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Stella Ehr. Adela Ehr. [API_EMPTY_RESPONSE] 8 Digitized by the Internet Archive in 2007 with funding from Microsoft Corporation
http://www.archive.org/details/reportonmethodso00barnrich S-53A R.A. no. 31-10
Main Lib. Agric. Dept. Issued March 15, 1907.
United States Department of Agriculture,
BUREAU OF CHEMISTRY—Circular No. 33.
H. W. WILEY, Chief of Bureau.
REPORT ON METHODS OF BEER ANALYSIS.
By H. E. BARNARD, Chemist Indiana State Board of Health, and Associate Referee on Food Adulteration, Association of Official Agricultural Chemists.
INTRODUCTION.
The methods for the analysis of beers having been studied for several years by the Association of Official Agricultural Chemists, the work has culminated in the following exhaustive report submitted by the referee at the convention held in 1906, and the methods reported are now before the association for adoption as official. For this reason, as well as because of the length of the report and the fact that while important it is of interest to a comparatively limited number of chemists, the methods are here published in circular form.
Respectfully,
H. W. WILEY, Chief, Bureau of Chemistry. Secretary, Association of Official Agricultural Chemists. Approved: JAMES WILSON, Secretary of Agriculture. WASHINGTON, D. C., January 16, 1907.
21185—No. 33—07 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ORGANIZATION OF THE COOPERATIVE WORK, 1906.
At the meeting of the Association of Official Agricultural Chemists in 1904, tentative methods for beer analysis were reported and pub- lished in the Proceedings of that year. These methods have been sub- mitted to all of the brewing schools of the country and to the committee of scientists of the United States Brewers' Association. The correspondence which followed developed many interesting points, and led to the adoption of certain methods that seemed worthy of study. In May, 1905, there was sent to eight members of the association five brewing institutes and laboratories, each with a sample of beer, and instructions for making work, the following letter, accompanying samples as described and giving methods for analysis to be used in the investigations:
Dear Sir: In response to your offer to do cooperative work on beer analysis, I am indebted to you for sending me a sample of your beer. I have carefully shipped you by express. The methods as suggested explain themselves, I believe. We have made analyses of this sample by three different methods, obtaining results obtained by the different methods, omitting, if you wish, the glycerol and car- bonic acid determinations. The results show that the beer contains about 3 per cent served with sodium sulphite and the other with sodium flouride. The beers have been passed through a filter before analysis. I shall be glad to receive your report on the samples, together with such com- ments as you may make on the various methods as to their accuracy, practicability, etc., etc., and will be pleased to give further information upon request. Thanking you for your willingness to aid me in this work, I am, Very truly yours,
[Submitted to collaborators for trial, 1906.]
At present there is a decided lack of uniformity in the methods em- ployed in the analysis of fermented beverages. Food chemists rely for the most part on the provisional methods published in Bulletin No. of the American Chemical Society. It is well known that many brew- ists in the brewing industry use certain other methods, and there is a lack of agreement as to the most suitable and accurate method of analy- sis. In order that we may up-date standard methods as fairly and accurately as possible it will be necessary to determine what are the different methods employed for the determination of the various factors a thorough trial. It is therefore, recommended that in making analyses of the samples the direct method be followed as closely as possible and results expressed in the form indicated.
PREPARATION OF SAMPLE
Bottled beers are always under pressure because of the carbon dioxide present, either as the result of natural fermentation or artificial carbonation. To remove all traces of air from bottled beer it is necessary to heat it until it begins to boil vigorously to hasten the escape of gas ; (B) drive off air by pouring sample from one tank into another tank containing water at a temperature below 18° C. to rise. In pre- paring the sample see that the temperature is not lower than 15° C.
Object: To determine, first, whether method (A) secures a complete separation of air from bottled beer; secondly, whether any loss of alcohol is observed when samples are exposed to open air, in as much (B).
Provisional methods for the analysis of foods, p. 92.
(3)
(Cir. 80) 4
Specific Gravity.
Determine specific gravity of sample after removal of carbon dioxide by means of the pyrometer, by a small, accurately graduated hydrometer, by a Westphal bal- ance, or by a hydrometer and a Westphal balance. The sample is placed in the flask, when using the hydrometer that the liquid is quickly raised to room temperature without allowing it to come into contact with the outside of the flask and before weighing, to prevent condensa- tion of moisture on the outside of the flask.
A. Determine specific gravity at 15°C. B. Determine specific gravity at 20°C.
Calculate apparent extract or balling of beer according to Schulte and Ostertam's table, or according to Schulte's table. Calculate percentage of alcohol in the sample and balancing extract table (if available).
Object: To determine errors introduced by use of different tables.
Alcohol.
