FACTORY PREPARATION OF ROASTED COFFEE
Coffee roasting as a business—Wholesale coffee-roasting machinery—Separating, milling, and mixing or blending green coffee, and roasting by coal, coke, gas, and electricity—Facts about coffee roasting—Cost of roasting—Green-coffee shrinkage table—”Dry” and “wet” roasts—On roasting coffee efficiently—A typical coal roaster—Cooling and stoning—Finishing or glazing—Blending roasted coffees—Blends for restaurants—Grinding and packaging—Coffee additions and fillers—Treated coffees, and dry extracts
THE coffee bean is not ready for beverage purposes until it has been properly “manufactured”, that is, roasted, or “cooked”. Only in this way can all the stimulating, flavoring, and aromatic principles concealed in the minute cells of the bean be extracted at one time. An infusion from green coffee has a decidedly unpleasant taste and hardly any color. Likewise, an underdone roast has a disagreeable “grassy” flavor; while an overdone roast gives a charred taste that is unpalatable to the average citizen of the United States.
Coffee Roasting as a Business
In spite of the generally admitted fact that freshly roasted coffee makes the best infusion, most of the coffee used today is not roasted at or near the place where it is brewed, but in factories that are provided with special equipment for the roasting of coffee in a wholesale way. The reasons for this are various, partly relating to the mere economy of buying and manufacturing on a large scale, and partly relating to the trained skill that is needed both for selecting suitable green coffees to make a satisfactory blend, and for the roasting work itself. The proportion of consumers (including restaurants and hotels) who roast their own coffee is so small as to be negligible, at least in the United States. The average person who buys coffee today, for brewing use, never sees green coffee at all, unless as an “educational exhibit” in some dealer’s display window.
The reasons just mentioned, which have made coffee roasting a real business, all tend, of course, to make the roasting establishments of large size; but this tendency is offset by the problem of distributing the roasting coffee so that it will reach the ultimate consumer in good condition. Roasting enterprises on a comparatively small scale (not by consumers, but by sufficiently expert dealers) would probably be much more numerous on account of the “fresh-roast” argument, except for the fact that coffee-roasting machines can not be installed so easily as the grinding mills, meat-choppers, and slicing machines, that find extended use in small stores. The steam, smoke, and chaff given off by the coffee as it is roasted must be disposed of by an outdoor connection, without annoying the neighbors or creating a fire hazard.
From these general remarks, it can easily be seen that the size of individual roasting establishments will vary greatly, according to the skill of the proprietor in meeting the disadvantages of working on either the smallest or the largest scale. A wholesale plant may be considered to be one in which coffee is roasted in batches of one bag or more at a time; and with this definition, nearly all the roasting in the United States is done in a wholesale way.
For many years the regular factory machines have been of a size suitable for roasting two bags of coffee at a time; but roasters of larger size have recently come into considerable use.
Plants treating from fifty to a hundred and fifty bags per day are the most common; but the daily capacity runs up to a thousand bags or more. The minimum cost of equipping a plant is somewhere between five thousand dollars and ten thousand dollars. The individual machines are of standard construction; but the arrangement in a particular building, especially for the larger plants, is worked out with great care and with numerous special features, so that the goods can be handled from start to finish with minimum expense for floor space, labor, power, etc.
The practical coffee roaster locates his roasting room in the top floor of his factory building, where light and ventilation are generally best. He usually has a large skylight in the roof, directly over the roasting equipment. In addition to the advantage as regards good light and the convenient discharge of smoke, steam, and odors, through the roof, the top-story location makes it possible to send the roasted coffee by gravity through the various bins which may be needed in connection with subsequent operations, such as grinding, and for temporary storage before the final packaging and shipping.
Wholesale Coffee-Roasting Machinery
The indispensable coffee operations are roasting and cooling; and in practically all United States plants the cooling is followed by “stoning”. This is an air-suction operation that effects, aided by gravity, the removal of any stones or other hard material that would damage the grinding mill. The best commercial cleaning and grading of the green coffee has usually left in every bag a few small stones. These can be got rid of better after the coffee is roasted; because it is then not only lighter, but more bulky.
Besides these three operations of roasting, cooling, and stoning, the plant may have machinery for treating the coffee both before it is roasted and after it leaves the stoner.
A SIXTEEN-CYLINDER COAL ROASTING PLANT IN A NEW YORK FACTORY
This is a view of the roasting room of B. Fischer & Co. and shows a battery of Burns coal roasters
Treatment of the green coffee in roasting establishments is of less importance now than in years gone by; first, because most coffees now come to market more perfectly graded and cleaned than formerly; and second, because the whole-bean appearance of the coffee has become of less account, as wholesale grinding operations have increased. Nevertheless, many plants consider it highly important to have a separator for grading the coffee closely as regards the size of the beans—and particularly for the separation of round beans, or “peaberry”—as well as milling machinery for making the coffee as clean as possible before it is roasted. One green coffee operation that has lost none of its old-time importance, but on the contrary is more needed as the plants increase in size, is the mixing of different varieties of coffee—in proportions that have been decided on by sample tests—so as to get a uniform blend.
The mixer does not blend the various coffees any more surely than a good roaster cylinder will do it, but treats batches of much larger size. This means saving a great amount of labor that would be necessary for putting the desired quantity of component coffees into each individual roaster.
A proper installation of green coffee machinery requires various bins of ample capacity, and bucket elevators by which the coffee can be sent without manual labor from one operation to another. In modern plants, all the bins and elevators are constructed of metal. The separator, with its bins and elevator, may be installed independently of the rest of the plant, the graded coffee being all bagged up again and treated as new raw stock—some of it to be held for later use, or perhaps sold again unroasted. The milling machine and the mixer, however, are usually so placed and connected that the coffee can be sent from one to the other, and to the roaster feed hoppers, without any manual labor.
