W . I?.
2398 i
~
IBAUGHMAN, D. BXAUNS AND G. S. JAMEGSBN.
~ PROM~ THE OIL, ~ FAT ~ AND W ~ A X LABORATORY, ~ ~ ]i3URI?AW ~ ~OF Q~PARTMBWT OR A G R r c u I , m x t s
~~~~~~~~~" ~ O
N
3
BY 'Ot'ALTER
P.
BAUCXMAN,
DIRK
BRAUXS,
AND
GBOIiGS
s. JAMISSON,
Received Septcnrbcr 14, 19.W.
Considerable quantities of unniarkeZable cantdoup (cucumis mda L.) are allowed to remain on the fields. If the melons are collected and dumped into shallow pits, they soon decompose so completely that the seeds can readily be recovered by aakirig them from the pits. A large sample of cantaloup seed was received from the Imperial Valley, ~ a ~ ~ f o r An ~ i ~ether a . extraction showed that these seeds contained about 30.4ojO of oil. The seeds were pressed by H. S. Bailey, formerly in charge of this laboratory, in an expeller, and the oil was used for this investigation, the results of which are given below. hysical and Chemical Examination.-The cold-pressed virgin oil has a pale yellow color, an odor resembling that of olive oil and a pleasant fruity taste. The physical and chemical characteristics are given in Table 1. T'he iodine number indicates that it might be a semi-drying oil, but no film developed even after the oil had been exposed to the air on a glass plaie for one week. The acetyl value indicates the presence of a small E H ~ Q Uof~ ~hydroxylated acids. Glycerides of volatile acids arc almost completely absent as shown by the low Keichert-Meissl and Polenske numbers. Only 0.4% of acids soluble in water was found. The oil does not easily become rancid. This sample had been stored for 2 years at room temperature in a stoppered-glass bottle yet it had acquired no rancid odor nor taste and the acid value (mg. of potassium hydroxide required to neutralize the free acids in one g. of oil) was only 0.43. The saturated and unsaturated acids were determined by the lead-salt ether method. It is well known that it is not possible to effect a complete separation by this procedure. The saturated acid fraction always absorbs some iod" p;howirrg the presence of unsaturated acids. Also the unsaturated a fraciion i s contaminated with small amounts of saturated acids, but this error is much smaller than the first. By refraining from excessively washing the precipitated lead salts of the saturated acids with ether the error caused by their slight solubility in ether is reduced. Of course, the amount of unsaturated acids remaining with the saturated acid fraction is greater. IIowever, the amount can be calculated and the proper correction made iodine number of saturated acid fraction as follows: - x IOO = A (per iodine number of unsaturated acid fraction cent. of unsaturated acids contaminating the saturated acid fraction) The proper correction is then obtained by means of the formula ( A X B)/EOO in which B is the per cent. of impure saturated acids, This c o r r e ~ t ~ ~ ~ ,
I
2399
CANTALOUP SEBD OIL.
is subtracted from the per cent. of imbure saturated acids and added to the per cent. of unsaturated acids actually determined. TADLBI.-~CANTALOUP &ED OIL. Chemical and Physical Characteristics. o .92 I O Specific gravity 2 s ' / 2 5 '. . . . . . . . . . . . . . . . . . . . . . . Saponification value.. . . . . Folenske number ......... Acetyl number.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acid value,. , ITnsapocifiable matter, %. . . . . . . . . . . . . . . . . . . . . Soluble acids (5;butyric acid). . Insoluble acids %. . . . . . . . . . . . . . . . . . . . . . . . . . . . Unsaturated acids (determined) YCc. ............ Saturated acids (determined) yo... . . . . . . . . . . . . . Unsaturated acids (corrected) yo... . . . . . . . . . . . . Saturated acids (corrected) , , , , , , , , , , , , , , , .
so.
