Translation Series No. 538

Home , Shark meat, Trout

FISHERIES RESEARCH BOARD OF CANADA Translation Series No. 538 .

A comparative study on the fatty acid composition and cholesterol content of the dorsal flesh of fish

by Yaichiro Shimma and Hisako Taguchi

Original title: Gyorui Senikuchu no Koresuteronu-ryo to Shibosan Soshiki ni tsuite

From: Bulletin of the 'Japanese Society of Scientific Fisheries 30: 179-188, 1964

Translated by Translation Bureau(GN) Foreign Languages Division Department of the Secretary of State of Canada

Fisheries Research Board of 'Canada

1965

16pages typescript • • DEPARTI4ENT OF THE SECRETARY OF STATE SECRÉTARIAT D'ÉTAT BUREAU FOR TRANSLATIONS BUREAUDES TRADUCTIONS FOREIGN LANGUAGES DIVISION DES LANGUES DIVISION CANADA ÉTRANGÈRES

eiCk e .1+1 1-4 TRANSLATION SERVICES CANADA INSTITUTE FOR S. T. I. NATIONAL RESEARCH COUNCIL : TRANSLATED FROM - TRADUCTION DE INTO - _

t.ral)f.:121(.7`.E•0 Enaliteh flTT A IN SUBJECT - SUJET CANA Dg I---

ViGharies

AUTHOR - AUTEUR Ynichiro 'Obitirna and Iliveko SYaguahL

TITLE IN ENGLISH - TITRE ANGLAIS

A Comarativo Study on the Yhtly Auld Oolapeatton nd ehoIcutorol Content of the Dorml Yleoh of noh

TITLE IN FOREIGN LANGUAGE - TITRE EN LANGUE ÉTRANGèRE

Cyore SOnikueu no Kom3utorornleo to Shibœan Soshia ni tWito

REFERENCE RÉFÉRENCE (NAME OF ' BOOK OR PUBLICATION - NOM.DU LIVRE OU PUBLICATION) . Bulletin me the Jamamlo.Sobiety of.0oiontiflo ViCaerim Vol„ 50, 'No. 2, 1964

PUBLISHER - ÉDITEUR .

CITY - VILLE DATE PAGES 1964 179 . lsa

REQUEST RECEIVED FROM gpherico RelJourch Board of Canada OUR NUMBER REQUIS PAR. NOTRE DOSSIER N° • "

• - DEPARTMENT 0.(7.A10-riee TRANSLATOR G 1 .1.010231.11,A MINISTÉRE TRADUCTEUR. • •

YOUR NUMBER • 769'1814 DATE COMPLETED ibb e VOTRE DOSSIER NO • REMPLIE LE 5. 1965

DATE RECEIVED Jan. 23, 1965 REÇU LE ‘-k a 3 Q, s- Bulletin of the Japanese Society of Scientific Fisheries Vol. 30, No. 2, 1964

A comparative study on the fatty acid composition and (179) cholesterol content of the dorsal flesh of fish*

Yaichior Shimma and Hisako_ Taguchi** (Received October 4, 1963)

The difference in fatty acid composition between two group of shellfish, the gasteropoda and pelecypoda, has been dealt with in another paper in this issue, on the basis of which it may be inferred that the fatty acid composition of non-depot lipids of fish flesh might also vary with living enviro- nments or feeding habits. Consequently, thirty-six species of fish including shark, bony fish, and their processed products, were obtained from a retail outlet to study the composition patterns. Lipids were extracted from dorsal muscles, which usually contain depot lipids in less amount than the flesh of other parts. The total cholesterol content and fatty acid composition of each were examined in the same manner as described for shell fish. The following summarize the finding from data shown in Table 1 and 2: 1. In dorsal flesh, cholesterol content varied from 9.5 mg in flying fish to 72 mg in pond smelt; while this content in the majority of salt-water fish fell in the 40+10 mg range, the figure for rainbow trout, loach and pond smelt was slightly higher at 70-72 mg. 2. Lipids of dorsal flesh showed a lower content of such fatty acids as C saturated acid, C C and and a higher quantity of C 14 16:1' 18:1' C20:1 226 than lipids of ventral flesh. 3. The pattern of fatty acid composition shown in Table 3 was obtained by averaging the results from seventeen marine bony fish and three cured products which had less than 1% of oil content in the dorsal flesh and more than 15% of fatty acid in the lipids. C22:6 4. With respect to inshore bottom fish, C226acid was found to be around one-tenth of the total acid content. Two species of shark had similar fatty acid compositions (Fig. 4), but they differed from the pattern indicated in Table 3.

