602
T H E J O C R N . 4 L O F I i V D C S T R I A L A - Y D EAVGISEERI.VG C H E M I S T R Y
filter paper i n a Gooch crucible with suction. Wash twice with cold distilled mater without allowing t h e precipitate t o become d r y . Transfer t h e precipitate t o t h e original beaker. a d d water a n d heat t o boiling. T i t r a t e with 0.0j S N a O H . using phenolphthalein as t h e indicator. 9.6 X cc. 0.0jiV N a O H = p a r t s per million SO,. T h e benzidine hydrochloride solution is made up as follows: Place 8 g. of benzidine i n an agate mortar a n d a d d enough water t o make a paste. Wash t h e paste i n t o a I liter flask, a d d I O cc. concentrated H C l ? a n d make u p t o t h e m a r k . Filter, if necessary. I cc. = 0 . 0 0 2 6 g. Sod. coscLcsIoss I-The benzidine hydrochloride method is applicable for t h e determination of sulfates in water. 11-The results with t h e use of benzidine hydrochloride compare favorably with those obtained with t h e use of barium chloride. 111-The benzidine hydrochloride method is much more rapid t h a n t h e barium chloride method. for which reason it is very well a d a p t e d t o routine water analysis. W A T E R AND S E W A G E LABORATORY U N I V E R S I T Y OF K A N S A S . L A W R E K C E
__~_~___ EXAMINATION OF TOMATO PULP By TV. D. BIGELOW A H D F. F. F I T Z G E R A L D Received June 1, 1915
T o m a t o pulp is prepared i n very large quantities for t h e manufacture of ketchup a n d pulp. While a considerable a m o u n t of pulp used for t h i s purpose is made b y t h e ketchup manufacturers, t h e preparation of pulp for sale as such has reached considerable proportions. There is also a n increasing a m o u n t of t h i s product placed on t h e market in small containers for household use i n t h e preparation of soup. While t h e greater p a r t of t h e pulp placed on t h e market is made from whole tomatoes, t h e r e are a number of plants t h a t manufacture pulp i r o m trimming stock in connection with t h e canning of tomatoes. Since t h e l a t t e r product is given a lower grade commercially t h a n whole t o m a t o pulp a n d has a somewhat different composition, it becomes i m p o r t a n t t o be able t o distinguish t h e t w o b y examination in t h e laboratory. I t is found t h a t t h e results of t h e samples examined in t h i s laboratory during t h e last season afford a basis for t h i s distinction. T h e y also make it possible t o simplify t h e examination which we ha\-e heretofore found necessary. COMPOSITIOS
O F IVHO1.F.
TOJIATO P U L P
T h e results obtained b y t h e examination of 3 3 samples of whole t o m a t o pulp are given in Table I . T h e concentration of t h e samples \-aries from unconcentrated pulp as it r u n s from t h e cyclone, t o pulps of very heavy consistency. This table contains t h e d a t a from m-hich Table I11 a n d IT‘ were calculated, although during t h e season a partial analysis was made of a large n u m ber of other samples, a n d t h e d a t a secured therefrom were in all respects confirmatory of t h e relations calculated from Table I .
Vol.
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I n addition t o t h e d a t a obtained b y t h e Yarious determinations. Table I gives t h e relation between t h e results of t h e determinations for each individual sample. F o r instance, t h e ratio of pulp solids t o filt r a t e solids (pulp solids divided b y filtrate solids) varies in t h e different samples from 1.091 t o 1 . 1 5 4 , a n d , with t h e exception of t w o samples, it varies from 1.100 t o 1 . 1 4 j . T h e average of t h e 33 samples was 1 . 1 2 . T h e relation of insoluble solids t o t o t a l solids (expressed as per cent of insoluble solids in total solids) is shown in Table I . Considering t h e variations in t h e methods employed b y different manufacturers in t h e preparation of t o m a t o pulp, t h e per cent of insoluble solids in t h e t o t a l solids as shown b y t h i s column is closer t h a n we might expect. Trarying in most of t h e samples from 11 t o 1 4 per cent. T h e per cent of sugar in t h e soluble solids, as shown b y Table I . varies in most of t h e samples from jo t o j j per cent. This figure cannot be expected t o be constant in different localities a n d i n different years. T h e acid, estimated as citric, constitutes in most of t h e samples from 9 t o I O per cent of t h e soluble solids. Of especial interest is t h e refractive constant of t h e filtered liquor? shown in t h e last column of Table I . T h e refractiT-e constant of t h e various samples is much more uniform t h a n might be expected from a product of this nature. On t h e whole, Table I is chiefly interesting as affording t h e d a t a from which Tables I11 a n d IT’ were calculated. T h e uniformity of t h e relations shown in Table IS: is such t h a t i t is usually possible from one determination on t h e filtrate a n d t h e determination of solids i n t h e pulp b y drying t o distinguish pulp made from whole tomatoes from t h a t made from t r i m ming stock. For instance, if t h e specific gravity or index of refraction of a filtrate prepared from a pulp of unknown origin, a n d t h e per cent of solids in t h e pulp b y drying, do not agree with t h e relation between these determinations as shown i n Table I\--i t m a y be assumed t h a t t h e sample was not prepared from whole tomatoes, or t h a t some other substance, such as s a l t , has been added. Moreover, trimming stock pulp rarely conforms t o t h e relations found in whole t o m a t o pulp. For instance, t h e insoluble solids are usually higher a n d t h e acid lower in trimming stock pulp. COJIPOSITIOS
O F T R I h I M I S G STOCK PULP
In Table I 1 are given t h e results of t h e examination of 2 1 typical samples of trimming stock pulp prepared a t different plants a n d i n different localities. This table is of especial interest in showing t h a t t h e relations between t h e results of t h e various analytical determinations differ from those of whole t o m a t o pulps as given i n Table IT. For instance, in S o . 14 j o t h e immersion refractometer reading is .4j.go, a n d t h e per cent of solids is 9 . j 4 , whereas, according t o Table I\’, t h e per cent of solids i n t h e pulp corresponding t o a n index of refraction of 4 j . 9 0 should be 8. j j. T h e specific gravity of t h e pulp is 1 . 0 3 j 3 , which. according t o Table I\-. should correspond t o 8.98 instead of 9 . jq. Of course it cannot be said definitely t h a t a pulp
JUIY.
