INDUSTRIAL AND ENGINEERING CHEMISTRY
1136
I n this work it has been shown that the percentage of foreign suspended matter and water is much less in French than in American pine gums of the same class. The turpentine yield, on the dry basis, from French gum is approximately 1 per cent higher than that for American gum of the same class. The specific gravity and refractive index of the French is slightly higher than for the American turpentine. The odor of the French gum and turpentine is decidedly different from that of the American. The French has a distinct odor of limonene, while the American has a pleasant aromatic odor. Both the French and the American pine gum and turpentine are strongly levorotatory, the French being somewhat more so than the American. The strong levorotatory characteristics of the American turpentine obtained from the pine gum used in this investigation show this gum to be mostly of the slash variety. Results obtained from the turpentine
Vol. 23, No. 10
and rosin derived from French pine gum correspond closely to those obtained from the regular commercial French turpentine and rosin samples. The initial boiling range of the French turpentine is slightly lower than that of the American, but the French contains more of the higher boiling components as shown by the Engler distillation test. The acid number of the French rosins is slightly lower than that of the American rosins of the same grade. Both French and American rosins show dextrorotatory readings. Crystallization tests on all of the French rosins studied in this investigation show them to be identical in their tendency to crystallize. This tendency of the French rosins to crystallize is much greater than that of the American gum rosins, but less than that of the ordinary wood rosins. The French rosin samples examined were clearer and freer from suspended particles than the average American gum rosin.
Vitamin A Content of Body Oils of Pacific Coast Salmon' R. W. Truesdai12and L. C. Boynton3 DEPARTMENT OF CHEMISTRY, UNIVERSITY OF WASHINGTON, SEATTLE,WASH.
R
EFERENCES to bioz
Five samples of salmon body oils are prepared under standardized conditions fromi five common species of salmon. The vitamin A content of these body oils is determined by the biological assay recommended by Sherman and Munsell, and for comparison a medicinal cod-liver oil is used as a control. Ninety-three mg. of chinook oil, 186 mg. of sockeye oil, 226 mg. of silver oil, 227 mg. of humpback oil, 221 mg. of chum oil, and 1 mg. of cod-liver oil are fed per animal per day. The results obtained show chinook and sockeye oils to contain more vitamin A than silver, humpback, or chum oils. All the salmon body oils tested are found to be decidedly inferior to a medicinal cod-liver oil of high grade as a source of vitamin A.
liver oils and fish body oils are numerous. Holmes and Pigott (2) reported body oil of sockeye s a l m o n as not being comparable in vitamin A potency with medicinal cod-liver oil. R e c e n t l y Nelson and Manning (3) reported a commercial salmon oil to be about one-third as rich in this factor as a medicinal cod-liver oil of known high vitamin A content. They further state, "But medicinal cod-liver oils have been tested in this laboratory which contain no more vitamin A than the sample of salmon oil." The purpose of the present biological tests was to secure quantitative data upon the relative vitamin A content of body oils of the five common species of Pacific Coast salmon, genus Oncorhynchus (Table I), widely used as food. The oils were compared with a high-grade medicinal cod-liver oil,' used as a standard of comparison throughout. Considerable variation in the vitamin A potency of the different oils was anticipated since the several species differ greatly in their color and fat content.
These fish were received well iced and unopened, and p within 24 h o u r s after the c a t c h t h e edible flesh was rendered for an hour at 80" to 85" C. The oil was immediately expressed, separated f r o m w a t e r , filtered, and sealed in ground-glass stoppered containers which were kept in a refrigerator during the entire period of experimentation. Certain common physical and chemical constants of the oils were determined and are recorded in Table 111.
