presses. After removal from the press the cocoa cakes are allowed to cool and are then reduced in disintegrators and finally pulverized to yield cocoa powder. In short, the cocoa press cake, from which cocoa powder or breakfast cocoa is prepared by pulverizing, is merely chocolate deprived of a portion of its fat or cacao butter. The expressed butter also may now be considered a primary product of the cacao bean, since the demand for cacao butter has outrun the supply from normal cocoa manufacture. During the last two or three years the market has been extraordinarily favorable to the production of the butter; so favorable that its manufacture, generally, has become economically independent of the commercial value of its complementary product, the press cake. It has paid American manufacturers to grind and press cacao beans for the butter alone, even if dead loss of the press cake had to be assumed. The primary cause of this novel condition is, of course, the enormous demand for cacao butter, but a contributing cause is the low cost of the imported beans concomitant with the protective tariff on the butter.

For many years cacao beans were pressed in order to prepare cocoa powder and the butter was an incidental product. Indeed, in the early days of cocoa manufacture in this country the cacao butter was often a by-product of little value, used to a limited extent as an unguent, as a base for toilet preparations, and in pharmacy. At times profitable disposal of this fat became a real problem to the maker of cocoa. Conditions changed entirely, however, with the development of the great trade in such chocolate confections as milk chocolate, sweet chocolate, and chocolate coatings. In the manufacture of these commodities more cacao butter is required than is present in the chocolate liquor used, so that additional cacao nibs must be deprived of a part of their fat to furnish this extra butter. For a time the quantity of cacao butter produced in the manufacture of cocoa was sufficient to supply the requirements for the special confectionary chocolate trade, and importations of the cheaply produced European butter also helped to maintain the balance when the domestic supply became inadequate.

BY-PRODUCTS

In the past the only important by-product of the industry in the United States normally cheap enough to be of interest to the fertilizer trade has been the husk or shell refuse. There was no such commodity as by-product cocoa cake a few years ago, and of course no solvent-extracted cocoa was produced. Under the new conditions, however, there has not been sufficient increase in the demand for powdered cocoa to take care of the very great increase in the production of the press cake. As a consequence a varying but important proportion of the cake produced has been a drug on the market. Also, since the manufacturer's chief concern has been

As one manufacturer has pointed out, this does not necessarily mean that the pressing of cacao for its butter is a profitable commercial undertaking by itself, but that under certain market conditions a chocolate manufacturer may be warranted in pressing for butter for his own use, especially if his pressing equipment is not being operated at capacity on regular cocoa,

Under the tariff act of 1922 (59), cacao beans are imported duty free, whereas cacao butter is dutiable at 25 per cent ad valorem. Powdered cocoa also bears a duty of 17% per cent ad valorem, but not less than 2 cents per pound ($40 per ton).

A small amount of the fines may occasionally have been available for use as fertilizer material; but in general this refuse has been burned, it is believed.

the production of cacao butter, much of the press cake not intended. for use as cocoa powder has been either low grade (too poor in quality to satisfy the legal requirements for powdered cocoa), or pressed "dry" in very powerful presses to a minimum fat content.

In this bulletin the cake produced as a by-product in the manufacture of cacao butter is designated low-grade or by-product cocoa cake, to distinguish it from the cake intended for the preparation of the powder used in making potable cocoa.

The cake has had so little value at times that some manufacturers have used their surplus for fuel in order to get rid of it. Persons familiar with the situation and the material have therefore turned to utilization as fertilizer as offering a more profitable outlet for the surplus cake; and the United States Department of Agriculture from time to time has received samples of the pressed cake with requests that the material be analyzed and its value as fertilizer determined.

The defatted cocoa residue from press cake that has been subjected to solvent-extraction for recovery of its fat, appears to have been of little or no value, except as fertilizer material.