191j
T H E .JOL7RS.I L O F I S D t 7 S T R I . I L A S D E S G I S E E R I S G C H E J I I S T K Y
which on examination is found t o conform t o all t h e relations shown in Table 11- is necessarily whole t o mato pulp. I t is entirely possible for an occasional sample of trimming stock pulp t o conform t o all t h e relations shown in t h a t t a b l e ; moreover. t h e extent t o which different samples of trimming stock pulp will vary from t h e relations shown in Table IT' differs with t h e manner of preparation. For instance. if a portion of t h e juice is discarded in t h e manufacture of trimming stock pulp, as is still t h e practice of some manufacturers, t h e variation from whole t o m a t o pulp will be greater t h a n otherwise a n d t h e variation will increase with t h e a m o u n t of juice discarded. METHODS O F AS.4LTSIS
also be applied t o tile esT h e metllods amination of raw tomatoes a n d canned tomatoes. I n applying t h e relations given below t o t h e res u l t s obtained b y t h e examination of t o m a t o pulp COMPOSITION OF PT;LPS Sp. gr. a t SAMPLE So. 20" C. 1 2 9 0 . . . . . . . . I .(1252
. . . . . . . . 1.02i.7 . . . . . . . . 1.0234 . , , , , 1 .02Y.i . . . . . . . 1.02i2 1295 . . . . 1.0361 1296 . . . . . I .o,m I 2 9 7 . , . , . 1 0465 1299 . , . . , . 1 . 0 4 1 i l.100. . . . . . 1.0322 1.301, , . , , , I ,0312 1302 . . . . . 1.0310 1.303 . . . . . 1.0340 1304. . . . . . . 1.0292 1.10.5 . . . . . . I ,037 I 1.106. . . . . 1 .ns70 I291 1292 1293 1294
I307Ib).. . . . 1481. . . . . 14x2 . . . . . . . 1 4 8 . 7 , .. . . . . . 1484. , , , , . 1485., . , , , , l477(fl. . l4iY. . . . . . . 1486 . . .
P e r cent Per cent total insoluble solids(a) solids 5.94 6.54 5.50 i.02 6.48 8.67 9.00 ll.20 10.Oi 7.70 7.36 7.45 8.17 6.88 9.03 8.95 7.86 10.82 10.83
0.66 0.78 0.80 0.74 0.69 0.95 1.06 1.19
1.23 0.93 0.91 0.91 0.91 0.88 1.19 0.98
603
or cup for t h e determination of specific gravity. air bubbles are introduced which it is found impossihle t o remove n-ithout the aid of a centrifuge. These can be completely removed b y whirling the specific gravity flask in a centrifuge for about one minute a t a speed of ahout 1000 r . p. m. A hand Babcock milk tester is satisfactory for this purpose. This causes t h e pulp t o settle into t h e flask. because of the elimination of the air bubbles. T h e flask is again filled a n d centrifuged; this is continued until t h e surface of t h e pulp remains a t t h e t o p of t h e flask. --I. fcw drops of pulp are added t o bring t h e contents above t h e t o p of t h e flask a n d t h e pulp is t h e n "st.ruck off" with a straight edge, t h e outside of t h e flask washed a n d dried a n d t h e flask a n d contents weighed. -1table can be constructed readily giving in parallel columns t h e weight of flask a n d contents a n d the specific gravity of t h e pulp. For t h e use of Table IT:. t h e
TABLEI-COXPOSITIOS OF IVHOLETOMATO I'ULPS FILTRATE: FROM PULPS Ratio Per cent Immersion of pulp insoluble SOLIDS OF FILTRATE Refractive S p . gr. Per Per Per cent refracsolids t o solids in -. constant of at cent cent acid torneter filtrate total Percentages Ratio sugar filtered 20' C. solids(a) sugar(d) a s citric 17.5' C . solids solids Sugar Acid t o acid liquoriil I , 133 11.1 46.0 11.1 4.1 5.24 2.41 0 58 36,24 1 ,0233 54,.? 9.4 5 8 3 .10 0 53 37.80 1 . I45 11.9 1 ,0252 5.71 14.6 IO. 1 5 .0 2.48 0.49 34.51 1.127 50.8 1.0211 4.88 9.i 5.5 0 61 40.04 1.118 10.5 53.4 I ,0276 6.28 3.35 3 20 38.27 I . I13 10.6 55.0 9.5 5.8 5.82 0.55 1.0256 0.67 46.03 1.127 11.0 56.8 8.7 6.5 I ,0340 7.69 4.36
.
1.0i46 1 ,0394 1 ,0304
....
1 ,0293 1,0323 1.02i4
:
8.05 10.27 9.09 6.88 6.68 6.61 1.29 6.20
7.98 8.01 6.97 9.64 9.86 in. 19 9.23
4.4;
5.61 4.96
3,55 3.27 3.43
3.77 3.03 4.14 4 i l
0 66
0.89
0.81 0.6i 0.69 0.64 0. 71 0.64 0.82 0.69 0.66 0.99 0.94 0.98 0.81 0 i2 0 Y i
3 79 1.0328 1.01 I 0308 5 15 1,0421 l.044Y ... 5,62 I . 0422 I ,0444 , .. 11.21 1.0441 5.6: I , 10464 , .. 1 11423 10.2; I . 0396 5.42 4.35 I , 0,347 8.55 1 ,0332 7 . Ti 12.75 6 ,55 1 .I1610 13.86 ... 1,0579 1 . 2 1 I , 0386 8 . 9 6 1 10411 10.00 .?, 7 6 I .0169 4.34 0.62 1.0158 4.40 1491,. . . . . . 1.0198 4.9; 0.63 1.0188 L l 5 1.0318 i.31 1496 , , . , , . 1 . 0 3 4 1 8.27 1.0331 i.61 151.i. , . . , , , , . 1.11352 8.56 1.15 1.0195 4 54 152') , , , , , , . I , 020'1 5.11 0.89 i 42 1530 , , , 1.0252 6.21 0.98 1.0231 1.0273 6 27 1531 . . . . . . . . . 1.0291 7.1; 1.08 . . . .... 11.22 0.91 1.0468 10 33 .... .... l 2 ? 4 ( r ) , . . , , , , 1.0486 1.125 . . . . . . . . . I , 0 3 2 i 7.86 0.93 ... 6 99 . ,. .... ( 6 ) This sample contained salt. ( a ) Determined by drying in I'uruo a t i o o C. i h ! Composite of 1290 t o 1306 inclusive. ( d ) Expressed as invert.