When the roaster sells his product in package form ready for the consumer, he will have a packaging department in which are grinding, weighing, labeling, and packing machines and equipment. In some of the more progressive plants, particularly in the United States, all the packing units are incorporated in one machine, so that the different steps in the work are carried on automatically and in one continuous operation.
Green-Coffee-Mixer ConnectionsTo operate at full capacity, without using the story above as well as below the mixer, requires a bucket elevator and three bins, each holding a full mixing batch. The above diagram explains this setting. The mixed coffee in the discharge bin is either drawn out into bags or sent by an elevator to a milling machine or direct to the coffee roasters. A batch ready for mixing can always be accumulated in the feed bin while the previous batch is being mixed or discharged.
The fan is usually hung to the ceiling over the mixer as indicated, and connected to the suction box by a 1-in. round pipe. The fan outlet can be carried directly out-of-doors; but the dusty discharge is objectionable in most installations, and this pipe is usually carried to a dust collector from the top of which the roof outlet is connected.
The efficient roaster-executive equips his entire plant with approved labor-saving devices. In the better establishments, the coffee is carried along by mechanical conveyors through all the operations from the first cleaning machine to the final packaging.
As already mentioned, a machine frequently found in wholesale plants is the separator, or grader. This apparatus, which is the same in principle in all countries, but varies in size and form according to local requirements, consists of a series of perforated screens. The perforations differ in size; and as the coffee is shaken on them, the small beans drop through the holes, the larger ones passing across the screen and dropping into a receptacle or chute ready for the next operation. The screens are made to grade the beans into large and small peaberry; large, medium, and small flat beans; brokens; and other commercial sizes. The average separator will grade fifteen to twenty bags of coffee in an hour.
Green-coffee-milling machine having a capacity of forty bags of green coffee per hour; with sifter, feed-pipe suction, and a final separate suction at the discharge hopper
Green-coffee separator without fan; with feed elevator, discharge chutes, and motor drive. View of right-hand side and feed end
|GREEN-COFFEE SEPARATING AND MILLING MACHINES|
Milling machines, for cleaning the green coffee, operate on practically the same principle the world over, varying in capacity and details of construction. A popular type used in the United States has two metal cylinders, one set within the other, and revolving in opposite directions. The inner cylinder is ribbed with flanges, and the outer one is lined with wire cloth. As these cylinders revolve, the beans pass between them rubbing against themselves and the rough sides of the cylinders. This action serves to remove dirt and other foreign matter that may be clinging to the beans, and also gives them an attractive polish. An exhaust fan sucks away the dirt milled off in the process. This type of machine will mill about forty bags of green coffee in an hour.
Mixing or Blending Green Coffee
Most roasters blend the different types of coffee while green. Some blend them after they have been roasted separately. When blended before roasting, the coffees are mixed by a machine built especially for that purpose. The mixing machine in general use in all countries consists of a large metal cylinder which, in wholesale operations, is revolved by the factory’s general power plant or by a separate motor. The cylinder is equipped on the inside with sets of reverse-screw mixing flanges that tumble the beans around until they are thoroughly blended; and there is usually a fan attachment to remove dust. This operation serves also to smooth down and to polish the surfaces of the beans, which adds to the style of the coffee when roasted. The average blending machine will mix from ten to twenty bags of coffee at a time. The actual mixing requires less than five minutes, but a longer period is needed for feeding and discharging. This is the last of the so-called “green-coffee operations”. The next step is roasting.
Roasting by Coal, Coke, Gas, and Electricity
Coffee is roasted commercially in cylinder or ball receptacles revolving in heated chambers, the degree of heat reaching about 420° Fahr. The cylinder type of roaster is invariably used in the United States; while both the cylinder and the ball types are popular in England, France, Germany, Holland, and other foreign countries.
An English Four-Machine Gas Coffee-Roasting Plant
The equipment includes three Morewood indirect-flame, and one quick direct-flame machines
Each roasterman has his own opinion about the fuel that gives the best result, and throughout the world the choice lies between anthracite coal, coke, and gas; though[Pg 386] hard wood is frequently used in countries where other fuels are not available or not economical. Electric heat has been tried for commercial roasting in Germany (1906), in England (1909), and in the United States (1918); but the experimenters have always found the cost of electric fuel to be prohibitive in competition with coal and gas. An electric roaster was demonstrated at the Food Conservation Show in New York, in 1918, at a time when the federal government was urging the necessity of conserving coal as a war economy measure. The inventor claimed that his machine would reduce roasting cost, improve the flavor and the aroma, and maintain a constant and easily controlled heat. He declared also that when roasted in his devices, less coffee was required for brewing.
An expert coffee-roasting-machinery man who has been working on the development of a practical electric roaster says that if it were possible to bake the coffee in an oven, just as the baker does his bread, the fuel cost would then compare favorably with that of gas or coal. It is because the heat chamber must have an exhaust to release the chaff and smoke that the use of electricity to replace the heat loss proves prohibitive when compared with coal or gas.
In all types of coal and coke burning roasters, the cylinders are heated by a fire underneath; while in gas roasters, the flame may be underneath or within the cylinder itself. Roasters in which the heat is within the cylinder are known as direct-flame or inner-heated machines. All three systems are used in the United States and Europe.
Facts About Coffee Roasting
The modern commercial roasting outfit is as near fool-proof as human genius has been able to devise. The more advanced types are almost automatic in operation, and are designed to insure uniformity of roasts. In such machines the green coffee is conveyed to the roasting cylinder by means of bucket elevators, which pour the beans into a feed hopper. From the feed hopper, the coffee is dumped through the opening in the front head-piece into the cylinder. The cylinder is perforated, and has inside flanges which keep tossing the coffee about while the cylinder revolves, so that the coffee will not burn during the roasting process.