* Tokai Regional Fisheries Research Laboratory Study No. B 400. ** Tokai Regional Fisheries Research Laboratory, Tsukishima, Chuo-ku, Tokyo 5. Fresh-water fish, such as loach and sweet smelt, contained 1.3 - 2.5% of acid with a distinct amount of C acid which was C22:6 183 scarcely present in salt-water fish (Figs. 1 and 2). In rainbow trout and pond smelt, however, C acid ranged from 14.9-28.9%, approximating the 226 quantity found in marine fish (Fig. 3).

An analysis of the fatty acid composition of shellfish has been 1) presented by the authors in another paper, showing that there is a dis- tict difference in composition between pelecypods and gasteropods. In this paper, similar findings on the fatty acid composition of fish by means of gas chromatography are reported, along with cholesterol content observations using the Liebermann-Burchard reaction. The methods hitherto employed to analyze fatty acid composition had rendered accurate findings extremely painstaking and difficult; nevertheless, because of the high productivity and wide utilization of the preserved fats of fish - body oil and liver oil - a number of reports on the subject have been made by a number of researchers. On the other hand, because of the relatively low oil content of dorsal flesh in comparison with other parts, very little is known with regard to its lipids. Although it is uncertain whether this applies to all fish or not, it is generally agreed that phosphoric lipids 2) contain many fatty acids of a high degree of unsaturabi1ity . The phosphoric 3) lipid content of dorsal flesh ranges from 0.5-0.9% , so that when the oil content of dorsal flesh is 1% or less, it is easy to suppose that the fatty (180) acid composition of dorsal flesh will differ considerably from that of preserved fats. The purpose of this report is to show, by analyzing the lipids of dorsal flesh of a number of different species of fish, the comparative differences in oil and cholesterol content between species as well as between dorsal and ventral flesh.

As for the cholesterol content of fish, it has been firmly reported as being 50-70 mg/100 g in the cod, haddock and rainbow trout, with other 4) fish presumed to contain similar amounts, which point we sought to verify.

METHOD OF INVESTIGATION AND EXPERIMENT

The 36 species of salt-water and fresh-water fish as listed in Table 1, including the three cured products, were obtained at Tsukiji whole- sale Fish Market in Tokyo and Mazuru Fish Market in Kanagawa Prefecture 3

Table 1. Oil and Cholesterol Content of Dorsal Flesh of Fish

Cholesterol Cont. NO Sample Oil cont. In tissue 1 r acific herring (Clupea harengus pallasi) 0.37% 68 mg/g 25 mg/100g (Ventral 4.8 13.8 66)

2 round herring (Etrumeus micropus) 1.5 15.0 23 (Ventral 7.2 4.6 33)

3 Shad (Dorosoma thrissa) 0.75 35 26 (Ventral 10.5 4,7 49)

4 Pacific saury (Cololabis saira) 1.19 16 19

5 Flying fish (Prognichthys agoo) 0.17 56 9.5 (Ventral 1.82 13 24)

6 Jack mackerel (Caranx mertensi) 0.69 69 48

7 "Akaze" horse-mackerel (Decapterus muroads1) 0.91 34 31 (Ventral I 15.8 2.8 44)

8 "Muro" horse-mackeral (Decapterus lajang) 0.47 58 27

9 Saurel horse-mackeral (Trachurus japonicus) large size 1.17 38 44 small size 0.60 81 49

10 Butterfish (Centrolophus janponicus) 0.50 71 36

11 Sea bass (A) (Lateolabrax japonicus) 0.78 56 44 (B) 0:72 53 38

12 Bluefin tuna (Thunnus maccoii) 1.3 27 • 35

13 "Sumiyaki" (Prometheichthys promethe 28 45 us) 1.6 14 Snapper (A) (Etelis evurus) 0.29 115 33 (B) 0.42 117 49