or canned tomatoes. i t is assumed t h a t no substance such as sugar or salt has been added. If sodium chloride is found t o be present in excess of t h e a m o u n t normal t o tomatoes (from o . o j t o 0.1 per c e n t ) , it is necessary t o determine t h e a m o u n t of salt a n d make correction therefor before applying t h e relations given h el o w . I n csamining raw tomatoes, care must be t a k e n t o secure n representative sample of t h e juice. 'This cannot bc done b y applying pressure directly, as t h e juice of t h e seed receptacles is of different composition from t h a t of t h e fleshy p a r t of t h e tomato. I t is necessary. therefore, t o crush t h e sample a n d thoroughly cook it in a flask surrounded b y boiling water a n d connected with a reflux condenser. DETERhIINATION OF SPECIFIC GR.4VITI
In pouring t h e sample of t o m a t o pulp into a flask
46 86
1.11;
56,iO .i 1,i 5
1.091 1,108
42.84
1.119
41 .56
1.102 I . 127
41 i6 44.65
39.74 4 i . SO 4 i 60 43. 1 5 54,20 54.75 56.45 5 2 . IO 45.85 6 7 . 15 51.57
.....
3 2 ,h i 44 86 46.20 32.Y6 36.31
40.n~ 57.62 43.80
(e) (.f)
1.120 1.110 1.132 I . 11;
1.126 1.123 I . 100 1.100 1 114
I , 106
11.8 10.6 12.2
I?. 1 12.4 12.2 11.1 I2 8 13.7 11 0 12.Y
.
.
55.5 54.6 54.6 51.6 48.9 51.9 51.7
8.2 8.9 8.9 9.7 10.3 9.7
48.9 51.Y 58.8 M .4 53.4 57.0 55.6 58.; 56.3 31 4
10.4 10.3 8.7 Y i
9.7
in
,?
Y 6 9.6 8 8
''
,'
6.8 6.3 6.1 5.3 4.8 5.4 5 .3
4.7 i0
. . . . 0.20551 n 20549 0.20546
6.8 5 7
5.2 6 0 5.8 6 .i 6.0 6.7
,./ I . Ill(e) . . . 1.116 9 8 . . . 14.3 I . 154 12.7 1.128 1,131 13.9 13.5 1.125 1.125 17.4 I I45 15 8 15.1 1.143 .... I , 124(r) 11.8 .... ... 1. I23 .... .... . . Salt-free ratio. Calculated hy iormula of Lorentz-Lorenz,
(n2
0 20544 0 20545 0 20554
0.20550 0 20544 0.20529
.....
0 20554
. . . .
0.20565 0,20554 0.20556 0.20556 0 20551
0,2054;
-
'
+ a?'
specific gravity should be determined at zoo C. If t h e temperature Yaries from this, t h e specific gravity m a y be corrected b y t h e correction table for Bris hydrometers, changing t h e Brix degrees in t h a t tahle t o t h e corresponding specific gravity, a n d also allon-ing for t h e fact t h a t t h e correction table mentioned is based on ~ j l ; ~ instead ' of 20' C. D E T E R Y I S X T I O S O F SOLIDS I . B Y T H E EXAMISATIOS O F T H E pcLp-The total solids in t o m a t o pulp m a y be determined by drying irt i'acuo a t 70' C . ; 'by drying a t atmospheric pressure a t t h e temperature of boiling water; b y calculation from t h e specific gravity of t h e pulp; or from t h e percent of solids, specific gravity or index of refraction of t h e filtrate. T h e solids obtained h y different methods on 3 1 samples of pulp are given in Table 111. ( a ) . B S DRYISG-By drying either in Y C Z C - I L U or at
604
T H E J O C R X d L OF I-VDL7STRI.IL . I S D ENGI-YEERI,VG C H E M I S T R Y
atmospheric pressure, i t is our experience t h a t after t h e sample has reached apparent dryness, four hours' drying gives complete results: F r o m 2 t o 1 grams should be t a k e n for t h e determination, a n d enough water added t o distribute t h e sample uniformly over t h e b o t t o m of t h e flat-bottomed dish. T h e solids as determined b y drying i j z ' I ' U C U O a t i o o C . are a b o u t 108.j per cent of t h e result obtained b y drying a t t h e temperature of boiling water a t atmospheric TABLE11-COMPOSITION C O M P O S I T I O N OF P U L P S
only one case did i t exceed 0.20 per cent. T h e results obtained b y t h e subsequent examination of a considerable number of other samples confirm t!ii? relation. ( b ) . B Y C A L C U L A T I O N FROXI T H E SPECIFIC G R A \ I T Y O F T H E PULP-There is a very exact relation between t h e specific gravity of pulp (determined b y t h e method given above) a n d t h e per cent of total solids as d e termined b y drying. T h e solids corresponding t o OF
TRIXMING STOCK P U L P S B Y FILTERING PULPS Ratio
LIQUOROBTAIPiED
