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An experimental investigation of molecular weight, refractive index, and emulsification of California sardine oil.

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An experimental investigation of molecular weight, refractive index, and emulsification of California sardine oil.

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Content AN EXPERIMENTAL INVESTIGATION OF MOLECULAR WEIGHT,
REFRACTIVE INDEX, AND IMDLSIFICATION OF
CALIFORNIA SARDINE OIL
A Thesis
Presented to
the Faculty of the School of Chemistry
University of Southern California
In Partial Fulfillment
of the Requirements for the Degrees
Master of Science and Master of Arts
by
Emileen W. Walden and James T. Jennings
August 1937
UMI Number: EP41500
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This thesis, written by
.................... WALDEN..........
under the direction of h£UL- Faculty Committee,
and approved by all its members, has been
presented to and accepted by the Council on
Graduate Study and Research in partial fulfill
m ent of the requirements for the degree of
I |f
MASTER OF SCIENCE...
Dean
Secretary
jP^...Segtember__1937.
Faculty Com mittee
'hairman
This thesis, written by
......... JMES.T....JMNINGS............
under the direction of Faculty Committee,
and approved by all its members, has been
presented to and accepted by the Council on
Graduate Study and Research in partial fulfill
ment of the requirements for the degree of
MASTER OP ARTS
Secretary
£ )a^,.Septemberl93?
Faculty Com mittee
Chairman
TABLE OF CONTENTS
CHAPTER PAGE
I. THE PROBLEM........................ , ......... 1
Statement of the problem ......... ........... 1
Importance of the study........................... . . . 1
Nature of the sardine oil used......... 2
Organization of the thesis ....... ............... 3
II. .MOLECULAR WEIGHT DETERMINATIONS OF SAMPLES OF HEAT-BODIED
SARDINE OIL........................................... 5
The method used ....... ..... 5
Experimental procedure .... ......... ........ 6
Dissolving of the oil sample and determination of the
freezing-point of the solution.............. 8
Calculation of molecular weight ............ ...... 8
Interpretation of results .......... ........... 9
III. THE REFRACTIVE INDEX OF HEAT-BODIED SARDINE OIL........... 17
Interpretation of results ... ......... 17
IV. EMULSIFICATION OF SARDINE OIL............................ 24
General discussion of emulsions ......... 24
Results with different emulsifying agents ....... .... 27
Triethanolamine ........ .................... . 27
Gelatin . . . J • . ........ ........... 27
Gum acacia......... 29
Egg-yolk........................ 29
Com starch.............. 31
ii
c h a p t e r pagke
Casein .......... ....... 31
Sodium hydroxide ....... ............... 32
Conclusions ..... ............. ......... 34
V. SUMMARY AND CONCLUSIONS .......................... 35
Summary ........ ....... ............ 35
Conclusions ........... 35
BIBLIOGRAPHY ......... ............................ . 37
LIST OF TABUS
TABLE
PAGE
I.
Molecular Weights of Sardine Oil, "A1 1 Series Samples . • ♦ 11
II.
Molecular Weights of Sardine Oil, "B" Series Samples . • • 12
III. Molecular Weights of Sardine Oil, *'CW Series Samples . • • 13
IV. Refractive Indices of Sardine Oil, "Aw Series Samples e * 19
V. Refractive Indices of Sardine Oil, "BM Series Samples • • 20
VI. Refractive Indices of Sardine Oil, ”CW Series Samples • 21
VII. Emulsification of Sardine Oil with Triethanolamine . . 28
VIII. Emulsification of Sardine Oil with Gelatin ......... 30
IX. Emulsification of Sardine Oil with Sodium Hydroxide . • • 33
LIST OF FIGURES
FIGURE PAGE
1. Beckmann Freezing-point Apparatus............ 7
2. Time-temperature Schedules Used for Heat-bodying Sardine
Oil.................................................. 14
3. Change in Molecular Weight of Sardine Oil with Time When
Heat-bodied .............. 15
4. Change in Refractive Index of Sardine Oil with Time When
Heat-bodied ............. .................. 22
5* Refractive Index Plotted Against Molecular Weight of Heat
bodied Sardine Oil ....... ............... 23
CHAPTER I
THE PROBLEM
Statement of the problem. The purpose of this study was to in
vestigate experimentally some of the chemical and physical properties
of "Varnish Maker^s” grade of California sardine oil. The properties
studied included the molecular weight and the refractive index of sam
ples of the sardine oil that had been polymerized by heat-bodying in
air and in vacuum. Emulsification of the unpolymerized "Varnish leaker*s”
grade of sardine oil was also investigated, using several common emul
sifying agents, each with various proportions of the oil and employing
different methods of agitation.
Importance of the study. This study was important by virtue of
its contribution to the experimental data being amassed concerning
California sardine oil, both by the Vegetable Oil Products Company and
by the California Flaxseed Products Company, for the Los Angeles Paint
and Varnish Production Club. These companies have been gathering data
on the refractive index, calculated iodine number, time and temperature
schedule, viscosity, and molecular weight, in an effort to explain the
chemical and physical changes that take place in sardine oil during the
industrial process of heat-bodying or polymerization. All of the data,
including some of that contributed by the investigation being reported,
will appear under the tentative title "Properties of Sardine Oil, Heat
Bodied in Air and Vacuum,” in the Official Digest of the Federation of
Paint and Varnish Production Clubs. probably in the November, 1937, issue.
