I N DUSTR IA L A 3D EN GI N EER IN G CHE M ISTR Y
August, 1932
per cent P20jfor the dolomite mixtures, the citrate-insoluble determination gave only 0.020 and 0.053 per cent for the 1- and 2-gram charges, respectively, and with no change produced in the reaction value of the citrate solution by either charge. OF P20jFROY DI- TO TRI-FORM TABLEXI. CONVERSIOS
( I n mixtures of c. P. dicalcium phosphate a i t h 100-mesh dolomitea and limestones during 50-day period, as measured b y evolved CO1 and b y citrate insoluble) PzOr I N DIPHOSPHATE MIXISSOLVBLE TURES
CITRATE SOLS.
A F T E R DIGESTIOX A N D FII.TRITION~
Found, citrate digestion, without preliminary washing DoloLimestone mite
Computed from CO? evolved from dry mix Dolo.. Limemite stone
Limestone PH % % 70 % 7.3 0.020 0.082 1.286 2.703 7.6 0.053 0.729 t o acid phosphate and limestone proportions of 60%
Dolomite
PH 1-gram charge 7 . 0 2-eram rharee 7 . 0 a Corresponding and 30.5%. b Volume 200 cc., pH 7.0. i~ ~ ~~~
I
The citrate digestion of the I-gram charge of the limestone mixture showed only about one-sixteenth of the amount of tricalcium phosphate that the carbon dioxide results demonstrated was present, and the neutral citrate solution increased to a pH of only 7.3. But, against the computed carbon dioxide equivalent of 2.703 per cent insoluble P2Oj for the limestone mixture, 0.729 per cent citrate-Insoluble was found by ammonium citrate digestion of the 2-gram charge, with a pH increase to 7.6. The solvent action of the ammonium citrate solution upon the tricalcium phosphate formed \vas therefore 2.621 and 1.974 per cent for the
941
1- and 2-gram charges, respectively, of the high-calcium limestone mixture. Because of the differences between the properties of calcium and magnesium phosphates, the chemistry of the reactions between superphosphate and dolomite embodies some interesting points. These will be dealt with in a separate contribution.
LITERATURE CITED Assoc. Official .Igr. Chem., Methods, pp. 2-4, 1925. Brackett, R. X., and Freeman, B., J. IND. ESG. CHEM.,7, 620 11QI.i) \ - - - - ,
Brogdon, J. S., 4 m . Fertilizer. 39,9 (1913). Buch, 2. anorg. Chem., 52,323 (1907). Burgess, J. L., N. C. State Dept. d g r . , Bull. 228 (1917); 265 (1920). Cameron, F. K., and Bell, J. M., Bur. Soils, Bull. 41 (1907). Fraps, G.S., Texas Agr. Expt. Sta., Bull. 223 (1917). Hall and Vogel, J. South African (‘hem. Inst., 7, 11 (1924). Harris, H. C., J . Am. SOC.A y r o n . , 20,381 (1928). Haskins, H. D., J . dssoc. Oficial A g r . (‘hem., 5,460 (1922). Larison, E. L., Am. Fertilizer, 73,548 (1030). MacIntire, W.H., and Sanders, K. B., J . Am. SOC.r l g r o n ., 20, 764 (1928).
Maerntire, W ,H., and Shaw, W. M., Ibid., 22, 14 (1930). MacIntire, W’.H., and Shaw, W.M., Ibid., 22,272 (1930). Magruder, E. W., J. IND.EBG.CHEM.,9, 155 (1917). Mooers, C. A , , Tenn. Agr. Expt. Sta., BdI. 90 (1910). Mooers, C. A , Ihid., Circular. 1922. Parker, F. W., Ani. Fertilizer, 76, 2, 13 (1932). Roberts, G., Kentucky A g r . Expt. Sta., C‘ircu’ar, 192:3. Shuey, P. M., IND. ENG.CHEM.,17,269 (1925). Williams, C. B., N. C. Agr. Expt. Sta., C‘irc. 24,6 (1916). RECEIVED March 14, 1932.
Detection of Washed, Abrased, and Oiled Eggs PAULFRANCIS SHARP,Department of Dairy Industry, Cornel1 University, Ithaca, N. Y.
