August, 1946
INDUSTRIAL AND ENGINEERING CHEMISTRY
continued for about 20 hours and produced a stand oil of 138 poises at 30" C., measured in a Hijppler viscometer. Stand oil R swas a mixture of oil H (SO\%) with bleached linseed oil (2070), obtained by heating and stirring for a short time a t 176" C. As Figure 1 shows, both stand oils decrca.ed in viscosity at high $hearing stresses. 1
+d
0
853
EFFECT O F MIXLNG
Similar measurements were carried out on mixtures of staiid oils and unpolymerized linseed oil (Figure 2). Stand oil G n'ab prepared by heating bleached linseed oil for a long time in a glass receiver at 290' C. while nitrogen gas rn as passed through Stand oil Fc was prepared by heating bleached linseed oil for 3 hours at 290" in a tin-coated copper vessel while nitrogen gas was passed through (viscosity, 297 poises at 30" C.). The resulting stand oil was mixed with 31y0 linseed oil to form oil F,. The curves show that oils G, He, and Fd have the same viscosities at low shearing stresses. \i7ith a greatw variation in the viscosities of the components, there is a. greater decrease in viscosity at increasing shearing stress. A stand oil giving minimum decrease of viscbosity at increasing shearing stress must be prepared by heating -t:il Smith, L. B. P e t t . and Esther Phipard.
prevention of rancidity, and formation of dark pigments, would result in superior products. Such superiority was reflected in the increased acceptance, which stimulated research and led to development of ultimate quality in dehydrated foods previously unassociated with them. The growth of the dehydration industry during the last three years is indicated by the following figures: The production of white potatoes during the period 194243 was about 50 million pounds (dry n eight) ; the 1944-45 production rose to 129 million pounds. Figures for the corresponding years in the case of beets are 3 million and 7 million pounds, for cabbage 7 million and 10 million pounds, onions 6 million and 21 million pounds, and w e e t potatoes 8 million and 16 million pounds. 16 the evaluation of dehydrated foods, the retention of nutritive value is an obvious criterion. Paradoxically, the literature on this phase of the subject is not veiy extensive. The few pub-
Vol. 38, No. 8
INDUSTRIAL AND ENGINEERING CHEMISTRY
854 TABLE I. Type
Carotene
Ascorbic Acid
SrITA?dIh’ DATA ON
Thiamine
DEHYDRATED PRODUCTS
Riboflavin
Niacin
(IN k ~ I L L I G R A ? I SPER 100 C R A \ h )
TSPP
Camten?
F H I T E POTATOES
Shredded
Average Julienne
bverage Diced
0.03 0.03 0.02 0.04 0.02 0.03 0.10 0.03 0.08 0.01 0.05 0.03 0.03 0.02 0.02
... 0.00 ...
... ...
... Average Diced (sulfited)
0.03
...
15 14 13 23 32 20 13 26 16 71 31 100 78 40 23 8 13 12 11 32
0.10 0.11 0.12 0.07 0.08 0.10 0.09 0.11 0.08 0.09 0.09 0.08 0.10 0.11 0.09 0.09 0.10 0.11 0.09 0.10 .0.10 0 11
40
0.06
0 10
4.5
2.0 5.4 !.3 a. 1 4.9 3.5 4.9 4.1 4.6
Direri
0.US 0 02 0.04
Julienne Averagr
Average Julienne Average Diced
Average
16.1
14.5 14.0 13.3 14.5 9.3 14.1 11.7 12.7 12.1 12.3 11.1 10.5 15.4 14.3 14.0 19.2 13.5
23 39 33 36 33 23 54 39 46 54 19 37 32 32 30 22 48 36
0.04 0.10 0.1, 0.23 0.13 0.06 0.25 0.15 0.18 0.23 0.18 0.18 0.13 0.28 0.23 0.23 0.38 0.22
Flaken
0.14 0.10 0.10 0.16 0.13 0.10 0.15 0.13 0.15 0.25 0.12 0.11 0.11 0.17 0.13 0.12 0.26 0.16
lverage
60.0 69.0 57.0 72.0 67.0 56.0 98.0 86.0 69.0 71.0
10 16 1 2 9 5 16 20 21 11
0.27 0.21 0.31 0.30 0.37 0.38 0.27 0.20 0.27 0.29
Average Shredded (sulfited)
0.13
\ L ri
agr
.. _
1.2 1.5 1.1 1.5 0 8 1 2
0.1.5
34
0.04 0.03
3
0.04 0.04 04
i)
18
0.35 0.34 0.13 0.26 0.07 0.23
0.26 0.12 0.12 0.11 0.14
1.3 U9 1.3 0.7 1.2
0 0 0 0
45 19 43 75 61
n. 1.5
11
2
n
L
0 40
0.15 0 30 0.25 0.16 0.09 0.1%
3 4
0.50 0.75 0.54 0.73 0.52 0.61
0.15 0.30 0.25 0.18 0.19 0.21
3 .0 4.0 3 .1 2.6 2.6 3 1
0.15 0.30 0.20 0.13 0.18 0.20
3.0 4.7 2.2 2.5 2.7 3.0
0.09
I. 8
0.30
6.5
0.06
0.9 0.7 0.6 0.7
l.U
4.2
2.0 1.3 1.8
? 3
I
iveragr
0.11 0.12 0.12 0.16 0.15 0.13
ivprage
0.11 0.12 0.11 0.20 0.04 0.12
1.5
1.8 1.7 1.9 1.7 1.7 2.1 1.9 2.2 2.1 1.9 2.1 1.8
..