2
Nature of the sardine oil used. The sardine oil samples used in
this investigation were supplied by the Vegetable Oil Products Company
in collaboration with the California Flaxseed Products Company. The
former describes the oil as "an alkali refined, clay bleached, winter
ized, Pacific Coast sardine oil." This oil is not rated as deodorized,
although it is so considered in the varnish industry. Each of the three
series of samples, representing different methods of heat treatment,
started with this "Varnish Maker’s" grade of sardine oil. The time-
temperature schedules followed in processing are shown in Tables IV, V,
and VI, pages 19 to 21; and the corresponding times and temperatures at
which the samples were taken are graphically represented in Figure 2,
page 14. The "A" and "B" batches of oil were heated in open kettles,
the "A" series being heated at a higher temperature for a much longer
period of time. The "C" series was heated in vacuum for a short time to
about the same temperature as the "B" batch of oil, the samples being
drawn with shorter time intervals and toward the end of the heating
process. With each type of heat-bodying, the oil progressively changed
from the pale yellow, free-flowing oil to one with deepening color, in
creasing viscosity, and a tendency to become cloudy with separating
stearine.
Due to the relatively recent advent of sardine oil into industrial
use, a review of the literature revealed little material of significance
to this study. Many of the articles dealt with specific properties of
the oil as affecting its use in certain industries, notably in the manu
facture of paint and varnish, linoleum, and oilcloth. A few of the ar
ticles discussed the value of sardine oil as a source of vitamins for
3
chickens when mixed with their feed. Some properties of the oil were
found listed; but it was considered more appropriate in describing the
particular grade of oil used, to report the data supplied by the com
panies that furnished the oil.
According to a communication to the writers from the California
Flaxseed Products Company.
The composition of the oil apparently has not been definitely
established. Referring to various sources in the literature, we
find that the following component fatty acid glycerides have been
identified:
Myristic C14H28O2 6%
Palmitic C16H32O2 12-14$
Stearic ^18^36^2 2— 4$
Falmitoleie GieH3G02 14-16$
Linoleic C^gHggOg 30$
fGgo to C24 ^ Clupanodonie]
Therapic V
Jecorie J
with 4 to 6
double bonds
18$
The above data should not be interpreted as the specific composi
tion of sardine oil. However, these approximate relations can be
considered as representative of the average product.
The Vegetable Oil Products Company Technical Bulletin No. 5 (re
vised July 1, 1937) gives the following physical and chemical constants
for the grade of oil being considered: Wijs iodine value, a minlmnm of
195; maximum acid number, 0.5; winterized, hours oil remains clear when
chilled at 0° C., 8; Gardner Holdt viscosity, A; specific gravity at
15.5° C., a minimum of 0.930; color on the Lovibond scale, a maximum of
35Y/3.0R. The oil having been "winterized" or "zerolized" means that
the amount of unsaturated acid radicles has been lowered by cooling the
oil and removing the settled solids.
Organ!zation of the thesis. Chapter I has dealt with a statement
4
of the problem, its importance, and the nature of the sardine oil under
consideration. Chapter II treats of the method employed and the results
obtained in the determinations of molecular weight of the various sam
ples of oil. The refractive index of each of the oil samples is given
in Chapter III. The methods used in emulsifying the oil and the results
obtained are presented in Chapter IV. In Chapter V appears a summary of
the work completed.
CHAPTER II
MOLECULAR WEIGHT DETERMINATIONS OF SAMPLES
OF HEAT-BODIED SARDINE OIL
The molecular weight of several samples in each of the three se
ries of heat-bodied sardine oil was determined from the freezing-point
depression of a benzene solution of the oil, by means of the Beckmann
freezing-point method. This chapter includes a description of the meth
od used and the reasons for its selection, the experimental procedure
followed, the calculation of molecular weights, charts and figures of
data and results, and an Interpretation of the results.
The method used. The freezing-point of a solution is the temper
ature at which the solution exists in equilibrium with the solid sol
vent.^- As pointed out by one authority, the freezing-point of a liquid
is lowered by the addition of a solute; and the amount of this depres
sion is directly proportional to the concentration of the solution.2
The method of determining molecular weights devised by Beckmann:is' based
on this freezing-point lowering, and involves finding the freezing-point
first of the pure solvent and then of the solution containing a weighed
amount of solute. From the amount of depression the molecular weight of
the solute can be calculated as described on page 8.
* E. B. Millard, Physical Chemistry for Colleges (New York:
McGraw-Hill Book Company, Inc., 1936), p. 169.
2 F. H. Getman and F. Daniels, Outlines of Theoretical Chemistry
(New York: John Wiley and Sons, 1931), p. 174.
6
Benzene was found to be a satisfactory solvent for the oil, with
a convenient freezing-point, and with a fairly large molal freezing-point
constant. For these reasons the Beckmann freezing-point method for de
termining the molecular weight of each oil sample, using a Beckmann dif
ferential thermometer, was adopted. In addition, freezing-point depres
sions
... have two distinct advantages over boiling-point elevations, in
that the latter are considerably influenced by changing atmospheric
pressure during the process of a determination, while the freezing-
point depressions are not affected ... Also, at the low tempera
tures of freezing solutions, there is less danger of losing the sol
vent by evaporation.3
Experimental procedure. The steps in a molecular weight determi
nation included the "setting** of the thermometer, determination of the
freezing-point of benzene, dissolving of the oil sample and determination
of the freezing-point of the solution, and calculation of the molecular
weight of the oil sample. The Beckmann thermometer was set and the
freezing-point of the benzene determined in the usual manner, following
the experimental procedure outlined by Reilly and Rae.4 In Figure 1, a
diagram of the Beckmann freezing-point apparatus used, A is the Beckmann
thermometer, B and G are mercury reservoirs, D is the freezing chamber,
E is the outer jacket, F is the ice-water bath, G is the thermometer for
the bath, and H is the wire stirrer for the solvent. The dissolving of
the oil sample and the calculation of its molecular weight are elaborated
below.
