Coffee roasting

“ Retail coffee roasting is similar to the wholesale operation. When the cylinder has become heated, the green coffee is run in and allowed to roast in the revolving cylinder for about half an hour. If the coffee is the average green kind, the full heat may be applied at once; but if old and dry, a lesser degree is used. When the roast begins to snap, the flame is turned lower to allow the beans to cook through evenly ”

“ 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. ”

“ Roasted coffee loses from 20 to 30 per cent, by sufficient roasting, and the powder suffers much by exposure to the air; but, while raw, it not only does not lose its flavour for a year or two, but improves by keeping. If a cup of the best coffee be placed upon a table boiling hot, it will fill the room with its fragrance; but the coffee, when warmed again after being cold, will be found to have lost most of its flavour. ”

“ 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.
French Gas Coffee-Roasting Plant Equipped with Moderne Machines
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. ”

“ 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. ”

“ Nowadays, Rio coffee has pretty well the whole world for its parish. Wherefore the best one can do, is to get it sound, well roasted, and as fresh as may be. Much as I love and practice home preparation, I am willing to let the Trust or who will, roast my coffee. Roasting is parlous work, hot, tedious, and tiresome, also mighty apt to result in scorching if not burning. One last caution—never meddle with the salt unless sure your hand is light, your memory so trustworthy you will not put it in twice. ”

“ The aroma, upon which the good taste of the coffee depends, is only developed in the berry by the roasting process, which also is necessary to diminish its toughness, and fit it for grinding. While roasting, coffee loses from fifteen to twenty-five percent of its weight, and gains from thirty to fifty percent in bulk. More depends upon the proper roasting than upon the quality of the coffee itself. One or two scorched or burned berries will materially injure the flavor of several cupfuls. Even a slight overheating diminishes the good taste. ”

“ The coffee-roasting apparatus is usually a malleable iron cylinder mounted to revolve over the fire on a hollow axle which allows the escape of gases generated during torrefaction. The roasting of coffee should be done as short a time as practicable before the grinding for use, and as ground coffee especially parts rapidly with its aroma, the grinding should only be done when coffee is about to be prepared. ”

“ The wide-awake retail coffee roaster always features his roasting machine, which is generally highly ornamental and draws attention even when not in use. Some progressive merchants plan to roast coffee at noon time and at night, when homeward-bound passers-by are hungry and are particularly susceptible to the pungent aroma of roasting coffee. It is a quite common plan for the retail roaster to arrange the exhaust of the machine so that the full strength of the odor is blown into the street. ”

“ Coffee should be roasted uniform and as quickly as possible, only it must not be scorched or spotted, otherwise it will have a bitter burned taste. If roasted properly it will very considerably increase its bulk and will be plump, swelled out and crisp; easily crushed in the hand or between the fingers.
In his Spice Mill Companion, published in 1879, Jabez Burns said further in regard to roasting:
All coffees do not roast alike; some will be a bright light color when done, and others will be dark before done. ”

“ Roasting.—In the process of roasting, coffee seeds swell up by the liberation of gases within their substance,—their weight decreasing in proportion to the extent to which the operation is carried. Roasting also develops with the aromatic caffeone above alluded to a bitter soluble principle, and it liberates a portion of the caffeine from its combination with the caffetannic acid. Roasting is an operation of the greatest nicety, and one, moreover, of a crucial nature, for equally by insufficient and by excessive roasting much of the aroma of the coffee is lost ”

“ Coffee roasting plants were installed in all the large camps at home and overseas, for the double purpose of giving the soldier better coffee—coffee made within twenty-four hours after the bean had been roasted—and to prevent the waste, about two cents on each pound, which results when the roasted coffee is kept for long periods and so deteriorates in strength and quality. ”

“ Roasting.—Take a sufficient quantity of nuts to cover the bottom of an iron pot two or three inches deep, place them on the fire to roast, stirring them constantly with the spatula that the heat may be imparted to them equally. A coffee-roasting machine would answer for this purpose admirably, taking care not to torrefy them too much, as the oil of the nut suffers thereby, and it becomes a dark brown or black, grows bitter and spoils the color of the chocolate. Musty or moldy nuts must be roasted more than the others, so as to deprive them of their bad taste and smell. ”

“ Roasting is necessary to develop the aroma and goodness 26of coffee. This delicate operation changes its chemical composition and develops the caffeine and volatile oil. If roasted too little the coffee retains a raw taste; if too much, a part is changed to charcoal and much aroma lost. The outside may be burned and the inside left raw, or some grains may be half raw and others burned. Coffee loses in weight from 15 to 20 and even 25 per cent., and gains in bulk from 30 to 60 per cent., according as it is roasted to a reddish, chestnut, or dark brown. ”