1 5 3
YELLOW PEAS o n 3 5 1 1 4
3 CHICKEN
0.50 0 70 0.49 0.76 0.60 0.61
NOODLE SOUP
2.2
0.05
1.7 9.1 2.0
TOMATO JCICECOCKTAIL 4 90 80 0.45
I .
0 30 0.25 0.17 0.39 0.20 0.26
I
1
0.15
CRANBERRIE~ 0.30 0.25 0.34 0.30 0.30 0.32 0.25 0.25 0.24 0.28
2.6 .5 . 0 2.5 2.2 2.8 2.5 6.0 3.0 2.4 3.2
Average
0 75 0 32 0 15 n 44
28 58 18 32
0.20 0.13 0.14 0. lfi
WHOLE PRUNE6
0 32 0 79
0.05
0.08
BPRICOTHALVEE 6 0.01
2
0.15
PEACH H l L V E S
0.45 0.30 0.19 0.30 0.31
145 266 180 165 189
0.50 0.19 0.45 0.50 0.41
0.45 0.40 0.32
0.45 0.28
360 323
0.40 0.40
...
365 355
0.09 0.22 0.11 0.11 0.13
...
Average
3
0 11
0.04
CABBAOE Shredded (unsulfited)
?
0.18 0.09 0.04 0.25 0.10
?
35 35 60 23
...
lverasp
3.8 6.2 .5. 1
1
04
0.15 0.89
4..5
5 3
r)
0 . 05
4.3
-1.0 4.9 4.6 3 ,R 4.2 4. I
0
n .o.s
CARROTS Diced
Sincin
CJSIOSS
SWEETPOTATOES Sliced
Kibuflavin
BEET0
0.09 0.18 0.09 0.33 0.29 0.20 0.1% 0.22 0.04 0.13 0.15 0.42 0.50 0.35 0.30 0.30 0.30 0.41 0.35 0.34 0.30 0.36
E
hscorbic Acid Thiamine
0.36
351
0.30 0.37
0.33 0.37 0.37
2.2 2.5 1.9 3.0 2 4 3.9 2.7 2.1 2.2 2.7
lished reports relate, in large part, t o analyses on products dehydrated on a laboratory scale, and extrapolation of such data to c o m m e r c i a l l y produced material is probably scientifically unsound. Because of the paucity of data on commercial samples of dehydrated foods, the Army asked that the National Research Council, through its Committee on Food Composition, sponsor a survey t o ascertain the nutritive value of the various products purchased for feeding soldiers in the foreign theaters. Naturally, the survey placed emphasis on products which were of greatest importance and acceptability t o the soldier. The survey was started early in 1944 and, when completed, involved almost a hundred commercial samples. The products included were: white and sweet potatoes, carrots, cabbage, beets, onions, navy bean soup, yellow pea soup, chicken noodle soup, green pea soup, tomato juice cocktail, cranberries, prunes, apri-
2 5
40
0.01
0 I7
APPLE N ~ O G E T B 12 0.00
Average
7 7 10 9
0.02 0.04 0.01 0.02
cots, peaches, and apple nuggets. Special care was exercised to assure products directly off the production line so that storage losses could not complicate the picture. Samples were prepared from the usual 5-gallon packages in the case of vegetables and from the smaller cartons when soups and dehydrated fruits were being tested. Approximately 50-gram samples were sent to the collaborating laboratories, and large subsamples were requested to ensure a minimum of sample deviation. All results reported represent data from at least two laboratories and, where agreement mas not good, a referee analysis was solicited. As the survey progressed, it became evident that variations of considerable magnitude existed in the same product. For example, a tenfold variation in the ascorbic acid content and a similar variation in the thiamine content of white potatoes was noted. It was for such reason that complete operational and raw product
856
INDUSTRIAL AND ENGINEERING CHEMISTRY
Limit specified by the Army for dehydrated veget.ables. Samples for these determinations, in contrast to t,hose sent out for vitamin analysis, r e r e not prepared immediately: t,herefore, some gain or loss of moisture may have taken place. I n general, it is perhaps fair to state that the major point iii favor of dehydrated products is their concentrated form w d adaptability to storage. The common observation is that thow products showing good vitamin retention are usually those POPsessing superior palatability and acceptance. From this standpoint alone the criterion of high vitamin content in thr prodiict is to be encouraged. ACKNOWLEDGBIEST
I n this survey the assistance of t'he laboratories of Y.H. Cheldulin, Joseph H. Roe, P. B. Pearson, G. 0. Kohler, E. 11.Nelson, and C. A. Elvehjem is acknowledged in connection with t,he vitamin assays. A. Kramer is responsible for the mineral and prosimate data, and his contributions to the eurvcy are also a c k n o ~ ~ l edged. LITERATURE CITED
I
1) Booher, L. F., Harteler, E. R.. and Hmiton. E. 1T , U. S.Deprt .4gr , Cwc. 638 ( I 942).