There are, therefore, at the present time three types of cocoa byproducts with a market value sufficiently low to make them of interest to the fertilizer trade: (1) The surplus powdered cocoa and lowgrade press cake ; (2) the fat-free, solvent-extracted cake residue; and (3) the shells.

BY-PRODUCT COCOA PRESS CAKE AND POWDER

One of the first samples of cocoa press cake submitted to the department, with a request from the manufacturer for suggestions as to how the material could be utilized, on examination was found to contain over 23 per cent of cacao fat, and to be similar in composition to "breakfast cocoa." The manufacturer stated that he had a great oversupply of this press cake at the time, with absolutely no demand. In view of the very apparent economic saving to be attained through full and efficient utilization of the constituents of such a product,10 it was decided (1) to seek information on the quantity of similar material available and the extent to which it was being subjected to solvent-extraction for the commercial recovery of cacao fat, and (2) to ascertain its properties in relation to possible ultimate utilization as fertilizer material.

Authentic information of this sort and statistical data on the production of press-cake residues from the manufacture of cacao butter were not found either in the standard textbooks on the cocoa and chocolate industry, or in the trade journals. Hence it was necessary to seek the desired information directly from the producers. A questionnaire relating to the quantity of the material produced, the quantity available for fertilizer, and the proportion being subjected to solvent-extraction for the recovery of additional

* Included with the low-grade cake is a relatively small quantity of fines press cake, which includes the cacao germs.

This material contained somewhat more crude fiber and ash than would be permissible in breakfast cocoa, indicating that less care had been taken in the cleaning and removal of shells,

1 Cacao butter was quoted at 26 cents per pound at the time, so that the intrinsic value of the fat in 1 ton of the material represented by the sample was over $120.

fat, was submitted to 24 individuals and firms, of which 17 were known producers of cacao butter in the United States.

A majority of the leading establishments (according to classification based on the value of the cocoa, cacao butter and chocolate produced annually) were included among those receiving the questionnaire. The replies and other correspondence received from 12 firms and an association of manufacturers, representative of the cacao industry in America, gave an intimate and fairly comprehensive picture of the situation. This was supplemented in January, 1925, by a visit to several producers and a study of the manufacturing processes at a leading cacao-pressing plant, and at the one establishment practicing the solvent-extraction of cocoa.

Fifty-five establishments were primarily engaged in the manufacture of cacao products at the time of the compiling of the latest published report of the Bureau of the Census (49),11 and it is reasonably certain that most of these plants produce some by-product or surplus press cake and powder. Less than a dozen manufacturers, however, have produced the low-grade cake in important quantities.

PRODUCTION

The following figures on the total production of low-grade cake are estimates based on data obtained in this study. No exact, nation-wide production survey has ever been made for this byproduct. The figures obtained directly from producers were tabulated, and the estimates represent the correlation of these data with all other available information.

It is concluded that 15,000 tons is a very conservative estimate of the quantity of low-grade or surplus cocoa cake produced during the calendar year 1923, and the total for that year may have exceeded 21,000 tons. Production apparently increased during 1924, as reliable reports from individuals engaged in the industry indicate that not less than 25,000 tons of the by-product cake was produced during that calendar year. The outlook for 1925 was for at least maintained production.

The greatest annual production of by-product cake actually reported by a single establishment was 3,000 tons for the year 1924.

The segregation of production evident in the cocoa industry should be very favorable to profitable disposal of the low-priced by-product. A large part of the total tonnage produced is localized about such great distributing centers as New York, Philadelphia, and Boston.

