t
T H E JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
478
small, yellow. The latex. while similar t o t h a t of L. Caiiadensis. is not as abundant. L. Scariola lacks the strong characteristic odor noticed in its relative. Found abundantly throughout Eastern United States flourishing under the most adverse conditions. Although regarded as an unimportant weed by Darlington i n his “American Weeds and Useful Plants,” published in 1847, it has spread through the greater part of the pluvial portion of the United States. and is now regarded as one of our most troublesome weeds. It thrives upon soils regardless of their lack of plant food or moisture. This plant is often mistaken for “Sowthistle ’’ (Sonchus), commonly known as “ Hungarian Lettuce.” The latexes of these plants contain rubber, a waxy acetone soluble body [resin(?)], and a substance of acid nature soluble in weak alkalies, and of intensely bitter. taste. COMPOSITION OF
... . . . . . . .
LATUCALATEXES Lactuca Lactuca canadensis scwiola Per cent Per cent
Resin(?). . . . .. ... Rubber.. . . . . . . . . . . . . . .
11.42 2.19
12.85 1.58
Rubber.-The quality of the rubber obtained from both these species is exceptionally good, being very firm and strong. There seems to be very little difference in quality between the two products. I n quantity the latex of the native species is the richer. I n preparing these rubbers, i t was necessary, on account of the presence of the acid-like substance, t o heat the crude acetone precipitate with boiling alcoholic potash or to precipitate directly the benzole rubber solutioh with this reagent, and then purify the resin extract. Resin.-The purified acetone extract is a brittle, light brown substance of waxy feel, and slight bitter taste. Soluble in acetone, alcohol, glacial acetic acid and benzole. Orgavtic Acid( ?)-Insoluble in hot water; insoluble in acetone; soluble in weak alkalies to a fine cherryred solution. Intensely bitter taste ; characteristic plant odor. Lactuca Canadensis contains, according t o Maisch,~ a bitter principle which has been pronounced equal to lactucariurn of German origin. Lactucarium is a recognized drug of the pharmacopoeia, classified as a sedative and diuretic, and known as “lettuce opium” on account of its medicinal action which is due t o lactucin or lactzicic acid. Lactucarium is an imported drug originating in Scotland, Rhenish Prussia. and France. I n Scotland its production is an industry. The combined production of lactucarium and rubber may be a possible industry for the North Temperate Zone AKRON, OHIO
A COMPARATIVE STUDY OF THE COMPOSITION OF HOPS GROWN IN DIFFERENT PARTS OF THE WORLDa By H. V. TARTAR AND B. PILKINCTON
In the markets, hops grown in different parts of the world sell for different prices. In this country
* A . J. P.,1869, p. 145. Paper presented at the Annual Meeting of the American Chemical Society, Milwaukee, March, 1913. 2
Vol. 5 , No. 6
New York hops usually sell a t a higher figure than Pacific Coast hops. I n the autumn of 1 9 1 1 , while Oregon hops were selling for 40 to 45 cents a pound, New York hops sold for 5 5 cents a pound and the Saaz hops imported from Europe sold for more than $1.00 a pound. Upon observing such a condition as this, one is naturally led t o ask: Why all this difference in price? Is the composition of hops from one locality so widely different from those of another locality as to make them have so much greater value for brewing purposes? Does the climatic conditions of different countries so vastly affect the actual value of hops? The writers tried putting such questions as these to men who had been long engaged in hop growing and buying. I n response, various and often very conflicting answers were received. The answers obtained from different brewers were quite as much a t variance. I n fact, out of all the answers received to our questions, there were not two that exactly agreed. The data obtained would not permit of any definite conclusion, except that people of long experience in the commercial valuation of hops were widely a t variance, and no doubt, in many instances, governed by prejudice. Consequently, in the autumn of 1911, a chemical study of hops from various localities was begun, the object of the study being t o ascertain what differences there are in the composition of hops grown in different parts of the world. The samples