3 Millard, 0£. cit.. p. 173.
4 J. Reilly and W. N. Rae, Physico-Chemical Methods (Hew York:
D. Van Nostrand Company, Inc., 1933) / pp'. 437-40.
FIGURE 1
BECKMANN FREEZING-POINT APPARATUS
8
Dissolving of the oil sample and determination of the freezing-
point of the solution. About 0.5 grams of sardine oil were accurately-
weighed into a small flask, and dissolved in 20 cc. of benzene measured
by means of a pipette. The pipette had previously been calibrated so
that the weight of benzene delivered was accurately known. When the oil
had completely dissolved, the solution was poured into the inner tube D
and its freezing-point determined in the same manner as for pure benzene.
Precautions were taken to prevent, as much as possible, evaporation of
the highly volatile solvent. The experimental conditions were carefully
duplicated for each determination in order to assure consistency of re
sults. A few of the oil samples were found to contain a polymer cloud of
separating, solid stearin; these were cleared by heating in a water bath
for a few minutes to about 60° 0.
Calculation of molecular weight. In calculating the molecular
weight of a given sample of sardine oil, use was made of the principle
that if g grams of solute are dissolved in G grams of solvent, and the
freezing-point is thereby lowered by the amount Atf, then the molecular
weight M of the solute is given by the equation,
_ 1000 • Kf» g
G . Atf
where Kf is the molal freezing-point depression constant of the solvent.
This constant has the value 5.12 for benzene.5 Tables I, II, and III
list the data which, when substituted in the above equation, yielded the
molecular weights shown for the "A,** MB,M and "CM series of oil samples
5 Getman and Daniels, op. cit.. pp. 176-77.
respectively. A typical calculation, that for A-3 $1, follows:
1000*5.12»0.656 „
“ ' 17.43 (5.349-5.174) " 1101
If the first two determinations of the molecular weight of a given
sample' agreed within a few tenths of a per cent, the average of these was
taken as the molecular weight of the sample. When the agreement was
around one per cent, successive determinations were made and the molecular
weight taken as the average of the three values closest in agreement.
Interpretation of results. Table I shows that, beginning with the
sample A-3 drawn at a temperature of 555° F., this temperature then being
maintained for the entire period, successive samples of the "A1 * series
were found, starting with the molecular weight of 1104, to increase each
hour by the respective amounts 167, 101, 70, 40, 23, and 31, to a final
value of 1536. The apparent discrepancy of the increase in molecular
weight of the final sample would be explained by the longer time interval
as the oil slowly cooled to room temperature.
In the case of the WBM series, tabulated in Table II, the first
sample was taken at room temperature, the second sample two hours later
when the temperature had reached 400° F., and the successive samples to
B-8 at temperature increments of twenty-five degrees until a main mum of
535° was reached. This temperature was maintained for twenty-five min
utes , the last two samples being drawn as the oil cooled to 525° F.
During the initial three hours of heating, as the temperature rose to
about 500°, the molecular weight of the oil decreased from 833 to 815 and
then returned slowly to the original value. In the final three hours of
heating, the molecular weight increased rapidly from 833 to 1143, the
10
value for the last sample.
Table III shows that the WCM series of samples, starting at 505°
3?., were taken at half-hour intervals until the temperature reached a
rngnrtmnm of 530° four hours later. These samples were heated in vacuum,
whereas the "A" and "Bw samples were heated in an open kettle exposed to
the air. The molecular weights of the HC* series samples increased at a
fairly steady rate from 1036 to 1242, a gain of but 206 for the four hours
of heating.
Tables I, II, and III present the experimental data and the molec
ular weights determined for the samples of sardine oil in each of the
three series. Figure 2 shows a diagram of the time-temperature schedule
followed, and Figure 3 graphically represents the change in molecular
weight of the oil with time, under the different conditions of heat-
bodying.
From an examination of Figures 2 and 3, it can be seen for series
"B,” where the oil was heat-bodied at a relatively low temperature for a
short time, that during the initial stages of heating there was not only
a time lag in polymerization, but the molecular weight of the oil actually
decreased about eighteen points. Then the molecular weight of the poly
merizing oil increased very rapidly to about eleven hundred, finally in
creasing more slowly as the oil was allowed to cool.
The curve for the "A" series of samples shows the rate of polymer
ization of the oil when the heating was continued for a much longer period
of time at a constant, rather high temperature of 555° F. As shown by
successive molecular weights, the rate of polymerization continued steadily
11
TABLE I
MOLECULAR WEIGHTS OF SARDINE OIL, HA* SERIES SAMPLES
• Sample
number
Grams
ofUoil
Grams of
benzene
F. P.
benzene
F. P. '
solution
F. P.
depression
Moi;
wt.