A. Measure 100 cc of the liquid at 20°C into a round-bottomed distillation flask, add 50 cc of distilled water, and if the beer is markedly acid, 0.1 or 0.2 gram of pre- cipitated tartaric acid may be added. Add 100 cc of boiling water, and when the liquid has accurately graduated 100 cc stopped flask, care being taken to prevent loss of alcohol during the distillation. This is best accomplished by inserting a two-part rubber stopper in the neck of the flask, one part being fitted over the neck of the flask and the other being slightly fitted to the end of the condenser and through which the small funnel which is used for collecting the distillate passes. The stopper is removed from time to time during the distillation with a small quantity of water, thus saving any alcohol which might otherwise be lost. The receiver is kept at 30°C, and all portions of the receiver, make up to the mark with distilled water, determine the spe- cific gravity of each portion by means of a Westphal balance. The percentage of alcohol by volume or grams per 100 cc from Squibb's alcohol table (p. 121), Bulk unit method (p. 122), or from any other table suitable for this purpose, by dividing the results expressed as grams per 100 cc by the specific gravity of the original sample.
B. When the specific gravity of the extract is known the alcohol content of the beer can be calculated by the following formula: $A = \frac{B_1 - B_2}{B_2}$ where $A$ = alcohol, $B_1$ = specific gravity of beer, $B_2$ = specific gravity of dehydrated beer.
C. Dehydratize 100 cc of beer in a porcelain dish on the water bath, make up to 100 cc and take the specific gravity, $A$, when $A$ = specific gravity of alco- hol, $B_1$ = the specific gravity of beer, and $B_2$ = the specific gravity of dehydrated beer.
D. Calculate the alcohol content from the reading of the Zeiss immersion refrac- tometer as follows:
where $E$ = alcohol content in grams per 100 cc.
E. Calculate from the formula $A = \frac{(B_1 - B_2) \times E}{(B_1 - B_2)}$, when $A$ = reading on immersion refractometer, $B_1$ = reading of beer, and $B_2$ = reading of dehydrated beer, and deter- mine percentage of alcohol from tables in paragraphs C and D.
Object: To determine most accurate method commensurate with rapidity of deter- mination.
EXTRACT AND SPECIFIC GRAVITY OF WORT.
Various methods are employed to obtain these figures, all of which are based on the amount of alcohol produced by the fermentation of a given quantity of sugar.
| Average 25 cc of beer in a tared aluminum dish to constant weight in a water bath at 68°F. |
| Calculate according to formula: $\text{specific gravity} \times (1-\text{extract})$ in which $g$ is the specific gravity of extract obtained in determination of extract and $x$ is percentage extract. |
| Determine value $g$ of extract from tables in paragraph C. |
| Calculate from formula: $\text{specific gravity} \times (1-\text{extract}) \times g$, when $g$ is determined from tables in paragraph C. |
| Determine value $x$ from tables in paragraph C. |
| Determine percentage extract as follows: |
| $\text{Percentage Extract} = \frac{x}{g} \times 100\%$ |
| Check whether or not method (A) gives incorrect results because of dehydration of maltose. |
| Calculate from formula: $\text{specific gravity} \times (1-\text{extract}) \times g$, when $g$ is determined from tables in paragraph C. |
| Determine value $x$ from tables in paragraph C. |
| Determine percentage extract as follows: |
| $\text{Percentage Extract} = \frac{x}{g} \times 100\%$ |
| Check whether or not method (A) gives incorrect results because of dehydration of maltose. |
| Calculate from formula: $\text{specific gravity} \times (1-\text{extract}) \times g$, when $g$ is determined from tables in paragraph C. |
| Determine value $x$ from tables in paragraph C. |
| Determine percentage extract as follows: |
| $\text{Percentage Extract} = \frac{x}{g} \times 100\%$ |
| Check whether or not method (A) gives incorrect results because of dehydration of maltose. |
| Calculate from formula: $\text{specific gravity} \times (1-\text{extract}) \times g$, when $g$ is determined from tables in paragraph C. |
| Determine value $x$ from tables in paragraph C. |
| Determine percentage extract as follows: |
| $\text{Percentage Extract} = \frac{x}{g} \times 100\%$ |
| Check whether or not method (A) gives incorrect results because of dehydration of maltose. |
Calculate from the following formulae. A. O=O+1-E, when Geographical extract ofwort, A=alcohol by weight, and E=extract of dealkoholized beer. B. C=O+E-A, when E=real extract and A=apparent extract.
C. O=E-A, when E=real extract and A=alcohol extract.
D. O=100-(2.0605xA)+100 when A=alcohol and E=extract.
E. G=(g-4.8)/100, specific gravity of the original Wort, at the specific- gravity of the dealkoholized beer, and g=the amount of alcohol destroyed by fermenta- tion obtained from table in Allen's Commercial Organic Analysis, volume 1, page 135.
From extract calculated as in A, B, C, and D, compute from Schulz and Oster- mann's, Bilbo's, and Balling's tables the percentage of sugar in the work.
DEGREE OF FERMENTATION.
Calculate from the formula D=$\frac{200}{B}$ in which D is the degree of fermentation, A the percentage of alcohol by weight, and B the original extract.
TOXIC ACIDS.
A. Heat 90 cc of the sample to incipient boiling with bismuth sublimate 515 and triturate with decinormal sodium hydroxide solution 100 cc. Filter on a paper as indicator. Each cubic centimeter of decinormal alkali employed is equivalent to 0.009 gram of lactic acid. The residue of cupric oxide is filtered off and the clear filtrate is titrated with decinormal sodium hydroxide by 0.045 for the acidity of the original beer and by 0.047 for the lactic acid per 100 cc.