To roast coffee by coal or coke usually requires from twenty-five to thirty minutes, depending on the moisture-content of the beans; whether they are spongy or flinty; whether a light, medium, or dark[Pg 387] roast is desired; and on the skill of the operator. Gas roasting requires from fifteen to twenty minutes. The quicker the roast, the better the coffee, is the opinion of many trade leaders, one of whom says:
It is a growing belief that in roasts of short duration the largest percentage of the aromatic properties is retained. A slow roast has the effect of baking and does not give full development; also, slow roasts seldom produce bright roasts, and they usually make the coffee hard instead of brittle, even when the color standard has been attained.
While coffees of widely varying degrees of moisture require somewhat different treatment, the consensus of opinion is that the best results are obtained from a slow fire at the beginning, until some of the moisture has been driven off, when the stronger application of heat may be given for development. An intense heat in the beginning often results in “tipping”, or charring, the little germ at the end, the most sensitive part of the bean.
Scorched beans have been caught at some point in the cylinder, often in a bent flange. Burning on one face, sometimes called “kissing the cheeks”, is caused by the too rapid revolution of the cylinder, so that some of the coffee “carries over”. In the best practise, crowding of cylinders is avoided; many roasters making it a rule not to exceed ninety percent of the rated capacity of the cylinder.
Those operating gas roasters may effect a fuel economy by running a low grade coffee in the cylinder after the last roast has been drawn and the gas extinguished; five minutes’ revolution absorbs the heat and drives off a proportion of moisture. The coffee, which may then be left in the cylinder, requires less time and fuel in the morning, and the roast is finished while the cylinder is warming up. Double roasting brightens a roast, but is a detriment to the cup quality. A dull roasting coffee may be improved by revolving the green coffee in a cylinder without heat for twenty minutes, which has the effect of milling.
The use of a small amount of water upon roasts gives better control by checking the roast at the proper point—the crucial time of its greatest heat; also, it swells and brightens the coffee, and tends to close the outer pores. While the addition of water is open to abuse, few roasters have soaked their coffees enough to offset the natural shrinkage as much as three or four percent. Such practise would result greatly to the detriment of the cup quality.
There is no universal standard for the degree to which coffee should be roasted. In the United States, there are demands for all degrees; from the light roast, in favor in England, to the extremely dark roast in vogue in France, Italy, Brazil,[Pg 388] Turkey, and in the producing countries. The North American trade recognizes these different roasts: light, cinnamon, medium, high, city, full city, French, and Italian. The city roast is a dark bean, while full city is a few degrees darker. In the French roast, the bean is cooked until the natural oil appears on the surface; and in the Italian, it is roasted to the point of actual carbonization, so that it can be easily powdered. Germany likes a roast similar to the French type; while Scandinavia prefers the high Italian roast.
In the United States, the lighter roast is favored on the Pacific coast; the darkest, in the South; and a medium-colored roast, in the Eastern states. The cinnamon roast is most favored by the trade in Boston.
While coffee roasting in the United States usually takes from fifteen to thirty minutes, depending on the fuel and the machine employed, manufacturers of gas machines on the German market claim to roast it in superior fashion in from three and a half to ten minutes. This subject is discussed more in detail in chapter XXXIV.
Coffee loses weight during the roasting process, the loss varying according to the degree of roasting and the nature of the bean. Coffee roasters figure, however, that the average loss is sixteen percent of the weight of the green bean. It has been estimated that one hundred pounds of coffee in the cherry produces twenty-five pounds in the parchment; that one hundred pounds in parchment produces eighty-four pounds of cleaned coffee; and that one hundred pounds of cleaned coffee produces eighty-four pounds roasted.
There are four of these machines. The cylinders are twelve feet in diameter, six feet deep, and can roast 5,000 pounds of coffee every half-hour. The hard-coal brick furnace is seen at the left, from which a blower forces the heated air through a pipe into the revolving cylinder of coffee. The coffee is fed from above and is emptied into the cooling pans beneath
A view of Reid, Murdoch & Co.’s roasting room, Chicago, equipped with Monitor machines
During the roasting process the coffee undergoes a great chemical change. After it has been in the cylinder a short time, the color of the bean becomes a yellowish brown, which gradually deepens as it cooks. Likewise, as the beans become heated, they shrivel up until about half done, or at the “developing” point. At this stage, they begin to swell, and then “pop open”, increasing fifty percent in bulk. This is when the experienced roasterman turns on all the heat he can command to finish the roasting as quickly as possible.
“Dry” and “Wet” Roasts
At frequent intervals, he thrusts his “trier”—an instrument shaped somewhat like an elongated spoon—into the cylinder, and takes out a sample of coffee to compare with his type sample. When the coffee is done, he shuts off the heat and checks the cooking by reducing the temperature of the coffee and of the cylinder as quickly as can be done. In the wet roast method he will spray the coffee, while the cylinder is still revolving, with three to four quarts of water to every 130 pounds of coffee. In the dry method he depends altogether upon his cooling apparatus.
Roasters generally are not in favor of the excessive watering of coffee in and after the roasting process for the purpose of reducing shrinkage. “Heading” the coffee, or checking the roast before turning it out of the roasting cylinder, is quite another matter and is considered legitimate. Where coffees are watered in the cylinder at the close of the roast to reduce the shrinkage, it is possible to get back only about four percent of the shrinkage by such treatment and the practise is frowned upon by the best roasters.