A-3 #1 0.656 17.43' 5.349 5.174 0.175
1101
a-3 m 0.693 17.43 5.349 5.166 0.183 1111
A-3 #3
0.689 17.43 5.349 5.165 0.184
Average
1099
1104
A-5 #1 0.755 17.43
5.292 5.118
0.174
1272
A-5 0.661 17.43 5.292 5.139
0.153
Average
1269
1271
A—7 #1 0.761 17.43
5.292 5.127 0.165 1356
A—7 #2 0.790
17.43 ' ■ 5.292 5.125 0.167 1388
A-7 #3
0.525 17.43 4.883 4.771 -0.112 1379
A—7 #4 0.941 17.43 4.883 4.681 0.202-
Average
1368
1372
A-9 #1 0.653 17.43 4.883 4.750 0.133
1441
a-9 m
0.806 17.43 5.292
5.128
0.164 144^
A-9 #3 0.615 17.43
5.292 5.167 0.125
Average
1444
. 1442
A—11 #1 0.642 17.43 5.-292 5.165
0.127
1483
A—11 J2 0.411 17.43
5.380 5.298 0.082 1472
A—11 #3 0.605 17.43
5.380 5.261 0.119
Average
1492
1482
A-13 #1
O.348
17.43 4.883 4.815 . 0.068 1501
a-13 m
0.360
17.43 ■ 4.883 4.813
0.070
Average
1^09
1505
A—15 #1
0.418
17.43
5.380 5.300 0.080 1532
A-15
0.330 17.43 4.943
4.880
0.063 1538
A-15 #3
0.367 17.43 4*943 4.873
0.070
— Average
1539
1536
12
TABLE II
MOLECULAR WEIGHTS OF SARDINE OIL, «B* SERIES SAMPLES
Sample
number
Grams
of oil
Grams of
benzene
F. P.
benzene
f. : p.
solution
F. p.
depression
Mol.
wt.
B-l #1 0.481 17.30 5*501 5.330 0.171 832
B-l #2 0.485 17.30 5*501 5.328
0.173 830
B-l #3 0.583 17.30 5*501 5.295 0.206
Average'
8^7
833
B-<2 #1 0.491 17.27 5*501 5.322
0.179 813
B-«2 . #2
-0.534
17.27 5*501 5*308
0.193
820
B-« #3 0.623
17*27
5*334
5.107 0.227
Average
814
816
B-3 #1 0.584 17.27
5*334
5.121 0*213 813
b-3 m 0.5% 17.27
5.334
5.118 0.216 819
B-3 #3
0.788 17.27
5.334
5.047 0.287
Average
812
815
B-4 #1 0.574
17.27
5.334 5.124
0.210 810
B-4 #2 0.565 17.27
5.334
5.129 0.205 817
B-4 #3
0.757 17.27
5^334
5.060
0.274
Average
820
818
B-5 #1
0.561 17.27
5.395
5.197 0.198 820
b-5 m.
0.690 17.27 5.395 5.147 0.248
Average
825
823
B-8 #1 0.840 17.27
5.395 5.143
0.252 988
B-8 #2 0.871 17.27
5.395 5.129 0*266 972
B-8 #3 0.796 17*27 5.487 5.249 0.238
Average
983
981
B-9 #1 0.802
17.43
5*487
5.263 0.224
1050
B-9 #2 0.751 17.43
5.487 5.278 . 0.209
Average
1£&
1052
B—10 #1 0.761
17.43 5*487 5.287 0.200 1118
B-1Q #2 0.783 17.43 5.487 5.280 0*207
1123
B-10 #3 0.878
17.43 5.487 5.256
0.231 1115
Average 1119
B—11 #1 0.577
17.43 5.314 5.165 0.149 1138
B—11 #2 0.771
17.43 5.314 5.115 0.199 1138
Average 1138
13
TABLE III
MOLECULAR WEIGHTS OF SARDINE OIL, SERIES SAMPLES
Sample
number
Grams
of oil
Grams of
benzene
,F. P.
benzene
F. P.
solution
F. p;
depression
Mol.
TWt.
C-l #1
c-i m
0.7^8
0.626
17.43
17.43
- 5.314
5.314
5.102
5.137
0.212
0.177
Average
1036
1038
1037
C-2 #1
G-2 #2
0.693
0,706
17.43
17.43
5.314
5.314
5.125
5.121
0.189
0.193
Average
1075
1072
1074
0-4 #1
C-4 #2
0.755
0.349
17.43
17.43
5.349
5.349
5.155
5.173
0.194
0.176
Average
1142
11&
1142
C-5 #1
C-5 #2
C-5 #3
0.640
0.749
0.598
- 17.43
17.43
17.43
-5.394
5.394
5.394
5.235
5.205
5.244
0.159
- 0.189
0.150
Average
1181
1162
1170
1171
0-7 #1
C-7 #2
0.885
0.662
17.43
17.43
5.394
5.394
5.181
5.235
0.213
0.159
• Average
1220
12.22
1221
G -t 8 . #1
C-8 #2
“ 0.695
0^561
17.43
17.43
5.394
5.394
5.230
5.261
0.164
0.133
Average
1244
1239
1242

16
to become less rapid during the entire heating process, and to become
very slow after about fifteen hours* heating. At this point the molecu
lar weight had become 1505. The final sample taken after the oil had
cooled to room temperature, had polymerized a little further to give a
molecular weight of 1536.
No definite conclusions can be made concerning the *Cn series of
samples, heat-bodied at a lower temperature in vacuum, since the samples
furnished covered such a short time and temperature range. During the
time of continued heating, however, the rate of polymerization, as shown
by the molecular weight-time curve, increased at a steady rate to about
1200 at 530° F.
The three curves of Figures 2 and 3 considered together seem to
justify the assumption that both the duration of heating and the tempera
ture attained are important factors controlling the rate of polymerization;
consequently both must be taken into account in working out time-temperature
schedules for the heat-bodying of sardine oil to any desired point. When
the process was carried out in vacuum, the same time and temperature re
sulted in a somewhat greater degree of polymerization, but in a more
clouded product for the samples of higher molecular weight.
CHAPTER III
THE REFRACTIVE INDEX OF HEAT-BODIED SARDINE OIL
This chapter deals with the determination of the refractive index
of the samples in each of the three series of California sardine oil pre
pared and heat-bodied as described above, page 9. An Abbe refractometer
was used for the determinations at a constant temperature of 23.9° C.^
Successive readings were made on each sample of oil until agreement was
obtained to within one ten-thousandth unit on the refractometer scale#
Tables IT, T, and VI give the refractive index of each sample of oil in
the WA,W "B,w and "C” series respectively. Figure 3 shows the curve ob
tained by plotting refractive index against the time of heat-bodying? and
Figure 4 shows the relationship between the refractive index and the mo
lecular weight for each of the three series of samples.
