August, 1946 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y 853

continued for about 20 hours and produced a stand oil of 138 poises at 30" C., measured in a Hijppler viscometer. Stand oil Rs was 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

Figure 2. Viicosit y Anomalies of JIixed Linseed Stand Oils

The figure 10' dynes per sq. em. as the highest shar ing stress in printing presses was deduced in Saal and Labout's report (see Acknowledgment). The calculation is too extensive to be published here, but we were able to confirm it by the following experiment: In printing a paper with a highly viscous linseed &and oil without pigment, a t a certain printing velocity a constant picking phenomenon was found, as would be expected. The same picking was obtainable a t the same printing velocity with a pure mineral oil of much lower viscosity. The memure- ments showed that a t a shearing stress of approximately 10' dynes per sq. cm. the linseed stand oil and the mineral oil had the same viscosity. I t should be emphasized that picking in- vestigations should not be carried out on stand oils or, Tome, on printing inks, but always on mineral oils of true Sen-tonian flow.

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 viscosi- ties at low shearing stresses. \i7ith a greatw variation in the viscosities of the components, there is a. greater decrease in vis- cosity at increasing shearing stress.

A stand oil giving minimum decrease of viscbosity at increasing shearing stress must be prepared by heating <:rude vegetable oil until the required viscosity is reached. The mixing of highly viscous stand oil and low viscosity stand oil results in greater anomdirs.

ACKNOWLEDGMENT

The viscometer used in this investigation was made in the laboratories of the Bataafsche Petroleum Maxtschappij and de- scribed in a report on an examination of printing inks carried out by R. E. J. S a d and J. W. A. Labout by request of the In- stituut voor Grafische Techniek. The authors wish to thank R. N. J. Saal for valuable advice and criticism.

, LITERATURE CITED

(1) Freundlich, H. , and Albu, H. IT., 2. angew. C'hem., 44, 56 (1931) . (2) Houwink, R., "Elastizitat, Plastizitiit, und Struktur der Ma-

(3) Meerman, P. G., Verfkronieli, 17, 7 (1944) . (4) Nisizawa, Y., Kolloid-Z., 55, 343 (1931) . ( 5 ) Ostwald, Wo., Trakas, V., and Kohler, R., Zbid., 46, 136 (1928) . (6) Saal, R. N. J., and Koens, G., J . Inst. Petroleum Tech., 19, 1176

(7) Wacholtz, F., Fette u. Seifen, 48, 423 (1941) .

terie", Dresden-Leipzig, Theodor Steinkopf, 1938.

(1933) .

Nutritive Value of Dehydrated J

Vegetables and Fruits PAUL L. PAVCEK AND THE COR/IMITTEE O S FOOD COMPOSITION1

Food cind Y i i trition Board, .Yational Researrh Council, Whshington, D . C .

KDER the stimulus resulting from the increased demands U by the Army and Navy for dehydrated foods, rather revo- lutionary advances along technical lines took place in the dehy- dration industry. Khereas during the last war dehydrated foods were unpalatable and possessed poor storage life, many of the re- cently developed dehydrated products show promise of reaching into present civilian acceptance. Much of this superiority of the nen- dehydrated foods is due to recognition and application of basic principles related t o varietal differences and degree of maturity in the raw product, as well as pioneering developments in washing, blaiiehing, and drying. It TUB to be expected that improved techniques dclcloped in the laborntory and the emphasis placed by the industry on fundamentals, such :ts inactivation of enzymes,

1 The members of the coininittee are: C . .L ELvelijem (chairman), Paul I.. Pavcek (secretary), Charlotte Chatfield, C. S. Frey, Ancel Keys, L. A . S h y n a r d , E. 11. h-elson. P>-t:il Smith, L. B. Pet 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 nutri- tive value is an obvious criterion. Paradoxically, the literature on this phase of the subject is not veiy extensive. The few pub-

854 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 38, No. 8

Type

Shredded

Average Julienne

bverage Diced

Average

(sulfited) Diced

Sliced

Average Julienne

Average Diced

Average

Diced

lverage

Shredded (unsulfited)

Average

(sulfited) Shredded

Average

Carotene

0.03 0.03 0.02 0 .04 0.02 0.03 0 .10 0 .03 0.08 0 .01 0 . 0 5 0 . 0 3 0 . 0 3 0 . 0 2 0 .02

0.00 . . . . . . . . . . . . . . . 0.03

. . .