U
SDER the ordinary system of poultry management a very considerable percentage of the eggs gathered are dirty. I’ennington and Pierce (6) examined eggs entering the S e w York market, and in one series of 258,496 dozen they found 12.58 per cent dirty; in another series of 238,446 dozen. 13.40 per cent were dirty. Perhaps some of the eggs which they reported as clean had been washed ( 5 ) . S o one knoas how many of the “clean” eggs on the market are actually cleaned dirty eggs. Huttar ( 2 ) found that the percentage of dirty eggs produced by the Corndl poultry flock vaned from 9.8 per cent in July to 24.6 per cent in March. Van Wagenen ( I O ) , in extending Huttar‘s studies, found that the percentage of dirty eggs varied from 77 with straw litter and no nesting material t o 23.2 per cent 11 it11 5traw litter and shavings for nesting material. The bacterial spoilage of dirty eggs is very much greater than the bacterial spoilagr of eggs d i i c h have never been dirty (1, 4 , 5). For this reason, aq ne11 as becau.e of their unsanitary appearance, buyers pay less for dirty eggs than for clean ones. This cut in price has led poultry producers to clean their dirty eggq. If the cleaning has been careledy done or the eggs just wiped, a stain remains on the shell and the cleaning can generally be detected. If the cleaning has been carefully and thoroughly done, no stain remains and there has been no ~ a ofydetecting the fact that the eggs have been cleaned (5). If cleaned dirty eggs are used locally or pass rapidly through the channels of trade, they may go into immediate consump-
tion before the bacteria which may be present in a considerable number of the eggs cause marked spoilage. If either cleaned dirty or dirty eggs are held a t relatively high temperatures or for appreciable periods of time, bacterial deterioration may take place in about 3 to $50 per cent or more, depending on the amount of dirt on the shell and the subsequent treatment of the eggs. If the eggs have never been dirty and are properly cared for, only about 2 to 3 per cent will show bacterial growth ( 1 , 4, 7 ) . The spoilage in cold otorage of a large number of eggs each year is often attributed by egg dealers to the storage of washed eggs unknowingly. I t seems to be desirable for intelligent marketing and disposal of eggs that tests for cleaned eggq be available. Cleaning removes the dirt which when present would be evidence leading to the expectation that a considrrable nunher of the eggs would eventually show bacterial spoilagcl. Heavy bacterial infection is not always detected by candling, as Jenkins and Hendrickson (a‘) have shown. Jenkins, Hepburn, S w n , and Sherwvood (4)found that after storage a larger number of dirty eggs contained bacteria than normal clean eggs, and that a larger number of washed dirty eggs contained bacteria than dirty un\i ashed eggs. Bryant ( I ) found that the kind of solution used in wa ing eggs apparently has no marked influence in controlling bacterial spoilage. This indicates that the bacteria map have already penetrated the shell, and that the solution5 used in cleaning the qhell do not reach the bacteria which are already
942
INDUSTRIAL AND ENG INEERING CHEMISTRY
inside of the egg. Cleaning eggs with sandpaper did not prevent bacterial spoilage. Everything so far indicates that the best solution of the dirty egg problem is to prevent the eggs from becoming dirty in the first place. It seems possible that the number of dirty eggs could be reduced to 3 to 6 per cent. It probably would not require a great deal more work to prevent the eggs from becoming dirty than is now required to clean them.
Vol. 24, No. 8
surface of each egg. The drop was allowed to remain undisturbed for 5 minutes. The egg was then inverted so that the drop hung from the under surface of the egg. The drop was touched to the surface of a microscopic slide, and the egg was passed rapidly up and down through the drop twentyfive times. This yields an extract of the shell surface ready for testing for either chloride or potassium. The extracts from three eggs can be placed conveniently on one slide. TESTING WITH SILVERNITRATE. To the drop of shell METHODFOR WASHEDEGGS extract on the slide was added one drop of 0.1 11; silver niWASHEDEGGS. Egg candlers often state that they can trate solution, and this was mixed by means of a small wire. recognize washed eggs. They can recognize poorly washed If the egg was not washed, a flocculent precipitate formed; but, if it was washed, the solueggsand eggs whichhave been l i g h t l y c l e a n e d with a damp tion remained clear, or a t most cloth, for such cleaning usually a very fine precipitate formed d o e s n o t r e m o v e t h e stain which could be d e t e c t e d only A method of recognizing washed eggs is and leaves the shell s m e a r y . with a m i c r o s c o p e using redescribed which is based on the observation that flected light. I n most cases the If t h e eggs h a v e b e e n thordifference b e t ween w a s h e d oughly and c a r e f u l l y washed the material on the surface of the shell contains and unwashed eggs was quite by certain procedures, candlers potassium and chloride which are removed by easily recognized with the unare unable to recognize them washing. W h e n microprecipitation