of Oregon were selected by chemists from this laboratory and were representative. Doctor Alfred C. Chapman, a British chemist who has carried on extensive hop investigations, selected the English samples. We are indebted t o Mr. Paul Weidner, Sr., an experienced and reliable hop dealer of Detroit, Michigan, far the samples of Washington (state) hops and also the two samples of Saaz hops. Mr. E. Clemens Horst, who grows hops extensively in the state of California, secured the samples of Californians. At the suggestion of the Director of the New York Agricultural Experiment Station (at Geneva, N. Y.), Mr. E. J . Conger, of Waterville, New York, was employud to select the samples from t h a t state. Doctcr A. J. Lehedler, of the Pabst Brewing Company, a t Milwaukee, selected the samples of Wisconsins. All the samples were as representative as could be secured in this way from the different locnlitiw from which they were chosen. The samples were taken soon after the hop harvest and were analyLed within a few weeks aFter reaching the laboratory. Meanwhile, thvy were carefully stored in a cold, dry room t o prevent any mnrked changes in composition from taking place. Because of the nature of the literature on the chemical composition of the hop. i t may be vel1 to state, by way of explanation, that investigators are agreed that the principal constitcents of the hop cone are: a volatile oil, a hard resin commonly designated as the “gamma” resin, two :oft bitter :esins designated as the “alpha” and ‘‘betii’’ resins, a wax, arid a tannin. The constituents designated as resins are not true resins,
June, 1913
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I X E E R I N G CHEiV’ISTRY
but owing to the common use of the term in this connection, the authors have continued its use. The recent work of SillerI indicates t h a t the gamma resin may be composed of two different substances, but the work is hardly conclusive and we believe needs further study. Recent investigations show t h a t the major part of the actual brewing value of hops lies in the content of soft bitter resins. These substances give to the hop its -preservative and flavoring qualities. The volatile oil and tannin may be of minor value in the commercial uses of the hop. I t is quite generally conceded by the different authorities on the subject t h a t the hard resin and wax possess no value so far as the brewing industry is concerned. In the analytical work, the methods which have been worked out in this laboratory” for the determination of the hard, total, and soft (bitter) resins were employed. The separation of the alpha and beta bitter resins was carried out according t o the method
It will be noted that there is a somewhat wide variation in the amount of moisture in the samples. This is perhaps due to the fact that some of the samples were stored in a dry storeroom a little longer than others and dried out somewhat. The writers have found that the amount of moisture in hops does not vary widely and is usually between 6 and I O per cent. The results show t h a t the genuine Saaz hops have no seeds. The amount of seeds in the New Yorks and Wisconsins is not large. I n the case of the English samples the range is from 6.15 t o 12.50 per cent. The samples of Pacific Coast hops contained from 4.86 t o 18.35 per cent. Examinations made in this laboratory of samples of Oregon hops, other than>he samples here reported, show a high percentage of seeds. The amount of extraneous matter found gives a n indication of the care taken in picking the hops in different localities. For example, the Saaz samples were free leaves and stems and the English and Wis-
COMPOSITIONOF HOPS GROWNIN DIFFERENTPARTSOF THE WORLD. PERCENTAGES Total soft Hard Moisbitter gamma Total Beta Alpha WaX Tannin resin resin resin resin ture resin
NAMEOF LOCALITY 3.90 Washington (state). New York No. 1 ............... 2 . 4 0 New York No. 2 . . 3.10 New York No. 3 . . ............. 4 . 1 0 New York No. 4 . . ............. 4 . 9 0
........... ..
California No. 2 . . . . . . . . . . . . . . . 3 . 7 0 California No. 3 . . . . . . . . . . . . . . . 5 . 1 0 California No. 4 . . . . . . 5.70
.....
England (Sussex). England (Farnham). . . . . . . . . . . . 4 , 8 0 Oregon No. 2
.............
Oregon No. 4 . . . . . . . . . . . . . . . . . 6 80 Saaz No 1 6 50 Saaz No. 2.. 8.20
.......... ..................