Generally speaking, water is turned into the roasting cylinder to quench the roast. The amount varies with the style of machine, whether gas or coal. Usually the water turns to steam, and the result is not an absorption of the water but a momentary checking of the roast with a tendency to swell and to brighten the coffee. This is, comparatively speaking, a “dry roast”, but not an absolutely dry roast. It is doubtful if more than one percent of American coffee roasters employ an absolutely “dry” roast—it does not give satisfactory results. The word has been abused for advertising purposes. Of course, a dry roasted coffee is a better article for making a satisfactory beverage than one that has been soaked with water; but the word “dry” must be given a definite meaning, which the trade generally will agree to uphold, if it is to have any real meaning or value to the consumer. Until some standard for roasted coffee shall be established, it is to be feared the term “dry roast” will continue to be used for coffee roasted by almost any other process.
Upper-Story View of a Jubilee Plant, Showing Roaster, Cooler, and Stoner Equipment
The parts under roasting-room floor are shown in the illustration below
Showing connection from floor hopper to stoner on the left, and suspended bucket-elevator boot with four-bag dump hopper on the right
COMPLETE GAS COFFEE-PLANT INSTALLATION
The Bureau of Chemistry held a hearing in 1914 at Washington, at which the question of a ruling on watering coffees was discussed. The trade was well represented, but no agreement was reached. It was deemed inadvisable to make a definite rule on the watering of coffee; because the water content can not be controlled, as the bean starts to absorb moisture as soon as it leaves the roaster.
On Roasting Coffee Efficiently
A.L. Burns, New York, is well qualified to speak on this subject. He says:
Roasting coffee is not so difficult a matter as is often claimed by operators and “experts” who seek thus to magnify their importance; but it is nevertheless a process about which a great deal may be learned in the school of practical experience. With one of our modern machines anybody with ordinary intelligence and nerve can take off a roast after one trial which would pass muster in many establishments, but that same person applying himself to the roasting job for a week will either be turning out vastly better roasts or will have demonstrated that he never can excel as a roasterman.
Modern coffee roasting machines provide for easy control of the heat (from coal, coke, or gas fuel), for constantly mixing the coffee in such a manner that the heat is transmitted uniformly to the entire batch, for carrying away all steam and smoke rapidly, for easy testing of the progress of the roast, and for immediate discharge when desired. The operator’s problem therefore is the regulation of the heat and deciding just when the desired roasting has been accomplished.
If all coffees were alike, roasting would soon be almost automatic. In some plants most of the work is on one uniform grade or blend. But coffees which vary greatly in moisture-content, in flinty or spongy nature, and in various other characteristics, will puzzle the operator until he establishes a personal acquaintance with them in various combinations in repeated roasting operations. The roasterman therefore must be able to observe closely, to draw sensible conclusions, and to remember what he learns. Roasting coffee is work of a sort which anybody can do, which a few people can do really well, and no one so well but that further improvement is possible.
There is no absolute standard of what the best roasting results are. Some dealers want the coffee beans swelled up to the bursting point, while others would object to so showy a development. Some care nothing at all about appearance as compared with cup value, while others insist on a bright style even at some sacrifice of quality. Business judgment must decide what goods can be sold most profitably.
The loss of coffee in weight in the roasting operation, or shrinkage as it is called, is a matter which offers opportunities for false claims of advantage in roasting processes. Anybody can see that if just as good roasted coffee could be produced with a lessened shrinkage there would be a chance for a decided increase in profits. It is a sort of finding-money proposition which always turns out to be too good to be true. The purpose of roasting coffee is to produce an article entirely different from green coffee, which is accomplished mainly by driving out moisture. If coffee is roasted thoroughly, inside as well as outside, so as to give the greatest roasted coffee value, it must sustain a proper loss in weight which there is no legitimate way to avoid. The amount of shrinkage varies a great deal with the kind of coffee and its age, also with the kind of roasting desired.
Adding a little water to the coffee at the end of the operation has the advantage of checking the roast at the desired point and helping to swell and brighten the coffee, but it is a practice which is sometimes abused by soaking the coffee with water so as to reduce the shrinkage. This is done either dishonestly, to steal coffee which belongs to somebody else, or foolishly; for the heavier coffee has a lessened cup value which more than counterbalances the apparent gain.
A Typical Coal Roaster
A typical United States coal roaster is shown in the accompanying cut. It is the[Pg 392] latest form of that type of Burns machine which requires a brickwork setting. The picture shows the roaster ready to operate, except for smoke pipe and power connections.
The front of the machine shown has a cast-iron plate having brackets which support the cylinder front bearing, and double fire doors below for the furnace and the ash pit. The movable part of the roaster is hidden by the front head, a heavy casting which stands still except when moved by hand through a half-turn for feeding and discharging.
The cylinder is driven by gears at the back, revolving constantly at uniform speed. The inside of the cylinder is arranged with reverse-spiral flanges which mix the coffee perfectly and make uneven roasting impossible; and they discharge promptly every grain of coffee when the front-head opening is turned to the lower position. The roaster is generally operated with coal fuel, but can be used with gas by installing a suitable burner under the cylinder.
|Cost Card for Roasters
Showing the value added to the cost of green coffee by roasting
By A.C. Aborn
Basis: 16 percent Shrinkage.
3⁄4 cent a pound for Roasting.
|G = Cost Green, Cents per Lb.
R = Cost Roasted, Cents per Lb.
A GREEN COFFEE SHRINKAGE TABLE
Showing shrinkage in roasting of raw coffee in quantities from sixty pounds up to
three hundred pounds, and at six different shrinkage percentages
Compiled by R.C. Wilhelm, New York
Cooling and Stoning
“Coffee which leaves the roaster beautifully uniform in appearance”, says A.L. Burns, “may lose all uniformity by delayed or inadequate cooling. Separated beans of coffee will cool off by themselves; but when heaped together, the inner part of the mass will get hotter and even take fire…. Coffee must be spread over a considerable surface, or all kept moving, and have at the same time a lot of air forced through it. Otherwise, there will be some darkening and over-development of part of the coffee, and a loss of the uniformity which is the first requirement of good roasting.”