NAME Chinook Sockeye Silver Humpback Chum
OIL Table I-Biological a n d C o m m o n N a m e s of Different Species Chinook spring king red salmon Oncorhynchus fschavylscha Sockeye,' bluebs'ck, Aiaska red Oncorhynchus ncrka Silver, coho, medium red, silversides Oncorhynchus kilsufch Oncorhynchus gorbuscha Humpback, pink Chum, keta, dog, calico Oncorhynchus kcfa
Materials Studied
Table I1 relates data pertaining to the fish which were the best obtainable during the periodic salmon runs. Received May 1, 1931. Department of Chemistry, Pomona College, Claremont, Calif. Medical School, University of Rochester, Rochester, N . Y. 4 Control number 25338235 M, furnished through the courtesy of the E. L. Patch Co. 1 f
Table 11-Description of F i s h Used NUMBER APPROXIOF TOTAL MATE FISH WEIGHT AGE LOCALITY CAUGHT Pounds Years 1 23 4 Off Cape Flattery 4 20 4 South of San Juan Islands 5 31 5 Off Whidby Island 5 30 2 Off Whidby Island 4 40.5 3 Between Everett and Port Townsend
Table 111-Physical and Chemical C o n s t a n t s of Oils REFRACTIVE SAPONIFREE SP. G R INDEX FICATION IODINE FATTY Av. BODY 25' C:' 25' C: VALUE NUMBER" ACID FAT(6)
%
%
0.9144 0.9145 0.9195 0.9187 0.9160
1.4728 1.4763 1.4784 1.4778 1.4780
169.1 168.6 188.2 167.9 187.9
131.5 160.6 135.8 148.0 136.1
0.56 0.21 0.14 0.26 0.42
13.41 8.58 8.49 8.20 6.15
Cod-liver 0.9182 5 Hanus method.
1.4787
185.5
155.1
0.59
.. .
Chinook Sockeye Silver Humpback Chum
Specifications of the U. S. Pharmacopeia X for the chemical and physical constants of cod-liver oil are: specific gravity, 0.918 to 0.927 a t 25" C.; saponification value, 180 to 190; iodine number, 140 to 180; free fatty acid, not more than 1.41 per cent; and unsaponifiable matter, not more than 1.5 per cent. The latter constant was not deter-
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1931
mined for these oils. It will be noted that the free fattyacid constants for these oils meet the U. S. P. specifications. The values for the other three sets of constants, however, do not in general meet these specifications.
the larger dosages failed to consume all of the oil with regularity. Records of such cases obviously have not been included in this report. Table V contains, in summary form, the average rat-growth records made by groups of animals receiving such amounts of the oils tested as resulted in growth most nearly approximating the standard growth-curve gain of 25 grams in 8 weeks. Considerable preliminary feedings were necessary in establishing these dosages. Table V-Average
186-9
43 mg
10-9
Chart I-Average
226mg
PP7mg
Growth Curves of R a t s
The colors of the oils, which varied in a most marked manner, suggested a possible relationship between pigmental intensities and the vitamin A content. Attempts had been made to correlate the intensity of yellow-plant pigmentation and its vitamin -4content. Recent investigations indicate a conversion of carotin into vitamin A by animals. In order to express quantitatively the colors of the oils, they were compared colorimetrically with a standard containing 100 mg. picramic acid and 200 mg. sodium carbonate per liter as suggested by Benedict (1) for blood-sugar determinations. Table IV gives these da.ta. Table IV--.Relative Color Intensities COLORIMETER RELATIVE COLOR OIL READ1NDsa INTENSITIESb 10.5 0.9 Chinook 1.9 5.3 Sockeye 6.3 1.6 Silver 22.9 0.4 Humpback 40.5 11. 2 Chum a Picramic acid solution = 10. b Picramic acid solution = 1.0.