15 "Ki" sea-bream (Tail's tumifrons) 0.42 45 19

16 "Ma" sea-bream (Chrysophrys major) 0.29 114 33

17 "Nibe" (Miichthys imbricatus) 0.81 64 52

18 "Fusei" (Pesudosciaena crocea). 0.94 57 54 (Ventral ' 43 6.2 266) 4

19 MMegochi" (Inegocia meerdervoosti) 0.37 59 22

20 Goby (eicanthogobius flavimanus) 0.34 103 35

21 Gurnard (Chelidonichths kumu) 0.31 176 55

22 Pacific cod (Gadus macrocephalus) 0.32 117 37

23 Conger (Astroconger myriaster 8.49 5.3 45

24 Puffer (Sphoeroides vermicularis) 0.70 63 44 (Liver 26 11.4 296)

25 Angler (Liphoimus setigerus) 0.48 72 35

26 Chum salmon (Oncorhynchuè keta) 4.5 9.5 42 (Ventral 44 2.4 106)

27 Rainbow trout* (Salmo gairdnerii irideus) 5.6 12.5 70

28 Pond Smelt (Hypomesus olidus) 0.73 99 72

29 Whitebait** (Salangichthys microdon) 1.3 102 133

30 Sweet smelt (Plecoglossus altirelis) 2.8 9.1 25

31 Loach (Misgurnus fossilis) 0.82 86 71

32 Dog fish (Squalus sucklii) 11.2 3.5 39

33 Porbeagle shark (Lamna cornubica) 1.91 23 44

34 Pacific cod salted' 0.33 79 26

35 Red fish soaked in Sake less (Sebastes sp) 0.21 212 45

36 Barracuda salted ..(Sphyraena .schlgéli) 0.65 78 51

* Instead of dorsal part, minced edible portion of cultivated fish was used. ** Includes visceral parts. between July 1962 and February 1963. As a standard rule, 5-10 g of tissue were sliced from the central portion of the dorsal flesh. However, in the case of the cured products as well as the tuna and shark, pre-cut pieces were obtained, while the rainbow trout used in minced form and the whitebait used in it entirety including its vesceral parts. For comparative purposes, lipids were also extracted from the ventral flesh of seven species as well as from the liver of the puffer. 5

The purpose of lipid extraction and all other steps including the a application of gas chromatography used in this experiment were identical with 1) those employed in our study on shellfish published earlier, as was also the quantitative analysis of cholesterol content using Niefts 5) method previous- ly reported.

EXPERIMENT RESULTS AND REMARKS Oil and Cholesterol Content

The oil content and cholesterol content of each sample was shown in Table 1. While the majority of caes indicated the oil content of dorsal flesh to be less than 1%, in the dog fish it was 11.2% and in the conger 8.4%, both being markedly higher than the rest of the samples, followed by other high values including the rainbow trout with 5.6%, the chum salmon with 4.5% and t 6) the sweet smelt with 2.8%. It has been observed by Yamada that the flesh of the dog fish differs from that of other fish, in that àil droplets are present in its muscle fibres, and also that in the case of the conger, a large accumulation of lipids was evident between muscle fibres. The cholesterol content of dorsal flesh ranged from a minimum of 3.5 mg per 1 g of extracted oil for the dog fish to a maximut of 212 mg for the red fish. When its content per 100 g of tissue was calculated, among_the salt-water fish (including the three cured products and shark), except for the flying fish which revealed a very low 9.5 mg, all species fell in the 19-55 mg range, of which nine were below 29 mg, ten between 30-39 mg, ten between 40- 49 mg, and four above 50 mg. In contrast, a relatively high cholesterol content was found in the majority of fresh-water and still-water fish, 70-72 mg being observed in the loach, rainbow trout and pond smelt. In the whitebait, the cholesterol content was an extraordinarily high 133 mg, but this is pro- bably attributable to the fact that its vesceral parts were included in the extraction process. While ventral flesh with a high oil content always has a higher cholesterol content than dorsal flesh, yet in such cases as the round herring and "Akaze" horse-mackerel, a relatively small difference was obtained, whereas in the case of the flying fish, "Fusei", and chum salmon, and extremely large difference resulted. Particularly when the oil content is high, as with the "Fusei" and chum salmon, evidently the cholesterol conten increases strikingly. As to the connection between cholesterol content and fatty acid composition, no relationship whatever could be discerned. While unable to determin the relative proportion of isolated forms and ester forms of cholesterol for all samples, in experimentation with the ventral flesh of the shad as . well as the tuna, jack mackerel, and "Fusei", no ester forms could be observed and it appeared that in these samples the cholesterol content of 27.6 mg, 9.8 mg were of ester forms, it is felt that fur- ther investigations in the formal compositions of cholesterol in muscle fibres are necessary. On the other hand, in such tissues of high oil content as the ventral flesh of the round herring (oil content 7.2%), the liver of the puffer (oil content 25.9%), and the ventral flesh of the "Fusei" (oil content 43.5%), the ester forms comprised 15%, 30.5%, and 50% respectively of the total cholesterol content, which suggests that as the oil content increases, the proportion of ester forms likewise increase.

