作者：Riley, James Garfield
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A Study Of American Beers and Ales试读：
INTRODUCTION.
The investigation, the results of which are reported in this bulletin, was undertaken for the purpose of securing information in regard to the composition of brewery products made in this country. The main object of this investigation was to find, if possible, a means of distinguishing beers and ales made entirely from malt from those made from malt together with other cereal products, such as rice, corn, and cerealin.
It was concluded, after looking into the literature, that in order to accomplish this purpose it would be necessary to collect a series of samples made from the various raw materials ordinarily used and make a study of the effect of these raw materials upon the composition of the finished product.
The investigation seemed desirable for the reason that practically all of the existing data related to foreign beers, in the preparation of which a type of malt was used entirely different from that ordinarily used in the production of American beers. Furthermore, very few of the existing data relating either to foreign or domestic beers were based upon samples concerning which exact information was available in regard to the raw materials used in the wort.
METHOD OF UNDERTAKING THE INVESTIGATION.
It was felt that it would be wholly unsatisfactory to make this investigation by means of laboratory brewings on a small scale, as the results thus obtained would not show the true conditions, because it is not possible in the laboratory to duplicate exactly the mashing or fermenting processes actually used in a commercial way. It was decided, therefore, to attempt, with the cooperation of several breweries, to make this study under the exact conditions prevailing in commercial plants. Access was secured to several breweries making different types of products from various kinds of raw materials, under such conditions that it was possible to obtain a complete history of the beer through its various stages to the finished product. One of the writers (Riley) watched the method of manufacture during its whole process and obtained samples of the product at the various stages of manufacture. Thus, it was possible to procure finished samples with practically the same degree of certainty, as regards knowledge of composition and history, as would have been the case had they been prepared in the laboratory.
In three different breweries manufacturing a wide range of products samples of the wort and beer were obtained in this manner, the entire process of manufacture being studied in detail. A record showing the kind and amount of raw materials placed in the mash and in the cooker was made of the samples collected from these three breweries. A record also was kept of the time and temperature of each operation until the mash was ready to run into the kettle. The filtering [1]and sparging of the mash, the time of boiling in the kettle, the amount of hops added and the point at which they were added, and [2]the break of the wort were all noted. After the wort had been [3]pumped from the kettle its course was followed through the hop jack [4]over the coolers to the settling tank. The specific gravity or Balling of [5]the original wort, the temperature at which the product was pitched, the aeration of the wort, the kind and amount of yeast added, as well as the time and maximum temperature of the primary fermentation, also were noted. The course of the beer through the storage vats, chip casks, and filters to the racks was watched, and samples of the wort and of the beer in its various stages of production were collected and examined. [1] Washing the grains with hot water to remove the extract or valuable constituents as completely as possible. [2] Precipitation and uniting, in the form of flakes, of the coagulable albuminoids, leaving the liquid clear. [3] A filtering tank. [4] Percentage of solids in the liquor according to the Balling hydrometer. [5] Pitching is the operation of adding the yeast to the wort.
METHODS OF ANALYSIS.
The methods of analysis used were those given in Bulletin 107, revised (U. S. Dept. Agr., Bur. Chem.), pages 90-94, with the exception that the determination of phosphoric acid was made by the method used in fertilizer analysis (ibid., pp. 2-5), destroying the organic material in the beer by digestion with strong sulphuric acid and nitric acid and determining the phosphoric acid finally by the optional volumetric method (ibid., p. 4). The uranium acetate method given for beers was not used, for the reason that it was found to be exceedingly [1]difficult to obtain accurate results on dark-colored beers. [1] Riley, in his report to the Association of Official Agricultural Chemists for the year 1913, stated that the method giving the most uniform results was that of ashing the beer with an excess of standard calcium acetate, and that while the moist combustion method in the hands of those familiar with it gave satisfactory results, the various collaborators working with the method did not get as uniform results as with the method of ashing with calcium acetate. J. Assoc. Off. Agr. Chemists 1 (1915), 138-143.
