All About Coffee by William H. Ukers (interesting novels in english TXT) 📖
- Author: William H. Ukers
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Coffee-tannin, which is not the commercial tannic acid, is eliminated to practically nothing in the quick brewing methods.
The chemical analysis of brewed coffee shows the following:
per Cup Comparative
Proportions Percolator method, [379] fine gran. 5 minutes' steeping 2.90 grains ————— Boiling Method, medium gran. 2.35 grains ———— Steeping Method, medium gran. 2.31 grains ——— Filtration (or Drip) Method Pulverized 0.29 grains —
Brewing is the final manufacturing process of coffee. All previous perfection is dependent upon it. Like food products which lose nutritive value by bad cooking, coffee loses its best values by wrong brewing. Brewed by the very simple correct methods, it is an unfailingly clear, fragrant, taste-charming beverage, universally loved and scientifically approved.
The committee made a further report in 1914, and some of the findings were subsequently published in an association booklet called The Coffee Book, used in connection with the second National Coffee Week campaign in 1915. In it were these:
Grinding Definitions Powdered
Like—flour. Pulverized
Like—not coarser than
fine corn meal. Very Fine and Fine
Like—from corn meal to
fine granulated sugar. Medium
Like—coarse granulated
sugar.
Also, the committee emphasized its previous findings, particularly this one: "Filter bags should be kept in cold water when not in use. Drying causes decomposition. Keeps sweet if kept wet. Use muslin for filter bag and pulverized granulation."
The association brought out this same year, on recommendation of the committee, its Home coffee mill, an "ideal and standard coffee mill for home use." It was a wall mill equipped with a glass-front metal hopper and employing a ratchet spring-lock nut and double-action grinders. The mill was later improved with an all-glass hopper and a tumbler bracket. More than 20,000 of these mills have been sold.
At the suggestion of the author, the efficiency of nine different coffee-making devices (including boiling and drip pots, pumping percolators, cloth and paper filters) was investigated in the laboratories of the Mellon Institute of Industrial Research of the University of Pittsburgh in 1915; and Dr. Raymond F. Bacon submitted a report that showed that the boiling method produced the highest percentage of caffetannic acid and caffein; the French drip process the lowest. The investigation disclosed also a more palatable brew at 195° to 200° F. than at the boiling point.
Another notable contribution to the science of coffee brewing was made by the Home Economics Laboratories of the University of Kansas in 1916. The experiments extended over one year. They showed that strength and color in coffee brews are independent of blend and price and are most fully obtained by pulverized granulation, which was found to be the most efficient; that the consumer pays for flavor and that filtration yielded the best brew. The French drip, or true percolator, did not figure in these experiments.
At the 1915 convention of the National Coffee Roasters Association, Mr. Aborn reported that 4,000 copies of the committee's findings on grinding and brewing had been given away: and the facts were further circulated in 2,000,000 booklets issued during two years. He told of tests which showed that while there might be reasons of commercial expediency for packing ground coffee, it could not be defended as a quality principle; also that plate-grinders produced a more efficient drawing granulation than roller grinders, and that the idea that the steel-cut process eliminates dirt was an absurdity, as "the finest ground coffee is not dirt but coffee in its most efficient drawing condition." He added, "I have paid no attention to chaff removal in these tests as the uselessness of such removal has been repeatedly shown up." The reference here was to his 1914 and 1913 reports, in which it was stated that "removing the chaff in the steel-cut process does not remove any of the tannin, and for this purpose the steel-cut process is wholely futile, and a wasteful and unnecessary tax upon cost", and that "the removal of the chaff appreciably affects the flavor and depreciates the cup value."
This report repeated previous findings against the pumping percolator as producing an inefficient brew and being a very faulty utensil. Mr. Aborn concluded his report by saying:
The old time boiling method has fewer and fewer defenders and holds its own only as a superstition. I therefore pass it over as a discarded issue.... It is but repetition of former reports for me to say that pulverized granulation is the most efficient granulation; that it assures the highest quality of brew and the lowest proportion of coffee to a given strength; that it is the most saving and most satisfying grinding for all to use; that it (the coffee) must be fresh ground; that the filtration method is the most correct in fundamental principles and that used with a muslin bag it assures the consumer coffee of the purest, finest flavored quality, highest health value and sure economy.
The campaign of education was continued during 1916, producing encouraging results among schools, colleges, the medical fraternity, newspapers, with the trade and the consumer. It marked the first big constructive work combining the practical and scientific phases of grinding and brewing methods. In his report at the 1916 convention of the National Coffee Roasters Association, Mr. Aborn reviewed the four years work, and pointed out what had been accomplished. He told of a new booklet, to be called the True Book on Coffee Grinding and Brewing, and an educational exhibit box for schools about to be issued. Due to opposition which developed from trade interests that were putting out steel-cut and other grinds of coffee not favored by the committee, and also because many members thought the association should not exploit any particular method of grinding or brewing, it was decided to make no further publication of the coffee grinding and brewing conclusions of the committee until they had been confirmed by laboratory research.