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 1 4 . 3 14.0 19 .2 13.5

60.0 69.0 57 .0 72.0 67.0 56.0 98 .0 86.0 69 .0 71 .0

0 .45 0.30 0.19 0 .30 0 . 3 1

0 . 4 5 0.28 . . . . . . 0.36

TABLE I. SrITA?dIh’ DATA ON DEHYDRATED PRODUCTS (IN k~ILLIGRA?IS PER 100 C R A \ h )

Ascorbic Acid Thiamine

F H I T E P O T A T O E S

15 0.09 14 0 .18 13 0 . 0 9 23 0 .33 32 0.29 20 0.20 13 0 .1% 26 0 . 2 2 16 0.04 71 0.13 31 0 . 1 5

100 0.42 78 0 .50 40 0 .35 23 0 . 3 0 8 0 .30

13 0 . 3 0 0.41 0 . 3 5 0.34 12

11 0.30 32 0.36

E

40 0 . 0 6

SWEET POTATOES 23 0.04

33 0 . 1 , 36 0.23 33 0 .13

39 0 .10

23 0 . 0 6 54 0 .25 39 0 .15 46 0 .18 54 0 . 2 3 19 0.18 37 0 .18 32 0 .13 32 0.28 30 0 .23 22 0 . 2 3 48 0 .38 36 0.22

CARROTS 10 0 . 2 7 16 0 .21 1 0.31 2 0 .30 9 0.37 5 0 .38

16 0.27 20 0.20 21 0.27 11 0.29

CABBAOE

145 0.50 266 0.19 180 0.45 165 0.50 189 0.41

360 0.09 323 0 .22

0.11

351 0.13 355 365 0.11

Riboflavin

0.10 0 .11 0.12 0.07 0.08 0.10 0.09 0 . 1 1 0.08 0.09 0.09 0.08 0.10 0.11 0 .09 0.09 0.10 0.11 0.09 0 . 1 0

.0 .10 0 11

0 1 0

0.14 0.10 0.10 0.16 0 .13 0.10 0.15 0 . 1 3 0 . 1 5 0 . 2 5 0 . 1 2 0 .11 0 .11 0.17 0.13 0.12 0.26 0.16

0 .30 0 . 2 5 0.34 0 .30 0 . 3 0 0.32 0 . 2 5 0.25 0 . 2 4 0 . 2 8

0 . 4 5 0 .40 0.32 0.30 0 . 3 7

0.40 0 . 4 0 0 . 3 3 0.37 0.37

Niacin

4 . 5 2 . 0 5.4

a . 1 4 .9 3 .5 4 . 9 4 . 1 4 . 6 4 . 3

-1.0 4 . 9 4 . 6 3 , R

4 . I 4..5 3 . 8 6 . 2 .5. 1 5 3

!.3

4 . 2

. _ 1 . I

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 2 . 2 I . I 1.7 9.1 2 . 0

2 .6 .5 . 0 2 . 5 2 . 2 2 . 8 2 . 5 6 .0 3 .0 2 . 4 3 . 2

2 . 2 2 . 5 1 .9 3 . 0 2 4

3 .9 2.7 2 .1 2.2 2 . 7

TSPP

Direri

Julienne Averagr

Flaken

lverasp

\ L ri agr

iveragr

ivprage

Average

Average

hscorbic Camten? Acid Thiamine

0.US 0 02 0 .04

n .o.s r) 04

0 . 05 0.15 0.89 0.1.5

0 11 . . .