Per Cent Per Immersion of pulp insoluble cent Per cent iecific Per Per cent refracsolids t o solids sugar in acid in Ratio ot g vity a t Per cent cent acid as tometer a t filtrate in total solids solids acid t o 3' C. solids(a) sugar(e) citric l i 5 ' C. solids solids of liquor of liquor sugar 4.11 ,0337 i.68 0.58 45.90 1.241 ... 53.5 7.6 7.0 0.59 4.05 ,0334 7.62 45,7 5 . . . 7.7 1,233 53.2 6.9 .... .... 42.87 ,0302 7.11 .... .... ... 1.203 ... 40.75 ,0279 6 55 .... .... 1.203 .... .... , . . ... 37,SO .., , . 5.83 .... .... . . . .... ... 1.201 , . . 36.40 ... .... ,0232 5.53 1.197 .... .... ... ... 41.60 .... ... ,0288 6.86 .... .... . . 1.184 ... 36.10 ,0227 5 41 .. .... .... 1.184 .... ... ... 39.25 .02i5 6.14 . . . ... .... 1.218 .... ... ... . . . 30.35 1.203 .... ,0168 3.94 .... .... ... ... 52.47 .... .... ,0400 9.28 1.109 .... .... ... ... .. .... 49.33 1.117 ,0369 8.53 12.8 .... ... ... .... .... 52.40 ,0401 9.29 1.109 .... 11.4 ... ... ,0369 8.28 .... .... I. 175 49.37 .... ... 13.3 ... 33.27 .... .... 1.042 .... 3.7 ,0201 4.65 ... ... 1.040 66.92 .... ,0566 12.70 .... ... ... 4.7 .... .... 42.65 1.123 14.3 ,0304 6.89 .... ... ... 32.09 ,0184 4.29 2.35 0.30 1,140 54.8 7.0 14.7 7.8 ,0178 4.15 32.09 2.32 0.29 1.022 55.9 7.0 2.4 8.0 4.07 47.85 0.51 1.220 6.2 18.6 8.08 50.4 ,0359 8.0 3.51 0.46 .... i .29 1 . I45 11.7 44,69 6.3 48.3 7.6 ( d ) Clear liquor separated f r o m unconcentrated pulp on standing ( e ) Expressed a s invert.
COMPOSITION OF
Per Per cent cent intotal soluble SAMPLE h-0. solids(a) solids 1470.. . . . . . . I 9.54 .... 1471 . . . . . . . . . 1 .... 9.40 1470-1 . . . . . . . . 1 .... 8.56 7.88 1470-2 . . . . . . . . I .... 7.00 147&3 . . . . . . . . 1 .... 1470-4 . . . . . . . 1 .... 6.62 1471-1 . . . . . . . . 1 .... 8.12 6 41 1471-2 . . . . . . . 1 i.48 1471-3... . . . . . 1 . . . 1471-4 . . . . . . . . 1 4.74 .... 1572 . . . . . . . . . . 1 10.28 .... 1573 . . . . . . . . . . 1 1.22 9.53 1574 . . . . . . . . . . 1 1.17 10.29 1575 . . . . . . . . . . 1 1.29 9.73 1662(b).. . . . . . 1 4.85 n.18 1664(c), . . . . . . 1 13.2 0.62 1665.. . . . . . . . . 1 i.74 1.10 /01. . . . . . . . . 1 4.89 0.72 4.24 703(d) . . . . . . . I 0.10 9.85 io5 . . . . . . . . . . 1 1.83 706 . . . . . . . . . . 1 8.35 0.98 (a) Determined b y drying in ~iacuoa t 70' C , ( b ) Unconcentrated t o m a t o juice from peeling table (c) No. 1662 concentrated. Specific gravity a t 20° C.
Yol. 7 , S o . 7
pressure. This figure is t h e average of t h e results obtained b y t h e examination of 20 samples of pulp, i n all of which t h e per cent of solids obtained b y drying in vacuo agree quite closely with t h e per cent OF METHODSFOR THE DETERMINATION AND CALCULATION OF SOLIDS I N WHOLETOMATO PULP
pulps of various specific gravities are given in Table IV, or m a y be obtained from t h e following formula which is derived from t h e same t a b l e : Per cent SOLIDS = 228 (sp. gr. of pulp -1.000)
TABLE 111-COMPARISON
solution a t 2 0 ° C . ( b ) For the figures.inthis column the formula given in footnote ( u ) was employed and the results multiplied b y 1.12.
obtained b y drying a t atmospheric pressure multiplied b y 1.08j. In I j of t h e 2 0 samples examined. t h e difference did not exceed 0.10 per cent. a n d in
2.
BY
THE
+
EXAUISATIOIS
19.1 ( s p . gr. of pulp - 1 . 0 1 5 ) . OF
THE
FILTRATE-
If a sample of pulp of considerable size be thrown on a folded filter, a filtrate is obtained whose composition has a definite relation t o t h a t of t h e whole pulp. ( a ) . B Y DRYmc-The per cent of solids in t h e filtrate may be determined b y drying in v a c u o a t i o o C . . or under atmospheric pressure a t t h e temperature of boiling water. .Is in t h e case of t h e drying of pulp, a constant relation is found t o exist between t h e per cent of solids as determined b y drying i i t v a c u o a t 70' C . , a n d t h e per cent of solids as determined b y drying a t atmospheric pressure a t t h e temperature of boiling w-ster. The per cent of solids in t h e filtrate obtained by drying at atmospheric pressure. multiplied b y I . I z j, gives t h e per cent of solids obtained b y drying i n z'(ii.iio. This relation is shown in detail in Table IV. T h e per cent of solids in t h e filtered liquor obtained b y drying i i i v o c u o . multiplied b y 1 . 1 2 , gives t h e per cent of solids i n t h e original pulp obtained b y drying i n ' ~ " i c u o . This relationship is shown i n Table I , i n t h e column headed "Ratio of pulp solids t o f i l t r a t e solids," a n d also in Table II-. Of t h e 3 3 samples shown in Table I , t h e resul: obtained b y multiplying t h e per cent of solids in the filtrate (obtained b y drying in z~ac~uo)b y t h e facTor 1 . 1 2 is very nearly identical with t h e per cent of soiids in t h e pulp (obtained b y drying i n " ~ " u c ~ ~ oIr, ). 22 of t h e 33 samples t h e difference between these t w o figures is less t h a n 0.1 per cent. In I; samples it
.. .