tests of the aided eye if the slide was held as washed eggs. Mixtures of shell extract were made, the unwashed eggs gave naturally clean and thoroughly over a black surface in a strong tests for potassium and chloride, whereas the but preferably indirect light. washed eggs have been given to T h e p r e c i p i t a t e obtained washed eggs did not. a considerable number of canfrom unwashed eggs is somedlers, and no one has yet been The effect of the following factors on the tests what variable in amount but found who c o u l d d e f i n i t e l y was investigated: washing solutions, oil-treating, c o r r e s p o n d s to a b o u t that recognize the washed eggs. source of the eggs, season, color of shell, storage, obtained with a drop of 0.005 Many t i m e s t h e statement sweating, scraping, sanding. Oil-treated eggs N sodium chloride. The prehas been made that w a s h i n g cipitate is, however, different can be recognized by dipping a portion of the removes a p r o t e i n film from in physical appearance. Occathe surface of the egg. This shell of the egg in ethyl ether and observing the sionally a precipitate is formed statement is mainly not true, oily ring after the evaporation of the ether. w h i c h is n o t e a s i l y r e c o g if staining r e a c t i o n s for the Sand-blast treated eggs and scraped eggs can be nized by the unaided eye. Far protein on the surface of the recognized by the absence of the protein on the more reliable results can be obegg shell and tests for protein t a i n e d if the drop is viewed surface of the eggs, as brought into prominence in the extract can be taken as with a microscope having a magreliable evidence. The amount by staining. nification of twenty t o f o r t y of protein on the surface of unResults obtained in applying these tests to eggs times, preferably of biobjective washed individual eggs v a r i e s of unknown history are given. type. The p r e c i p i t a t e must much more than one can probe i l l u m i n a t e d by a strong duce by vigorous w a s h i n g of reflected light. In this study eggs which h a v e c o n s i d e r the beam from a p r o j e c t i o n able protein on their surfaces. The attempts to recognize washed eggs by testing for the type of lamp was thrown on the drop from the side, t h e rays passing nearly horizontally across the stage. removal of protein were unsuccessful. The precipitate obtained with silver nitrate is possibly It seemed possible that soluble inorganic constituents might be present on the surface of the egg which would be not all of inorganic material. It turns brown more rapidly removed by washing. Microprecipitation tests on water than does a silver chloride precipitate under similar condiextracts of the shell were made, and it was found that po- tions. A number of other protein-precipitating reagents tassium and chloride could be detected in the extract. Ex- were added to extracts from unwashed eggs to see if protracts from unwashed eggs which were allowed to dry slowly tein could be detected. The most definite precipitation test on the slide yielded considerable numbers of cubical crystals. for protein was obtained when mercuric chloride crystals These crystals were isotropic, as evidenced by examination were stirred in the drop, but only traces of precipitate were with polarized light. The tests indicated that the material formed. removed contained potassium chloride. A number of prePOTASSIUM TEST. Difficulties were encountered a t first liminary experiments showed that the test for chlorides in obtaining a definite potassium test. After some study had an advantage over the test for potassium in that the of various methods, the cobalt nitrite test was chosen. It precipitate was formed a t once. A considerable number seemed satisfactory when the reagent was prepared in the of eggs were examined to determine the reliability of the chlo- following way (9): ride test before it was decided to determine the reliability of Twenty grams of cobaltous nitrate, Co(NO&6H20, 25 grams the potassium test. The potassium test has an advantage sodium nitrite, 65 cc. of distilled water, and 10 cc. of glacial in that ordinary washing solutions do not interfere. Wash- of acetic acid were mixed in the cold. After the violent evolution ing was found to remove most of these two ions, so that an of fumes had ceased, the solution was warmed t o boiling, allowed extract from washed eggs gave a negative, or a t most a very t o cool for 24 hours, made up to a volume of 150 C C . ~and filtered. much fainter, test than did the extract from unwashed eggs. A drop of this solution was added t o the extract from th? shell. The eggs were placed The mixing was done with a fairly stiff wire by scratching the PREPARATION OF SHELLEXTRACT. end of the wire back and forth through the drop. Crystallizaon their sides on cup egg flats, and a drop of distilled water 1 Directions in Tunmann cell for e volume of 100 cc. was placed on the clean and unstained portion of the upper
V
A
August, 1932
INDUSTRIAL AND ENGINEERING
CHEMISTRY
943
tion usually began on these scratch marks within 5 minutes. In some instances the crystallization did not become definite until after about 15 to 20 minutes, so that the final observations should be made 20 minutes after the drops have been stirred.