The cooling apparatus consists of a movable, box-like metal car which can be brought up to the front of the roaster to the revolving cylinders. The car has a perforated false bottom, to which is attached a powerful exhaust-fan system that sucks the heat out of the coffee. In large plants,[Pg 395] utilizing two or more floors, the tilting-type cooling car is favored. This car permits instant discharge through an opening in the floor into a receiving tank suspended from the ceiling below and connected with the stoning apparatus. Recently, a flexible-arm cooler has been invented that provides full fan suction to a cooler car at all points in its track travel from the roaster to the emptying position.
The stoner, an essential part of the modern roasting plant, has for its function the removal of stones and other foreign matter of which the green-coffee operations have failed to get rid. The stoner is usually built in direct combination with the cooling equipment, and does its work by means of a gravity separation in an upward-moving column of air. The coffee passes into the suction boot of the stoner, either directly from the cooler box or from a floor hopper into which the cooler dumps, and is carried up the stoner pipe, or “riser”, by an air current of ample power which can be accurately regulated. This insures the carrying up of coffee only, the stones remaining at the bottom of the machine and being dumped at intervals into a pan underneath. The coffee, passing up the riser pipe, is delivered into a large “stoner hopper” which is usually hung to the ceiling of the roasting room. The correct construction of this hopper is of great importance, as the coffee must be deposited completely without breakage, and the air must pass on through the suction fan carrying nothing except bits of loose chaff.
A different type of cooler is in the form of an upright cylinder, consisting of two metal perforated drums, one set within the other. The inner drum is sufficiently small to allow the coffee to move freely between the drums. Inside the smaller one is an exhaust pipe which draws the heat and chaff out of the coffee. This device is recommended for use only in connection with wet roasted coffee.
Still another type consists of a single perforated cylinder set horizontal with the floor, and revolving alongside of an exhaust box which sucks out the heat and chaff as the coffee is tumbled about in the cylinder. A rocking type, that is not generally employed, is constructed on the principle of the screen used by housebuilders to separate coarse sand from the fine, and is[Pg 396] pivoted at the middle so that it can be rocked end to end.
Finishing or Glazing
Finishing whole-bean roasted coffee, by giving it a friction polish while it is still moist, using a glaze solution or water only, is a practise not harmful if the proper solutions are employed. Roasted coffee dulls in ordinary handling, and it is claimed that coating not only improves its appearance, but serves also to preserve the natural flavor and aroma of the bean. A machine having flat-sided wooden cylinders with ventilated heads, and operated two-thirds full of coffee so as to get an effective rolling motion, is generally employed. Coatings composed of sugar and eggs are popular, but their use should be stated on the label.
Coffee roasters are divided on this question of coffee-coating. The best thought of the trade is undoubtedly opposed to the practise when it is done to conceal inferiority or abnormally to reduce shrinkage. Some New York coffee roasters, who made a thorough investigation of the matter, found coating coffee with a wholesome material not injurious and the coated coffee better in the cup. Dr. Harvey W. Wiley found, in the celebrated Ohio case against Arbuckle Brothers, that coating coffee with sugar and eggs produced beneficial results, and that the coating preserved the bean. The Bureau of Chemistry has never issued any ruling on the subject of coating coffee.
Blending Roasted Coffee
After cooling and stoning, unless it is to be polished or glazed, the coffee is ready for grinding and packing if it has been blended in the green state. Otherwise, the next step will be to mix the different varieties before grinding, although some packers blend the different kinds after they have been ground. To mix whole-bean roasted coffee without hurting its appearance is rather difficult, and there is no regular machine for such work.
Rarely is a single kind of coffee drunk straight. The common practise in all countries is to mix different varieties having opposing characteristics so as to obtain a smoother beverage. This is called blending, a process that has attained the standing of an art in the United States. Most package coffees are blends. In addition to other qualities, the practical coffee blender must have a natural aptitude for the work. He must also have long experience before he becomes proficient, and must be acquainted with the different properties of all the coffees grown, or at least of those that come to his market. Furthermore, he must know the variations in characteristics of current crops; for in most coffees no two crops are equal in trade values. Innumerable blends[Pg 397] are possible with more than a hundred different coffees to draw upon.
A blend may consist of two or more kinds of coffee, but the general practise is to employ several kinds; so that, if at any time one can not be obtained, its absence from the blend will not be so noticeable as would be the case if only two or three kinds were used.
In blending coffees, consideration is given first to the shades of flavor in the cup and next to price. The blender describes flavors as, acidy, bitter, smooth, neutral, flat, wild, grassy, groundy, sour, fermented, and hidey; and he mixes the coffees accordingly to obtain the desired taste in the cup. Naturally the wild, sour, groundy, fermented, and hidey kinds are avoided as much as possible. Coffees with a Rio flavor are used only in the cheaper blends.
Generally speaking, a properly balanced blend should have a full rich body as a basis; and to this should be added a growth to give it some acid character, and one to give it increased aroma.
Personal preference is the determining factor in making up a blend. Some blenders prefer a coffee with plenty of acid taste; while others choose the non-acid cup. For the first-named kind, the blender will mix together the coffees that have an acidy characteristic; while for a non-acidy blend, he will mix an acidy growth with one having a neutral flavor.
This is a self-contained plant for one or two bags, and comprises a roaster, rotary cooler, elevator feed hopper, electric motor, and stoning and chaffing attachments. It may be equipped for gas]
Coffees can be divided into four great classes, the neutral-flavored, the sweet, the acidy, and the bitter. All East Indian coffees, except Ceylons, Malabars, and the other Hindoostan growths, are classified as bitter, as are old brown Bucaramangas, brown Bogotas, and brown Santos. The acid coffees are generally the new-crop washed varieties of the western hemisphere, such as Mexicans, Costa Ricas, Bogotas, Caracas, Guatemalas, Santos, etc. However, the acidity may be toned down by age[Pg 398] so that they become sweet or sweet-bitter. Red Santos is generally a sweet coffee, and is prized by blenders. High-grade washed Santo Domingo and Haiti coffees are sweet both when new crop and when aged.