Vol. 38, No. 8
'urn. L. E., and Hehorleill. 1). G., Ixu. LNG.CHEM.,36, 912(1944). (3'1 F c n t o n . F., Barilea, B., >foyer. J. C.. Wheeler. K. A., and Tressler. I).I. E:NG. CHEJI.,12, 337-8 (1940).
r6) Loeffler, H. J., and Pontixg, J . I]., IYD.EYG.CHGM.. ..\N.+L. ED., 14, 846-9 (1942).
elson. W.I,,, and Gortner, '7) ;\Iallotte, 51. F., Dawson, C . I1 W. A , ISD.ENG.CHEX.,38, 437-41 (1946). (Si Aforgan, :I. F., Carl. B. C., Hunner, 1f. C.. Kidder. L. E., Hurnrnel, hl., and Peat, ,J. 11..F r i d Products .I., 23, 207-11, 219-21 (1944).
(9) I{m, J. E.. and Kuethrv, C. .I..J . Hid. Chem.. 147, 399-407 (1943). (10) Sarott, H. P., and CliPldeliii. V~ H.. Ibid., 155, 153-60 c1944). (11) Srhults, -1.S.,Atkin, L.. and Prey, C . N., IND. ENU. CHEJI.. ANAL.ED.,14, 35-9 (1942). (12) Snell. E. E.. and Strong, F. .\I.,IDi?., 11, 346-50 (1939). (13) Snel!. E. E.,and TTright, L. D.. J . Biol. Chem.. 139, G75-8G (1941). 14: Tresder, D. K., Mloyer, J. C.. and W h d e r . K. A.. A m . J . Pub. Health, 33, 975-9 (1943).
Accelerated Breaking of Unstable Emulsions H. P. AIEISSNER AND B. CHERTOWMassachusetts I n s t i t u t e of Technology, Cambridge, Mass.
T
A method is discussed for accelerating the break of I n the investigations deEMPORARY emulsions scribed in this paper, a emulsions containing no surface active agents such may be encountered inquantitative study was initias are sometimes encountered in steam distillation, dustrially in liquid-liquid exsolvent extraction, and other processes. The method inally undertaken to determine traction processes and in volves agitating the emulsion w i t h one to four times its the effect of phase ratio on steam distillations; they may volume of dispersed phase material and then allowing the the rate of breaking unstable result when one liquid phase system to stand idle, w hereupon the originally cloudy emulsions. It was found that is dispersed in another in the phase clariiies rapidly. This method was effective in some quantitative reproducibility absence of a stabilizer or after systems, called totally recolerable, regardless of which of of breaking rate could be the emulsifying agent has the two phases present was dispersed. In all other cases, obtained only with a high been destroyed er othernise degree of control. As was called semirecolerable, the method vas effectil e only removed from a stabilized when one of the two phases was dispersed. Successful to he expected from results emulsion. Unlike the large cladlcation was usually attained with a polar but not a of other investigators, results amount of work reported on nonpolar dispersed phase. A totally recoverable system, varied, depending upon traces stabilized systems ( f - 4 ) , relatherefore, usually showed that both phases present conof impurities, slight differtivelylittle has been published tained polar components, whereas a semirecoverable sysences in amounts of impurion unstabilized emulsions. I n tem contained a nonpolar and a polar phase. ties, amount of air bubbles 1910 Ostwald (6) showed that drawn into the system during if an emulsion can be conaeitation. variation in tvue sidered to consist of equaland violence of agitation, upon which phase of the system under sized spherical droplets of one phase dispersed in a second study wet the container walls first, and so on. Many of these continuous phase, the droplets would all touch when the ratio of variables could not be practically controlled in industrial scale dispersed to continuous phase volume was increased to 74.02: operations. Certain qualitative observations, and also a re25.98 or, roughly, about 3: 1. Inversion in a n unstabilized system covery procedure for accelerating the clarification of these would then occur, with the dispersed phase becoming the cont,inuemulsions. however, were unaffected by these factors. The ous phase. Stamm and Iiraemer ( 9 ) studied the rates of brea,k object of this paper is to describe the lat,ter findings. of unstable systems as influenced by various factors, and Roberts (7) investigated their inversion behavior. Hauser and EXPERIMENTAL PROCEDURE Lynn ( 5 ) among others state that phase volume ratio (hereafter Expcrinicntal work involved preparation of c-riiulsions by called phase ratio) has an important influence on the stability of various methods and observation of their qualitative behavior emulsions generally. ' 4 recent development in breaking unstable during brcak. For the systems stutlictl (Tables I and II), a emulsions has been reported by the Selas Corporation (8) nhereby range of phase ratios from 20:l to 1:20 F a s usually explored. 3eparation is effected through the use of a porous medium which .\gitation methods of rmulsion preparat ion were chosen t o cover permits the passage of only that phase Fhich wets it. I
_