Evaluation of Fatty Acids

The evaluation of fatty acids from the gas chromatograms obtained was undertaken in the same manner as in the other report, using the relative retention volume of standard esters as the basis. Consequently, in this experiment also, we were unable to distinguish individual values in the case of acids involving very close or redundant peaks, such as C and C or 183 201' C and so that in these cases we merely estimated the main acids by 20:4 C22:1' means of the urea treatment. To show the chromatograms of all the samples would be superfluous, and so we have shown in Figures 1, 2, and 3, the corn- (182) parative chromatograms of the Pacific saury, sweet smelt, and rainbow trout, along with their respective results after the urea treatment. In the case of the Pacific saury, by virtue of the fact that the peaks appearing after 11 minutes and 18.5 minutes diminish after the urea treatment, they are presumed to be indicative of and respectively. C20:1 C22:1 With the sweet smelt and rainbow trout, on the other hand, the coruesponding peaks were intesified by the urea treatment, inferring the presence of C 18:3 and C . 204 7

Fig. 1. Gas Chromatograms of the Pacific Saury

Fig. 2. Gas Chromatograms of the Sweet Smelt

Fig. 3. Gas Chromatograms of the rainbow trout 8

In the study of shellfish, a peak of (405)* was noted between C 22:1 and which was not intensified by the urea treatmen:t, but in the major- C20:5' ity of our fish samples, this peak was not evident, and only after the urea treatment could a peak be detected in this position. Consequently, it is evident that the fatty acid responsible for this peak differs from that of shellfish, and identifies itself with metamer as reported by Ito 8) • On C20:4(11) the other hand, in the urea complex filtrate, a peak of (610) distinctly appeared as it did in the case of the shellfish, suggesting the presence of a certain amount of what is believed to be C in fish as well as in shell- 224 fish. In the ventral flesh of the round herring, and the jack mackerel and butterfish, a peak of (666) could be discerned, which was intensified by the urea treatment. There being no standard esters gvailable for comparison purposes, it could not be identified with certainty, but we presumed it to be C metamer and designated it to distinguish it from that of peak 225 C22:5(I) (768) which we designated C 22:5(11). Where peak (593) or C24:1 was clearly evident was limited to the six samples of Pacific saury, "Megochi", goby, gurnard, loach and shark, and in the others this peak was almost or completely non-existent.