17.55 14.20 13.89 18.51 16.06 17.31 17.10 12.29 15.76 15.82 12.21 11.70 12.70 12.34 18 35 18.12 18.57 19.80 16.25 13.75
15.64 12.81 12.59 16.61 14,20 15.08 15.72 10.79 14.10 8.68 9.97 10.51 10.35 11.06 16.75 16.54 16.57 17.62 14.19 12.60
1.91 1.39 1.30 1.90 1.86 2.23 1.38 2.32 1.66 7.14 2.24 1.19 2.35 1.28 1.60 1.58 2.00 2.18 2.06 1.15
outlined by Siller.3 Chapman’s4 method was used for the determination of tannin Moisture was estimated by drying in vacuo over sulfuric acid at room temperature. The determination of wax was made incident t o securing the solutions necessary to the determination of the total resins. The extract obtained by extracting the hops with ether was taken up with alcohol, and the wax. insoluble in this solvent, was collected on a tared filter washed with alcohol. dried a t room temperature and weighed. Owing to the exceedingly small amount of volatile nil presmt and the consequent difficulty of making a quantitative determination, the estimation of this constituent was omitted. Determinations of the amounts of seeds and extraneous matter (leaves, stems, etc.’, were also made. Other analyses (except in the case of the Wisconsins) than those reported in the following table have been made, but the general relationships were about the same as in those here recorded and the analytical data are omitted to economize space. Zta. Untersuch. Nahruno-Genuss., 18. 241. THISJOURNAL, 4, 209 (1912). 3 LOC. Clt.
J . Inst. Brew., 13, 646 (1907); 15, 360 (1909).
479
14.85 8.92 8.91 13.81 11.01 11.61 11.65 4.43 9.14 7.93 6.60 7.30 6.05 6.65 10.56 10.36 8.27 9.48 7.20 7.62
0.79 3.89 3.68 2 .SO 3.19 3.92 4.07 5.54 4.96 0.75 3.37 3.21 4.27 4.41 6.19 6.11 8.30 8.14 6.99 4.98
0.37 0.60 0.68 0.71 0.72 0.48 0.52 0.40 0.33
2.02 1.30 1.95 3.06 2.73 2.04 2.52 1.52 1.40 not determined 2 . 4 0 0.50 1.16 0.47 1.58 0.44 2.22 1.66 0.39 0.33 1.67 0.37 2.64 0.37 2.97 0.41 1.99 0.54 not determined 0.45 not determined
.
Seeds
Leaves and stems
4.86 2.50 2.34 0.06 1.84 14.75 18.35 8.38 7.55 0.22 9.55 7.90 6.15 12 . 5 0 11.50 11.17 13.56 1.42
5 .o 15.4 15 .o 9.0 18.6 3.8 8.8 9.0 13.5 1.8 1.2 0.9 0.6
uone none
none none
0.0
7.6 7.2 6.2 4.0
consin samples contained less than 2 per cent. These results indicate that great care is taken in gathering the hops in these localities. I n the New Yorks the percentage of extraneous matter varies from 9 to 18.6 per cent. Evidently these hops had been picked in a very careless manner, since some of them contain more leaves and stems than any other samples the writers have examined. The amount of extraneous matter in the Pacific Coast hops ranges from 3.8 to 13.5 per cent. Other examinations made of our Coast hops show wide differences in the amount of foreign matter in the product put out by different growers. The results show that the percentage of leaves and stems is a matter t h a t should receive much consideration in the correct valuation of hops for commercial use. The content of soft bitter resins in the different samples is perhaps the most interesting of the results obtained, because of the great importance of these constituents. The Saaz, which demand such high prices in our markets, are somewhat lower in content of soft bitter resins than either the New York or Pacific Coast hops. The English samples are some-
480
T H E J O U R N A L OF IiVD U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
what lower in soft resin content than the Saaz samples. The Pacific Coasts, as a rule, have a higher percentage of soft resins than the New Yorks, English or Saaz. These results, with others which have been obtained throughout a series of investigations, lead the writers to believe that the Oregon grown hops have as great, if not greater, average content of soft bitter resins than hops grown in any other part of the world. The sample of Wisconsins contained a high percentage of hard worthless resin. Owing to the fact that oply a very small amount of hops is grown in that state. it has not been possible to secure further samples t o find out if this is generally true of the hops from that locality. The variation in the amount of wax is from 0.33 t o 0.71 per cent. The content of tannin seems t o vary widely, considering the amount present, even in samples from the same locality. These variations in the amounts of tannin and wax, however, are perhaps of little significance, since the wax is of no value and the tannin is perhaps of only minor value. On the whole, the results indicate that hops which are now holding a superior position in our markets are in reality inferior in composition compared with other hops which are rated lower commercially: this is especially true of hops from certain localities in Europe. CHEMICALLABORATORY AGRICULTURAL EXPERIMENT STATION CORVALLIS, OREGON