Two more or less distinct types of low-grade cocoa cake are being produced. The more common sort is pressed in the ordinary, older style of press used generally in the production of the powdered cocoa of commerce. Such presses are not highly efficient, considered solely from the point of view of the production of the cacao butter, and yield a press cake of rather high fat content, which is desirable when potable cocoa is being made. The by-product or low-grade cocoa cake produced in these presses contains from 15 or 16 to over 20 per cent of fat. The appearance of ordinary cocoa press cake is shown in Figure 1; the brick at the left serves to indicate the relative

11 Establishments producing cacao products but engaged primarily in the manufacture of chocolate confectionery are not included.

size of the cakes. Any surplus powdered cocoa originally intended for human consumption, which for one reason or another could not be marketed for that purpose, would also be included in this class. The other type of cocoa press cake is the result of endeavor to increase the yield of cacao butter, without regard to the composition of the residual cake. Very powerful and efficient pressing equipment has been designed and built in recent years especially for the purpose of leaving a minimum amount of cacao butter in the press cake. Cocoa cake produced with such equipment may contain as little as 9 per cent of fat, and is often called dry-pressed cake. Giant presses of the new type have produced cakes running as low as 8 per cent of fat. The average fat content of dry-pressed cocoa cake, however, is probably about 13 per cent, most of it testing between 10 and 15 per cent.

FIG. 1.-Cocoa press cake. The entire disk shows the appearance of the cakes produced in the ordinary type of hydraulic cocoa press

In 1924, although only a few factories were equipped for the production of the dry-pressed cake, the quantity produced amounted to over 4,000 tons.

Another sort of press cake should be mentioned. In at least one factory, where the amount of fines including the germs is said to be 2 to 4 per cent of the weight of raw beans, this material is allowed to accumulate and is then pressed by itself. It is rich in fat, but yields a low grade of butter and cake. (This cake is represented by sample 109, Tables 2 and 3, pp. 14 and 20.) Some of this cake has been sold to manufacturers of complete fertilizers. It is understood that a similar cocoa by-product of another factory is sold for use in the manufacture of cheap chewing tobacco.

The yields of cacao butter and regular nibs press cake from a given weight of cacao beans depend, of course, on the proportion of nibs, the fat-content of the roasted nibs, and the degree to

which the pressing is carried. Factors affecting the degree to which the fat is expelled in the press (or conversely the quantity of fat left in the press cake) are: (1) The actual pressure exerted per square inch of cake surface, (2) the temperature at which the pressing is conducted, and (3) the length of time during which the pressure (and temperature) are maintained. The thickness of the laver of liquor pressed and the type of press-mat used also may affect the quantity of butter obtained.

Cocoa presses are commonly operated with a pressure on the hydraulic ram of from 5,000 to 6,000 pounds per square inch. In the giant presses, capable of producing the driest press cake, the ram may be as large as 19 inches in diameter, a diameter greater than that of the pots in which the chocolate liquor is pressed. The actual pressure per square inch of cake surface in such presses may therefore exceed 6,000 pounds.

The temperature at which the liquor is maintained during ordinary cocoa pressing is about 60° C. (140° F.); and probably 40 minutes is the average pressing time. Higher pressing temperatures, though tending to increase the yield of cacao butter, are said to injure the quality of the cocoa. When the highest practicable yield of the butter is the chief consideration, however, that is, when the cake being made is low-grade or by-product cake, its quality is of no moment. Some of the driest low-grade cake encountered is said to have been pressed at a temperature of 90° C. or more for from 55 to 60 minutes. It is claimed that this higher temperature does not injure the quality of the cacao butter.

The liquor from freshly roasted nibs contains only about 1.5 per cent of moisture (26), so the loss in weight during pressing, due to evaporation, must be almost negligible. It follows that in ordinary factory practice the sum of the weights of the butter and cake obtained very nearly equals the weight of chocolate liquor pressed.

The following data on the theoretical yields of butter and press cake from 100 pounds of average roasted nibs or liquor show the effect of different degrees of pressing. Assuming that the freshly roasted nibs contain 1.5 per cent of moisture and 53 per cent of fat, and that the press cakes contain 2 per cent of moisture, Table 1 gives the theoretical yields of butter and cake per 100 pounds of roasted nibs or liquor.

TABLE 1.-Theoretical yields of cacao butter and cocoa cake per 100 pounds of nibs liquor