It was found in the estimation of dextrin by the Sachsse-Allihn method (ibid., p. 91) that there is an error in the method of calculation of the amount of dextrose formed from the amount of maltose in the original beer. Instead of multiplying the amount of maltose in the original beer by the factor 0.9, it should be multiplied by the factor 1.053, as 1 gram of anhydrous maltose yields, on hydrolysis, 1.053 grams of dextrose. The product is the quantity which should be subtracted from the total amount of dextrose found after hydrolysis. The extract in the beer was determined by use of the tables of Schultz and Ostermann (ibid., pp. 209-213). The same methods were used in the analyses of the worts as were used in the examination of the beers.
RESULTS OF ANALYSIS.
Tables I to IV contain the results of the analyses of the worts and finished fermented products obtained at the various breweries where this investigation was conducted, arranged so as to show readily the changes which took place during fermentation and, in a few cases, the changes which took place during storage. The results are all given in terms of grams per 100 cc, so that a direct comparison of the quantities of any particular ingredient in a definite volume of material may be made. The comparison of the grams per 100 cc of an ingredient in the wort, with the grams per 100 cc in the finished fermented product, is based on the assumption that there is no appreciable change in the volume of the wort during fermentation.
In Table I are given the results of the analyses of 7 malt worts and the beers produced from them. Table II contains the results of the analyses of 2 malt-and-rice worts and 2 malt-and-corn worts, and the beers produced from them. In Table III are given the results of the analyses of 4 porter worts and the finished porters produced from them. The results of the analyses of 9 ale worts and the finished ales are shown in Table IV. In these four tables the extract in the original wort has been calculated by multiplying the alcohol (expressed in terms of grams per 100 cc) by 2, and adding to the product the extract of the beer, porter, or ale (expressed in terms of grams per 100 cc). In the porter and ale worts a percentage of dextrose had been added as brewer's sugar. Since dextrose reduces more copper than does maltose in the determination of the sugars, in order to obtain the true percentage of total sugars it was necessary to calculate the amount of copper reduced by the known amount of dextrose present, and then to calculate the amount of maltose. The results thus obtained are given in Tables III and IV under the heading "Reducing sugars as anhydrous maltose."Table I.—Analyses of all-malt worts and of the beers made from them.SPrDatSpecifiAlcExtExtractDegTotaVolatReduciDeProAsPhosUnColor aoe of c ohoract in ree l ile ng xtriteinh.phoridet(LovibmdTakiGravityl..originalof acidacidsugars n.(N c ermond) plung at 15. wort ferms s as as × 6.acidinein 1/4-e ct.Sa6°C./(calculentaas acetianhydr25)(as d.inch Nmpl15.6°C.ated).tion.lactic.ous POcell.2o.e.c.maltos).5e.GraGraGramsGraGraGramsGraGraGraGraGraDegre msmspermsmspermsmsmsmsmses,perper100 cc.perper100 cc.perperperperperbrewer100100100 100 100100100100 c100's191 cc. cc.cc.cc. cc. cc. cc.c. cc.scale.1.2WJuly1.0518...13.......0.0.9.79...0.0.0.098...13.02or 5751980018622310t13-D2BJuly1.01253.5.12.8659..216.0011.342....0800.12.02e 1285168833611209670er17-D 2WJuly1.0517...13........198.0019.79......095...13.02or 