Fatty Acid Composition of Each Sample The proportional composition of fatty acids with respect to each of the samples tested has been summarized in Table 2. 1) Comparison of Dorsal Flesh and Ventral Flesh In comparing the lipids obtained from dorsal flesh with those ob- tianed from ventral flesh having a high oil content, the proportion of C 14:0' C C and C was consistently lower in dorsal flesh while the C 16:1' 18:1 201 226 content was higher. With regard to the other acids, wide variations occurred between individual samples, and no fixed trend could be perceived. While it has been known for some time that the oil from salt-water 8) fish contains a high lever of Ito recently analyzed eight types of C22:6' fish oil including herring oil by gas chromatography and reported that the level of C ranged from 3.2-17.3% (uncorrected 226 values). In the findings obtained by the authors, the level of in the ventral flesh (or liver) C22:6 * Figures in parenthesis denote relative retention volumes Table 2. Fatty Acid Composition of Fish Lipids Extracted from Dorsal and Ventral Flesh

ce- ce ci6 C17 CIS : 224 1 r. eat. ( 1$ ) ait aldehyde set : : 2. lat. : 1 9iat a : 2 ' :5 ce);4‘. z5C0 (u) . :1 1 Pacific herring 3.2.. 24.9 4.9 - _ ;.6 71..,ra,, ... ...,. . 5.6 - 22.5 - Ventral 6.t 1 3. 1 7.1 - 1.F., 21.7 1.7 19,2 :.Cs 19.9 Pound herring 17 0 27.2 6.2 1.7 0.6 7.3 12.1 1.4 1.4 10.2 3.2 - - 24.1

Ventral ' 5.7 1.3 - 16.3 7.g 3.c 1.5 7.4 14.5 1.9 3.0 10.1 3.5 3.7 2c.3 3 Shad 4.5 - 24.5 5.1 5.5 16.8' 1.6 1.2 1.5 5.4 2.1

Ventral 1 9.7 0.0 - _ m.0 9.5 - 1.2 5.1 22.0 2.7 2.9 2.1 c3.0 0.9 l,4 10.9 - 4 Pacific saury ! 6.9 0.7 1e.4 5-4 ..., - 3.5 7.3 1.7 4.7 13.5 6. 14.7 - 1.2 13.5 1.6 I 1 5 Flying fish I 1. 1.4 3444 2.7 _ _ 11. 7 10. 9 1.1 I,g 4.0 4.3 - - 25.3 - Ventral - 1, 3.5 1.2 20.5 6.7 - 3.1 1.3 G. 20.3 1.4 7.5 4 7 3.4 - 2.9 16.6 - 6 Jack mackerel - 1g„E; 1.2 - - 10.7 19.6 2.2 3.2 3.7 3.4 3.0 7 "Akaze" horse- 2,7 . 2.2 1.1 9.2 14.0 1.1 0.5 1.5 7.3 2.4 - 1.:'2, 27.9 mackerel _ Ventral 4.2 1,0 - 21.0 ... 2.0 1.3 6.6 17.2 1.9 1.3 2.7 7.6 1.0 - 1.5 11'..2 - 8 "Muro" horse- 2.4- 0.6 33.0 4.4 trco - 13.7 12.3 2.7 2.0 . 4.5 3.6 mackerel 9 Saurel horse- ILI 0. 20.6 g.0 1.7 /.6 6.3 20.0 1.5 --, mackerel large 4.7 8.0 5.9 small size 35 0. 23. 0 G.9 /..g 1. g.9 I5.o 1.6 2.2 ri.g 3.7 2.0 19.4 - -p 10 Butterfish ■.. L.3 txnee lo.6 k.2 tragic trzeo 5.4 16.1 1,2 11. 6 3.7 u.,- ...,...,-, , ,

2.5 11 Sea bass (A) me, ' e e _) 6 eer 6 . C'•.

7 . 7 (B) • '7..; 2e3 •

C• 12 Bluefin tuna e2.111,,,j 15:11 4.8 • 1.2 0.6 C1.2 21.2 1.7 Li 2.0 3.1 • •

13 "Sumiyaki" 3.2 22.4, - 7.7 27.1: 3.3 1.6 5.7 3.5 - •15.4

- 14 Snapper (A) ele 1.7 24.9 3.11 2.7 teuso 9.0 12.S 1.3 .1,.4 3.7

/g.6 1.5 - 1, 0 1,0 9.6 11.0 0.g 2.1 14.1 3.1 2.3 Mr•

15 ITKitT sea-bream 1.3 - 30)45.0 - g.1 15.o 1.9 3. 1 3.9 4.2 - 23

16 "Na" sea-bream 2.4 a 10.3 15.k 1.5 2.7 12.2 - 3.1 " 17 "Nibe" 2,5 25.g 13.1.4-:-.;,4„::: 9.7 21.4. 1,2 2)4 6,3 3.g• 12.6 .11.■