amined, including several hundred not reported in this table, three eggs were found that gave a water extract which did not yield a precipitate when silver nitrate was added. When the shells of these three eggs were stained with methylene I n Table I the same results were obtained when the tests blue, the absence of protein material on their surfaces was were observed with the unaided eye as when the microscope indicated. This shows that occasionally an unwashed egg was used. If the observations are made with the unaided will be found that will give the washed-egg reaction. In most cases the difference between the washed and uneye, the drops should be well lighted. The potassium test has the advantage that the common washing solutions do washed eggs is distinct, but some eggs give a border-line test and considerable experience is necessary to make a cornot interfere. The cobalt nitrite solution deteriorates and should Le rect decision in such cases. The lots were examined in order well stoppered. I n this work the solutions were not used of their lot numbers. A considerable number of tests were repeated in the first few lots and most of the mistakes after they were a month old. SEPARATION OF MIXTURES OF WASHEDAXD UNWASHED occurred in the first five lots. Only seven repeat tests were EGGS.The tests were used to separate eight lots of fresh made in lot 6, and only one in each of lots 7 and 8. The eggs containing an unknown mixture of washed and un- eggs were examined a t the rate of about seventy-two an hour, washed eggs. The eggs of each lot were numbered serially using a single test which allows time to record the results by others who prepared a thorough mixture of washed and and wash the slides. The results reported in Table I indicate that either the unwashed eggs and who kept the key until the results of the tests were obtained. The eggs which were washed had ac- chloride or the potassium test might be useful in recognizing tually been dirty. They were washed with tap water or washed eggs, and therefore several of the complications tap water with an abrasive soap, and were dried before an which might arise when it comes to applying the test to unelectric fan. The results obtained are giren in Table I. known lots of eggs mere investigated. TABLEI. E g g s examined
TESTSON
CHLORIDE LVD POTASSIUM
Lot number: Reported washed Reported not washed Reported washed but were not Reported not washed but were Reported washed but were not after retesting Reported not washed but were after retesting Reported washed but were not when examined without the microscope Washed egg8 which could be recognized by appearance of shell
1 2 -Chloride 50 144
3 ~~
25
77
25
67 2 1 (?) 0 0
0 0
.. ..
..0 ... ...
Lots 1, 3, and 6 were washed especially for this test. The washing was more thoroughly done than in the case of the other lots so that it was impossible to recognize any difference between the washed and unwashed eggs by the appearance of the shell. The remaining lots were made up from the daily run of washed eggs obtained from a poultry producer who regularly washed his dirty eggs. The ease of distinguishing between washed and unwashed eggs by means of these tests increases with the thoroughness of the washing. If the washing has not been thoroughly done, the precipitation tests are hardly needed, since the fact that the eggs have been washed or are stained or dirty can be recognized by the appearance of the shell. The visual inspection of the shell and the precipitation test methods of recognizing washed eggs overlap, as shown by the fact that nineteen of the washed eggs of lot 4, twenty-nine of lot 5, thirty-six of lot 7 , and thirty of lot 8 could be recognized as washed eggs by the appearance of the shell. In lots 1, 3, and 6, comprising 462 eggs, only one egg was missed using the chloride test. I n the remaining lots comprising 678 eggs, eight eggs were reported washed which were not, and four eggs were reported not washed which were washed; two of these four eggs were reported with a question mark, however. The tests on the eggs which were wrongly reported were repeated. One of the eight eggs was again wrongly reported as washed, and two of the supposedly washed eggs still indicated that they had not been washed. The possibility that an egg might have been wrongly marked is not remote. Great concentration on a tedious task was necessary to prevent mistakes in marking the eggs. Of the 514 eggs examined with the potassium test, only one egg was missed, and i t was reported with a question mark because it gave a trace of a test for potassium. As a rule only 2 or 3 per cent of the eggs were reported with a question mark. In all of the known unwashed eggs ex-
144 67
77 1 0 0 0 "
6
WASHED ASD -64 5 CI testtest 144 144 268 71 66 133 73 i a 135 0 3 2 2 1(?) 0 1 0 .,. 1 1 (?) ,.
CNWASHED EGQS -8-iC1 K C1 K K test test teat test test 268 114 114 132 132 60 133 56 57 60 135 58 57 72 72 0 0 1(?) 0 0 0 0 0 0 0 ,, ,, 1 (?) . . , ,..
. . .. .
4 19
:1 29
3 0
0 0
. . . . .. . 0 36
..
0 36
4 30
.
I
.
0 30
-TOTAL-
C1 K test test 1140 514 555 250 585 264 8 1(?) 4 0 1 1 (1 2 0
.... .. ..
...
EFFECT OF VARIOUS FACTORS ON TEST WASHIKGSOLUTIOKS. The greatest likelihood of interference with the tests described would occur in the cases of the chloride test. Many alkaline washing solutions contain trisodium phosphate, sodium carbonate, or sodium bicarbonate, each of which would give a precipitate with silver nitrate. A series of different solutions of proper concentration were used to wash eggs, and then the tests for chloride and potassium were made on the shell extracts. The solutions used and the results obtained are given in Table 11. TABLE 11. EFFECT OF WASHING SOLUTIONS ON TESTS (Some determinations made on name eggs both before and after oil-dipping) EQQBTESTEDBEFORE EQQSTESTEDAFTER OIL-DSPPINQ OIL-DIPPINQ EQQS Ppt. with Test P t. with Test S o m a . UBED TESTED AgNOs for K WgNOs for K Unwashed 42 42 42 42 42 Water 30 0 0 0 0 "4'21 12 12 0 .. NaCl 12 12 0 12 0 LiCl 30 30 0
..