6718762280t14-D2BJuly1.01243.5.12.9860..225.0021.362....078.9313.02e 13911625066142010er18-D ...WJuly1.0517...13........207.00110.04......099...13.0or 771852252t2BJuly1.01353.5.13.1058..234.0021.55......082...9.02e 148344476102150er19-D 2WJuly1.0517...13........198.0019.86......097...13.02or 8708412400t15-D2BJuly1.01303.5.12.6658..236.0021.592....081.5511.02e 15722277236392060er20-D 2WJuly1.0515...13........225.0019.84......097...13.02or 10688452450t16-D2BJuly1.01473.5.12.9856..221.0011.852....082.7810.02e 17666639186352080er21-D 1912.1WFeb.1.0455...12........216.0017.40......095...4.06or 29059172322t89-C1BMar.1.01713.6.12.1149..230.0031.352....082.833.06e 7020188737572462er89-C2 DApr.1.01673.5.12.1451..243.0121.472....090.793.00o 1812904068732229714-D 1WMar.1.0454...12........180.0017.41......101...2.06or 1028742382t99-C1BMar.1.01802.6.11.9448..234.0121.402....090.962.06e 18871607827372402er99-CTable II.—Analyses of malt-and-rice and malt-and-corn worts and of the beers made from them.SRaw PrDatSpecifAlcExtExtracDeTotVolaReducDeProAsPhoUnColor aMaterioe of ic ohract in greal tile ing xtriteinh.sphodet(Lovibmals.dTakGravitol.t.originae of aciacidsugarn.(N ric erond) pluing y at l wort ferds s s as × 6acidmiin 1/4-e ct.Sa15.(calculmeas as anhyd.(as neinch Nmpl6°C./ated).ntatilactiacetrous 25)POd.cell.2o.e.15.on.c.ic.maltos).56°C.e.GrGrGramGraGraGramGrGrGrGraGrDegre amamsmsmssamamammsames,ssperperperperssspersbreweperper100 100100 100 perperper100 perr's1010cc. cc.cc.cc.101010cc.10scale.0 0 0 0 0 0 cc.cc.cc.cc.cc.cc.280 per WJul1.0459...12.......0.0.8.64....0.0....2.02cent mory 21512400171190690alt andt4 143220 per 9116-cent Drice.2DoBJul1.01213.4.11.4257...0031.182....0550.2.02ey 3318097275475115480er1 19039112-D2DoWAug1.0464...12.........0018.70......072...2.02or.3012662200t 9 14439116-D2DoBAug1.01393.5.11.5954...0031.572....057.692.02e.1823872434140150er 16 0641912-1D160 per WDe1.0489...12.........0039.05......066......6cent morc.9514446222alt andt 5 119640 per 9119-cent Ccorn.1DoBDe1.01493.5.12.5854...0131.632....0561....6ec.456885171493021042er 12 8371911-1C1DodMar1.01593.5.12.4253...0141.872....056.99...6o.3376621803632202 12 7881917-2C1DoWDe1.0496...13.........0039.32......067......6orc.1414449212t 6 18679110-C1DoBDe1.01523.5.12.4354...0131.592....050.93...6ec.4161871715831202er 13 4371912-2C1DodMar1.01573.5.12.2653...0141.882....058.69...6o.2968671755831222 12 4281916-2CTable III.—Analyses of porter worts made from malt, cerealin, and brewer's sugar, and of the porters made from these worts.SPrDatSpecifiAlcExtExtractDegTotaVolatReduciDeProAsPhosUnColor aoe of c ohoract in ree l ile ng xtriteinh.phoridet(LovibmdTakiGravityl..originalof acidacidsugars n.(N c ermond) plung at 15. wort ferms s as as × 6.acidinein 1/4-e ct.Sa6°C./(calculentaas acetianhydr25)(as d.inch Nmpl15.6°C.ated).tion.lactic.ous POcell.2o.e.c.maltos).5e.GraGraGramsGraGraGramsGraGraGraGraGraDegre msmspermsmspermsmsmsmsmses,perper100 cc.perper100 cc.perperperperperbrewer100100100 100 100100100100 100's191 cc. cc.cc.cc. cc. cc. cc.cc. cc.scale.1.2WJuly1.0572...15.......0.0.8.67...0.0.0.069...58.02or 20252700026962270t23-D2PJuly1.01514.6.14.6258..324.0031.073....0520.59.02or 2630028234482208920te2r8-D2dAug1.01354.5.14.6661..380.0021.073....051.7860.02o. 2148701219482182046-D 2WAug1.0625...16........234.0029.74......072...65.02or. 11666852320t38-D2PAug1.01654.6.16.1059..342.0021.423....0531.60.02or. 1875600148477196020te4r4-D 2WAug1.0623...16........234.0029.68......069...55.02or. 18626672240t45-D2PAug1.01704.6.16.1658..288.0021.413....0581.55.09or. 2572724262482201015te0r1-B 2WJuly1.0633...16........234.00410.25......073...70.02or 21877212140t25-D2PJuly1.01784.6.16.3657..378.0021.403....0551.60.02or 2870964668476194210te3r1-D2dAug1.01624.6.16.1859..306.0031.443....053.9960.02o. 2482545844479189049-DTable IV.