,ess t h a n o 06 per c e n t . a n d in 13 samples it is less thrin o . o j per cent. I n only t w o samples does it e s cwl-i 0 . 1 7per cent. i ?J). n s CALCULATIOS F R O M T H E SPECIFIC G R A V I T Y O F THE: FILTRATE-The specific g r a v i t y of t h e filtered liquor m a y be determined b y means of a n ordinary p\-cnometer. F r o m t h e specific g r a v i t y a t 2 0 ' C.. :he per cent of solids in t h e filtrate as determined b y dr!-ing i i i I ~ < I ( . I ( O a t 70' C . . m a y be obtained f r o m IS
TABLE IV-TOM~TC
I t IS of interest t o note t h a t t h e table suggeitccl by Windisch for t h e determination of extract i n wine ( B u r e a u of Chemistry. U. S. Dept. -1gr , B i t / / 107, revised, T a b l e 1.) m a y be employed t o determine solids i n t o m a t o pulp f r o m t h e specific gravity of t h e filtered liquor f r o m t h e same. If t h e specific gravity of t h e liquor be determined a t z o o C , t h e figures in t h e adjoining column, under " E x t r a c t . " correspond very closely t o t h e per cent of t o t a l solids in t h e orig-
P U L P A S D FILTERED
LIQLO R
Tou.4ro P U L P
2.93 27.Y 1.0144 1.0146 1.0149 3.45 3.07 28.6 1.0151 3.10 3.11 28.8 1.0153 3..:5 3.15 29.0 ,0155 X60 3.20 2 9 . 2 ,015; .X65 3.24 29.4 0160 .i70 3.28 29.6 0162 .3.:.i .1.33 29.8 ,0164 i8(l ,3.38 30.0 ,0166 .3.5s 3.42 30.3 ,0168 7.40 3.46 30.,5 .OIX .I 1)s 3.51 30.7 .o1;3 +.(IO 3.55 30.') ,0175 4 ns .;.fro ,31 . I ,0177 4.10 3.64 31.3 .01i') 4.15 3.69 31.5 ,0181 4.70 3 . i 3 31.7 0183 4.29 3.78 31.Y ,0185 4 . i O 3.82 32.1 ,0188 4.3.i 3.86 32.3 ,0190 4 40 3.91 32.5 1.0192 4.1' 3.95 32.7 1.0194 4 .in 4.00 32.0 1.0196 45.5 4.04 33.1 1.0198 4 60 4.09 1.0200 4 65 4.13 33.6 1.0203 4:O 4.18 33.8 1.0205 4 : S 4 22 34.0 1.0207 4 . 8 0 4 2 6 34.2 1.020') 4.85 4.31 34.4 1.0211 4 . 9 0 4.36 34.6 1.0213 4.95 4.40 34.8 1.0216 .i n o 4.44 35.0 1.0218 .5.0.5 4 . 4 9 3 5 . 2 1.0220 5 . 1 0 4,53 35.4 1.0223 ,%I5 4 58 35.6 1.0225 .i.?n 4.62 35.8 1 . 0 2 2 7 i.25 4 66 36.0 1.022') q.10 4.71 36.2 1.0231 36.4 1.0233 5 35 4,;s i . 4 0 4.80 36.6 1.0235 5 45 4.84 36.8 1.0238 , 5 5 0 4.89 3 7 . 1 1.0240 ,i5 5 4.93 3 7 , , 3 1,0242 5 60 4.98 3 7 . 5 1.0244 5 6 5 5 . 0 2 3 7 . 7 1.0246 i 7 0 5.06 37.9 1.0249 .i:5 5.11 38.1 1.0251 .i80 5.15 38.3 1.0253 i 85 5.20 38.5 1.025: i 90 5.24 38.7 1.0251 i 'I.< 5.29 38.9 1.0250 h.no 5.33 39.1 1.0261 6 0 5 5.38 39.,3 1.0263 6 I O 5.42 39.5 1.0266 h . 1 5 5.46 39.7 1.0268 6 . 2 0 5.51 39.9 1.0270 h 2 5 5.56 4 0 . 1 1.0272 3 30
2.97 28.1 .i.40 3 . 0 2 28.3 .3 i . 5
3.70 3.76 3.81 3.87 3.02 3.98 4.03 4.09 4.15 4.20 4.26 4.31 4.3; 4.43 4.48 4.54 4.59 4.65 4.71 4.76 4.82 4.87 4.93 4.99 5.04 5.10 5.16 5.21 5.27 5.33 5.38
3.41 3.46 3.51 3.56 3.61 3.67 3.72 3.i7 3.82 3.8i 3.93 3.98 4.03 4.08 4.13
4.18 4.23 4.28 4.33 4.38 4.44 4.49 4.54 4.59 4.64
4.70 4.75 4.80
4.85 4.90 4.96 5 . 4 4 5.01 5.49 5.06 5.55 5 . 1 1 5.60 5.16 5.66 5.21' 5.72 5.26 5.77 5.31 5.83 5.36 5.88 5.41 .5.94 5.47 6.00 5.52 6.05 5 . 5 i 6.11 5.62 6.16 5.67 6.22 5.73 6.28 5.78 6.33 5.83 6.39 5.88 6.45 5.93 6.50 5.99 6.56 6.04 6.61 6.09 6.67 6.14 6 . i 2 6.19 6.78 6.24 6.84 6.29 6.89 6.35 e.95 6.41 , . 0 l 6.46