KC1
KI
KNOi KCtHsOs NaaPO4 NaHCOt NarCOt H C1 HrSOi NarSOc
Krs04
Soap Gelatin Eggalbumen
46 20 20
30
6 6 6 6 6 6 30 6 6 6
46
46
20
20 20 30 0 0 0 0 0 0 30 0 0 0
0 0 6 6 6 6
0 0 0 0 0
6
.. 48 .. .. ..6
6 6 6 0 0
..0 0 6
.. 48 .. ..
..0 0 0 0
0 0
..
0
0 0
It will be noted that if eggs are washed with solutions of several ions, a precipitate with silver nitrate is obtained, but only the potassium salts give the potassium test. This table seems to indicate that eggs might be washed with salt solutions such as potassium chloride and, therefore, would
,
944
INDUSTRIAL AND ENGINEERING CHEMISTRY
give both tests for unwashed eggs. However, several observations were made which indicate that eggs washed with potassium chloride could be recognized. The precipitate obtained with silver nitrate with the unwashed eggs usually gathers fairly rapidly into large flocks, whereas the precipitate obtained when the eggs have been washed with potassium chloride or salts which give a precipitate with silver nitrate is usually very finely divided and does not form large flocks so readily. In a mixed lot of eggs containing unwashed eggs, eggs washed with water, and eggs washed with potassium chloride, most of the eggs washed with potassium chloride were recognized by this reaction alone. Other observations were made which would render it likely that washing eggs with potassium chloride would be detected. Under uniformly controlled conditions of light and time, the precipitate obtained with silver nitrate and unwashed eggs darkens more rapidly than does the precipitate obtained when the eggs are washed with potassium chloride. Furthermore, if no precipitating reagent is added and the extracts are allowed to dry on the slide, a fairly uniform residue is obtained over the whole surface formerly occupied by the drop in the case of the unwashed egg; whereas if the egg has been washed with potassium chloride, the residue is much greater a t the periphery of the drop and the cubical crystals are much more numerous and freer from other material. If the eggs are washed with any of the solutions which give a precipitate with silver nitrate, the limits of the amount which can be permitted to remain on the shell and still give a precipitate which would correspond in amount to that obtained from unwashed eggs are rather narrow. The eggs which were washed with egg albumen solution could be recognized by the fact that their extract gave a heavy precipitate with Millon's reagent. The eggs which were washed with soap solutions could easily be recognized by feeling them. OILTREATEDEGGS. A large number of eggs are oiltreated in order to retard evaporation and the escape of carbon dioxide. Oil-dipping does not interfere with these tests, as shown by experience with several different oils which are used commercially. Some of the eggs used to test the effect of the various solutions as listed in Table I1 were dipped in a light mineral oil, The next day the tests were again made without extracting the oil from the surface of the shell. The same results were obtained as before oil-dipping. EGGSFROM VARIOUSSOURCES.The tests have been applied to fresh hens' eggs obtained from eighteen different states and of every degree of color of shell. Furthermore, fresh eggs have been tested a t all seasons of the year. KO influence of these factors on the test has been found. The water extract from the shell of goose eggs was shown to give the chloride and potassium test. STORAGEEGGS. The greatest interference so far encountered with the test for washed eggs has arisen in the case of storage eggs. During storage the potassium chloride largely disappears from the surface of the shell, so that a faint test for potassium and chloride indicates that the eggs are either washed or are storage eggs. From the standpoint of selecting eggs for storage, one wants to know before the eggs are stored that they have not been washed so that the interference will not be so serious. The most logical explanation for the disappearance of the potassium chloride from the shell during storage seems to be that it diffuses to the inside of the egg. If the egg is held in an atmosphere in which the humidity is higher than the vapor tension of a saturated solution of potassium chloride, the moisture will form a nearly saturated solution of potassium chloride on the shell. The potassium chloride will
Vol. 24, No. 8
tend to diffuse into the egg, since the concentration of potassium chloride within the egg is much less. If this is the true explanation, then the potassium chloride should disappear from the shell a t the higher and not a t the lower humidities. A number of eggs mere stored in jars in which the humidity was maintained constant a t various levels. The potassium chloride disappeared faster a t the higher humidities and did not seem to disappear a t humidities of 60 per cent or below. The disappearance was faster a t 25" than a t 0" C. Oil-dipping the eggs seemed to have little or no influence on the disappearance of the potassium chloride. Eggs were washed with a number of salt solutions (potassium chloride, sodium chloride, potassium iodide, potassium sulfate, lithium chloride, potassium acetate, and potassium nitrate) and were then stored a t 60, 70, 80, 85, and 90 per cent humidity and a t 25" and 0" C. The salts tended to disappear a t the higher humidities more rapidly than a t the lower. It was hoped that the differences in the humidity level a t which the salts disappeared would be related to their different solubilities, but the only clear-cut difference was noted in the eggs washed with potassium sulfate. The potassium test remained definite for a much longer time and a t a much higher humidity than was the case with the eggs washed with any of the other solutions or the unwashed