—Analyses of ale worts and of the ales made from them.SProduRaDatSpecifAlcExtExtracDeTotVolaReducDeProAsPhoUnColor act.w e of ic ohract in greal tile ing xtriteinh.sphodet(LovibmMTakGravitol.t.originae of aciacidsugarn.(N ric erond) plateing y at l wort ferds s s as × 6acidmiin 1/4-e rialSa15.(calculmeas as anhyd.(as neinch Ns.mpl6°C./ated).ntatilactiacetrous 25)POd.cell.2o.e.15.on.c.ic.maltos).56°C.e.GrGrGramGraGraGramGrGrGrGraGrDegre amamsmsmssamamammsames,ssperperperperssspersbreweperper100 100100 100 perperper100 perr's1010cc. cc.cc.cc.101010cc.10scale.0 0 0 0 0 0 191cc.cc.cc.cc.cc.cc.1.2Malt, WJul1.0608...16.......0.0.10.00...0.0.0....4.02cerealorty 2415300178230590in, an21802d4-breweDr's sugar2doAlJul1.01394.5.15.5761...0031.163....0390.5.02ey 829391225234219920275430-D2doAlAug1.01244.5.15.5663...0031.432....038.885.02e a. 229762882706944180fter104 st7-orDage.2doWAug1.0610...16.........00310.24......060...5.02ort. 730153772101434-D2doAlAug1.01235.5.15.8964...0031.262....043.905.02e. 1411673222585471801639-D2doAlOct.1.01065.5.15.8066...0031.102....041.935.09e 62628582256046185aft290er 4-stoBrage2doWAug1.0611...16.........00210.60......057...4.02ort. 1032149762003937-D2doAlAug1.01244.5.15.4863...0031.402....043.794.02e. 1793626921682441701243-D2Malt WJul1.0642...17.........00210.19......072...3.02and orty 1018077210cereal19622in2-D2doAlJul1.01335.5.16.2963...0041.253....055.733.02ey 1795472072850190260227-D2doWAug1.0668...17.........00210.99......072...3.02ort. 880189772106235-D2doAlAug1.01455.6.16.9862...0041.423....051.844.02e. 1534309029331541901240-D1doAlNo1.01345.6.17.1564...0041.652....053.983.06e v.5211372347650212aft 15636er 7-stoCrage2doWOct.1.0760...20.........00111.196....077.983.09ort 102319881952959406-B2doAlOct.1.02535.9.20.0554...0082.694....0581.3.09e 174319163693967271751312-B 191 2.1doAlJan1.02085.8.19.7858...0082.543....0571.4.03e . 3801864360426227329aft252er 2-stoDrage 191 1.2doWOct.1.0767...20.........00112.145....0781.3.09ort 11401985996284255207-B2doAlOct.1.02285.8.19.8657...0052.514....0571.2.09e 186752103600866250154614-B2doWOct.1.0781...20.........00211.735....0751.2.09ort 18751989593308356013-B2doAlOct.1.02445.9.20.0655...0062.624....0571.2.09e 245300132813167251451519-B 191 2.1doAlJan1.02105.8.19.5258...0132.543....0641.4.03e . 2671809360616028159aft322er 3-stoDrage 191 1.2doWAug1.0793...21.........00311.416....0912.75.02ort. 23052703486321104650-D2doStAug1.02425.9.20.4055...0032.034....0711.69.09out. 306902785585473284255603-BA study of these tables shows very clearly that during fermentation marked changes are brought about other than the mere conversion of sugar into alcohol. While it is well known that these changes take place it seems worth while to consider them here, because no similar study relating to American brewery products has been published. Further since we have the exact analysis of the wort and of the beer which was made from it, we have a special opportunity to examine quantitatively some of these changes, such as the production of alcohol, the fermentation of dextrin, the development of acids, and the losses of protein, ash, and phosphoric acid during fermentation.