I.I
7 9 . z (Iodine No. 151.8) 1 5 . 3(Iodine No. xo .o)
So . z 14.3
cids.-The bromine addition derivatives1 of the unsaturated acids were made. No hexabrornide was obtained, which indicates the absence of linolenic acid. A large quantity of linolic tetrabromide was obtained melting a t I 13-1 14'. The theoretical iodine number of linollic acid is 181.4 while the iodine number oE the unsaturated acid fraction is 151.8; so oleic acid whose iodine number is 90.1 must also be present. Using the iodine numbers to calculate the proportions of these z acids we get f17.67~of linolic acid and 32.4% of oleic acid in the tinsaturated acid fraction, or 56.60& of the glyceride of linolic acid and 2 7 . 2 % of oleic acid glyceride in the original oil. ~ a ~ Acids.-The ~ ~ a satiirated ~ ~ dacids obtained by the Iead salt ether method were esterified with. methyl alcohol. The mixture of methyl esters was subjected to fractional distillation under diminished pressure. T h e data of this distillation axe given in Table 11. As indicated, a prelirriinary distillation resulted in 5 fractions designated by letters, and D residue. Fraction A was redistilled into Fractions I , 2 and 3. Fractions 13 and C were combined and redistilled, resulting in &-actions 4, 5 and 6. Fraction E was not redistilled but E was combined with the original residue and redistilled into Fractions 8, 9 and 10 The iodine numbers and the saponification values of the various fractions, are given in Table 1x1, Cols, 2 and 3 . Froin this data it is. possible to calculate the saponification values and mean molecular weights of the saturated acid esters uncontaminated with unsaturated acid esters as explained in previous papers2 Lewkowitsch, "Chemical Technology and Analysis of Oils, Fats and Waxes," 5th Ed., VOl. I, pp. 568-578.
THISJOURNAL, 42,
1.52,
1197 (1900).
W . F. BAUGNMAN, D. BRAUNS '1ND G . S. JAMIESON.
2400
'?i?ABI,Z II.--CANTA&lJIJ SEBD OIL.. Fractional Distillation of Methyl Esters of Saturated Acids. 8.5 .5 G. of Esters subjected to Distillation. Original fractions.
Final fmctions.
A
Temperature,
c.
16j-165 5
B
165-169 I 68.-I 7 J 37.5-1 76 I 65-1 67
c
I 67
I
3
ID E
Pressure. Mm.
Weight. 6.
4. . Q 6 .o
( 2 3 .3)"
j .O
r8.2
3.3
5 .o
I
4. .o 3 .§
(23
.8
,8ja
( 8.4Y 3.9
3 .o 3 .cJ 3 .s
4
158-163
5
T 6 4 - 3 66
6 7
167-175 167-171
3.5
171-186
3 .5
(Ij.2)O
21.8
G ,j I1
Iirsidue
.o
8 9
179-1 83
3.0
( 3.8)a 13 , 64.
1233-195
10
19j-220
3 .o 3 .o
3 .o I .o
Residue
I
Total.. . , . , . . . , .
, ,
....
, ,
.5
85.4
Xot included in total.
In Col. 6 are given the mean molecular weights of the methyl esters of the saturated acids in the various fractions. Inspectioir of these results indicates the possible saturated acids that may be present. The molecular weights of Fractions I and 4., 262.6 and 266.4 are between the molecular weight of methyl myristate (242.3) and methyl palmitate (270.3) and suggest, -therefore, the presence of these z acids. The molecular weights OS all the other fractions lie between methyl palmitate and methyl stearate (298.4.). !+ 1he following acids were isolated and identified by recovering the free acids from the various fractions and subjecting them to fractional crystallization from alcohol until constant melting points were obtained. 5tear.ic acid, Ci8H3~02, m. p. 69'. Several recrystallizations of the free acids recovered from Fractions 9 and I O gave aproduct which melted at 5 8 - 4 9 '. An elementary analysis was made with the following results :' ; 56.04. Cek. for stearic acid: H,12.76;(3, 7 j . 9 8 . Found: 13, I Z . , ~ O c', Palwzztic acid, C16H3502, m. p. 62.6'. From Fractions I and 2 acids 'were isolated having a melting point. of 62-63 '. elementary' analysis $axe the following results: Calc. for palmitic acid: ET, 1 2 . 5 8 ; C,
j4.92.
il.%yr.istic acid, CL4?&02,m. p. 53.8.