eggs. There was a slight tendency for the potassium iodide, lithium chloride, and potassium acetate salts to disappear a t a lower humidity than the other salts, but the results were not clear-cut. Three different sets of storage experiments were carried out involving these factors. These experiments indicate that, if the eggs are stored a t 25" C. a t 80 per cent humidity or above, enough potassium chloride will diffuse into the egg so that a washed egg test would be obtained some time between 1 and 2 months' holding. The time of storage a t 0" C. required for the disappearance of the potassium chloride varied with the humidity, but would probably fall between 4 and 8 months for ordinary storage conditions. Usually the potassium and chloride have not entirely disappeared from the shells of storage eggs, so that the test is a little stronger than may be obtained in uniform lots of washed eggs. The tests are so faint in storage eggs that in mixed lots they would ordinarily be classed as washed. After enough experience, one can nearly always distinguish between washed, unwashed, and storage eggs in uniform lots. In one study of the chloride test applied to seventyfour dozen eggs which unknown to the observer contained five dozen storage eggs, these storage eggs were recognized as such in contradistinction to the other dozens, some of which were all washed, some of which contained no washed eggs, and some of which were a mixture of washed and unwashed eggs. WASHEDEGG TESTAPPLIEDTO ABRASEDEGGS. If the dirty spots on eggs have been removed by scraping with emery paper, sandpaper, steel wool, or materials of that kind, the protein material, together with the potassium chloride, is removed from the surface of the shell a t that particular spot. If the drop of water used for the washed egg test happens to be placed on the same spot, no potassium or chloride test will be obtained, and such an egg would be reported as washed, although actually it has been scraped. If the drop is placed on an unscraped portion of the shell, the test for potassium and chloride will be obtained. Since eggs are scraped because they were dirty, the fact that scraped eggs may often give the washed egg test is not serious because in both cases it indicates that the eggs have been dirty. Dirty eggs are sometimes cleaned by means of a sand blast. Eggs cleaned in this way usually yield an extract
hugust, 1932
945
I N D U S T R I A L A U D E NG I N E E R I NG C H E M I ST A Y
which gives no test for chloride or Dotassiuni and conse-
METHODFOR ABRASEDEGGS By immersing a n abrased egg in a dye solution which will stain the protein mat’erial on the surface of the shell, the scraped portions of the shell show up quite clearly as an unstained spot. Quite a number of dyes may be used for this purpose if the egg is not to be sold afterward. ethylene blue is very good, but the following were also found satisfactory: malachite green, safranine, brilliant green, crystal violet, eosin, gentian violet, methyl violet, fuchsin, toluidine blue. Janus green, aurantia, and several others out of a total of sixty dyes tested. -4 procedure was developed for staining scraped eggs which permits the decolorization and removal of the dye after the test has been made so that the eggs are salable. The test can be run on a large number of eggs a t one time. The eggs are placed in a metal tray or basket. They are first immersed in water for 4 or 5 seconds, and then for 30 seconds in an aqueous solution of rosaniline hydrochloride (1 gram per liter). Previous immersion in water is necessary to prevent the dye from penetrating too deeply by capillarity. This procedure stains the unscraped portion of the shells pink. The eggs are now observed to see if any has been scraped. The dye is then reduced by immersing the eggs for about 1 minute in a sodium bisulfite solution (2 per cent). Kext the eggs are immersed in water and the tray moved about several times during the course of 1 minute to wash the dye and sodium bisulfite from the shell. The eggs are then dried. SQD-BLASTTREATED EGGS. A sand blast is sometimes used to clean dirty eggs and t o “deprocess” eggs that have been oil-dipped. The water extract from these eggs usually fails to give a test for potassium and chloride, but they can be recognized when stained by the fact that most of the protein on the surface of the shell is removed. Sand-blast treated eggs were examined under the niicroscope, using a magnification of about forty times. Most of the eggs $0 treated could be recognized by the presence of small pits and pulrerized $pots, but the scarifying action was much less than one mould expect. The appearance of the shell of normal eggs shows a wide variation, and one must be familiar with such variations before he can recognize the effect of the sand blast.
METHODFOR OILEDEGGS Eggs are often treated with oil to prevent the escape of moisture and carbon dioxide. Oil-treated eggs can usually be recognized by the appearance of the shell, especially when a whole case is examined. It is, houever, sometimes difficult to say whether some small individual lot of eggs has been oiled or not. Oiled eggs can be detected by simply dipping the end of the egg in ethyl ether for a second. By holding the egg in a good light, an oily ring can be seen a t the edge of the ethertreated part if the egg has been oiled. The ether dissolves the oil and, in evaporating, concentrates it at the edge of the evaporating surface. The attempt is often made to remove the oily appearance of the shell of eggs by the sand-blast treatment. Sanded oiled eggs still give the oily ring, however. A number of other volatile oil solvents mere tried, but they were not satisfactory because they contained too large an amount of norivolatile oily materials.