The flesh of the chinook salmon is usually red, its color intensity comparing favorably with the sockeyi: salmon. However, it is not unusual to find specimens which have no color in their flesh; the body oils of these are similar in appearance to the clear mineral oils. The flesh of the chinook obtained was pink. Since no red chinook oil was tested, conclusions relative to any possible correlation between pigmental intensity and vitamin A potency, in this instance a t least, are impossible. The color intensities of the other salmon body oils were proportional to their vitamin A potency. Vitamin A Assays
The vitamin A content of the oils was determined by the Sherman and Munsell (5) method. Young albino rats, 2829 days of age and weighing between 35 and 55 grams, were placed, in groups, upon a vitamin A-free diet which otherwise was adequate. When their bodily store of vitamin A had been depleted, as evidenced by cessation of growth and other signs of nutritive decline, they were placed in individual cages, and their diet was supplemented by the oils being tested, which served as the only known source of this vitamin. Graded amounts of the oils, measured by calibrated stalagmometers, were fed three times weekly, on the basis of a 6-day week. The cod-liver oil was diluted with a peanut oil free of vitamin A. All controls received an equivalent amount of the diluent. If the dosages were large, as was the case with silver, chum, and humpback oils, they were fed daily for the &day week. With these large dosages complete consumption was assured only by removing the basal diet for several hours. Even with this forced feeding, a number of rats receiving
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Growth of Rats
Av. FOOD Av. WT. Av. GAIN EATEN AV. WT. START OF 8-WEEK S-WEEK OIL SUPPLE-OIL/RAT/ 28-29 OIL SUPPLE- TEST TEST MENT DAY ANIMALS DAYS MENT PERIOD PERIOD ME. Grams Grams Grams Grams 5 41.4 85.2 Chinook 93 34.6 539 4 39.2 67.2 Sockeye 186 46.5 489 226 4 46.7 106.2 18.0 503 Silver 2 44.0 96.0 3.5 Humpback 227 438 1 40.0 97.0 Chum 22 1 -29.0 510 21.4 469 5 44.8 92.0 Cod-liver 1 37 Peanut Peanut 38 13a 45.1 92.8 ,.. a Control animals: average weight at death, 75 gram?; average surviva1 period 15 d a w .
1
...
These average gains in weights are represented by curves in Chart I. Of 8 rats fed 226 mg. of silver oil daily, only 4 consumed the oil regularly, while only 2 of 7 fed humpback oil consumed their allotted daily dosages. A curve for chum oil is not included, as only one animal of a group of 8 consumed the oil and survived the test period. The curves are averages for the following numbers of animals: 5 fed chinook, 4 fed sockeye, 4 fed silver, 2 fed humpback, and 5 fed cod-liver oil. Discussion
The data obtained in this investigation indicate the chinook body oil as having the highest vitamin A content of the salmon body oils tested. Ninety-three mg. per day resulted in an average growth increase of 34.6 grams for the 8 weeks. Twice as much sockeye oil gave a growth of 46.5 grams. Two hundred and twenty-six mg. of silver oil produced a response similar to that produced by 1 mg. of codliver oil, a total of 18 and 21.4 grams, respectively. Two hundred and twenty-seven mg. of humpback oil barely maintained life over the 8 weeks, and 221 mg. of chum oil failed in all cases but one t o do so, the animals dying within from 5 to 7 weeks. It is apparent that these latter oils are inferior in their vitamin A content to the oils of the other three species. It is interesting to note that the vitamin A content of these oils falls in the same order as fat content of the flesh as determined by Shostrom, Clough, and Clark (Table 111), and, with the exception of the chinook, the reddest fish were also the richest in this vitamin. Data relative to animals upon oil dosages other than reported here have not been included. No effort has been made to interpolate, as a straight line function, the rate of growth of rats with vitamin content. Thus evaluation of the oils in terms of vitamin -4units is not reported. The biological assays reported above check within reasonable limits with those reported by Korris and Danielson (4) upon these same samples of salmon body oils, which had been tightly stoppered and held constantly in refrigeration, employing an improved technic for the colorimetric assay of vitamin A. Literature Citec,.~ 3 Benedict, J . Biol. Chem., 32, 203 (1918 Holmes and Pigott, Boston Med. Surg. 193, 726 (1925). Nelson and Manning, IND. END. CHF , 22, 1361 (1930). Norris and Danielson, J. Biol. Chem. dS, 469 (1929). ( 5 ) Sherman and Munsell, J . A m . Chem. j o c . , 47, 1639 (1925). (6) Shostrum, Clough, and Clark, IND. RND. CHEM.,16, 283 (1924)
(1) (2) (3) (4)