1.0161 1.0163 1.0166 1.0168 1.0170 1.0172 1.0174 1.0177 1,0179 1.0181 1.0183 1.018.5
1.0188 i.oi9n 1.0192 1.0194 1.0197 1.0199 1.0201 1.0203 1.0205 1.0208 1.0210 1.0212 1.0215 1.0217 1.0219 1.0222 1.0221 1.0226 1.0228 1.0230 1.0233 1.0235 1.0237 1.0240 1.0242 1.0244 1.024; 1.0249 1.0251 1.0253
1.0256 1.0258 1.0260 1.0263 1.0265 1.0267 1.0270 1.02i2 1.0274 1.0276 1.0279 1.0281
1.0283 1.0285 1.0288 1.0290 1.0292 1.0294
6.30 6.35 6.40 6.45 6 50
5.60 5.64 5.69 5.73 5.78
40.3 40.6 40.8 41.0 41.2
1.0274 1.0277 1.0279 1.0281 1.0283
7.06 7.12 ;,I7 7.23 7.28
6.51 6.56 6.61 6.66 6.71
1.0299 1,0301
1.0304 1.0306
0.4.5
6.55 6.60 6.65 6.70 6.75
5.82 5.86 5.91 5.95 6.00
41.4
41.6 41.8 42.0 42.2
1.0285 1.0287 1.0290 1.0292 1.0294
7.34 6.76 7.40 6.82 7 . 4 5 6.87 7 . 5 1 6.92 7 . 5 6 6.97
1.0308 1.0310 1.0313 1.0315 1.0317
6.80 6.85 6.90 6.95 7.00
6.04 6.09 6.14 6.18 6.22
42.4 42.6 42.8 43.1 43.3
1.0296 1.0298 1.0300 1.0303 1.0305
7.62 7.68 7.74 7.79 7.85
7 . 0 2 1.0320 7.08 1.0322 7.13 1.0324 7.18 1,0326 7 . 2 3 1.0329
7.05 7.10 7.15 7.20 7.25
6.26 6.31 6.36 6.40 6.44
43.5 43.7 43.9
1.0307 1.0309 1.031 I
7.28 7.33 7.3R
44.1 44..3
1.0313
7.90 7.96 8.02 8.07 8.17
9.60 9.65 9.70 9.75 9.80 9.85 9.90 9.95 10.00 10.05 10.10 10.15 10.20 10.25
7.30 6.48 44.5 7.35 6.53 44.7 7.40 6.58 44.9 7.45 6.62 45.1 7.30 6.66 45.3
1.0318 1.0320 1.0322 1.0324 1.0326
8.18 7.54 8.24 7.59
7.55 6.71
1.0328 1.0331 1.0333 1.0335 1.033i
8.46 8.52 8.57 8.63 8.68
i.79 1.0354 7.84 1.0356 z.89 1.0358 t . 9 5 1.0361 8.00 1.0363
6.93 6.98 7.02 7.07 8.00 7.11
46.6 1.0339 46.8 1.0341 47.0 1.0344 47.2 1.0346 47.4 1.0348
8.74 8.80 8.86 8.91 8.96
8.05 8.11 8.16 8.21 8.26
1.0365 1.0367 1.0370 1.0372 1.0374
8.05 8.10 8.15 8.20 8.2.5
43.6 1.0350 47.8 1.0352 48.0 1.0354 48.2 1.035i 48.4 1.0359
9.02 8.31 9.08 8.36 9.14 8.41 9.19 8.46 9.25 8.51
l.03ii 1.0379 1.0381 1.0383 1.0386
8.57 8.62 8.67 8.72 8.77
1,0388 1.0390 1.0393 1.0395 1.0397
8.83 8.88 8.93 8.98 9.80 9.03
i.04on 1.0402
45.5
7.60 6.76 45.7 7.65 6.80 4 i . 9 7- . 7 0 6.84 46.2 1 . 1 3 6.89 46.4
-_
7.80 7.85 7.90 i,95
7.16 7.20 7.24 7.28 7.33
1.0315
8.30 7.38 48.6 1.0361 8.35 7 . 4 2 48.8 1.0363 8.40 7.46 49.0 1.0366 8.45 7 . 5 1 49.2 1.0368 8.50 7 . 5 5 49.4 l . 0 3 i 0 8.55 8.60 8.65 8.70 8.75
2.60 i.64 7.68 z.73 i.78
8.80 8.85 8.90 8.95 9.00
7.82 7.86 7.91 7.95
9.58 9.64 9.70 9.75
50.7 50.9 51.1 51.3 8.00 51.5
1.0383 1.0385 1.0387 1.0389 1.0392
9.86 9.92 9.97 10.02 10.08
1.0394 1.0396 1.0398 1.0400 1.0402
'r:tL)ie IT-. It m a y also be calculated b y t h e following for:iiula. which was derived f r o m t h e s a m e t a b l e : Per c e n t
S O L I D S IS
FrrTXATE =
9.30 9.36 9.42 9,47 9.53
1.0372 1,0374 1.0376 1.0379 1.0381
51.7 51.9 52.1 52.3 52.5
230 (sp.gr. of filtrate -1.000).
T h e per cent of solids in t h e pulp m a y also be ascer:ained f r o m t h e specific g r a v i t y of t h e filtrate a t 20' C.. f r o m T a b l e I\-. T h e s a m e results m a y b e obtained f r o m t h e following formula, which was derived f r o m Table 111: I'er c e n t SOLIDS I S P U L P = 2 5 7 . 5 (Fp. gr. or filtrate at 200 c. -1,000).