0.04 0.03 0.04 0.04 0.04 i) 04

0.11 0 .12 0 .12 0.16 0.15 0.13

0.11 0.12 0.11 0.20 0.04 0.12

B E E T 0

0 0.18 0.09 0.04 0.25 ? 0.10

?

3 0.13

CJSIOSS 35 0 . 3 5 35 0.34 60 0 . 1 3 23 0.26 18 0.07 34 0 .23

0 45 3 0 19

0 43 0 7 5

L 0 40 2 n 61

3 0 . 5 0 4 0 .75

. . 0 . 5 4 1 0.73 5 0.52 3 0 .61

YELLOW PEA S o n 3 0 . 5 0 5 0 70 1 0 . 4 9 1 0.76 4 0.60 3 0 .61

C H I C K E N NOODLE SOUP

0.05 1 0 .15

TOMATO JCICE COCKTAIL 4 90

0 75 0 32 0 15 n 44

0 32

0 79

2 5

80 0.45

C R A N B E R R I E ~ 28 0 . 2 0 58 0 . 1 3 18 0.14 32 0. lfi

W H O L E P R U N E 6

2 0.05

BPRICOT HALVEE 6 0.01

P E A C H H l L V E S

40 0.01

APPLE N ~ O G E T B 12 0.00 7 0 . 0 2 7 0.04

10 0.01 9 0.02

Kibuflavin Sincin

0 30 0 .25 0 . 1 7 0.39 0.20 0 . 2 6

0.26 0 . 1 2 0 . 1 2 0.11 0 . 1 4 n. 1.5

0.15 0 30 0.25 0.16 0.09 0 .1%

0 . 1 5 0 . 3 0 0 .25 0.18 0.19 0 .21

0 .15 0 .30 0 .20 0 .13 0.18 0 .20

0.09

0 . 3 0

0 . 0 6

0 .08

0 .15

0 I 7

1 . 2 1 . 5 1 . 1 1 . 5 0 8 1 2

1.3 U 9 1 . 3 0 . 7 1 . 2 11

l . U 4 . 2 2 . 0 1 . 3 1 . 8 ? 3

3 . 0 4 . 0 3 . 1 2 .6 2 . 6 3 1

3 . 0 4 . 7 2 . 2 2 . 5 2 . 7 3 . 0

I .8

6 . 5

0 .9 0 . 7 0 . 6 0 .7

lished reports relate, in large part, t o analyses on products de- hydrated 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 un- sound. 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 to ascertain the nutritive value of the various products purchased for feeding soldiers in the foreign theaters. Natu- rally, the survey placed emphasis on products which were of great- est importance and acceptability to 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-

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 agree- ment 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 ex- ample, a tenfold variation in the ascorbic acid content and a simi- lar variation in the thiamine content of white potatoes was noted. It was for such reason that complete operational and raw product

856 I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y Vol. 38, No. 8

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.

In 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 POP-

sessing superior palatability and acceptance. From this stand- point alone the criterion of high vitamin content in thr prodiict is to be encouraged.

ACKNOWLEDGBIEST

In this survey the assistance of t'he laboratories of Y. H. Cheldu- lin, Joseph H. Roe, P. B. Pearson, G. 0. Kohler, E. 11. Nelson, and C. A. Elvehjem is acknowledged in connection with t,he vita- min assays. A. Kramer is responsible for the mineral and prosi- mate 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).

'urn. L. E., and Hehorleill. 1). G., Ixu. LNG. CHEM., 36, 912-

(3'1 F c n t o n . F., Barilea, B., >foyer. J. C.. Wheeler. K. A., and Tress- (1944).

ler. I). I<., Am. J . Pub. Health, 33, 799-806 (1943).