B. Heat 90 cc of each cubic centimeters of decinormal sodium hydroxide required to neu- tralize the acidity of 100 cc of the sample.
VOLATILE ACIDS.
A. The volatile acid as acetic acid is determined by titrating 20 cc of the alcohol distil- lative with decinormal sodium hydroxide solution 100 cc. Filter on a paper as indicator. The number of cubic centimeters of decinormal alkali employed multipli- bed by 0.090 gives the acidity expressed as grams of acetic acid per 100 cc.
B. The volatile acid as lactic acid is determined by titrating 20 cc of the alcohol distillate with decinormal sodium hydroxide solution required to neutralize the acidity of 100 cc of the sample.
Reducing Sugars.
Twenty-five cubic centimeters of the beer free from carbon dioxide are diluted with water to 50 cc and boiled for five minutes according to the solution described on page 49, Bulletin 63, the solution being boiled a minute instead of two minutes. Express the results in terms of maltose equivalent to the copper reduced, according to Table IX, page 144, Bulletin 63.
Dextrins.
A. Employ Sacheim's method for the hydrolysis of starch and determine dex- treins according to Allihn, as follows:
Fifty cubic centimeters of beer and 15 cc of ethyl alcohol are heated in a test tube water bath for two hours. Neutralize with caustic soda and dilute to 250 cc (or 300 cc if necessary) with water. Add 25 cc of a solution containing 2 grams of potassium iodide solution and boil two minutes. Multiply the oxyl of copper found by 6.8 to obtain the amount of dextrins present in grams per liter (or per quart). For example: VIII, p. 113, Bull. 63). The amount of dextrins thus found multiplied by 20 (or 30) gives the amount present in grams per liter (or per quart) in the original beer. From this result subtract that found in the original beer and multiply the remainder by 6.9, the result being the per- centage present in grams per liter (or per quart).
[Cit. 8] 6
B. Dextrin may be determined by the following differential method based on the difference between its optical activity and that of maltose: when Dextrin in grams per 100 cc. A = total rotation in degrees Ventkite in 200 mm tube, and M = percentage of maltose as determined gravimetrically.
DIRECT POLARIZATION. Read the polarization of the original sample in degrees Ventkite in a 200 mm tube. If the beer is turbid clarify by shaking with ammonia reamn.
INVERT POLARIZATION. To 10 cc of the beer in a small flask add 1 cc of concentrated hydrochloric acid, invert by slowly heating to 68° C., cool, polarize in a 200 mm tube and increase the reading one-tenth to allow for dilution.
GLYCEROL. Proceed as directed on page 82, Bulletin 65. The milk of lime is added during evaporation after the caron dioxid has been expelled. It is advisable that the filtrate be cooled before adding the glycerol. The amount of glycerol is equal to that of absolute alcohol and two portions of 75 cc each of absolute ether. If clear, continue as directed, if not clear, it is necessary to treat with above.
Asst.
Evaporate 25 cc of the sample to dryness, ignite all red reams until thoroughly charred, place in a muffle and continue ignition until ash is white. Leaching is rarely necessary.
PHOSPHORIC ACID. Measure out 5 cc of the beer, free from carbon dioxid, into a small beaker. Add 5 cc of an acid solution of sodium acetate and heat to boiling. Run in from a burette, standard phosphoric acid solution, until the color of the solution is changed to that of the beer, when placed on a white plate, colors a drop of potassium ferrocyanide slightly brown. The number of cubic centimeters of the sodium acetate solution necessary to change the color of the beer from light yellow to slightly brown is the amount of phosphoric acid in the beer. If the beer is very dark, employ the official method, gravimetric or volumetric, using the residue obtained in the filtration of the ash.
POTASSIUM DIOXIDE. Evaporate 25 cc of the original beer, to which has been added a small amount of tannin to prevent frothing, and proceed according to the Kjeldahl or Gunning method for the determination of nitrogen, and multiply the result by 6.25.
CARNOS DIOXIDE. Proceed as directed in Bulletin 65, page 95.
PREPARATIVES. Add 3 cc of dilute emulsin acid to the remaining residue after distillation, and shake with a little water. Filter through a filter paper moistened with water. Add supernatant liquid and test for salicylic acid, bencene acid, and meconin in the usual manner. Filter again through a filter paper moistened with water. Perform a nitric acid test before evaporating the remainder to dryness in a small porcelain evaporating dish.
Determine phthaline and sulphuric acid as determined under wine, page 90, Bul- letin 65. Determine ferric iron by the method of Blasse as follows: Thoroughly mix the sample and heat on a small sample to boiling. Add to the boiling liquor 2 cc of a 10% solu- tion centil solution of barium chloride and shake well. If ferric iron is present add to a advantage a centrifuge, wash upon a small filter and dry in the oven. Transfer to a platinum crucible and breaking up the dry precipitate and then adding the filter ash to the crucible.
