the discussion that follows, therefore, we have incorporated quantitative data only to a very limited extent.
Table 4, however, appears to have sufficient reliability and significance to warrant presentation. It summarizes the annual average consumption (production plus imports less exports or re-exports, in terms of oil or fat content) of the principal vegetable and animal fats in the United States, 1921-25, with certain important and less important exceptions. The two principal items omitted, fat of dressed meats and milk fats (including butter), are so difficult to estimate that we have not included them; yet their sum probably exceeds the sum of the fats and oils here itemized. They go largely into edible uses, except as milk is fed to animals, though in considerable measure meat fats are wasted in the household or subsequently recovered from household wastes for industrial use. The principal other items omitted are fats incidentally consumed in fish, poultry, grains, vegetables, and fruits. Judging from estimates of Raymond Pearl for the period 1911-12 to 1917-18 (Studies in Human Biology (Baltimore, Williams & Wilkins, 1924), pp. 388-94), the sum of these items is probably less than a billion pounds a year, exclusive of the fat in grain fed to cattle. Since most of the fats excluded from the table are of animal origin, it is apparent that vegetable oils, despite their large and growing importance, probably constitute less than one-fourth of the total fat and oil consumption in the United States.
Table 4. Consumption of Certain Oils and Fats in the United States, Average of Annual Figures, 1921-25*
Oil or Fat Average consumption
Vegetable -- Cottonseed 1,074 Coconut 472 Palm kernel 13 Palm 90 Corn 102 Olive 104 Peanut 20 Linseed 654 Chinawood 76 Soy bean 17 Castor 35 Total 2,657 Animal -- Lard 1,552 Oleo oil, oleostearin, edible tallow 147 Inedible tallow 346 Other inedible animal fats 364 Total 2,409 Fish -- Fish oils 134 Grand total 5,200
Computed from production data published by U.S. Department of Commerce in Animal and Vegetable Fats and Oils, 1919-23 and 1924-25, and from foreign trade data in Commerce and Navigation of the United States.
Of the fats itemized in Table 4, lard ranks first, followed by cottonseed oil and linseed oil, while coconut oil, which before the war was little used, now is in fourth place. Of the vegetable oils consumed as such, about half goes to edible uses, and the other half, including the drying oils, to industrial uses. If it were possible to include all the fats and oils, animal and vegetable, it would probably appear that at least four-fifths of the total net consumption (i.e., exclusive of fats fed to animals) go to edible uses.
For most other countries, in general, the data are even less satisfactory than in the United States.
Fats and Oils in the Diet
The function of fats and oils in the diet is mainly to furnish energy to operate the animal machine. In the body, fats are burned as truly as though they were burned in a candle or under a steam boiler, and the end-products of the combustion are the same -- carbon dioxide and water. Moreover, the amount of energy they furnish is the same, namely from 9 to 9.4 calories to the gram, whether they are burned within or outside an animal body. (A large calorie, which is the one here used, is the quantity of heat necessary to warm 1 kilogram of water from 0 deg Centigrade to 1 deg Centigrade. A small calorie is the quantity of heat necessary to warm 1 gram of water from 0 deg Centigrade to 1 deg Centigrade.) They yield more energy than the other important classes of foodstuffs, such as carbohydrates and protein (albumin) (see explanatory notes, IV. Conditions and Trends of Production -- Vegetable oils major products), which furnish from 3.8 to 4.2 calories to the gram.
Neither fats nor carbohydrates ingested are wholly burned at once unless they are needed for the operation of the animal machine. If not so needed, carbohydrates are for the most part completely changed in character by conversion into the fat characteristic of the species. This is stored in the body as a reserve against the possibility of a future period of food shortage. Indeed, most of the fat of domesticated animals is produced from starch. Thus the lard of the hogs of the corn belt is mainly derived from the starch of corn (maize). It has the characteristics of fat normal to the animal, is normally stiff, and hence is especially prized. Unlike ingested carbohydrate, the fat of the food, if it is not at once burned, is changed comparatively little. For the most part it is deposited in but slightly modified form with other fat, made by the animal from carbohydrate or protein, in the storehouses for fat -- the adipose tissue under the skin, in and about the viscera, and elsewhere. Therefore, if the food fat differs in its properties from the fat natural to the animal and if there is a great deal of it in the feed, the storage fat formed by the deposition of food fat gives an abnormal character to the fat which is obtained from the animal after slaughter. That is why, as stated above (I. Nature and Sources of Fats and Oils -- Animal and vegetable sources), the diet may influence the character of the fat obtained from slaughtered animals. This is a matter of practical importance at the present time in sections of the United States where hogs are fattened on peanuts, which contain much oil. The lard obtained from such hogs is abnormally soft and not liked by the consumer. Hence packers are usually willing to purchase such hogs only at a discount.