Practical coffee blenders do not mix two new-crop acid coffees, or two old-crop bitter kinds, unless their bitterness or acidity is counteracted by coffees with opposite flavors. One blender insists that every blend should contain three coffees.
Some Bourbon and flat-beaned Santos coffees are better when new, and some are better when old; but a blend of fine old-crop coffee with a snappy new-crop coffee gives a better result than either separately. A new-crop Bourbon and an old yellow flat bean make a better blend than a new-crop flat bean and an old-crop Bourbon. Probably the very best result in a low-priced blend may be obtained by using one-half old-crop Bourbon Santos with one-half new-crop Haiti or Santo Domingo of the cheaper grades.
Typical low-priced coffee blends in the United States may be made up of a good Santos, possibly a Bourbon, and some low-cost Mexican, Central American, Colombian, or Venezuelan coffee, the Santos counteracting these acidy Milds.
Going next higher in the scale of price, fancy old Bourbon Santos is used with one-third fancy old Cucuta or a good Trujillo.
For a blend costing about five cents more a pound retail, one-third fancy old Cucuta or Merida is blended with fancy old Bourbon Santos.
The highest-priced blend may contain two-thirds of a fine private estate Sumatra and one-third Mocha or Longberry Harari.
Alfred W. McCann, while advertising manager for Francis H. Leggett & Co., New York, in 1910, evolved a new coffee distinction based on the argument that certain coffees like Mochas, Mexicans, Bourbons, and Costa Ricas were developed in the cup[Pg 399] through the action on them of cream or milk; while others, such as Bogotas, Javas, Maracaibos, etc., flattened out when cream or milk was added. He argued, accordingly, that breakfast coffees should be made up from the former, but that the latter should not be used except for after-dinner coffees, to be drunk black. William B. Harris, then coffee expert for the United States Department of Agriculture, took issue with Mr. McCann, claiming that if a coffee is watery and lacks body, it will not take kindly to milk or cream, not because the chemical action of milk or cream flattens it out, but because there is nothing there in the first place. The strength of the brew being equal, all coffees will take cream or milk, Mr. Harris held.
M.J. McGarty said in 1915 that he had tried out many coffees in the cup, and could not see that adding milk made any difference. However, he found that sometimes a line of coffees will contain a sample that flattens out at the drinking point (the point where the boiling water has cooled to permit of its being drunk); and he thought this was what Mr. McCann had in mind, as, by adding milk to such a coffee, it was brought back to the drinking point. In other words, it was Mr. McGarty’s opinion that, in blending coffees, those coffees which hold their own from the start, or boiling point, until they become cold, or even improve right through, are more desirable for blending purposes; and that those that are best at the drinking point should be given the preference.
Coffee Blends for Restaurants
William B. Harris believes that the coffee of prime importance in preparing restaurant blends is Bogota. He advises the use of a full-bodied Bogota and an acid Bourbon Santos in the proportion of three-fourths Bogota to one-fourth Santos. Blends may also be made up from combinations of Bogota, Mexicans, and Guatemalas.
According to Mr. Harris, the average blend of good coffee when made up, two and one-half pounds of coffee to five gallons of water, will produce a liquor of good color and strength. For many hotels, however, this may not answer, as it is not heavy enough. More coffee must then be used, or ten percent of chicory added. A blend with chicory can be made by using two-thirds Bogota, one-third Bourbon Santos,[Pg 400] and ten percent chicory. No steward, hotel man, or restaurant man should, however, advertise “coffee” on his menu, and then serve a drink employing chicory; because, while there is no federal law against such a practise, there are state laws against it. Chicory is all right in its place; and many prefer a drink made from coffee and chicory; but such a drink can not properly be called coffee.
Hotel men should purchase their coffee in the bean, and do their own grinding. Then they need never have cause to complain that their coffee man deceived them, or that some salesman misled them. The hotel steward wishing to furnish his patrons with a heavy-bodied coffee, particularly a black after-dinner coffee, without chicory, will use three, four, or even four and one-half pounds of ground coffee to five gallons of water.
With so wide a choice of coffees to choose from, a coffee blender can make up many combinations to meet the demands of his trade. Probably no two blenders use exactly the same varieties in exactly the same proportions to make up a blend to sell at the same price. However, they all follow the same general principles laid down in the foregoing flavor classification of the world’s coffees.
Grinding and Packaging Coffee
Unless the coffee is to be sold in the bean, it is sent to the grinding and packing department, to be further prepared for the consumer. Since the federal food law has been in effect, the public has gained confidence in ground and bean coffee in packages; and today a large part of the coffee consumed in the United States is sold in one and two pound cartons and cans, already blended and ready for brewing.
A progressive coffee-packing house may have three different styles of grinding machines; one called the granulator for turning[Pg 401] out the so-called “steel-cut” coffee; the second, a pulverizer for making a really fine grind; and the third, a grinding mill for general factory work and producing a medium-ground coffee.
Commercial coffee-grinding machines are alike in principle in all countries, the beans being crushed or broken between toothed or corrugated metal or stone members, one revolving and the other being stationary. While all grinding machines are alike in principle, they may vary in capacity and design. The average granulator will turn out about five hundred pounds of “steel-cut” coffee in an hour; the pulverizer, from seventy-five to two hundred pounds; and the average grinding mill from five hundred to six hundred pounds. Some types of grinding machines have chaff-removing attachments to remove, by air suction, the chaff from the coffee as it is being ground.