[Dr. B] 7
Prepare a glass plate (preferably of the thin variety commonly used for lantern- slide covers) as follows: First, thoroughly clean and polish, and coat on one side by carefully dipping while hot in a mixture of equal parts of Carnauba wax and paraffin. Next, place the plate in a crucible containing 50 grams of water, and heat until the wax with a sharp instrument, such as a pointed piece of wood or ivory, which will penetrate the wax without breaking it. When the wax has melted, pour off the drops of concentrated sulphuric acid to the residue in the crucible and cover the cru- cible with the wax plate. Heat slowly until the wax is completely melted. Place in close contact with the top or unwaxed surface of the plate a cooling device consisting of a glass tube covered with a thin layer of paraffin. The temperature of this tube must be kept constant, continually through the tube. The whole arrangement is lowered so that the crud- ed wax is in contact with the bottom of the tube. Remove the glass plate and indicate the location of the distinguishing mark on the unwaxed surface of the plate where it was exposed to the heat. This mark will be wax by heat or a jet of steam and thoroughly clean the glass with a soft cloth. A distinct etching will be apparent on the glass where it was exposed if a fluorid is present.
ANALYTICAL RESULTS.
The accompanying tables give the results obtained by the different analysts on the two samples sent out. The various factors determined are reported in milli.
| Calculate from formula: $\text{specific gravity} \times (1-\text{extract}) \times g$, when $g$ is determined from tables in paragraph C. |
| Determine value $x$ from tables in paragraph C. |
| Determine percentage extract as follows: |
| Table 1.-Analysed results obtained by cooperating chemists on referee's sample of beer | |||||||
| [Results calculated to grams per 100 cc except where otherwise stated.] | |||||||
| Determinations. | W. M. | Francis | Max | Finnis | R. Hesl | B. Hesl | Edelh. |
| 1. Specific gravity at 15°C. | Cross. | 1.016 | 1.011 | 1.030 | 1.013 | 1.019 | 1.019 |
| 2. Alcoholic by distillation (percent by weight). | 95.7 | 95.7 | 95.7 | 95.7 | 95.7 | 95.7 | |
| 3. Acid by titration (percent by weight). | 0.88 | 0.88 | 0.88 | 0.88 | 0.88 | 0.88 | |
| 4. D.: by the immersion refractometer. | 2.87 | 2.87 | 2.87 | 2.87 | 2.87 | 2.87 | |
| 5. D.: by immersion polarimeter. | 2.87 | 2.87 | 2.87 | 2.87 | 2.87 | 2.87 | |
| 6. D.: by immersion spectrophotometer. | |||||||
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| TABLE 1.—Analitical results obtained by cooperating chemists or referee's sample of beer No. 1a—Continued. | |||||||||||||||||||||||||||||||||||||||||||||
| Determinations. | O. R. Markovskii W. M. Troup R. K. Thompson A. Laviel Norita Tsutsumi H. H. Hinton |
G. B. Thompson J. H. Hinton |
|||||||||||||||||||||||||||||||||||||||||||
| 1. Specific gravity at 10°C (... | 1.032 1.038 1.038 1.038 1.038 1.038 |
1.039 1.039 1.039 1.039 1.039 1.039 |
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| 2. Alcoholic A: by distillation (per cent by weight) | 5.85 5.85 5.85 5.85 5.85 5.85 |
5.90 5.90 5.90 5.90 5.90 5.90 |
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| 3. Alcoholic B: by distillation (per cent by weight) | 7.44 7.44 7.44 7.44 7.44 7.44 |
7.49 7.49 7.49 7.49 7.49 7.49 |
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| 4. D: by the immersion refractometer | |||||||||||||||||||||||||||||||||||||||||||||
| 5. Extinct: by direct weighing | |||||||||||||||||||||||||||||||||||||||||||||
| 6. E: by g.p.m.(=A) (1-6) | 6.74 6.74 6.74 6.74 |
6.79 6.79 6.79 6.79 |
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| 7. F: by immersion refractometer | |||||||||||||||||||||||||||||||||||||||||||||
| 8. G: by g.p.m.(=A) (1-8) | |||||||||||||||||||||||||||||||||||||||||||||
| 9. H: by direct weighing | |||||||||||||||||||||||||||||||||||||||||||||
| 10. | Extinct: by direct weighing | F: by immersion refractometer | G: by g.p.m.(=A) (1-8) | H: by g.p.m.(=A) (1-9) | I: by immersion refractometer | J: by g.p.m.(=A) (1-10) | K: by direct weighing | L: by immersion refractometer | M: by g.p.m.(=A) (1-10) | N: by direct weighing | O: by immersion refractometer | P: by g.p.m.(=A) (1-10) | Q: by direct weighing | R: by immersion refractometer | S: by g.p.m.(=A) (1-10) | T: by direct weighing | U: by immersion refractometer | V: by g.p.m.(=A) (1-10) | W: by direct weighing | X: by immersion refractometer | Y: by g.p.m.(=A) (1-10) | Z: by direct weighing | |||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No. |
| Determination. |
| W.M. |
| Max. |
| Min. |
| Franks & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Brylak & Co., Ltd. |
| Determination: | O.R. Markskii Troup | R.K. Kemp | A.Laviel | Norita | Tsutsumi | H.H. | Hinton | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co. | Brylak | & Co.