“ To buy this green coffee and roast it at home is to take slow poison, because this adulteration is not wholly dissipated by the process of roasting. The large roasters of the country do not buy this doctored berry; they care nothing for the appearance if the coffee roasts well, and is clear and free from "quakers" or decayed berries. Therefore it is better to buy roasted coffee of the retailer, either in paper packages or out of tins bearing the name of a reputable house, and refuse to purchase the green under any circumstances. ”

“ In countries where coffee is grown the leaves are used as much as the berry. Like tea, coffee must be roasted, that the fine flavor shall be developed. There are large establishments for roasting and grinding coffee. The work is done by machinery; and nearly always the grains arc evenly roasted, and just enough to give the right flavor. If the coffee, after roasting, is put in close tin cans, it will retain its best qualities for a long time. It can be ground when needed for use. ”

“ 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. ”

“ 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. ”

“ One coffee-roaster-machinery manufacturer has recently brought out a gas-fired, electrically operated fifty-pound miniature coffee-roasting plant designed for retail stores, which comprises a roaster, a rotary cooler, and a stoning device, that sells for six hundred and fifty dollars. ”

“ The exact effect which roasting with sugars has upon the flavor is not well understood; but it is known that it causes the beans to absorb more moisture, due to the hygroscopicity of the caramel formed. For instance, berries roasted with the addition of glucose syrup hold an additional 7 percent of water and give a darker infusion than normally roasted coffee. When the green coffee is glazed with cane sugar prior to roasting, the losses during the process are much higher than ordinarily, on account of the higher temperature required to attain the desired results. ”

“ Coffees of various kinds can not be roasted to a uniform color. Some will be of a light shade when sufficiently roasted while others will have to be roasted dark to develop the aroma. Therefore, appearance alone is not a proper test. Aroma-saving devices have had their day. Coffee is of no use unless the aroma is fully developed, and the more it is developed by roasting the better it is. What passes off in the roasting process can not be saved and is so small that if all of it in the country could be collected and freed of all foreign matter, it would not weigh an ounce. ”

“ In the modes of preparation for use, the sources of caffeine present some coincidences, with many diversities. The coffee-berry, except in some Eastern countries, is roasted, an operation to which its valued fragrance is almost wholly due. The roasting develops from inodorous constituents a very diffusible empyreumatic oil of very appetizing odor. In the more elaborate preparation of the tea-leaf a degree of roasting appears to be always necessary for development of agreeable flavor, while a certain extent of fermentation precedes the roasting in the manufacture of black teas. ”

“ In any village or city in France it is a common sight on a pleasant day to find the householder turning his [Pg 679] roaster on the curb in front of his home. Emmet G. Beeson, in The Tea and Coffee Trade Journal gives us this vignette of rural coffee roasting in the south of France:
In a certain town in the south of France I saw an old man with an outfit a little larger than the home variety, a machine with a capacity of about ten pounds. Instead of a cylinder in which to roast his coffee, he had perched on a sheet-iron frame a hollow round ball made of sheet iron. ”

“ 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. ”

“ Coffee may be compared in its effects on the system to beef-tea—it is valuable for its flavors rather than for actual nutritious principles.
It is a curious fact that coffee is most frequently made in such a way that its valuable flavors are undeveloped or destroyed. Care must be taken that the roasting be not carried so far as to char the coffee-beans, yet far enough to convert the sugar into caramel, and to change the nature of the volatile oil, so that the highest point of flavor will be reached. ”

“ But, on the other hand, unless the roasting be done very carefully, the coffee will not be good. A few burnt beans in a quart will ruin the drink. When careful attention to roasting cannot be given at home, it will be better to buy a supply already roasted, but never ground. A French small mill, which can be regulated to grind coarse or fine, can be bought for about a dollar and a half. With care it will last for ten or twenty years. Some firms put up coffee in tin cans. It costs more, but retains so much of the aroma as to be well worth the extra price. ”

“ The higher the roast is carried, the greater the shrinkage; but, as the analyses in the above table show, the loss of caffein proceeds out of proportion to the shrinkage, for the percentage of caffein constantly decreases with the increase in color. If the roast be carried almost to the point of carbonization, as in the case of the "Italian roast," the caffein content will be almost nil. This is not a suitable coffee for one desiring an almost caffein-free drink, for the empyreumatic products produced by this excessive roasting will be more toxic by far than the caffein itself would have been. ”