AkPPLIC.4TION O F
TESTS
TABLE111. RECOGSITIOSO F SAND-BLASTCLEAXISG SCRAPISG O F x.4TURAL A S D OIL-TREATED EGGS -EGGS
1 i i D I C . A T I N G CLE.ANIKG--
AND
EGGS
NicroGIVING Methylene ecopical POSITIVE EGGS AgNOa blue appearance TEST COlDITION EXAMIiiED test staining' of shell FOR O I L Natural 90 13 (60) 2 0 0 90 67 90(27) 88 Natural sanded 90 14 (56) 2 90 sanded 89 90(10) 71 90 whose surfaces indicated they had a parentheses indicate number of been cleaned by abrasion other t h a n sanding.
fi:$:
TABLEIV. TESTSFOR CLEASEDEGGSPURCHASED IS OPEN MARKET TOTAL
SIMPLE
1 2 3 4
5 6 7 8 9 10
11 12 13 14
~~
E G G S SHOWING CLEANED TOT.AL DIRTY EVIDENCE OF CLEAKING A N n DIRTY EGGS EGGS Washed Scraped EGGS E X A M I N E D
1 6 5 1 1 7
2 2 0
0 1 3 3 R
4 3 9 1 3 0 0 3
1 0 2 1 1
n
15 16
0 0 6 3 1 3 0 2 0 1 0 0 0 0
5 7 12 5 5
12 12
4 4 8 2 3 1 6
n
17
18 19 20 21 22 23 ~~
24 25 26 27 28 29 30 31
Total Per cent of total examined
0 2 4
n
1 0
n 11 0 1 4 0 4 5 11
4 0 0
0
11 12 12 12 11
12 3 5
2 4 11 0 2 5 0
4 5 11
12 12 11 12 12 11 4 12 12 10
12 12
12 12 11 11 ~-
12
11
12 11 12 12 12 12
-
-
-
_-
-_
63
77
35
141
359
17.5
21 4
9.7
39.3
Of the supposedly naturally clean eggs, thirteen gave a negative chloride test, and sixty of the ninety showed that they had been scraped. This dealer thought he was obtaining naturally clean eggs, while, as a matter of fact, about 66 per cent were cleaned dirty eggs. The results obtained with the unsanded oil-treated eggs should be considered a duplicate of the examination of the naturally clean eggs, and Table I11 shows the good agreement between the two aliquots. The fact that only two eggs in each lot indicated abrasion by microscopic examination indicates the fineness of the texture of the abrasive material. The naturally clean eggs, whether sanded or oiled and sanded, showed evidence of the sanding when the shells were stained with methylene blue. Most of the water extracts gave a negative chloride test. The sanding of these eggs must have been especially light, since it could be recognized that some of the eggs had been scraped before sanding. The abrasion of the shell by the sand blast could be recognized in most cases by a microscopical examination of the shell. The ether ring test for oil was conclusive in each case. Sarnples of eggs from about thirty cases of eggs were ex-
INDUSTRIAL AND ENGINEERING CHEMISTRY
946
Vol. 24, No. 8
amined from the current receipts of several egg dealers. A considerable number of washed and scraped eggs were detected. I n most instances the dealer was not aware that these particular poultry producers were supplying washed and scraped eggs. Further information was obtained by examining the eggs obtained by an inspection of the eggs offered for sale in one of the upstate cities of New York State. The results of the examination of these eggs are given in Table IV. I n making these tests, the eggs were numbered and mixed; after the examinations were made, the results were assembled on the basis of the original dozen. There is some overlapping of the tests, since some of the scraped eggs also gave the washed egg test, and some of the washed or scraped eggs might still be classifled as dirty.