K. v. BARTH-BREITENFELD Proposition of the samples. The two methods—shaking and pouring from one beaker into the other—are equally suitable for the determination of the specific gravity, being in the result, the specific gravity being the same according to both methods. The amount of alcohol, after shaking, is 0.0001 less than that obtained by pouring from one beaker into the other. Both methods, furthermore, secure a complete separation of the carbonic acid gas from the pyruvate solution. Determination of specific gravity by means of three determinations of specific gravity at different temperatures. The temperature of the pyruvate solution is lowered by 15° C., 17.5° C., and 20° C., respectively. In each case, three different water weights of the pyruvate, corresponding to the tempera- tures mentioned, are determined. For the purpose of comparison with the other determinations, the specific gravity increases only slightly with the lowering of the tempera- ture. The specific gravity is determined to 0.0007 in the specific gravity of alcohol. 0.0003 in the specific gravity of extract. 0.0001 in the specific gravity of beer itself. As the difference between these values never higher than indicated above, they can practically be substituted for one another. For this reason we would be in favor of the employment of the temperature of 20° C. as a normal temperature of the determination. The tables of Eilson and Balling give almost the same results with respect to the amount of alcohol in beer as those given by us. The difference between them is very high. Estimation of alcohol. We determined the alcohol by the distillation method strictly according to your suggestions, but having no Zeiss immersion refractometer at our disposal, we had to use a simple refractometer. We determined first by this instrument, and by the distillation method, with regard to the amount of alcohol or real extract, never differed more than 0.1 per cent. Between the alcohol values obtained by both methods there was always a difference of 0.1 per cent. Determination of extract.—No considerable difference between the methods of estimation of extract is found when we compare our results with those of Eilson and Balling. The first method, however, takes too long time to come into practical use. For this reason we have adopted a new method which we consider superior to either of the two previously described methods. We prefer the red phenolphthalein solution, prepared by adding 12 drops of the ordinary alcoholic solution to 1 gram of potassium hydroxide (or sodium hydroxide) and then point of titration is determined by transferring one drop of the solution to a beaker containing a little drop of beer as soon as the red color of the indi- cator does not appear. In answer to an inquiry, K. v. BARTH-BREITENFELD submitted the fol- lowing method for the determination of dextrin by means of the polarisation-difference: Twenty-five cubic centimeters of beer are clarified with 5 c. of animal cream and filtered through a filter paper (filter paper No. 6). The filtrate is diluted with water and filtered through a filter paper (filter paper No. 8), which is placed in a tube (the tube is filled up to its top with water). The filtrate is polarized in the 300 mm tube, using the Solek Venturke apparatus. The reading in degrees is multiplied by 5 c. amount of dilution, and from the total extinction thus obtained subtracted that obtained from a similar quantity of beer, determined by the gravimetric-analytical method. One gram of maltose contains approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if one gram maltose is found must contain approximately 1 gram dextrin; therefore, if onegramdextre Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Therefore, Inasmuch as in fermented normal beer the reducing sugar content varies considerably with different kinds and ages of beer and also with different conditions under which it has been brewed it appears impossible to deduce from an abnormally low amount of dextrin obtained by the polarization method an abnormal amount of reducing sugar contained in such beer. As large quantities of dextrose (glucose and fructose) have been used. As far as we know there has not been any previous attempt made in connection with the examination of beer we have found that the results obtained in this way corre- spond very well with those obtained by means of gravimetric analysis. In our laboratory almost all the beers are examined according to both methods which gives us an excellent control of our work and its accuracy. [Note] 11 MAX HENRIC **Fluoride.—We have found that when no fluoride has been added to a beer, 300 cc of each beer, when tested for fluorine by the adopted method, will show not any appreciable etching on glass. We also found that barley in its natural condition did not contain more than 0.005 per cent of fluorine. It is evident, therefore, that fluorine is present in a beer to such an extent in 300 cc, that it can be made to etch glass; it is, in our opinion, safe to assume that the average beer contains about 0.005 per cent of fluorine. This means that the proportion of one pound to 150 barrels, or approximately 6,005 per cent. Of this flourid two-thirds or 0.006 per cent is fluorine, that is, 6,005 times 0.006 = 36. The coating on the glass is made of a mixture of paraffin and wax. The tested flasks are filled with water and the glass is immersed in the solution for several hours. The coated ice is placed on top of this glass. The markings in the wax are not to be detected by the naked eye. A slight etching not visible in the reflected light, but visible when viewing upon the glass through a microscope, was obtained when absolutely pure sulphuric acid was employed, and even a slight etching visible in the reflected light without breathing upon the glass does not appear after a few minutes' exposure to air. Sulphuric acid is thus a very useful reagent for testing the presence of a normal constituent of many waters and brewing materials. Sulphuric acid is used in brewing as a clarifier. It was introduced in ordinary German and Austrian beers from 3 to 7 mg of sulphuric acid per liter; in French beers from 1 to 2 mg of sulphuric acid per liter; in English beers from 1 to 2 mg of sulphuric acid per liter and by action of yeast (according to Graef) appreciably more, say 3 mg per liter. It has been stated that 1 mg of sulphuric acid may be found in beer to which no sulphite has been added. We have, in our laboratory, found 13 mg of sulphuric acid in beers free from sul- phite. In some cases we have found as much as 28 mg of sulphuric