Interpretation of results. From a comparison of Figure 3, on page
15, with Figure 4, on page 22, it is apparent that the curves obtained by
plotting molecular weight against time and refractive index against cor
responding times, are of the same general shape in each case. This would
seem to indicate that some degree of relationship exists between the
changes in molecular weight and the changes in refractive index that occur
during the heat treatment of the oil. This relationship is further sub
stantiated by the curves of Figure 5, page 23, where the molecular weight
1 F. Daniels, J. H. Mathews, and J. W. Williams, Experimental Phys
ical Chemistry (New York: McGraw-Hill Book Company, Inc., 1929), p. 325.
18
was plotted against the corresponding refractive index for each sample
in the three series of determinations. I2xcept in the case of the WBM
series at low temperatures during the initial heating period, where there
was an apparent lag in polymerization as shown by the molecular weights,
the curve for each of the three series has approximately the same slope,
and tends to become a straight line over comparable temperature ranges.
In order, however, to formulate a definite mathematical relationship be
tween the molecular weight and the refractive index of heat-bodied sar
dine oil, it would be necessary that a much larger number of determina
tions be made over a greater variety of time-temperature schedules.
19
TABLE IV
REFRACTIVE INDICES OF SARDINE OIL, "A* SERIES SAMPLES
Sample Time Temp. °F. *R. I.
A—1 8*00 300 1.4797
A-2
10*30
525 1.4832
A-3 11*35 555 1.4863
A-4 12*35 555
1.4876
A-5 1*35 555 1.4884
A-6 2:35 555 1.4889
A-7 3*35 555 1.4893
A-8
A* 35 555
1.4897
' A-9 5*35 555
1.4900
A-10 6*35 555
1.4902
A-ll 7*35 555 1.4904
A—12
8*35 555
1.4907
A-13 9*35 555
1.4910
A-14 10*35 555
1.4912
A-15
Next
A.M.
77
1.4913
*R.I. of water » 1.3319
@ 23.9° C.
so
TABLE V
REFRACTIVE INDICES OF SARDINE OIL, «B* SERIES SAMPLES
Sample Time Temp. °F. R. I.
B-l 7:30 - .1.4803
B-S 9:30 400 1.4806
B-3 9:50 m
1.4808
B-4 10:05 450 1.4810
B-5 10 $25 475 1.4815
B—6 11:15
500 1.4832
B-7 11:4-5 525 1.4845
B~8 12 $20
535
1.4858
B-9 12:45 535
1.4867
B—10
1:15 530 1.4873
B-ll 1:45 525 1.4876
21
TABLE VI
REFRACTIVE INDICES OF SARDINE, OIL, «C" SERIES SAMPLES
Sample Time Temp* OF. R. I.
C-l 11*30 505 -- 1.4851
C-2 12*00 510 1.4857
C-3
12*30 518 . 1.4862
C-4
1*00
524
1.4867
C-5 1*30 525
1.4870
€r-6 2*00 526 1.4873
C-7 2*30 528 1.4876
G—8 3*15 530 1.4879
at#* com d c* —_
M „ /:im t t ..:____: td i_ t a ?__
CHAPTER IV
EMULSIFICATION OF SARDINE OIL
This chapter deals with the experimental work done on the emulsi-
fication of California sardine oil, using various common emulsifying
agents and several methods of agitation. The oil used was of the grade
known as "Varnish Maker’s" sardine oil. The emulsifying agents included
triethanolamine, gelatin, gum acacia, egg-yolk, corn starch, casein, and
sodium hydroxide. Continuous shaking, intermittent shaking, rolling in
a bottle, grinding in a mortar, and beating with an egg beater comprised
the methods of agitation employed with the different emulsifying agents.
With each agent, different proportions of oil were used. The topics
covered in this chapter appear in the following order: the general prop
erties of emulsions; a description of the experimental procedure followed
and the results obtained with each emulsifying agent; and conclusions.
General discussion of emulsions. "An emulsion," says Thomas,*1
"is a heterogeneous system consisting of drops of one liquid suspended in
the bulk of a second liquid." When two such immiscible liquids are agi
tated together, the liquid which is broken up into discrete droplets is
known as the dispersed or internal phase; the liquid which surrounds the
globules is known as the dispersing medium, or external phase
* ■ A. W. Thomas, Colloid Chemistry (New York: McGraw-Hill Book Com
pany, Inc., 1934), p. 412.
2 William Clayton, The Theory of Emulsions and Their Technical
Treatment (Philadelphia: P. Blakiston’s Son and Company, 1935)V p. 1.
25
There are two general classes of emulsions, simple emulsions of
two pure, immiscible liquids, and concentrated emulsions employing a
third stabilizing substance known as the emulsifying agent. Simple
emulsions ”. . • are not stable when containing more than one per cent
of the dispersed phase.”® Concentrated, more complex, stable emulsions
of either the oil in water ( 0/W) or water in oil (W/0) type are possible
when a third substance, the emulsifying agent, is absorbed at the inter-*
face, forming a stabilizing film.4 The viscosity of dilute emulsions
does not differ greatly from that of water; but the viscosity of concen
trated emulsions increases rapidly with an increase in concentration of
the dispersed phase.
