TABLEVII-EFFECT
No. 45 46 47 48 49 50 51 52 53 54 55
56
Whey cc. 100 95 90 80 100 95 90 80 100 95 90 80
731
INDUSTRIAL A N D ENGINEERING CHEMISTRY
July, 1923
I'noculation cc.
1 5 10 20
1
5 10 20 1 5 10 20
Incubating Period Days 3 3 3 3 6 6
6 6 9 9 9 9
AMOUNTOB INOCULATION ON PROPIONIC FERMENTATION Weight of Acid Produced Calculated t o 100 Cc. Weight of Acid Produced Ratio of Propionic Acetic Propionic Acetic Mols. Propionic G. G. G. G. t o Mols. Acetic Contaminated butyric acid present OF
2.23 2.22 2.50 2.01 2.46 2.53 2.36 1.90 2.15 2.26 3.60
0.8417 0.8397 0.9055 0.8414 1.3226 1.3135 1.3099 1 2980 1.6183 1.7403 1.8831
0.3053 0.3059 0.2943 0.3990 0.4366 0.4204 3.4487 0.5546 0.6041 0.6223 0.5881
0.8860 0.9330 1.1319 0.8414 1.3922 1.4593 1.6374 1.2980 1.7035 1.9336 2.3639
0.3213 0.3400 0.3679 0.3990 0.4595 0.4671 0.5609
0.5546
0.6359 0.6914 0.7351
32.2
34.1 41.3 30.7 50.8
53.3 59.7 47.4 62.1 70.6 85.9
29.0 30.6 33.2 30.6 41.4 42.1 50.5 50.0 57.3 62.3 66.2
These values are calculated for the whey cultures on the assumption t h a t 100 cc. of whey contain 5 g. of lactose.
cultures disappears largely after about 2 wks., the separately grown cultures becoming nearly as effective as those grown together. EFFECTOF VARYINGAMOUNTSOF INocuLura-With an organism growing so slowly as the propionic bacterium, the amount of inoculating medium should have considerable influence on the rate of fermentation, particularly in the first 10 days. Therefore, a series was run using various amounts of inoculum, other conditions being the most favorable which had been discovered in previous series. A mixed culture of the propionic organism and Lactobacillus casei was grown in whey for 11 days and then used for inoculation. The volatile acid in the inoculating culture a t the time of its use was determined, and corrections were applied to the results obtained. The values in each experiment were calculated to the basis of 100 cc. of whey for comparison. No correction could be determined which would account for the acids produced after inoculation from the lactose still present in the inoculating culture. However, since the quantities of unfermented lactose present in the amounts of inoculum used must have been rather small, the comparison of results from samples incubated the same length of time cannot be appreciably affected. The results are shown in Table VII. It is clear that 1 per cent inoculation is by no means sufficient to obtain the most rapid rate of fermentation. Increasing the amount of inoculation above 5 per cent shows only slight advantage. Five per cent is undoubtedly the most practical quantity t o use. While there are probably other effective means of accelerating the propionic fermentation, they are mostly factors that cannot be handled satisfactorily in the laboratory, but are bound up with the design and operation of large-scale equipment. Eventually, our minimum time of 12 days' incubation for an 85 per cent yield could probably be considerably diminished. With the development of a demand for propionic acid, it should be possible to meet it a t a reasonable cost by this process.
g
KETOXES There is a growing demand for solvents with the general properties of acetone, but with higher boiling points and lower solubility in water. For a long time acetone has been made on a large scale by the distillation of calcium acetate and of wood. Within recent years patents have been obtained for the catalytic conversion of acetic acid vapors into acetone.' These methods, applied to calcium propionate and propionic acid, respectively, yield diethyl ketone, b. p. 102.7' C . , slightly soluble in water. If a mixture of acetate and propionate, or of the acids, is used, the product contains acetone, methylethyl ketone, and diethyl ketone.* Methylethyl ketone boils at 81' C., and has a solubility in water intermediate between acetone and diethyl ketone. A mixture of ketones, 7 Brit. Patent 14,085 (1915); U. S. Patent 1,315,544 Patent, 1,315,525 (1919). * Schramm, Be?., 16 (1883). 1581.
evidently containing chiefly methylethyl ketone, is obtained from the distillation of the calcium salts extracted from wool s c o u r i n g ~ . ~This mixture has been recommended as a denaturant for ethyl alcohol. On the assumption that the volatile acids from the propionic fermentation exist in the proportion of 2 molecules of propionic to 1 of acetic-which they closely approximate-the limiting theoretical possibilities in the ratios of the constituents of the acetone oil obtained therefrom are 37.4 per cent diethyl ketone, 62.6 per cent methylethyl ketone, and no acetone, on the one hand, and 74.8 per cent diethyl ketone, no methylethyl ketone, and 25.2 per cent acetone, on the other. Some combination of values between these limits is to be expected. With the idea of determining roughly the possibilities of the ketone conversion as a means of utilizing the product of the propionic fermentation, several distillations of dried calcium salts were carried out. The products in each case gave nearly identical distillation curves. Several attempts t o determine the proportion of the components by chemical means failed to give satisfactory differentiation of the ketones. Finally, repeated fractionation through a narrow 2-ft. column of beads was resorted to. The final distribution of the fractions indicated approximately 20 per cent acetone, 40 per cent methylethyl ketone, and 40 per cent diethyl ketone. Because of incomplete conversion of the calcium salts due to lack of agitation in the retorts, and because of frequent cracking of the retorts, no reliable yield data were obtained. With continuous operation, there is no doubt that as satisfactory yields can be secured as are obtained in calcium acetate distillation. It is advisable to distil off the volatile acids from the fermentation mixture and to reconvert to calcium salts before the dry distillation. Distillation of the evaporated fermentation mixture without previous purification gives considerable quantities of evil smelling protein decomposition products that are difficult to eliminate satisfactorily in the subsequent fractionation.
(1919);
U. S.
A . and P. Buisine, Comp. rend., 128 (1889), 561.
Frank Cummings Cook Frank Cummings Cook, M.A., M.S., Yale; Ph.D., George Washington, died in Dallas, Texas, on June 19, after an operation for appendicitis. Since leaving Yale in 1904, Dr. Cook had been .connected with the Bureau of Chemistry, U. S. Department of Agriculture. At the time of his death, he was engaged in special research work on the control of insects infesting live stock, and was temporarily located a t Dallas, Texas. He was a member of the American Chemical Society, the Association of Official Agricultural Chemists, the Society of Biological Chemists, the Washington Academy of Sciences, and was a delegate to the International Congress of Applied Chemistry at Rome, 1906, and at London, 1909. He was the author of numerous papers and bulletins on food metabolism, enzymes, insecticides, fungicides, and related subjects. Dr. Cook had a host of friends in the chemical fraternity, by whom his untimely death will be keenly felt. He is survived by a wife and one son.