acid per liter, up to 60 barrels, or about 5 mg of sulphuric acid per liter, it is safe to say that no sulphite has been added. In other cases we have found as little as 1 mg of sulphuric acid added. Since this quantity will not preserve, and the addition of a corresponding amount of sulphite would therefore be barren of result, any amount up to this limit should be allowable. COMMENTS BY ASSOCIATE REFEREE. The results as compiled show two things clearly: They express the value of standard methods for analytical work. The ten analysts working upon a sample of beer which, although pasteurized, was still subject to change in composition during the weeks or months that elapsed between the time of sampling and analysis gave results fairly concordant results, the personal error usually being so small as to be negligible. On the other hand, the determination of the several factors by which the specific gravity of the sample is affected by the composi- tion of the sample, the same result was obtained when the carbon dioxid was removed by shaking, as when the beer was poured from one beaker to another without shaking. The specific gravity of the beer is practically the same at 15°C. as at 20°C. when compared with water at the same temperature, there being only 0.005 difference in the average. The various methods employed for the determination of alcohol give fairly concordant results. The use of the Zeiss immersion refrac- tometer gives results practically identical with those obtained by taking readings on immersion refractometer, R1 reading of beer R2 reading Zus. für das gesammte Brauwesen, 1904, p.: 617. [Cit., 8] 12 of dealcoholized beer, the value for A being determined from alcohol table accompanying the instrument. The extreme deviations gave fairly concordant results. The use of the immersion refractometer for this determination also gives accurate results. The dehydration of maltose in the estimation of extract by the immersion method is not so exact as that of the actual error. The determinations of extract and specific gravity of wort by different analysts agree very well, the greatest error being that introduced by the use of the immersion refractometer. A, B, C, and E offer no advantage over the more simple formula O=3A+2B. This formula is considered by brewers to express very nearly what takes place in practice. Kremer made a careful study of the different formulas, employing them in eight experimental brews of different character. He states that although the formula O=2A+2B is not correct from a scientific point of view, yet it is used by brewers, since it does not require to produce one part of alcohol, yet in practice it is the most accurate. The specific gravity of the wort varies greatly according to the temperature at which it is taken, but the results obtained closely, Ellson's tables giving somewhat higher results. The degree of fermentation calculated according to the formula $D = \frac{A}{2} - \frac{B}{3}$ gives entirely satisfactory results. The determination of total acids is not entirely satisfactory, since the end point with neutral litmus paper is obscure. The use of phenolphthalein is suggested as a preliminary test, in which a drop of 0.1 per cent sodium hydroxide is added to a drop of phenolphthalein on a porcelain plate; in this way a sharp end point is readily obtainable. The use of phenolphthalein does not give concordant results. The error in the case of both total and volatile acids may be due to the age of the sample when analysis was made. No correction is necessary in regard to reducing sugars, as the results are entirely satisfactory. The same is true of the dextrin determinations. Good results are obtained by the use of the formula D=$\frac{A}{2} - \frac{(M \times X)}{3}$ when D = dextrin in grams per 100 cc.; A, total rotation in degrees Ventzke in 200 mm tube, and M, percentage of malose as determined gravimetrically. This formula is based upon the difference of optical activity of dextrin and maltose. It has been found that this difference is a very determining factor which is otherwise somewhat difficult to obtain. It is impossible to explain the differences in polarization obtained by the various methods except on the assumption that the various instruments were not in accordance. The results of ash estimation are very close. The determination of specific gravity by volumetrically and gravimetrically, agree very well. The volumetric method, with standard uranium solution, is to be preferred on account of the rapidity with which it may be used. e Letters on Brewing, vol. 1, p. 9; vol. 1, No. 2, p. 19. [cn. iii] 13 All the analyst reporting on fluorids had no difficulty in detecting its presence in sample No. 1. The sulphurous acid estimation in the same sample also gave satisfactory results. CONCLUSIONS AND RECOMMENDATIONS. It is greatly to be regretted that there are in use several tables for the determination of alcohol and extract, and that the estimations are not made with due regard to the temperature at which they are made. The investiga- tions undertaken have not been arranged so as to show which of the various tables is the most reliable, nor what temperature is the most suitable for each table. It is evident that the adoption of standard tables would be necessary of the adoption of standard tables and a standard tempera- ture. The brewing schools all employ the Balling extract table; Bul- letin 67 gives both the Balling and the standard table, but it is not possible to say which of these two tables is to be preferred above the other it should be recog- nized as the standard table. In 1903 President Davidson, of the asso- ciation of official agricultural chemists, in his annual address recom- mended that the Balling table should be adopted as the standard table, and that it should be changed to one more nearly in accordance with room temperature. In 1904 the referee on beer repeated the recommendation and called attention to the fact that the Balling table was based upon a stand- ard temperature of 20° C., seems to be growing rapidly in this coun- try. It is being employed by the Bureau of Standards and many food chemists, but it has not been adopted by any official laboratory at standard temperature. The referee therefore suggests that a committee be appointed by this association for the purpose of revising the alcoholo- metric tables now given in Bulletin 65, that they may be adopted for use by all official laboratories. It is further recommended that the following methods of beer analysis be adopted as official for this association. PROPOSED OFFICIAL METHODS OF BEER ANALYSIS.
