Nor., 1921
T H E JOURNAL OF lNDUSTRIAL A N D ENGINEERING CHElMIXTRY
Month MOUTH CwT
-
CALCULATRD
cTANNIN CONTENT (BONE-DRY) Tots1 Solids Solubles Insolubles Tannins Non-tannins
...... .... .......... ........ .......
January 5 . . February 14.. Aprii 12 May 15.. June 15... July 20.. August 15.. September 15.., . November 1 5 . .
......... ....... ...
18.44 20.27 22.10 22.96 22.30 20.50 15.98 14.88 12.96
...... .... .......... .......... ........ ........ ... ...
18.11 24.7R 26.38 26.81 24.58 24.74 22.56 22.39 27 44
January 5.. February 14.. April 12 Mav 15 June 15.. July 20.. August 15........ September 15.. November 15..
I
Weslern Hemlock 17.78 0.66 19.64 0.63 21.66 0.45 22.28 0.68 21.70 0.60 19.16 1.34 15.48 0.50 14.57 0.31 12.89 0.07 Western Spruce 17.23 0.88 1.14 23.64 1.48 24.89 2.22 24.60 1.86 32.72 2.02 22.72 1.47 21.09 1.60 20.79 2.14 25.30
12.05 13.66 14,84 15.50 15.30 14.15 11.34 10.52 9.00
5.73 5.9s 6.82 6.78 6.40 5.01 4.14 4.05 3.89
12.01 14.96 17.19 16.58 1.5.46 15.24 15.10 16.39 17.54
5.22 8.68 7.70 8.02 7.25 7.48 5.99 4.40 7.76
regularly during the first six months of the year and then
1027
declines. For spruce, however, a similar regularity was not found; there appears to be a maximum in the spring of the year, then a gradual falling off with another maximum in the late fall. The accompanying curves show the tannin content in per cent, on a bone-dry basis, plotted against the time of the year in which the sample was collected. The tannin value found for hemlock is somewhat less than found for Western hemlock bark from the State of Washington by Dr. H. W. Wiley and also H. G. Tabor and referred to by Professor H. K. Bens0n.l Very few references to the tannin content of spruce could be found, the results obtained throughout were higher than expected, especially so, when compared with the results obtained by Professor Benson on a sample of sawmill bark, the history of which was unknown. The tannin content is known to be affected by many factors, among them being the length of time the log is floated in water, by how much of the cambium layer is taken with the sample, and probably by the age of the tree and length of seasoning.
SUMMARY The tannin content of freshly cut western hemlock (Tsuga heterophiZZa) bark varies from 9 to 15.5 per cent, according to the month of the year the sample is taken and averages, for the 9 mo. investigated, 13 per cent; that of spruce (Sitka) varies correspondingly from 12 to 17.5 per cent with the season, and averages about 15.6 per cent. It would appear that the extraction of tannin from the bark from the pulp and paper industries of British Columbia should be profitable.
The Alkaline Hydrolysis of Casein' By Mary A. Griggs DEPARTMENT OF CHEMISTRY, WELLESLEY COLLEQE, WELLESLEY, MASSACHUSETTS
It is the general belief that hydrolysis of proteins by acids gives the most satisfactory products for a study of the composition of the protein molecule or for the isolation of the different amino acids. In certain processes, however, where amino acid mixtures are required for chemical uses, such as the production of chloramines, or for the nutrition of bacteria, molds, etc., the usual methods of acid hydrolysis are not desirable because of the special apparatus required. Since alkaline hydrolysis of proteins can be carried out in iron or steel vessels and the products of the hydrolysis readily recovered, this method can often be used with advantage. Although alkaline hydrolysis promotes the racemization of optically active amino acids, this is not ordinarily a serious consideration. I n view of the scarcity of data relating to the conditions most favorable for alkaline hydrolysis, it became necessary in connection with a larger problem to study the changes in the hydrolysis of a characteriptic protein, casein, caused by variations in time of hydrolysis and in concentration of alkali, within certain limits. Abderhalden and Brahm2 found that a residue from the hydrolysis of Shantung silk which was not hydrolyzed further either by concentrated hydrochloric acid or by 25 per cent sulfuric acid gave a considerable yield of alanine when treated with 33 per cent soda lye. Abderhalden, Medigeceanu and Pincussohn3 studied the hydrolysis of silk by hydrochloric acid (1.2 sp. gr.), 25 per rent sulfuric acid, 25 per cent sodium hydroxide, and Raturated barium hydroxide, and concluded from repeated experiments that, within narrow limits, equivalent mixtures of amino acids were obtained whether acids or alkalies were used for the hydrolysis of 1 Received
June 8, 1921. Chcm.. 61 (lQOQ), 266. I b i d . , 61 (lQOQ), 205.