Boiling and filtration tests in the mountains of the Yellowstone Park by W.H. Aborn in 1916 showed that the limit of coffee brewing was reached at an altitude of nine thousand feet.
At the 1916 meeting, Dr. Floyd W. Robison of the Detroit Testing Laboratories, read a notable paper entitled "What do we know about coffee?," which hailed coffee as a food product, warned the roasters to beware of half-facts, and urged the importance of a research laboratory. It was published and given distribution by the association.
The educational exhibit box showing samples of coffee from plantation to cup, including five different grinds, was issued in 1917, and sold for one dollar.
The Better Coffee Making Committee also published in this year a booklet entitled Coffee Grinding and Brewing in which it summarized its work to date, and presented its special plea for cotton-cloth filters as the ideal coffee-making device.
This booklet aroused considerable discussion, particularly between those who favored the paper filter and those who, with Mr. Aborn, believed cotton cloth, such as muslin, to be the most efficient strainer. "Cotton", argued Mr. Aborn, "is an ideal sanitary strainer because it contains no chemical or questionable manufacturing element."
It was pointed out by Dr. Floyd W. Robison that while cotton cloth, such as muslin, does give a fairly clear coffee, it is not so clear as by the methods where a filter paper is used. He said:
Both methods have serious objectionable features. The muslin bag, particularly, is decidedly unsanitary, especially when used in restaurants and hotels. It is rarely kept clean, and one who has frequented restaurants and many hotel kitchens knows that it lends itself to very unclean and unsightly methods of handling. The food inspector has to check this up perhaps as often as any one feature about a restaurant.
The objection to the filter paper is not at all on the ground of sanitation. It is ideal in this respect. The claim is made, and at least, in part, substantiated, that it does hold back valuable features of the brew.
There are many points about the filter that have not been considered at all. Mr. Calkin believes that the very best type of filter is a bed of coffee itself, and I must say this has the sanction of good laboratory experience.
I.D. Richheimer[380], attacking the cotton cloth filter, said:
It is a known fact that the fats in coffee are very dense and represent twelve to fifteen percent of the coffee weight. These fats—due to the simplest chemical action of contact with air, moisture and continued heat—begin a fermentation in the completed beverage. In the cloth-filtering process—due to the rapid passage of water through grounds almost as quickly as poured—the largest percentage of fats is carried into the beverage. Fat being lighter than water rises to the top of water if given a certain amount of time during the brewing process. Were there no fats (which ferment) in coffee there would be no need for placing cloth-filtering material under water, as suggested, to keep them from becoming sour.
In the booklet referred to, Mr. Aborn expressed himself as follows on the filtration method:
The filtration method is not new, but well tried, thoroughly proven and long used, though often incorrectly. It is the method followed, more or less correctly, by all of the first-class hotels in the world. It is controlled by no patent or proprietary device, and requires a most inexpensive equipment. For a perfect result it but demands an accurate adherence to simple but vital principles. Deviations from these fundamentals, though apparently slight, cause failure. When they, and the necessary exact following of them, are clearly understood, any person, even a small child, can brew coffee with unvarying success.
The first point to consider in filtration is the dimensions of the filter bag, or container of the ground coffee, in relation to the quantity of coffee used and the granulation of same. If the filter be a muslin bag, free on all sides, the filtering surface is considerable and permits the necessary quick passage of water through the grounds, provided the bag is of a wide enough diameter as to prevent too great a depth of grounds through which the water cannot quickly penetrate. The error of too narrow a filter is a common one. It causes a delayed filtration, which means undesirably long contact of water and coffee and also the cooling of the liquid which in a correct, undelayed filtration is smoking hot at completion. The bag should also not be too long or be allowed to hang or soak in the liquid. A filter bag set tightly into a pot against its sides, thus surrounded with impenetrable walls, is greatly reduced in filtering surface, and the filtration is thereby slackened.
The filter material should not be too coarse in texture, like cheese cloth, or too heavy and impenetrable, like very heavy muslin. A moderate weight muslin, not too light, is efficient.
The degree of granulation also, of course, affects the rate of flow. The coarser the grind the faster the flow, which permits a larger quantity of coffee to a given diameter of filter bag.
A most frequent fault in the use of the filtration method is the failure to understand the fine degree of grinding necessary to the best results. When the grind is not sufficiently fine the extraction is, of course, weak. A fine grind (like fine cornmeal) is essential. It does not retard the flow if the filter is of right dimensions. A powdered grind (like flour) is so fine that it is apt to "mat" itself into a resisting floor.
Many users of the filtration method pour the liquid through more than once. This gains some added color, but adds undesirable element, depreciates flavor and is especially inadvisable
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