According to Thomas,® emulsifying or dispersing agents can be
classified as crystalloid, colloid, and insoluble solids. In general,
salts of carboxyl, sulfonic, sulfinic, ethereal sulfuric, or phenolic
groups constitute the crystalloidal dispersing agents. The agents most
commonly used, however, are colloidal in nature, and include soaps, res-
inates, proteins, gums and mucilages, carbohydrates, egg-yolk, cholesterol,
saponin, triethanolamine soaps, and lanolin. Finely divided, insoluble
solids sometimes used as emulsifying agents are basic copper sulfate,
® Harry N. Holmes, Introductory Colloid Chemistry (New York; John
Wiley and Sons, Inc., 1934), p. 71.
4 Clayton, op. cTt., p. 80.
® Emil Hatschek, An Introduction to the Physics and Chemistry of
Colloids (Philadelphia: P. Blaklston's Son and Company, 1925), p. 78.
® Thomas, op. cit., pp. 424-25.
26
kaolin, Fuller*s earth, and basic zinc and aluminum sulfates.
Whether an o/W or a W/0 type of emulsion is formed depends upon
such factors as the relative volumes of the two liquids used, whether one
phase is added in bulk or in small portions, and the type of emulsifying
agent employed. With sufficient agitation, however, the most stable type
of emulsion will invariably result.7 Bancroft8 adds that: ”... the
type of an emulsion depends upon the nature of the emulsifying agent and
not upon the relative masses of the two liquids.”
The simplest general formulation— which we owe to Briggs— is that
we get oil-in-water if the emulsifying agent at the interface is
chiefly in the water phase and water-in-oil if the emulsifying agent
at the interface is chiefly in the oil phase*8
Recognition of the-emulsion type was accomplished by two methods.
One method required adding separately a drop of oil and a drop of water
to a drop of the emulsion being tested. The liquid which readily mixed
with the emulsion was the liquid comprising the dispersion medium. The
second method consisted of sprinkling a few minute crystals of an oil-
soluble dye, either Sudan III or Scarlet'R,'on the surface of a drop of
the emulsion. A rapid spreading of the color of the dye indicated oil
as the external phase.These two means were used for mutual verifica
tion of the emulsion type.
7 Holmes, op. clt., p. 76.
8 V/. D. Bancroft, Applied Colloid Chemistry. General Theory (New
York: McGraw-Hill Book Company, Inc., 1926), p. 359.
8 Ibid., p. 352, citing Briggs (unpublished work).
Holmes,; op. cit.. p. SO.
RESULTS WITH DIFFERENT EMULSIFYING AGENTS
27
Triethanolamine. A four per cent solution of triethanolamine in
water was agitated with the sardine oil, acting as an emulsifying agent
by forming soaps with the fatty acids present in the oil. Table VII
gives the percentage of oil used (the remainder consisting of the solu
tion of the emulsifying agent), the method and time of agitation, the
immediate-appearance of the product, the per cent of the emulsion that
had broken at the end of two weeks, and the type of emulsion formed.
From an examination of Table VII, it is evident that intermittent
agitation for ten minutes, divided into alternate periods of five shakes
and of thirty seconds rest, continuous shaking for ten minutes, and con
tinuous rolling of the bottle for five minutes, all resulted in emulsions
of the same appearance, type, and relative separation of layers upon
standing. Ihether the oil was added gradually in small amounts or in
bulk before agitation, had no effect on the type of emulsion formed.
During the process of separation it was found in every case that the layer
of 0/W emulsion was of an ivory or white color and lay between a lower
opalescent layer of dilute, breaking 0/W emulsion and a yellow layer of
dilute, breaking W/o emulsion above. Agitation with the egg beater re
sulted in a larger percentage of stable 0/W emulsion.
Gelatin. A four-tenths per cent solution of gelatin in water was
used as an emulsifying agent with various proportions of the sardine oil.
An examination of-the data in Table VIII shows that stable emulsions were
formed only when the oil was added gradually, either with intermittent
S8
TABLE VII
EMULSIFICATION - OFuSAfiDINE OIL WITH -TRIETHANOLAMINE
No.
Per
cent
oil
Method-of
agitation
»
Immediate
appearance (
Per cent
broken .
end-S wks.
Emul
type
1 <26
........................j , . . .
( intermittent shak
ing for 10 minutes ® <
pale yellow creamj
foamy < •
90 ~0/W
•2
74
intermittent shak
ing for 10 minutes
light yellow,
smooth cream
98 o/w
3 74'
egg beater for 10
minutes
_ cream-colored
mayonnaise
40 o/w
4 74
rolled in bottle
for 5 minutes
light yellow cream;
began breaking
no emulsion
5 74
continuous shaking
for 10 minutes
light yellow cream;
began breaking
no emulsion
6 10 rolled in bottle
for 5 minutes
pale yellow cream;
began breaking
95
.o/w
7 50 —egg beater 10 mins.,
oil added gradually
light yellow cream;
very foamy
80 O/W
3 9°
egg beater: 10 mins.,
oil added gradually
thick, pale yellow
cream
10 O/W
. .9
60 egg beater 10 mins.;
4% oleic acid added
white, foam-like,
whipped cream
SO o/w
10
n
intermittent shak
ing, oil added grad.
cream-colored
mayonnaise
80 0/W
29
ghwTri ng by hand or continuous agitation with the egg beater. The emul
sion formed in each case was of the O/W type with a slight separation of
an opalescent liquid on the bottom. Gelatin, partly because of its fa
vorable viscosity when cooled below room temperature, acts as an emulsi
fying agent by forming a hydrated colloid with water.