membered that columns 2, 3, and 4 refer to the number of dozens which contained the number of cleaned eggs given in column 1. A few eggs gave both the washed and scraped egg test, and consequently would appear in both columns 2 and 3. Column 4 gives the total cleaned eggs after eliminating duplication. As an example, if a particular dozen contained one scraped egg and four other washed eggs, this dozen would be listed in column 2 as having four washed eggs, in column 3 as having one scraped egg, and in column 4 as having a total of five cleaned eggs. The results are particularly interesting in view of the statement sent to the participants, instructing them that cleaned eggs should not be submitted. In spite of these instructions, about 23.9 per cent of the eggs were cleaned as indicated by the tests. If we assume that twenty-seven of the seventy-four exhibitors followed instructions and did not TABLEV. DOZENS CONTAININQ NUMBERS OF WASHED, SCRAPED, submit cleaned eggs, then the cleaned eggs were confined AND TOTALCLEANED EQQSINDICATED BY FIRSTCOLUMN to the remaining forty-seven dozen, which makes a total CLEANED EQQB NUMBEROF DOZENS of 37.6 per cent of cleaned eggs in their lots. Their producPER DOZEN Washed Scraued Total cleaned tion of dirty eggs may have been greater than this, because 61 33 0 27 some selection was probably exercised. On the other hand, 3 1 13 8 2 6 7 10 it is interesting to note that every egg in three of the lots 5 1 2 3 7 7 1 4 was washed. It is known that some producers have so many 2 5 dirty eggs that it is more convenient to wash them all rather 0 6 1 7 than to wash the dirty eggs separately. 0 8 9 10 11 12 Total eggs Per cent bf total
1 1 0 3
i E 11.9
1 0 0
1 Z 16.0
2 0 3 2 23.9
From Table IV it will be noted that 17 per cent of the eggs were dirty, 21 per cent gave the washed egg test, and 9.7 per cent had been scraped. Of the eggs examined, 89 per cent either had been cleaned or were dirty. This gives some idea of the actual conditions of market eggs. As eggs progressively deteriorate, the yolk of the opened egg tends to become flatter, until finally the egg cannot be opened into a dish without the yolk breaking. The height of the yolk divided by its width has been called the yolk index (8),and is used to record changes in this factor. Also, as eggs deteriorate, the jelly-like white which surrounds the yolk becomes more and more flabby until finally the jellylike structure disappears. The dirty and cleaned eggs of Table IV were slightly lower in these two quality factors than were the naturally clean eggs. Tests were made on seventy-four dozen eggs submitted at an egg show in 1931. Only twenty-seven dozen contained no cleaned eggs. Dirty eggs were practically absent. The results are condensed to give Table V. For a better understanding of Table V, it should be re-
ANNUALSALESOF CARBON BLACK by the American industry to domestic and foreign markets aggregate over $10,000,000. Since the initial production of a few hundred pounds of carbon black shortly after the Civil War, the industry has grown rapidly, as may be evidenced from the record output of 379,942,000 pounds in 1930. This high level was not maintained last year when production dropped to 280,907,000 pounds. The Bureau of Mines reported that fifty-eight plants were operating last year, or ten less than in 1930. Texas is the leading state for the production of carbon black,, and the industry centered in the Panhandle and Breckenridge districts supplied about 79 per cent of the total output during 1931. Louisiana was second, furnishing approximately.20 per cent. The rubber industry is the principal consumer of carbon black, using about 83 per cent of the total production as a pigment and filler in tires and rubber goods. The second important use of
ACKNOWLEDGMENT George F. Stewart carried out the experiments in developing the procedure for removing the stain from the egg shells, and W. W. Hartman, of the Eastman Kodak Company, offered suggestions which led to this decolorization procedure. LITERATURE CITED (1) Bryant, R. L.,Cornell University, Thesis, 1928. (2) Huttar, J. C., Reliable Poult~yJ . , 34, 804 (1928). (3) Jenkins, M. K.,and Hendrickson, N., U. S. Dept. Am., Bull. 391 (1918). (4) Jenkins, M. K.,Hepburn, J. S., Swan, C., and Sherwood, C.M.S.,Ice and Refrigeration, 58, 140-7 (1920). ( 5 ) Jenkins, M. K.. and Pennington, M. E., U. S. Dept. Agr., Dept. Bull. 775 (1919). (6) Pennington, M. E., and Pierce, H. C., U. S. Dept. Agr. Yearbook, pp. 461-76 (1910). (7) Rettger, L. F.,Storrs Agr. Expt. Sta., Bull. 75, 191-213 (1913). (8) Sharp, P. F.,and Powell, C. K., IND.ENQ.CHEM.,22, 908-10 (1930). (9) Tunmann, O.,“Pflanzenmikrochemie,” p. 109, Gebrlfder Bortraeger, Berlin, 1913. (10) Van Wagenen, A., Cornell Univ. Dept. Poultry Husbandry Egg Market Reo., 5, No.38, 2-3 (1930). RECEIVED February 23, 1932.
the black is as a pigment for the preparation of inks and paints. The product is also utilized in manufacturing carbon paper, polishes, phonograph records, paper, artificial stone, and crayons. The United States is the worlds only source of supply of carbon black. Several foreign countries have surplus quantities of natural gas but do not manufacture the black. Germany has made several unsatisfactory efforts to prepare a black pigment which would compare favorably with carbon black. Carbon black was the sixth largest item of American chemical products exported during 1931. Besides a domestic consumption of 161,712,000pounds, exports of the pigment reached a record quantity of 96,714,116 pounds, or a gain of 14.8 per cent in quantity over 1930 shipments. The increase is attributed to greater utilization of the pigment by the rubber industry and t o low prices. The United Kingdom was the largest purchaser, followed by France, Germany, Canada, and Japan.