(A) DISTILLATION METHOD. 14 with glass beads kept moist with water. Wash down the beads several times during the distillation with a small quantity of water, thus saving any alcohol that may have been lost by evaporation. When the distillate has reached 20 C. make up to the mark with distilled water, determine the specific gravity at directed under specific gravity and obtain the corresponding percentage of alcohol by volume. The specific gravity of the original solution is determined by the same process. Convert the results expressed as grams per 100 cc to per cent by weight by dividing the results expressed as grams per 100 cc by the specific gravity of the original solution. (a) Optional Method Calculate the alcohol content from the reading of the Zeiss immersion refractometer on the distillate, reporting the results at 20 C. (A) Evaporate 25 cc of the beer in a tared platinum dish to constant weight in water at oven at 80 C. (b) Optional method no. 1. Calculate according to formula $a = p + (1 - a)$, in which $p$ is the specific gravity of the beer, $a$ is the specific gravity of the distillate obtained in the determination of alcohol, and determine value of $a$ from table of extract of beer-wort tables. (c) Optional method no. 2. Take immersion refractometer reading of deacidulated beer and calculate extract in grams per 100 cc.
Calculate percentage of extract from the formula $O = \frac{A}{B} - E$, when $O$ is original extract of wort, $A$ is original extract of deacidulated beer. From extract calculated as above compute from standard table the specific gravity of the wort.
Calculate from the formula $D = \frac{20A}{B}$ in which $D$ is the degree of fermentation $A =$ percentage of alcohol by weight, and $B$ is the original extract.
(A) Heat 20 cc of the sample to boiling to liberate carbon dioxide, and, titrate with decinormal sodium hydroxide, using neutral litmus as indicator. Each cubic centimeter of decinormal alkali employed is equivalent to 0.009 grams of lactic acid, and each gram of lactic acid requires 0.043 cubic centimeters of decinormal alkali. The titrating 20 cc of beer is multiplied by 0.043 for the acidity expressed as grams of lactic acid per 100 cc. (B) Calculate the cubic centimeters of decinormal sodium hydroxide required to neutralize the acidity of 100 cc of beer.
(A) The volatile acid, as acetic acid, is determined by titrating 20 cc of the alcoholic dilutate with decinormal sodium hydroxide solution, using phenolphthalein as indicator. Each cubic centimeter of decinormal alkali employed is equivalent to 0.009 grams of acetic acid, and each gram of acetic acid requires 0.043 cubic centimeters of decinormal alkali. The titrating 20 cc of beer is multiplied by 0.043 for the acidity expressed as grams of acetic acid per 100 cc. (B) Calculate the cubic centimeters of decinormal sodium hydroxide required to neutralize the acidity of 100 cc of beer.
Twenty-five cc of beer, free from carbon dioxide, is diluted with water to 100 cc. The reducing sugar is determined in 25 cc of this solution, as directed on page 49 of Bulletin No. 66, or in accordance with Table IX, page 144, Bulletin No. 66. [Note: This section appears to be incomplete or cut off.] 14 15 10. Dextrin. (a) SACHAN-ALLIUS method. Employ Sachan's method for the hydrolysis of starch and determine dextrine according to Allius, as follows: Fifty cc of beer and 18 cc of hydrochloric acid, specific gravity 1.125, are diluted to 200 cc with water and boiled for half an hour. Cool, dilute to 200 cc, and boil for two hours. Neutralize with caustic soda and dilute to 250 cc, or 300 cc in a beaker with hot water, and boil for one hour. Cool, dilute to 250 cc, and boil for one-half hour. Multiply the exfol of beer found by 8 to obtain the corresponding amount of dextrine and reduce this result to the original volume of beer by dividing by 8. The amount of dextrine thus found multiplied by 7 (or 24 if diluted to 300 cc) and divided by the specific gravity equals the dextrine in the original beer. From this result subtract the dextrine in the original maltose solution, which is equal to the remainder by 0.9, the result being the percentage of dextrin in the original wort. (b) Optional Method. Dextrin may be determined by the following method, based on the difference between its optical activity and that of maltose. When dextrin is present in a solution of maltose, in grams per 100 cc, A = total rotation in degrees in a tube of 200 mm and tube, and $x$ = percentage of maltose as determined gravimetrically.
Read the polarization of the original sample in degrees Ventszke in a 200 mm tube. If the beer is turbid, clarify by dialking with alumina cream.