Gum acacia. The pharmaceutical method of preparing emulsions by
triturating four parts oil, two parts gum acacia, and three parts water
together in a mortar was tried, using both the Continental and the
American methods of procedure. These two methods differ only in the
order of adding the ingredients. In the first method, the oil and gum
are thoroughly mixed, and the water added in bulk, the entire mass then
being stirred until a thick creamy emulsion results. In the American
method, the gum is first peptized by the water, the oil then being added
gradually as the mixture is triturated.
The Continental method is considered by Clayton^ to be superior;
but with the sardine oil, no apparent difference in results was observed.
In both cases an almost white, gelatinous emulsion was formed, with a
slight separation of opalescent liquid on the bottom after two weeks'
standing. The gum acacia acts as an emulsifying agent due to its func
tioning both as a finely divided solid and as a hydrophilic colloid.
Egg-yolk. A sardlne-oil mayonnaise was prepared with egg-yolk,
mustard-, salt, and vinegar. Fifteen cc. of egg-yolk were beaten with 0.5
grams each of mustard and salt, 100 cc. of the oil and 9 cc. of vinegar
11 Clayton, ojn cit., p. 63.
30
TABLE VIII
EMULSIFICATION OF SARDINE OIL WITH GELATIN
No. _
Per
cent
-^oil
Method of , r J J
agitation
Immediate
appearance
!
Per cent
broken
end 2 wks.
Emul,
type
1 26 intermittent shak
ing for 10 minutes
very pale,
yellow cream
97
—T----
o/w
-2
n
intermittent shak
ing for 10 minutes
light-yellow
cream.
90 o/w
3 n
egg beater for 10.
mins^il added grad.
pale-yellow
mayonnaise
2 o/w
A n
rolled in bottle
for 10 minutes
light-yellow
cream
no emulsion
5 n
continuous shaking
for 10 minutes
light-yellow
cream
80 o/w
6 90 egg beater 10 mins«>
oil added gradually
pale-yellow
mayonnaise
10 o/w
,7 n
intermittent shak
ing, oil added grad.
cream-colored
mayonnaise
5
o/w
31
being added gradually with continuous agitation by the egg beater. The
result was a light yellow, stiff mayonnaise that was completely stable,
and of fine, uniform texture. A similar mayonnaise was made with inter
mittent shaking by hand and with the same amounts of ingredients, except
that to obtain a comparable product nearly twice as much oil was required.
A third preparation was made using only one-half the original amount of
oil and agitating with the egg beater. A stable emulsion did not result,
oil separating out on top of the emulsion.
Both the mustard and the egg-yolk acted as emulsifying agents in
this case. The mustard formed a finely divided solid'at the oil-water
interface; and the egg-yolk acted as a hydrophilic colloid. Egg-yolk was
used in preference to the entire egg, as the white has only one-fourth
the emulsifying capacity of the yolk.12 All of the emulsions formed were
of the O/W type.
Corn starch. An attempt was made to prepare emulsions with corn
starch as the emulsifying agent, peptizing it both in cold water and by
warming. Regardless of the proportions of oil used or whether agitation
was by intermittent shaking, trituration in a mortar, or mixing with the
egg beater, no stable emulsions were formed. In a short time there was
complete separation into an oil layer on top and a suspension of starch
in water at the bottom.
Cjasein. Two grams of casein in each of three mortars was triturated
12 Holmes, op. cit., p. 78.
32
with 26 cc. of water. The first was 0.05 N with hydrochloric acid, the
second neutral, and the third 0.05 N with sodium hydroxide. The casein
was allowed to peptize for a period of four hours. Then 74 cc. of oil
was triturated into each of the three "solutions." Not even a temporary
emulsion formed with the neutral casein. With both the acid and basic
solutions an O/W emulsion resulted, which in the former solution broke
quite rapidly into a layer of oil over a white, curdy emulsion, while that
in the basic solution remained a stiff, pale yellow, stable emulsion. The
casein acts as a hydrated colloid adsorbed to form a protective film. In
the neutral water the casein was insufficiently peptized to the colloidal
state.1®
Sodium hydroxide. Emulsions were prepared using various propor
tions of 0.5 N sodium hydroxide and sardine oil. The sodium hydroxide
did not serve directly as an emulsifying agent but, by reaction with the
fatty acids present in the oil, formed soaps that acted as dispersing
agents by reason of being hydrophilic colloids.14 Table IX shows the re
sults obtained. Whether shaken intermittently by hand or agitated with
the egg beater, an 0/S? mayonnaise-like emulsion with a light yellow color
was formed. In each case there was a tendency for the emulsion to sepa
rate into an oil layer at the top and an amber-colored, watery layer at
the bottom. Greater stability was apparent as the proportion of oil was
increased.
13 M. H. Fischer and M. 0. Hooker, The Lyophilic Colloids
(Baltimore, Maryland! Charles C. Thomas, 1933), p. 135. ~ r
14 M. H. Fischer, Soaps and Proteins (New York: John Wiley and.
Sons, Inc., 1921), p. 175.
33
TABLE IX
EMULSIFICATION OF SARDINE OIL WITH SODIUM HYDROXIDE
No.
Per
cent
oil
Method of
■ * agitation
Immediate
appearance
Per cent
broken
end 2 wksi
&nul.
type
1 26 intermittent shak
ing for 10 minutes
........... — ■ ' ' ■
frothy, yellow
cream; breaking
90 o/w
a
n
-intermittent shak
ing for 10 minutes
frothy, yellow
cream
20 o/w
3 n
egg beater 10 mins.,
oil added gradually
yellow mayonnaise
some froth
: , 20 o/w
A
90 egg beater 10 mins.,
oil added gradually
stiff, yellow
mayonnaise
5
o/w
34
Conclusions. From the results obtained in the emulsification of
sardine oil, using several common representative emulsifying agents and
different methods of agitation, the following conclusions were drawn:
1. The most satisfactory method of agitation was with the egg
beater. Intermittent shaking, with alternate periods of five shakes and
thirty seconds rest, was easier and superior either to continuous shaking
for the same length of time or rolling the liquids in a bottle. With
gum acacia the only method necessarily tried was trituration in a mortar,
and was satisfactory only with this agent-.