A large number of trade terms for designating different grinds of coffee are used in the United States, some of them meaning the same thing, while similar names are sometimes contradictory. A canvass of the leading American coffee packers in 1917 discovered that there were fifteen terms in use, and that there were thirty-four different meanings attached to them. For the term “fine” there were five different definitions; “medium” had five; “coarse”, seven; “pulverized”, four; “steel-cut”, seven; “ground”, two; “powdered”, one; “percolator”, two; “steel-cut-chaff-removed”, one; “Turkish ground”, one; while “granulated”, “Greek ground”, “extra fine”, “standard”, and “regular” were not defined.
The term “steel-cut” is generally understood to mean that in the grinding process the chaff has been removed and an approximate uniformity of granules has been obtained by sifting. The term does not necessarily mean that the grinding mills have steel burrs. In fact, most firms employ burrs made of cast-iron or of a composition metal known as “burr metal”, because of its combined hardness and toughness.
The “steel-cut” idea is another of those sophistries for which American advertising methods have been largely responsible in the development of the package-coffee business in the United States. The term “steel-cut” lost all its value as an advertising catchword for the original user when every other dealer began to use it, no matter how the ground coffee was produced. When the public has been taught that coffee should be “steel-cut”, it is hard to sell it ground coffee unless it is called “steel-cut”; although a truer education of the consumer would have caused him to insist on buying whole bean coffee to be ground at home.
Smyser Package-Making-and-Filling Machine at the Arbuckle Plant, New YorkThis machine was invented by Henry E. Smyser of Philadelphia, who secured the first patent in 1880, but it has been much improved by the Arbuckle engineers. The half shown on the left makes the one-pound paper bags complete, including the separate lining of parchment, fills the bag, automatically inserts a premium list at the same time, packs it down, seals it, and delivers it on a short conveyor to the other half (shown on the right) where the package is wrapped in the outside glassine paper and pushed out on a table for the girls to put into shipping cases
“Steel-cut” coffee, that is, a medium-ground coffee with the chaff blown out, does not compare in cup test with coffee that has been more scientifically ground and not[Pg 402] given the chaff removal treatment that is largely associated in the public mind with the idea of the steel-cut process.
According to the results of the trade canvass previously referred to, it would appear that the terms most suited to convey the right idea of the different grades of grinding, and likely to be acceptable to the greatest number, would be “coarse” (for boiling, and including all the coarser grades); “medium” (for coffee made in the ordinary pot, including the so-called “steel-cut”); “fine” (like granulated sugar, and used for percolators); “very fine” (like cornmeal, and used for drip or filtration methods); “powdered” (like flour, and used for Turkish coffee).
Coffee begins to lose its strength immediately after roasting, the rate of loss increasing rapidly after grinding. In a test carried out by a Michigan coffee packer, it was discovered that a mixture of a very fine with a coarse grind gives the best results in the cup. It was also determined that coarse ground coffee loses its strength more rapidly than the medium ground; while the latter deteriorates more quickly than a fine ground; and so on, down the scale. His conclusions were that the most satisfactory grind for putting into packages that are likely to stand for some time before being consumed is a mixture consisting of about ninety percent finely ground coffee and ten percent coarse. His theory is that the fine grind supplies sufficiently high body extraction; the coarse, the needful flavor and aroma. On this irregular grind a United States patent (No. 14,520) has been granted, in which the inventor claims that the ninety percent of fine eliminates the interstices—that allow too free ventilation in a coarse ground coffee—and consequently prevents the loss of the highly volatile constituents of the ten percent of coarse-ground particles, and at the same time gives a full-body extraction.
Making and Filling Containers
As stated before, a large proportion of the coffee sold in the United States is put up into packages, ready for brewing. Such containers are grouped under the name of the material of which they are made; such as tin, fiber, cardboard, paper, wood, and combinations of these materials, such as a fiber can with tin top and bottom. Generally, coffee containers are lined with chemically treated paper or foil to keep in the aroma and flavor, and to keep out moisture and contaminating odors.
As the package business grew in the United States, the machinery manufacturers kept pace; until now there are machines that, in one continuous operation, open up a “flat” paper carton, seal the bottom fold, line the carton with a protecting paper, weigh the coffee as it comes down from an overhead hopper into the carton, fold the top and seal it, and then wrap the whole package in a waxed or[Pg 403] paraffined paper, delivering the package ready for shipment without having been touched by a human hand from the first operation to the last. Such a machine can put out fifteen to eighteen thousand packages a day.
Another type of machine automatically manufactures two and three-ply paper cans such as are used widely for cereal packages. It winds the ribbons of heavy paper in a spiral shape, automatically gluing the papers together to make a can that will not permit its contents to leak out. The machine turns out its product in long cylinders, like mailing tubes, which are cut into the desired lengths to make the cans. The paper or tin tops and bottoms are stamped out on a punch press.
Coffee cans are generally filled by hand; that is, the can is placed under the spout of an automatic filling and weighing machine by an operator who slips on the cover when the can is properly filled. The weighing machine has a hopper which lets the coffee down into a device that gauges the correct amount, say a pound or two pounds, and then pours it into the can. The machine weighs the can and its contents, and if they do not show the exact predetermined weight, the device automatically operates to supply the necessary quantity. After weighing, the can is carried on a traveling belt to the labeling machine, where the label is automatically applied and glued. Then the can is put through a drying compartment to make the label stick quickly.
The girl is feeding the “flats” into an Improved Johnson bottom-sealer. The carton travels to a Scott weigher on the right and thence to the top-sealer on the left
Paper bags are filled much the same way as the tin and the fiber cans. In fact, some packers fill their paper and fiber cartons by the same system; although the tendency among the largest companies is to instal the complete automatic packaging equipment, because of its speed and economy in packaging. Frequently, the weighing machines[Pg 404] are used in filling wooden and fiber drums holding twenty-five, fifty, and one hundred pounds of coffee, to be sold in bulk to the retailer.