Found: H, 12.47;G , 5 4 . 7 2 .
The Fraction I , alcoholic motherliq.uor from the palmitic acid crystallization, was diluted with a small ;mrzount of 'water and a crop of crystals obtained which, after several '(.Analysis by G&uies & 17.
CANTrlLOWP SEED OILS.
2401:
recrystallizations, melted a t 54’. The fraction was not large enough for an elementary analysis. It is now established that the saturated acids present are myristic, palmitic and stearic and the proportions present in each fraction have been calculated from the molecular weights with the results given in Table 111. TABLE111-CAHTALOUPSEEDOIL. Results of Analyses of Fractions Obtained by Distilling Methyl Esters of Saturated Acids.
-
.....
6.2212.6 2,.. , , 8 . 5 204.9 3 . . . . . 2 0 . 8 197.2 4... . 6 . 5 209.7 j.. . . . 1 0 . 3 20.3 .8 6 . . . . . 2 0 . 8 197.2 7 . . . . . 2 0 . 7 196.9 S . . . . . 2 6 . 1 192 .j 9 . . . . . 27.3 190.9 I89,I 1 0. . . . . 3 1 . 5 I
------- ---
Unsaturated Mean molec- Myristic Palmitic Saponifiacids. ular weight of acid. acid. e----esters of satuIodine cation c?. G. %. G. rated acids. %. G. number. value.
Frartions.
\
0 . 1 4 262.6 24.9 0 . 8 2 .... .... L .OZ 272.6 0 . 2 5 282.9 . . . . . . . . 0 . 1 7 266.4 12.6 0 . 5 0 .... .... I . @ 274,I 0 . 9 0 282.9 . . . . . . . . 1.52 283 .5 . . . . . . . . 2.32 291 .o . . . . . . . . 38.1 0.54 293.9 . . . . .... 20.9 0 . 2 1 397.5 . . . . __ 4.1 5.6 13.8 4.3 6.8 13.8 13.8 17.3
66.1 2.18 8 2 . 3 15 .oo 44.9 0 . 8 1 78.3 3.05 76 .j 16.68 4 4 . 9 2.92 43.2 4.75 20.4 2.73 12 , I 0 .36 2.1
I .32
0.02 I__
Stearic acid,
%.
G.
........ 7.4 36.8
1.35 0.66
12.1 2 64 36.8 2 . 3 9 38.6 4.25 5 7 . 9 7.76 6j.5 I .96 72.8 ______ 0.73
4 8 ,j o
21.71
Table IV gives in Col. 2 the percentage composition of the saturated acid fraction, in COS. 3 the percentages present in the original oil, and in Col. 4 the percentages of glycerides in the original oil. TABLEIV.-CANTALOUP SEEDOIL. Compositioii of Saturated Acids.
c.
Myristic., . . . . . . . . . . . . . . . I .3: Palmitic. . . . . . . . . . . . . . . . . . 48..50 2I .74 Stearic. . . . . . . . . . . . . . . . . . . __ Total.. . . . . . . . . . . . . . . 7 1 . 56
Original oil.
Glycerides in original oil.
%. 0.3
%. 0 3
30.4 ____
9.7 4.3
-_4 . 5
.o
14.3
I5 .0
yo. I .8 67 .8 IO0
10.2
Summary. A sample of cantaloup seed was found to contain 3 0 . 4 7 ~oil. The chemical and physical characteristics of the oil were determined. A study was also made of the chemical composition, the results of which are given in the following table. COMPOSITION
O F CANTALOUP SEED OIL. . . . . . . . . . . 0.3 nfyristic acid.. . . . . . . . Palmitic arid. . . . . . . . . . . . . . . . . . . . . . . Glycerides of { Stearic a r i d . . . . . . . . . . . . . . . . . . . . . . . . Oleic acid. . . . . . . .............. 27.2 Linolic acid. . . . . . . . . . . . . . . . . . 56.6 Unsaponifiable matter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I .I __ 99.9
(
1
i
WASHINGTON,D. C.