18 "Fusei" - 21.5 30.s tzuott 1.2 7.7 19.7 1.3 1.6 1.5 5.6 4.5 1.7 2.2 19.0

Ventral 3.9 0.8 - 26.5'17.0 - 1.4 5.9 23.4 2.0 1.3 1.6 4.4 2,1 rs: 77

19 "Megochi" 2.g - • 23.9 s.4 - 2.3 1.g L9 12.2 1.6 5.0 9.5 6.4 - 2.1; 1 5.1 2,7 2 20 Goby 2,2 - 20.2 5:8- 2,0 1,8 '10.4 l • g •3•4 3.2 15.61 4.4 - 3.9 11. 4

21 Gurnard 0.7 2.4 . 13.9 :2,8 1,2 1,5 g.9 10.9 0.7 1.3 7.3 • 44 1.1 2.4 , •

22 Pacific cod '1.0 ELISM 10.2 3,6 0.4 147 1145 1.0 .11101. 2.0 17.9 5.6 ,-..î. 1.9 - 29.2 -

23 Conger . 5.5 - its 9.7 1.6 4» 3.3 e.0 2,5 2.6 11,9 0.-0 3.4 ... 5,1 , '7,S - 24 Puffer - 29.7 5.0 - 12.4 1g.3 3.0 24.7 5, 4.s - -- 5.7 -: Liver . 5.7 - • 19.0 11.5 7.3 214.0 - 10.6 4.6 7.11 - 1,.2

-; .Zr JIM 25 Angler ' 28„2 15.6 203.5 1.7. - 5.5 5.2 - o CO

. , i : . . 34 Pacific cod sal r - 7.t.wy ,-, ..;/e 0 e,:ï .,,- - 29.4 ed :,-- e- 35 Fed fish - 23.1 5.5 - lb.? 14,:4 - - - 5.1 -6. 1 3.I. _ ,ze o - 36 Barracuda salte 2.9 - - 17.2 - ..):.-7 1.4 - 1.2 . 25.7: ,., 4.,.. 5: 16 '..::7 • 0.4'2 G2CP:1,- , ( . r . - 1-. oc,11 cat. mod4 si :2 ett : 1 Gat : 2. :2: t4 Ilidt3 ..:.> 34 25 4: 11 5ti) :..e ;„ : 26 Chum salmon r...4- 2. e:. r IG 3 g.3 '2.7 24.c 1.4 /4.4 .i. - 6.5 2- 2 g - U f0) -... re - Ventral C40 . 13.5 9.0. - -- 2.S 25.3. 1.9 . 15.7 ' - - 6.s 14.s - 3.6 1 rz n., , rl ,er, r 27 Rainbow trout ..,,, ,,, e'.).5.. 4 4) "" "' 4.3 19.2 9.1 2.2 9.3 - 1o.4. 2.9 i.7 76.o

28 Pond Smelt 1.9 .,. trace z2.5 6.4 - 1.7 1/4J.7 3.S' 143 • 13 ' 2.7 - - 13.4 2.Z1.3 i,52.9 - . 29 Whitebait '3.5 - ô.9 1.5.d 9.3 2.1 1.4 4.5 15.7 4.5 23 5.1 . - ID.0 6.3. 2.9 - 14.9 \ \ . 30 Sweet Smel 7.3 1.1 29.1 15.0 3.9 _ 2.6 11.5 Iè..a 1.3 17.e - - 2.4 - 1.2 - 31 Loach 6 :24 2.9 - 15.4 16:7 3.e - • 5.9.14.7 ..6.2 7. " Li - 4.2 G.6 - 2.7 2.5 32 Dog fish 1.9 - . 15.1, 6.5 _ 3J&7 2.3 12ae r 0 .7 - -',., '.e 3. , .,_ 33 Porbeagle shark - 2.5- 12,2 le.j - 2,t 1J .1.0 . ..4.1 1.2 2.g 2.7 -, 13.7 ,. ,-J 3.5

* In these fresh-water fish, C was the major component instread of C which is 183 201 the major in salt-water fish (see Figs. 1 and 2).

of the chum salmon, Pacific herring, puffer, and "Fusei" was low, being 3.6, (186) 3.8, 5.7, and 7.7% respectively, while in the round herring it was a high 20.3%.