The dietary fats may be divided into four groups: (1) those consumed as such on the table; (2) those employed in the preparation of foods; (3) those consumed incidentally in the ingestion of meats and other animal products; and (4) those consumed incidentally in cereals, legumes, fruits, and vegetables. The fats consumed as such on the table in the United States are principally butter, butter substitutes (chiefly coconut and oleo oil), and salad oils (principally cottonseed, corn, and olive oils). The fats and oils used in the preparation of food are butter, lard, lard compounds (for the most part cottonseed oil), cottonseed oil as such, corn oil, peanut oil, butter substitutes, and, in certain types of confectionery, coconut oil and cacao butter. Fats and oils consumed incidentally in the ingestion of meats and dairy products are found principally in milk, cheese, poultry, eggs, beef, mutton and lamb, pork, and fish. The fat of meats is of course to a material extent not ingested but wasted except in so far as it is recovered in garbage and similar greases. The fats of the cereals, legumes, fruits, and vegetables as a class are important in the aggregate nutritionally, but have little direct commercial importance, since few foodstuffs are purchased on the basis of fat content. Practically all foodstuffs except sugar, water, and certain condiments contain some fat. Fresh fruits and vegetables contain merely traces; nuts, on the other hand, are rich in fats, as are also chocolate products. Oat meal and corn meal that is made without removing the germ are relatively rich in fat; wheat flour is poorer. (This type of corn meal is sometimes known as old-fashioned or waterground corn meal because it was the only type made in former times when water power was the commonest motive power for American mills. It does not keep well, for it turns rancid easily.) According to Pearl (Pearl, The Nation's Food, Philadelphia and London, Saunders, 1920), the incidental fat ingested in the form of cereals, vegetables, fruit, nuts, fish, poultry, and eggs amounts to 16-18 grams per capita per day. (A little more than half an ounce.)
A study of the trends of consumption encounters the difficulty that statistics of fat in the diet over a series of decades are not available. Certain inferences seem nevertheless warranted. Trends of consumption may be grouped in two classes according as they are due primarily to changes in habits or primarily to substitutions made by manufacturers of which the consumer may or may not be aware. The two classes of course overlap, for in certain cases both factors play a part. Thus a manufacturer may create a new product which leads to a new food habit or, vice versa, consumer demand may lead to substitution or creation of a new product by the manufacturer.
Influence of Changes in Food Habits
Change of food habits may be of two sorts. It may be purely quantitative or it may be qualitative. By a quantitative change is meant increase or decrease in consumption of a given fat rather than the substitution in the diet of one fat for another. By qualitative change is meant primarily a substitution of one fat for another. However, since for physiological reasons the intake of food is practically constant for any individual under any given set of circumstances, a decrease in fat ingestion usually involves either a substitution for it of some other kind of food, or of some other kind of fat. Conversely, an increase usually involves a decrease in consumption of some other kind of food or of fat. Since all fats and oils have very nearly the same food value, one can be substituted for another without change in the volume of food ingested. (This statement applies to energy values. Certain fats contain small quantities of chemical substances of unknown chemical nature but of great importance to health. These are known as vitamins or food accessories. Different fats contain different amounts of them depending upon their origin, method of preparation, and other factors. From the point of view of their vitamin content all fats are not of equal nutritive value; but these are considerations not discussed here.) However, if another food be substituted, the volume of the diet is thereby necessarily increased since no other food has, weight for weight, so great an energy value (see above, Fats and oils in the diet). It follows that if the replacement of fat in the diet by other foods goes too far the diet must become very bulky if it is still to furnish the same energy value, and this fact sets mechanical limits to the substitution of other foodstuffs for fat in the diet.
Since the caloric requirements of an individual, as stated above, are constant under given conditions, it follows that under these circumstances a reduction in consumption of a fat involves the substitution for it of either an equal amount of some other fat or a corresponding amount of some other foodstuffs. But conditions do not remain constant for any person. He grows old and requires less food. He may become stouter or leaner, then consuming either more or less food. He may change his means of livelihood from one requiring hard manual labor involving high food requirements to a sedentary occupation requiring a low food intake. He may migrate from a very cold climate where food requirements are relatively high to a hot one where they are relatively low. In any nation all these changes are taking place in some individuals in one direction, in others in the opposite direction. For short periods, the result is a reasonably constant consumption.