1.0331 I 0333
1.0336 7.43 1.0338 7.48 1.0340
1.0342 1.0345 8.30 7.64 1.0347 2.99 1.0349 8.35 8.40 , . , 4 1.0352
49.6 49.8 50.0 50.2 50.4
9.05 8.05 9.10 8.09 9.15 8.13 9.20 8.18 9.25 8.22
1.02~7
1.0404
1.0406 1.0408
9.09 1.0410 1.0413 9.19 1.0415 9.24 1,0417 9 . 2 0 1.0419 in.i.1- 9.35 1 . 0 4 2 1 1 O . I Y 9.40 1.0424 30.25 9.45 1.0426 10.30 9.50 1.0428 30.35 9.55 1.0430 9.14
y.30 9.35
8.27
8 . 3 1 52.9
10.4;
9.40
8.35 8.40 8.45 8.49 8.53 8.58 8.62 8.67 8.71 8.75
io..jl 10.58
Y 50 9.55
8.80
8.85 8.89 8.93 8.98 9.02 9.07 9.11
10.30
9.15
10.35 10.40
9.20 9.25 9.29 9.33 9.38
10.45
10.50 10.55
10.60 10.65 10.70 10.75 10.80 10.85 10.90 10.95 11.00 1.05 1.10
1.15 1.20 1.25 1.30
1.35 1.40 1.45 1.50 l,.55 1.60 1.65 1.70 1.75 1.80
1.85 1.90 1.95 2.00 12.05 12.10 12.15 12.20 12.75 12.30
9.42 'Y.47 9.51
9.55 9.60 9.65 9.70 9.74 9.78 9.82 9.87 9.92 9.96 10.00 10.04 10.09 10.13 10.18 10.22 10.27 10.31 10.35 10.40 10.45 10.49 10.53 10.58 10.63 10.67 10.71 10.75 10.80 10.84 10.89 10.94 10.98 11.02 11.07
12.35 12.40 12.45 12.50 1 1 . 1 1
,52.7 1.0404 1.0406 5 3 . 1 1.0409 i 3 . 3 1.041 I .i.? 5 I 0413 5 3 7 1.0412 53.9 1.0411 54.1 1.0419 54.,7 1 . 0 4 2 2 54.5 1 . 0 4 2 4 54.7 1.0426 55.0 1.0428 5 5 . 2 1.0430 55.4 1.0433 55.6 1.0435 55.8 1,0437 56.0 1.0439 56.2 1.0441 56.4 1.0444 56.6 1.0446 56.8 1.0448 ,57.0 1.0450 5 7 . 2 1.0452 5 7 . 4 1,0454 57.6 1,0457 57.8 1.0459 58.0 1.0461 58.2 1.0463 58.4 1.0465 58.6 1.0467 58.8 1.0469 59.0 1.0471 59.2 1.0474 59.4 1.04ifi 59.6 1.0478 59.0 1.0480 60.1 1.0482 60.3 1.0484 60.5 1.0487 60.7 1.0489 60.9 1.0491 61.1 1.0493 61.3 1.0495 61.5 1.0498 61.7 1.0500 61.9 1.0502 62.1 1.0504 62.3 1.0506 62.5 1.0508 6 2 . ~ 1.0511 62.9 1.0513 63.1 1.0515 63.3 1.0517 63.5 1.0519 63.7 1.0521 64.0 1.0523 64.2 1.0525 64.4 1.0527 64.6 1.0529 64.8 1.0531 65.0 1.0533 65.2 1.0535 65.4 1.0537 65.6 1.0539 65.8 1.0241
1041
10.64
9.60 9.65 9.70 9.75 9.80 9.86 9.91 9.96 10.01 io.06 10.1 I I O 16
10.70 i n 7.5 10.80 10.86 10.91 0.97 1.02 1.08 10.21 1.14 10.26 1.20 10.31 1.25 10.37 1 . 3 0 10.42 1.36 10.47 1.41 10.52 1.47 10.57 1 . 5 3 10.63 1.59 1 n . m 1.64 10.73 1.70 10.78 1.7.5 10.8.1 11.81 10.89 I 1.87 10.94 1 1 . 9 . 3 10.9') I 1.99 I 1.04 12.05 11.09 2.10
2.1.5 2.21 2.26 2.32 12.37 12.43 12.49 12.55 12.60 12.65 12.71 12.77 12.83 12.88 12.94 12.99 13.05 13.10 13.16 13.2: 13.2, 13.32 13.38 13.44 13.50 13.55 13.60 13.66 13.72 13.78 13.83 13.89 13.95 14.01
1.0433 1.0435
1.0437 1,0440 1.0442 1.0444 I 044:
1.04io
1.0451
1.0453 1.0456 1.0458 1.0461
1.0463 1.046i 1.0467 1.0469 1.0472
1.0474 1.0476 1.04i8 1.0481 1.048,3 1.048.i 1.048: 1.0490 1.0492 1,0494 1.0496 1.0499 11.15 1.0501 1 1 . 2 0 1.0503 11.25 1.0505 1 1 . 3 0 1.0508 11.35 1.0510 11.40 1 . 0 5 1 7 11.45 1.051,5 1 1 . ~ 0 1.051; 11.55 1.0519 11.60 1.0522 11.66 1.0524 1 1 . 7 1 1.0526 11.76 1.0528 11.81 1.0531 11.86 1.0533 11.92 1.0535 l1.Yi 1.0538 12.02 1.0540 12.07 1.0542 12.12 1.0544 12.18 1.054: 12.23 1.0540 12.28 1 . 0 5 5 1 12.33 1.0554 12.38 1.0556 12.44 1.0558 12.49 1.0560 12.54 1.0562 12.59 1.0565 12.64 1.0567 12.70 1.056'~ 12.75 1.0572 12.80 1 0574 12.85 1.0576 i z . w 1.0,iiY
inal pulp. still closer agreement is obtained if t h e figure o . o j be deducted f r o m t h e percentage of e s t r a c t given in t h e table. A \
(C).
BY
C A L C L L A T I O S FROM THE 1 S I ) E S O F XEFRAL-
FILTRATES-The i n d e s of refraction of t h e liquor obtained b y filtering t o m a t o pulp m a y be determined b y means of either t h e Zeiss-Xbb& refractometer. o r t h e immersion refractometer a t t h e t e m p e r a t u r e of 17.j o C. T h e l a t t e r is preferable as TIOX
OF
THE
606
T H E JOCR-VAL OF I S D C S T R I d L . i S D E S G I S E E R I S G C H E M I S T R Y
i t permits of much greater accuracy. T h e corresponding percentage Of “lids in the and the percentage Of “lids in the Pulp f r o m which it is prepared may be ascertained f r o m the index Of refraction b y Table 11’. T h e per cent of solids in t h e filt r a t e m a y also be calculated f r o m t h e scale reading of t h e immersion refractometer a t 17.j o C . , b y t h e following f o r m u l a , which is derived from Table IT‘: Per cent SOLIDS I N FILTRATE = 0.258 (scale reading -15)
DETERMIKATIOS O F SCGAR
T h e sugar of tomatoes
probably always pre,ent
as invert sugar, If cane sugar is ever present I n l h e r a w product i t is doubtless inverted during t h e concentration of pulp, The per cent of sugar giT.en i n Tables I and 11 T~.asdetermined b y the method of nlunson and ffalker.l D E T E R MI S A T I O 5 0 F A C I D I T Y
- 0.0165 (scale reading - 26.4).