On the other hand, the level of C 226 in dorsal flesh was considerably higher, with the nnapper showing 44.9% and the majority of the other samples falling in the 15-30% range. Among those with a low C 226 content were the angler and goby with 11.8% each and the "Megochi" with 9.1%, suggesting that the C level is low in transitional area fish of limited locomotive 226 activity. Nevertheless, in the gurnard the level of vas 38.8%, and in C22:6 the Pacific cod, which is also a demersal fish, its level was 29.2%, so that it is rather difficult to draw any simple conclusions. With respect to the saurel horse-mackerel, sea bass and snapper, two samples of each were analyzed, and when the fatty acid composition of that having a high oil content was compared with that having a low oil content, a relationship similar to that between ventral flesh and dorsal flesh was observed, with the level of C being consistently lower in the sample haVing a high 226 oil content. Accordingly, in the Pacific saury, conger and dog fish, the C 226 level was comparatively low, by virtueof the high oil content in their dorsal 9) flesh and the presence of preserved fats containing little In Zama's C22:6' analysis of the body fats of chum salmon in spawning migration, it has been reported that the iodine content of those in the spawning area was higher than in those found downstream, concluding that the fat consumed as locomotive ener- gy during migration has a lower iodine content than organic fat.

Table 3. Composition of the Main Fatty Acids in the Dorsal Flesh of Bony Sea Fish (gean Values)

, 4 G16 018 020 G22 càto emr'G. .1 slai;. :1 . 2 1' .3or 2 1 25 :6

1.8 22.2. 4.9 8.4 15.6 1.5 2.9 7.5 . 4.2;', 0.9 27.1

*Figures referring to C 20:1 and C 221 may include a small quantity of C 18:3 respectively. and C20:4 13 1.

Figure 4. Cas Chromatograms of Sharks

2) Fatty Acid Composition of Salt-water Fish (187)

As pointed out by Ito, the lipids of many salt-water fish are com- posed of almost identical fatty acids, and the only difference appears to be in the proportional content of each. As can be seen from the results shown in Table 2, with the exception of those with a high oil content, the dorsal lipids of salt-water fish all indicate a similar composition, with no discern- ible significant difference. The fatty acid composition of the three cured products as well is similar to that of other samples, and although it cannot be stated with absolute certainty, not having analyzed these samples before during, it is felt that the fatty acid composition remains largely unéhanged by such preservation processes as salting or soaking in Sake-lees. Selecting only those samples whose oil content was less than 1%, and studying the pattern of their composition from the data in Table 2, two broad groups can be derived, the first comprising those samples whose C22 . 6 content is in the neighbourhood of 10%, such as the "Ma" sea-bream, "Nibe", "Megochi", goby, and angler, and the second consisting of those that are higher. With reference to the 17 samples in the latter group as well as the three cured products with similar composition, the mean levels of the main acids were determined as shown in Table 3. To accept such a compositional breakdown as being the representative pattern of the4dorsal lipids of salt-water fish should incur no great error. As samples of non-bony fish, the dog fish and shark were analyzed, and the chromatograms of the two indicate a close similarity as shown

• in Figure 4. Only in the relative content of and C was there any C22:5 226 difference, which may be attributed to the wide difference in the oil content between the dorsal flesh of the two. As for shark meat, because of its high 14

oil content, it would not have been valid to compare it with the composition of the aforementioned salt-water fish; nevertheless, in the case of the porbeagle shark, the C content amounted to 13.7%, suggesting that the level of C 225 22:5 in soft-boned fish is higher than in hard-boned fish.