In order to study the question of the yield of alcohol, to test the present factor used for the calculation of the solids in the original wort, and to show the approximate amount of dextrin, calculations were made, the results of which are presented in Table V.Table V.—Changes taking place in the conversion of worts into beers and ales.Loss in Loss in Alcohol.Loss in solids Difference between Product.solids.sugar.divided by loss in solids and loss alcohol.in sugar. GramsGramsGrams Gramsper 100 per 100 per 100 per 100 cc.cc.cc.cc.Beer (all-malt)8.598.453.852.230.14Do8.558.433.912.18.12Do8.278.493.832.13.22Do8.488.273.722.27.21Do8.027.993.662.19.03Beer (60 per cent m7.277.423.452.10.15alt and 40 per cent corn)Do7.537.733.332.00.20Beer (80 per cent m7.357.463.312.22.11alt and 20 per cent rice)Do7.077.133.182.22.06Beer (all-malt)6.046.053.022.00.01Do5.866.012.872.04.15Average for beers 2.14.04Porter (small)9.237.604.302.141.63Porter (large)9.918.324.702.101.59Do10.068.274.752.111.79Do9.907.824.722.092.08Ale10.318.844.822.131.47Do10.638.985.112.081.65Do10.709.204.932.171.50Do11.158.945.162.152.21Do11.509.575.342.151.93Do11.629.065.352.172.56Pale ale11.049.505.432.031.54Do11.889.635.672.092.25Do11.759.115.532.122.64Brown stout12.039.385.692.112.65Average for ales.........2.121.96Average for beers .........2.13...and alesIn Table V have been collected results (calculated from Tables I-IV) which show the loss in solids between the wort and the finished fermented product, the loss in sugar, the yield of alcohol, the loss in solids divided by the alcohol, and the difference between the loss in solids and the loss in sugar. By dividing alcohol into loss in solids there was secured a factor which makes possible the estimation of the solids in the original wort, provided that alcohol and extract are known. This factor also shows the yield of alcohol for a given amount of solids disappearing during fermentation. It has been found in the case of the beers that this factor averages 2.14, while in the case of the ales it averages 2.12, making an average for all of the products of 2.13. This clearly shows that in the yield of alcohol for a given amount of fermentable solids there is no appreciable difference between top fermentation products, such as ales, and bottom fermentation products, such as beers.
A marked difference in loss in solids is shown, however, when we compare the beers with the ales. In the case of the beers we find there is practically no difference between the loss in solids and the loss in sugar, while in the case of the porters and ales there is a very appreciable difference. The difference between the loss in solids and the loss in sugar is only 0.04 per cent for all of the beers; while in the case of the porters and ales the difference varies from 1.47 per cent to 2.65 per cent, with an average of 1.96 per cent. These figures clearly show that in the case of the porters and ales there has been some material other than sugar fermented. Unfortunately, the determination of dextrin was not made in all of the worts, so that the actual decrease in dextrin can be shown only in a few cases. But in those cases where we have the actual results the difference between loss in solids and the loss in sugar compares very closely with the actual amount of dextrin disappearing during fermentation.
DEVELOPMENT OF ACIDS DURING FERMENTATION.
A comparison of the amounts of volatile and fixed acids in the worts and in the finished beers shows that normally there is no appreciable development of volatile acid during fermentation and only a slight increase in the fixed acid. This increase in fixed acid averages in the case of the beers 0.049 per cent, while in the case of the ales the increase averages 0.103 per cent.
DECREASE IN PROTEIN, ASH, AND PHOSPHORIC ACID.
A general study of the preceding tables will show that there is an appreciable loss of protein, ash, and phosphoric acid during the fermentation. Table VI has been prepared to show the average loss during fermentation of the various classes of worts with respect to their protein, ash, and phosphoric acid contents.
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