A CRITlCAL STUDY OF THE FACTORS CAUSING THE MODIFIED BABCOCK TO RUN LOWER ON ICE CREAM THAN THE ROESE-GOTTLIEB METHOD By J. 0. HALVERSON Received February 26, 1913
PuRPosE.-The need of a rapid and simple volumetric method for the determination of fat in sweetened dairy products has been shown.1 This is necessary for a rapid, more accurate fat control test for the ice cream trade, which has now grown t o a n extensive industry, and is also needed because of the more rigid enforcement of the pure food laws. Such a n ice cream test is needed by the food control chemist as well a s the manufacturer. It is the purpose of this investigation to give this proposed test an exhaustive and critical study t o determine what fat ldsses occur and where they occur, thus causing this method to run lower than the RoeseGottlieb. This would ais0 give more data on the manipulation and factors affecting the accuracy of this test. I t has been shown' that the Modified Babcock method averages 0.6 low with the Roese-Gottlieb method. The variation in the fat readings due t o temperature and meniscus have been eliminated by using the standard temperature 130' to 140OF. and by the use of glymol. The low per cent reading of the fat column is chiefly due to the following factors which will be considered. FACTORS C A U S I N G L O W F A T R E A D I N G I. 1
Residual fat in bulb solution. THISJOURNAL, 6, 403.
2.
V O ~j, . NO. 6
Residual fat in drained-off acid-sugar solution.
3. Per cent of graduation on the test bottles, reads
low. 4. Volatile fatty acids lost.
5. Loss of glycerol. FACTORS C A U S I N G H I G H F A T R E A D I N G
Impurities in the fat column. Per cent of graduqtion on the test bottles reads
I. 2.
high, C o m p a r i s o n of the P e r cevtt F a t F o u n d b y the Modified Babcock a n d Roese-Gottlieb Methods o n S a m p l e ~ ~ / ~ g / ~ z . - D e t e r m i n a t i o run n s by the Modified Babcock method on sample No. 11/19/12, with charges taken a t different times, were always checked a t the same time by the Roese-Gottlieb method. Any variation in withdrawing charges, therefore, frdm the sample are given in Table I . TABLEI-PER
Detn. NO.
FATFOUND BY THE MODIFIED BABCOCK AND ROESEGOTTLIEB METHODS. SAMPLE 11/19/12 Modified Babcock RoeseCalcuDirect Standard Gottlieb lated reading reading method reading
CENT
................
1
2 3. 4.
.........
...............
................ .....
5. 6
7 8.
16.25 16.30 17.25 16.85
Av
.....
17.07 16.91
17.28
...
...
...
... ,..
--
-
-
__
16.66
16.59
16.99
...
17.00 16.60 16.50 16.75
16.45 17.18 16.75
... ...
. . . . . . . . . . . . . . . 16.85 . . . . . 16.80
..... ...............
16.15 16.30 17.10 16.80
16.75 16.90
...
... ...
--
-
-
-
16.83
16.71
16.79
...
Two sets of quadruplicate tests were run under normal conditions (Table I). Determinations I t o 4 on a preliminary set ; determinations j t o 8 on a second set, of which both direct and standard readings were taken. These determinations in both sets were checked a t the same time by the Roese-Gottlieb method to obtain the absolute per cent of fat. Thus the first set of determinations was checked by three Gottlieb tests, one of which was lost. The second set was likewise checked b y three tests by the same method. The determinations b y the Roese-Gottlieb method vary somewhat, due to the difficulty of obtaining uniform charges on samples which have stood several days. However, the averages of each set of standard readings by the Modified Babcock run low by 0.40 and 0.08 per cent. This tendency on eight determinations averages 0.24 per cent and is only 0.4 as great as found from a larger number of determinations in a previous paper. LOSSES A N D G A I N S AFFECTIXG T H E A C C U R A C Y O F T H E FAT COLUMN
Residual F a t L o s t i n Acid-sugar S o l u t i o n D r a w n Off.-This consists of the fat held in the acid-sugar solution which is drained off and lost but not that which adheres to the glass of the bulb. This fat from the acid solution was thrice extracted with anhydrous ethyl ether in a separatory funnel, the ether distilled off and the fat weighed to constant weight, drying in half-hour periods. The fat was then dis
.