(1941). (41 Hennessy. D. J.. ISD. I ~ G . (?HEMI., .kN4I.. ED., 13, 216.-18

(5 ) Lease, E. J., and 11it3chell. .l. ET.. I\i>. E:NG. CHEJI., 12, 337-8

r6) Loeffler, H. J., and Pontixg, J . I]., IYD. EYG. CHGM.. ..\N.+L. ED.,

'7) ;\Iallotte, 51. F., Dawson, C . I1 elson. W. I,,, and Gortner, 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,

(9) I{m, J. E.. and Kuethrv, C. .I.. J . Hid. Chem.. 147, 399-407

(10) Sarott, H. P., and CliPldeliii. V~ H.. Ibid. , 155, 153-60

(11) Srhults, -1. S., Atkin, L.. and Prey, C . N., IND. ENU. CHEJI..

(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

14: Tresder, D. K., Mloyer, J. C.. and W h d e r . K. A.. Am. J . Pub.

(1940).

14, 846-9 (1942).

219-21 (1944).

(1943).

c1944).

ANAL. ED., 14, 35-9 (1942).

(1941).

Health, 33, 975-9 (1943).

Accelerated Breaking of Unstable Emulsions

H. P. AIEISSNER AND B. CHERTOW- Massachusetts Ins t i tu t e of Technology, Cambridge, Mass.

EMPORARY emulsions T may be encountered in- dustrially in liquid-liquid ex- traction processes and in steam distillations; they may result when one liquid phase is dispersed in another in the absence of a stabilizer or after the emulsifying agent has been destroyed er othernise removed from a stabilized emulsion. Unlike the large amount of work reported on stabilized systems ( f - 4 ) , rela- tivelylittle has been published on unstabilized emulsions. I n 1910 Ostwald (6) showed that if an emulsion can be con- sidered to consist of equal-

A method is discussed for accelerating the break of emulsions containing no surface active agents such as are sometimes encountered in steam distillation, solvent extraction, and other processes. The method in- volves agitating the emulsion w i t h one to four times its volume of dispersed phase material and then allowing the system to stand idle, w hereupon the originally cloudy phase clariiies rapidly. This method was effective in some systems, called totally recolerable, regardless of which of the two phases present was dispersed. In all other cases, called semirecolerable, the method vas effectil e only when one of the two phases was dispersed. Successful cladlcation was usually attained with a polar but not a nonpolar dispersed phase. A totally recoverable system, therefore, usually showed that both phases present con- tained polar components, whereas a semirecoverable sys- tem contained a nonpolar and a polar phase.

In the investigations de- scribed in this paper, a quantitative study was initi- ally undertaken to determine the effect of phase ratio on the rate of breaking unstable emulsions. It was found that quantitative reproducibility of breaking rate could be obtained only with a high degree of control. As was to he expected from results of other investigators, results varied, depending upon traces of impurities, slight differ- ences in amounts of impuri- ties, amount of air bubbles drawn into the system during aeitation. variation in tvue

sized spherical droplets of one phase dispersed in a second continuous phase, the droplets would all touch when the ratio of dispersed to continuous phase volume was increased to 74.02: 25.98 or, roughly, about 3: 1. Inversion in an unstabilized system would then occur, with the dispersed phase becoming the cont,inu- ous phase. Stamm and Iiraemer (9 ) studied the rates of brea,k of unstable systems as influenced by various factors, and Roberts (7) investigated their inversion behavior. Hauser and Lynn (5) among others state that phase volume ratio (hereafter called phase ratio) has an important influence on the stability of emulsions generally. '4 recent development in breaking unstable emulsions has been reported by the Selas Corporation (8) nhereby 3eparation is effected through the use of a porous medium which permits the passage of only that phase Fhich wets it.

I _

and violence of agitation, upon which phase of the system under study wet the container walls first, and so on. Many of these variables could not be practically controlled in industrial scale operations. Certain qualitative observations, and also a re- covery procedure for accelerating the clarification of these emulsions. however, were unaffected by these factors. The object of this paper is to describe the lat,ter findings.

EXPERIMENTAL PROCEDURE

Expcrinicntal work involved preparation of c-riiulsions by various methods and observation of their qualitative behavior during brcak. For the systems stutlictl (Tables I and II), a range of phase ratios from 20:l to 1:20 Fas usually explored. .\gitation methods of rmulsion preparat ion were chosen t o cover