Three Types of Automatic Coffee-Weighing Machines
Left—Duplex net weigher. Center—Pneumatic cross-weight machine. Right—Scott net weigher
Coffee Additions and Fillers
In all large coffee-consuming countries, coffee additions and fillers have always been used. Large numbers of French, Italian, Dutch, and German consumers insist on having chicory with their coffee, just as do many Southerners in the United States.
The chief commercial reason for using coffee additions and fillers is to keep down the cost of blends. For this purpose, chicory and many kinds of cooked cereals are most generally used; while frequently roasted and ground peas, beans, and other vegetables that will not impair the flavor or aroma of the brew, are employed in foreign countries. Before Parliament passed the Adulterant Act, some British coffee men used as fillers cacao husks, acorns, figs, and lupins, in addition to chicory and the other favorite fillers.
Up to the year 1907, when the United States Food and Drugs Act became effective, chicory and cereal additions were widely used by coffee packers and retailers in this country. With the enforcement of the law requiring the label of a package to state when a filler is employed, the use of additions gradually fell off in most sections.
In botanical description and chemical composition chicory, the most favored addition, has no relationship with coffee. When roasted and ground, it resembles coffee in appearance; but it has an entirely different flavor. However, many coffee-drinkers prefer their beverage when this alien flavor has been added to it.
Treated Coffees and Dry Extracts
The manufacture of prepared, or refined, coffees has become an important branch of the business in the United States and Europe. Prepared coffees can be divided into two general groups: treated coffees, from which the caffein has been removed to some degree; and dry coffee extracts (soluble coffee), which are readily dissolved in a cup of hot or cold water.
To decaffeinate coffee, the most common practise is to make the green beans soft by steaming under pressure, and then to apply benzol or chloroform or alcohol to the softened coffee to dissolve and to extract the caffein. Afterward, the extracting solvents are driven out of the coffee by re-steaming. However, chemists have not yet been able to expel all the caffein in treating coffee commercially, the best efforts resulting in from 0.3 to 0.07 percent remaining. After treatment, the coffee beans are then roasted, packed, and sold like ordinary coffee.
Vacuum Drum DrierVacuum drum drier, No. 1 size; diameter of drum, 12 inches; length, 20 inches; used for converting coffee extract and other liquids into dry powder form. This is the smallest size, and was developed for drying smaller quantities of liquids than could be handled economically in the larger sizes. To provide accessibility of the interior for cleansing, the outer casing may be moved back on the track of the bedplate (as shown in the cut), so that free access may be had to the drum and interior of the casing.
Rapid-Circulation EvaporatorUsed to concentrate coffee extracts and other liquids. The tubes are easily reached through the open door for cleansing. Interior of the vapor body is reached through a manhole.
Rear View of Drum Drier Vacuum drum dryer. No. 1 size; rear view, showing outer casing rolled back from the drum.
Cross-Section of Vacuum DrierThis shows the interior arrangement and principle of operation. The drawing represents a larger size than the photograph, and while the arrangement of some parts is slightly different, the principle of operation is the same.
|UNITS USED IN THE MANUFACTURE OF SOLUBLE COFFEE|
In manufacturing dry coffee extract in the form of a powder that is readily soluble in water, the general method is to extract the drinking properties from ground roasted coffee by means of water, and to evaporate the resulting liquid until only the coffee powder is left. Several methods have been developed and patented to prevent the valuable flavor elements from being evaporated with the water.
A typical dry-coffee-extract-making equipment consists of a battery of percolators, or “leachers”, a vacuum evaporating device, and a vacuum drier. The leachers do not differ materially from the ordinary restaurant percolators, a battery usually including from three to seven units, each charge of water going through all the percolations. The resulting heavy liquid then goes to the evaporator to be concentrated into a thick liquor. The evaporator consists of a horizontal cylindrical vapor compartment connected with an inclined cylindrical steam chest in which are numerous tubes, or flues, that occupy almost the whole chest. These tubes are heated by steam. The coffee liquor is passed through the tubes at high speed and thrown with great force against a baffle plate at the opening to the vapor chest. The vapor passes around the baffle plate to a separator. The liquor drops to the lower part of the steam-chest (which is free from tubes), and is ready to be drawn out for the next process, the drying.
At this stage, the extract is a heavily concentrated syrup and is ready to be converted into powder. This is done in the vacuum drier, which consists of a hollow revolving drum surrounded by a tightly sealed cast-iron casing. The drum is heated by steam injected into its interior, and is revolved in a high vacuum. In operation, a coating of coffee liquor is applied automatically, by means of a special device, to the outside of the drum. The liquor is taken by gravity from the reservoir containing the liquid supply and is forced upward by means of a pump into the liquid supply pan, directly under the drum, with sufficient pressure to cause the liquid to adhere to the drum, the excess liquor overflowing from the pan into the reservoir. The coating on the drum is controlled or regulated by a spreader. The heat and the vacuum reduce the extract to a dry powder in less than one revolution of the drum. As the drum completes three-quarters of a turn, a scraper knife removes the coffee powder, which is delivered to a receiver below the drum. Modern vacuum-drum driers have a capacity of from twenty-five to five hundred pounds of dry soluble coffee per hour.
C.W. Trigg and W.A. Hamor were granted a patent in the United States in 1919 on a new process for making an aromatized coffee extract. In this process, the caffeol of the coffee is volatilized and is then brought into contact with an absorbing medium such as is used in the extraction of perfumes. The absorbing medium is then treated with a solvent of the caffeol, and the solution is separated from the petrolatum. Then the coffee solution is concentrated to an extract by evaporation; after which, the extract and the caffeol are combined into a soluble coffee. Five additional patents were granted on this same process in 1921.