If t h e index of refraction has been determined b y means of a n AbbC refractometer, t h e per cent of solids i n t h e filtrate m a y be calculated b y t h e following formula : P e r cent SOLIDS I N FILTRATE = 666 ( ~ Z D-1,3332) - 20.7 ( Z D -1.3376). T h e per cent of total solids in t o m a t o pulp m a y also be ascertained from t h e index of refraction of t h e liquor prepared b y filtering t h e pulp as shown in Table IT‘; or, it m a y be calculated from t h e immersion refractometer reading b y t h e following formula, which is derived from Table IV: P e r cent S O L I D S I N P U L P = 0.289 (scale reading of filtrate -15)
T‘ol. 7 . S o . 7
- 0.0185 (scale reading -26.4).
If t h e index of refraction of t h e filtrate has been determined b y means of a n AbbC refractometer, t h e per cent of solids in t h e pulp m a y be calculated b y t h e following formula: Per cent SOLIDSI X PULP = i 4 8 ( W D -1.3332) - 25.5 ( n -1.3376). ~ It is of interest t o n o t e t h a t t h e relation between t h e index of refraction of t h e liquor obtained b y filtering t o m a t o pulp a n d t h e per cent of solids in t h a t liquid is very similar t o t h e relation between t h e index of refraction a n d dis;olved solids i n beer a n d wine ext r a c t , as shown in t h e table prepared b y 1Vagner.l In t h e formula given above. as well as in Table I V , i t is assumed t h a t salt is absent. If i t b e desired t o calculate t h e percentage of solids in a sample containing salt from t h e index of refraction of t h e filtrate, i t is necessary first t o determine t h e a m o u n t of salt present a n d make correction therefor. For t h i s purpose t h e table of Wagner2 m a y be employed. T h i s correction is necessary, however. if t h e percentage of solids be determined b y drying, or calculated f r o m specific gravity. DETERMIKATIOK O F IKSOLUBLE SOLIDS
Transfer 20 grams of the pulp t o an eight-ounce nursing bottle, nearly filled with hot water, mix by shaking, and centrifuge until the insoluble matter is collected in a cake in the bottom of the bottle. Transfer the supernatant liquor onto a double, tared filter paper covering the bottom of a Buchner funnel, using suction t o facilitate filtration. Again fill the nursing bottle with hot water, stir the cake of insoluble solids so that it is thoroughly mixed with the water, centrifuge, and decant the supernatant liquor on the filter. Repeat the centrifuging and the filtration of the supernatant liquor once more, and then finally transfer the insoluble solids to the filter paper and thoroughly wash with hot water. Dry the paper and insoluble solids, and weigh. The insoluble solids are quite hydroscopic and the weight must he taken quickly. 1 “ U e b e r q u a n t i t a t i v e Bestimmungen misseriger Lbsungen mit d e m Zeiss-schen Eintauchrefraktometer,” T a b l e X V I I . Ibid.. Table I.
Accurate results cannot be obtained b y t h e titration of t o m a t o products in t h e presence of t h e insoluble solids. If i t be desired t o determine t h e acidity in t h e entire sample of tomatoes or t o m a t o pulp rather t h a n in t h e expressed juice, t h e insoluble solids should first be removed b y t h e method given in t h e determinntion of insoluble solids. T h e per cent of acid given in Tables I a n d I1 was obtained b y titrating t h e liquor obtained b y filtering t h e pulp. I n products of this nature, t h e addition of a n alkali causes a brownish color which has a tendency t o obscure t h e end point shown b y t h e indicator. T o obviate this, t h e sample should be diluted t o a t least zoo cc. a n d a larger a m o u n t of indicator employed t h a n is necessary with a clear solution. T h e following details are suggested: Dilute 20 grams of the filtrate under examination with over zoo cc. of water. Add a t least I, 2 cc. of phenolphthalein solution (prepared by dissolving I gram of phenolphthalein in IOO cc. of 95 per cent alcohol) and titrate with sodium hydroxide until the end point is obtained. Add I cc. of tenthnormal hydrochloric acid, heat the solution quickly to boiling and boil one minute to expel carbon dioxide. Cool the solution quickly t o about room temperature, and then add tenth-normal sodium hydroxide until the end point is obtained. The volume of hydrochloric acid added must, of course, be taken into consideration in the final result. h7ATIONAL C A N N E R S ’ ASSOCIATION,
WASHINGTON, D. C
A CONCISE GROUP METHOD FOR THE DETECTION O F GELATINIZING AGENTS, PASTY MATERIAL AND THICKENERS, USED IN FOOD PRODUCTS B y LEON -4. CONGDON Received J a n u a r y 12, 1915
T h e extreme difficulty of detecting various gelatinizing agents, pasty material a n d thickeners used in food products, has led t h e writer t o work o u t a group method, b y which these substances can be identified even if t h e unknown contains one or all of t h e common substances used for gelatinizing agents, e t c . , such as starch, dextrin, gelatine, acacia, agar-agar, tragacanth, albumen a n d pectin bodies of t h e fruit juices. T h e use of these substances has been quite general in recent years. Hence a s t u d y of these materials a n d their detection in food products is imp o r t a n t t o t h e chemist. Thickeners. pasty materials, a n d gelatinizing agents frequently are used t o cheapen t h e genuine articles of food. I n t h i s class m a y be mentioned agar-agar, which has been found in imitation lemon slices; starch, agar-agar, a n d gelatine in imitation jelly; dextrin in imitation cocoa cubes. These materials are also used t o cover u p inferiority. I n this class might b e mentioned albumen, or n-hite 1
Bureau of Chemistry, U . S. Dept. Xgr., Bull. 107, revised.