To 10 cc of the beer in a small flask add 1 cc of concentrated hydrochloric acid, invert by slowly heating to boiling, and polarize in a 200 mm tube, and increase the reading one-tenth to allow for dilution.
Proceed as directed on page 62, Bulletin 65. The milk of lime is added during evaporation after the carbon dioxide has been expelled. It is advisable that the filter cake be washed with water before adding glycerol. Add 1 part glycerol to absolute alcohol and 2 portions of $\frac{7}{5}$ each of ethyl ether. If clear, continue as directed. If not clear, it is necessary to treat again as below.
Evaporate 25 cc of the sample to dryness, ignite at low redness until thoroughly charred, place in a muffle and continue the ignition until ash is white. Leaching is rarely necessary.
Measure out 50 cc of the original sample and add hydrochloric acid into a small beaker. Add 5 cc of an acid solution of sodium acetate and heat to boiling. Run in with a burette, standard ammonium solution, 0.5 cc at a time, testing each time until a drop of the solution turns blue when added to a drop of phenolphthalein indicator. The number of cubic centimeters of the urammonium-acetate solution necessary, multiplied by $\frac{7}{5}$ gives the phosphoric acid in the beer. If the beer is very dark, employ the official gravimetric or volumetric method, using the residue obtained in the determination of the ash.
Evaporate 25 cc of the original beer, to which has been added a small amount of tannin to prevent frothing, not more than $\frac{1}{4}$ gram per liter. Kjeldahl's or Gunning method for the determination of nitrogen will give results nearly equal to those obtained by 6.2%. [Cit. BI] 16 17. GARBON DIOXIDE. See Bulletin 65, p. 95, 1902. 18. PREPARATIVES. Add 5 cc of dilute sulphuric acid to 100 cc of beer from which the alcohol has been driven off, and shake out with an equal volume of a mixture of ether and ben- zene. Four cc of the supernatant liquor are now sublimed in a test tube, and another four cc are added to the same tube. It is well to use 2 or 3 cc of the liquid in a test tube for the salicylic acid test before expelling the remainder to dryness in a small porcelain evaporating dish. (a) SULFURIC AND SULPHURIC ACIDS. Place 25 cc of a solution of potassium hydrorhate containing 56 grams per liter in a flask of approximately 200 cc capacity. Introduce 50 cc of beer by means of a pipette, and heat on a water bath at about 60° C. for 15 minutes, shaking every five minutes with occasional agitation. Add 10 cc of I-3 sulphuric acid and a few cubic centimeters of starch solution, and titrate the mixture with a fifth-normal iodin solution until the blue color just disappears. The time required for this opera- tion until the blue color will last several minutes. One cubic centimeter of fifthnor- mal iodine solution corresponds to 0.0001 gram of alcohol. The total amount of the four cubic centimeters of the iodin solution employed, multiplied by 0.00128, gives the weight of the total sulphuric acid expressed in grams per 150 cc. (b) FLORIDE (METHOD OF BLEACH). Thoroughly mix the sample and heat 150 cc to boiling. Add to the boiling liquid 5 cc of a 10 per cent solution of sodium hydroxide and 10 cc of Coffee; the precipitate is a com- pact mass, using to advantage a centrifuge, wash upon a small filter and dry in the oven. To this residue add 25 cc of water and heat on a water bath at about 60° C., adding the filter ash to crucible. Prepare a glass plate (preferably of the thin variety) composed of two pieces of glass cemented together with a little paraffin wax (paraf- fin wax is used because it is more easily removed than other waxes). Place one piece of glass on top and coat on one side by carefully dipping while hot in a mixture of equal parts of Charniaux wax and paraffin. Near the middle of the plate make a small cross or other definite pattern with a sharp knife or other sharp instrument. This pattern may be wood or ivory, which will remove the wax and expose the glass without scratching the surface. Place the crucible on top of this plate so that it rests on the pattern made with wood or ivory, which will remove the wax and expose the glass without scratching the surface. Cover the crucible with a glass cover, having a hole cut in its center large enough to admit the crucible and cover with the waxed plate, having the mark nearly over the center and making sure that no air can enter through any crack in the cover. Heat gently over a low flame so that the wax does not melt. Heat the bottom of the crucible gently over a low flame or on an electric stove for an hour. Remove the glass cover and allow to cool; then remove the waxed plate from under it. Remove any remaining wax from under the plate by means of gummed strips of paper, melt off the wax by heat or a jet of steam and thoroughly wash out all traces of it; if any faint etching will be apparent on the glass where it was exposed if a funnel be present. (Cfr. III) O [API_EMPTY_RESPONSE] RETURN MAIN CIRCULATION TO ALL BOOKS ARE SUBJECT TO RECALL RENEW BOOKS BY CALLING 642-3405 DUE AS STAMPED BELOW FEB 01 1996 RECEIVED NOV 02 1995 CIRCULATION DEPT. UNIVERSITY OF CALIFORNIA, BERKELEY BERKELEY, CA 94720 FORM NO. DD6 U.C. BERKELEY LIBRARIES
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