12. physdol.
a
the silk. Van Slyke2 used casein, among other proteins, in determining the conditions for complete hydrolysis by acid. These experiments showed that the amino nitfrogen reaches a definite maximum a t which the hydrolysis by acids is complete and that this maximum does not vary whether the temperature of the experiment is 100"or 150". The yield of amino nitrogen is also the same whether the protein is boiled for 24 hrs. with 20 per cent hydrochloric acid or heated in an autoclave at 150" for 1 . 5 hrs. with 10 per cent hydrochloric acid. The yield of amide nitrogen increased quite regularly with the time and temperature of the hydrolysis. The present work on the hydrolysis of casein by sodium hydroxide also showed the usual maximum yield of amino nitrogen, but in this case the maximum varied considerably with the concentration of the alkali and appeared much more quickly with the more concentrated solutions. The yield of amide nitrogen found was irregular owing to the volatilizing of ammonia from the alkaline solution, but in general it increased with the time of hydrolysis.
EXPERIMENTAL The material used was a sample of natural-sour casein. The hydrolysis was carried on in an autoclave immersed in an oil bath a t *150° C. The time was reckoned beginning when the temperature of the contents of the autoclave reached 150'. The casein was added to the cold water while it was being stirred vigorously, to prevent lumping, and the dissolved alkali was then added, and the whole thoroughly stirred before it was transferred to the autoclave. After hydrolysis, the autoclave was allowed to cool before it was opened. A filtered portion was then distilled into standard sulfuric acid for the determination of ammonia. 1
THISJOURNAL, 7 (1915), 915.
* J . B i d . Chcm., 12 (1912),295.
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T H E JOURNAL OF’ INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 13, No. 11
only a low yield of amino nitrogen is obtained. When the concentration is increased to 8 per cent, the yield of amino nitrogen is greatly increased, while a further increase in concentration to 10 per cent shows only a few per cent more amino nitrogen. The maximum yield with 10 per cent sodium hydroxide is 10 per cent higher than with 8 per cent sodium hydroxide and is attained about 2 hrs. earlier. TABLEI-VARIATION
IN
YIELD OF AMINONITROGEN WITH CONCENTRATION OR T .. ALKAT
NaOH Amino Casein Concentration Time Nitrogen Grams Per cent Hours Grams 100 6 6 4.052 1001 8 6 6,358 100 10 6 7.175 1 Calculated by interpolation from Curve 111.
Amino Nitrogen Per cent of Total Nitroaen 31.91 50.07
sfi so
TABLS 11-RELATION BETWEEN YIELD OF AMINONITROGEN AND TIME oir HYDROLYSIS NaOH Amino Amino Nitrogen Casein Concentration Time Nitrogen Per cent of Total Grams Per cent Hours Grams Nitrogen 3 8 5.698 4 8 5.913 5 8 6.008 8 6 6.358 7 6.438 8 8 6.164 8 8 6,040 8 9 6.020 8 8 13 6.080 6.629 10 4 4.75 10 7.623 10 7 6.817
Accordingly the optimum method is to use 10 per cent sodium hydroxide for the hydrolysis of casein and to run the process 5 hrs. The author plans to extend this investigation to other proteins in the chemical laboratory a t Wellesley College. ACKNOWLEDGMENT The author wishes to express to Professor Ralph H. McKee of Columbia University her appreciation of the opportunity given by him to do this work in his private laboratory, and to Dr. Edward M. Frankel her gratitude for his suggestions, interest, and assistance in this work.
Malt Extracts and Shortening Agents Registered by American I n s t i t u t e of Baking
60
?
m
:
Q
,/o f i - r c e n s
55
\
I
I
2
I 4
NODX
1
I
1
6 8 77me - Hours FIG. 2
I
I
/O
/2
passed. The curve, Fig. 1, indicated that still higher concentrations of alkali would not be worth while, so no further series of experiments were tried. SUMMARY The following results show that when the hydrolyzing solution contains 6 per cent by weight of sodium hydroxide 1J.
Biol. Chem., 19 (19121,275.
Definite progress is being made by the American Institute of Baking in the examination and registration of baking materials. Bulletin 6 issued by the Institute in September contains a list of fifty malt extracts and shortening agents which have been tested and approved by the Institute. The right is reserved to cancel certificates of registration whenever it is apparent that the character of the registered article no longer entitles it to favorable recognition, and in such cases the baking industry will be fully informed by the Institute. Additional lists of registered products will be published by the Institute from time to time and bakers are asked to assist in the work by submitting for examination all new products which may be offered them. Manufacturers are also asked to submit their products for examination. On and after November 1, the Institute will receive applications and samples for registration from manufacturers of milk products and special preparations which may be classified as “yeast foods” and “bread improvers.” The examination of the latter class of products will not cause a discontinuance of the examination of shortening agents and malt preparations. It is also expected that the scope of examinations and registrations will be extended to other articles used in baking as soon as this is feasible. & In Bulletin 6 it is stated that the Institute is making no attempt to classify the products examined from the standpoint of comparative value. The object of the examination is primarily to establish the statements of the manufacturer as to composition and claims. The actual choice of a.particular brand of an article used;in baking is a matter governed by economic and practical considerations, provided of course that the products have passed the standard tests. Experiments-with the growing of the chaulmoogra tree a t the United States plant introduction garden near Chico. Cal., are being conducted with a view of determining the expediency of producing chaulmoogra oil from American grown trees instead of depending on India for this valuable medicinal product.