2. Stable emulsions were formed only when the percentage of oil
was seventy-four or more, except with the gum acacia, using pharmaceutical
proportions.
3. The most stable emulsions were those containing ninety per cent
of oil, egg-yolk producing the most satisfactory emulsion.
4. All of the stable emulsions, being quite concentrated, were
highly viscous and set to a gel.
5. In every case the stable emulsion was of the oil-in-water type.
Where separation occurred, the top layer was a very dilute water-in-oil
emulsion.
6. The emulsifying value of the various agents toward sardine oil
was found to be in the following approximate order of decreasing effective
ness:
1. Egg-yolk. 4# Casein, basic. 7. Corn starch.
2. Gelatin. 5, Sodium hydroxide solution.
3. Gum acacia. g# Triethanolamine.
CHAPTER V
SUMMARY AND CONCLUSIONS
Summary. This experimental investigation has concerned "Varnish
Makers" grade of California sardine oil. The molecular weight and the
refractive index of samples of the oil, polymerized during three methods
of heat-bodying, were determined. The molecular weights were found by
following the Beckmann freezing-point method; and the refractive indices
were obtained using an Abbe refractometer. Emulsions of the unpolymer
ized oil were prepared with several emulsifying agents and employing dif
ferent means of agitation. The conclusions drawn from the experimental
results follow.
Conclusions. The molecular weights of successive samples of the
oil became slightly less and then slowly returned to the original value
of 833 during the initial three hours of heating. As the heating was
continued and the temperature increased from 500° to 555° F. (the highest
temperature attained), the molecular weight increased rapidly to a value
of about 1300. With continued heating at the maximum temperature, the
rate of increase in molecular weight of the oil became less and less, a
value of 1505 being reached after a period of thirteen hours' heating.
While cooling to room temperature, the oil further polymerized to a final.
molecular weight of 1536. The progress of polymerization of the oil heat-
bodied in vacuum was similar to that of the oil kettled in air over a com
parable temperature range. A sufficient spread of samples was not avail
able, however, to make a definite conclusion possible.
36
The refractive index of the polymerizing oil increased in much
the same manner as did the molecular weight. The refractive index pro
gressed from an initial value of about 1.4300 (corresponding to a molec
ular weight of 833) to a final value of 1.4913 (corresponding to a molec
ular weight of 1536). The curves obtained by plotting refractive index
against the molecular weight of the samples were found to have nearly the
same slope, approaching a straight line for the higher polymers. The
predictive value of this relationship must be further verified by more
extensive experimentation.
In emulsifying the sardine oil it was found that agitation by in
termittent shaking or with the egg beater were the most effective methods
of those employed. The order of decreasing effectiveness of the emulsi
fying agents was found to be egg-yolk, gelatin, gum acacia, casein (basic),
sodium hydroxide, triethanolamine, and corn starch. All the concentrated
emulsions formed were of the oil-in-water type, and those of greatest
stability contained ninety per cent oil and resembled a jellied mayonnaise.
BIBLIOGRAPHY
BIBLIOGRAPHY
Bancroft, W. D., Applied Colloid Chemistry, General Theory. New York:
McGraw-Hill Book Company, Inc., 1936. 489 pp.
California Flaxseed Products Company, a private communication, July 23,
1937.
Clayton, William, The Theory of Emulsions and Their Technical Treatment.
Philadelphia: P. Blakisto^s Son and Company, 1935. 283 pp.
Daniels, F., J. H. Mathews, and J. W. Williams, Experimental Physical
Chemistry. New York: McGraw-Hill Book Cor?)any, Inc., 1929. 475 pp.
Fischer, M. H., Soaps and Proteins. New York: John Wiley and Sons, Inc.,
1921. 272 pp.
Fischer, M. H., and M. 0. Hooker, The lyophllic Colloids. Baltimore,
Maryland: Charles C. Thomas, 1933. 246 pp.
Getman, F. H., and F. Daniels, Outlines of Theoretical Chemistry. New
York: John Wiley and Sons, Inc., 1931. 643 pp.
Hatschek, Emil, An Introduction to the Physics and Chemistry of Colloids.
Philadelphia: P. Blakiston*s Son and Company, 1925. 183 pp.
Holmes, Harry N., Introductory Colloid Chemistry. New York: John Wiley
and Sons, Inc., 1934. 198 pp.
Millard, E. B., Physical Chemistry for Colleges. New York: McGraw-Hill
Book Company, Inc., 1936. 524 pp.
Reilly, J., end W. N. Rae, Physico-Chemical Methods. New York: D. Van
Nostrand Company, Inc., revised edition, 1933. 822 pp.
Thomas, A. W., Colloid Chemistry. New York: McGraw-Hill Book Company,
Inc., 1934. 512 pp.
Vegetable Oil Products Company Technical Bulletin No. 5, July 1, 1937.
ISfere, J. C., The Chemistry of the Colloideil State. New York: John Wiley
and Sons, Inc., 1936. 334 pp.

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Creator Jennings, James T. (author), Walden, Emileen W. (author)

Core Title An experimental investigation of molecular weight, refractive index, and emulsification of California sardine oil.

Contributor Digitized by ProQuest (provenance)

Degree Master of Science

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag agriculture, food science and technology,OAI-PMH Harvest

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