3) Fatty Acid Composition of Fresh-water and Still-water fish With the exception of the pond smelt and loach, the oil content of the dorsal flesh of these samples is relatively high, so that any comparison with salt-water fish could not be valid; nevertheless, in the sweet smelt and loach, the level of C and C acid is low, and the level of and C 20 22 C18:2 183 is higher than in salt-water fish. It is general knowledge that the preserved fats of fresh-water fish contain only a small quantity of and if a re- C22•6 presentative pattern for fresh-water fish corresponding to the aforementioned pattern for salt-water fish were to be derived, it would likely be very close to the composition of the sweet smelt and loach, but because of the insuffi- ciency of samples, no clear result could be obtained. In the dorsal flesh of the chum salmon also, the level of C 20 and C 22 high-grade unsàturated acid was low, differing significantly from the composition of salt-water fish, but this may be due to the high 4.5% oil content of its dorsal flesh and the fact that it is comprised almost entirely of 10) preserved fats. It had been reported that very little variation is present in the body oil of chum salmon with respect to location in the body, and the results shown in Table 3 verify the complete similarity in composition between dorsal lipids and ventral lipids. It is also very interesting to note that this composition closely resembles that of the ventral flesh of the Pacific herring. In the rainbow trout, pond smelt and whitebait, the level of C 22:6 and C was high, 205 approximating that of salt-water fish. In the case of the rainbow trout, as shown in Figure 3, the level of and was also C18:2 C18:3 high, permitting the statement that it possesses the combined characteristics of both salt-water and fresh-water fish.

— SUMMARY Lipids were extracted from the dorsal flesh of 33 species of fish and three cured products obtained through retail outlets, and a comparative 15

study was made of their oil content, cholesterol content and fatty acid composition, with the following results:

1. The cholesterol content in 100 g of dorsal flesh ranged from a minimum of 9.5 mg in the flying fish to a maximum of 72 mg in the pond smelt, with the majority of salt-water fish falling in the 40 10 mg range while the rainbow trout, pond smelt and loach of fresh-water or still-water origin were in the 70-72 mg range.

2. In comparison to lipids of ventral flesh, the lipids of dorsal flesh indicated a lower content of C saturated acid, C c and C 14 16:1' 18:1 201 and a higher level of C 226. 3. In sample tissues of high oil content, the fatty acid composition varied widely with individual species, but in the 17 samples of salt-water fish and the three cured products whose dorsal flesh had an oil content of less than 1%, their fatty acid composition showed a closely similar pattern, with the proportional content of the main fatty acids approximating that shown in Table 3.

4. In the "Megochi", govy, angler, "Ma" sea-bream and "Nibe", however, the level of C 226 was low, being in the neighbourhood of 10%, while the fatty acid composition of the dog fish and porbeagle shark differed some- waht from the pattern for hard-boned fish.

5. In the sweet smelt and loach of fresh-water origin, the level of C was 1.3-2.5%, with a distinct amount of being present, whereas 22:6 C18:3 in the rainbow trout, pond smelt and whitebait, the level of C ranged from 226 14.9-28.9% and approximated that of salt-water fish. (188)

The authors wish to thank Dr. Roslyn B. Alfin-Slater and her staff in the Department of Public Health, University of California at Los Angeles, for providing this opportunity to study as well as offering helpful suggestions on gas chromatography. 16

BIBLIOGRAPHY

1) The authors: This Bulletin, 30, 153 (1964). 2) e.g. Lovern, J.A.: Biochem. J., 63, 373 (1956). 3) e.g. Katata, Muneo: This Bulletin, 26, 425 (1960). 4) Lovern, J.A.: "Fish in nutrition" International Congress Washington, D.C. (1961), p. 90 (Fishing News (Books) Ltd. London, England). 5) Neift, M.L. et al: J. Biol. Chem., 177, 143 (1949). 6) Yamada, Mitsuaya: unpublished 7) 011ey, J. et al.: Biochem. J., 57, 610 (1954). 8) Ito, Yutaka: Oil Chemistry, 12, 279 (1963). 9) Zama, Hiroichi: This Bulletin, k8, 618 (1953), 19, 1087 (1957). 10) Fukayama, Yoshimichi: This Bulletin, 8, 220 (1940).