Over a long period of time this is no longer true. The age distribution of populations changes. If the birth-rate falls and the average span of life lengthens, the proportion of old people who consume little food increases, the proportion of young people who consume much decreases. If it becomes unfashionable to be stout, less food is consumed by the nation as a whole. If the proportion of manual laborers becomes less and that of machine tenders and sedentary workers greater, the per capita consumption of food tends to fall. Since fat is the most concentrated form of food energy, its intake tends to be reduced rather more than that of other forms of food.
In the United States exactly these changes have been taking place for decades; and there is evidence of a corresponding decline in the nutritional use of fats and oils, as part of a general reduction in the per capita food requirements. This reduction is the result of substitution of machine labor for man labor, the decline of outdoor employment in severe winter weather, the improved heating of buildings, the trend to lower average body weights of the people generally, and changes in the age distribution of the population. The population is acquiring more sedentary characteristics, needs less food, and the average per capita requirements of foodstuffs in terms of calories are automatically reduced. Most of these factors are the result of the economic evolution of the country and in essence reflect improvement in the standard of living.
The rise of the standard of living is responsible for certain other changes in food habits. It results in a diversification of the diet with increase in the use of dairy products, fruit, vegetables, and sugar, and decline in the ingestion of cereals and fats. (Cf. The Decline in Per Capita Consumption of Flour in the United States, Wheat Studies of the Food Research Institute, July 1926, II, 265-92.) This general statement does not hold for the fat of milk, the use of which is on the increase. Fat consumed incidentally to the ingestion of meats and dairy products has always been heavy. The consumption of milk and poultry fat is increasing, that of beef, sheep, and hog fats is declining. Plain cooking is being replaced by more fancy cooking, which includes more discriminating culinary uses of fats and oils. American practice has departed from the British custom of boiling vegetables without fat. Much of the crackers and bakers' bread consumed now contains shortening. The increased consumption of sugar has carried with it enlarged use of shortening agents. At the table the use of butter as a spreading material is on the increase. The wider use of fresh fruits and vegetables has resulted in greater consumption of salads, which in turn has increased the use of salad oils.
These facts might seem to suggest increased use of fats and oils. A survey of the entire field, however, suggests that the net result is a lower per capita ingestion of fats in general. The heavy fat rations of hard workers are a thing of the past -- fat-backs and sow-belly are no longer staples. We use more butter, but less hog fat. The current public taste for younger and lighter-weight animals represents a substantial reduction in fat. It seems fair to infer that, milk fat and poultry fat aside, the decline in the ingestion of fats applies to animal fats. Over a generation, indeed, it is possible that there may have been an absolute increase in the per capita consumption of vegetable oils with an absolute decline in the per capita consumption of animal fats outside of milk fat.
Influence of Changes in Food Manufacture
The changes in trends of food-fat consumption are not all by any means due solely to change in habits. Some of those that are quantitatively extremely important are due to substitutions on the initiative of manufacturers of food-fat preparations -- for example, the substitution of lard compounds for lard -- or to the increasing availability of new types of fat -- for example, coconut oil. Some of the possibilities of substitution in food uses have already been touched upon incidentally. However, since dietary consumption is the major and the higher or premium use of fats, the practice and possibility of substitution require elaboration because they are basic to any consideration of the commodity economics of this important group of raw materials. The substitution of one fat for another, indeed the mere possibility of such substitution, naturally has the greatest influence upon prices. Given sufficient price inducement, one fat may in some cases displace another with the widest repercussions upon the producer, the farmer, the trader, and the manufacturer. It is one of the purposes of the Fat and Oil Studies of the Food Research Institute to present studies from time to time upon far-reaching movements of this general character.
That considerations of price, costs of conversion and refining, lack of technological skill, and legislation in the interests of public health and sanitation limit the volume of inedible fats turned to edible uses, has already been pointed out. But there are other factors as well that limit not merely the diversion of inedible fats to edible uses but also the substitution of one edible fat for another. The most prominent of these are greater or lesser adaptability of different fats to use in the preparation of different foodstuffs, and psychological and sentimental factors that in the food industries play a greater part than in the arts.
Next: V. Conditions and Trends of Consumption -- Development of lard compounds and margarin
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