Nov., 1914
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
variation in temperature in different analyses. I n some we get conditions favorable for a loss of alkali, in some for a loss of A1203 a n d sometimes for both. We have, with great care in heating, obtained only slightly low results where both A1203 a n d K a 2 0 were very high as in cryolite. T h e loss therefore probably can be prevented. Boric oxide tends t o alleviate t h e difficulty caused by alumina a n d i t does not in a n y way interfere with later determinations. Borosilicates with up t o j per cent A1203 give fairly good results. One showed 4.82 per cent A1203 a n d 0.1010 g. alkali chlorides b y regular methods a n d 4.93 per cent A1203a n d 0 . 1 0 2 7 g. alkali chlorides by t h e oxalate method. T h e results on glass G mentioned in t h e table are not very good, however. With glasses not containing Bz03 t h e addition of boric acid before evaporation with H F a n d H2C20.rdecreased t h e fluorine content of t h e soluble oxalates a n d also gave higher results for A1203 a n d alkali without showing a n y Bz03 present with t h e alkali. From t h e results so far we do not feel confidence in t h e method for such glasses as show undecomposed silico-fluorides, for while accurate determinations m a y be obtained with special precautions t h e method has no advantages under such conditions. For glasses which do not contain much A1203 t h e method seems well a d a p t e d , especially for t h e analysis of a series of glasses of very nearly t h e same composition. We have also found i t convenient for t h e rapid determination of As203 or Sb203 in glass.
899
As iron a n d alumina are rarely present in large amounts in glass a n d as t h e time of t h e soda fusion with glass can be c u t t o a few minutes t h e method seemed quite readily adaptable. The first glass tried was a soda alumina borosilicate which, f r o m analysis, showed a possible B203 content of 10.40 per cent by difference. Three determinations by Wherry’s method showed 10.72, 1 0 . j 7 , 10.67 per cent B203 or a n average of 10.64 per cent. A soda borosilicate containing a small amount of BaO a n d S b ~ 0 3showed 2 j.5 7 per cent B203 by Wherry’s method a n d 25.7j per cent by difference. Other glasses of same t y p e showed: P e r cent B203 by titration 25.10 12.71 17.57 14.90
P e r cent BzOs by difference 25.12 12.15 17.51 15.01
With a zinc borosilicate very unsatisfactory results were obtained, t h e B 2 0 3 content b y titration running f r o m 4 t o g per cent when only 2 per cent mas present. Several mixtures of ZnO a n d sand with a known a m o u n t of B203 were r u n through by Wherry’s method a n d results for B203 were always high even after very long boiling. Solutions of ZnCI2 a n d borax were boiled with CaC03 for varying lengths of time a n d using slight excess a n d large excess of CaC03 a n d zinc was always found in t h e filtrate from t h e C a C 0 3 precipitate. CaO was substituted for CaC03 b u t with no better success. iXa2C03 completely removed t h e zinc from solution a n d b y a double precipitation, using first N a ~ C 0 3a n d t h e n C a C 0 3 , we obtained 0.0360, D E T E R M I N A T I O N O F B O R I C ACID 0.0361 a n d 0.036 j g. BzO3 when t h e theoretical amount I n t h e analysis of borosilicate glasses we have found was 0.0365 g. P b O was found t o cause t h e same t h a t for t h e determination of boric oxide t h e method trouble as ZnO a n d t h e same modification of t h e described b y Wherry’ is very useful: “Fuse the sample with about 3 g. of Na2C03 for 15 minutes. method gave satisfactory results. We have been Take up with 2 0 to 30 cc. of dilute HCl adding a few drops of able t o use t h e modified method on a large number of ” 0 3 to oxidize ferrous iron. Place in a 250 cc. round-bottomed glasses with satisfactory results. T h e modified method t h e n is a s follows: Fuse flask, heat nearly to boiling, and add dry precipitated CaC03 in moderate excess. Connect with a return condenser and boil 0.5 g. of glass with 3 g. N a 2 C 0 3for one or two minutes vigorously for about I O minutes. Filter out the precipitate after mass is liquid. Take u p with 2 0 t o 30 cc. of hot through a small Biichner funnel, washing several times with hot water a n d when t h e melt is entirely decomposed filter water, but keeping the total volume of liquid below IOO cc. o u t a n y insoluble oxides. After washing, transfer Return the filtrate to the flask, add a pinch of CaC03 and again filtrate a n d washings t o a 250 cc. round-bottomed flask, heat t o boiling; then connect with a filter pump, through a splash a d d about 7 cc. concentrated HC1, heat nearly t o trap, and continue suction until the boiling has nearly ceased. Cool to the ordinary temperature, filter if the precipitate has a boiling a n d a d d d r y precipitated CaC03 in moderate red color from iron, add four or five drops of phenolphthalein excess. From here on t h e method is as given b y and run in slowly N / I ONaOH solution until the liquid is strongly Wherry except t h a t we used Ba(OH), instead of NaOH. pink in color. Introduce about I g. of mannite and shake, where- It is also advisable t o use suction f o r filtering t h e upon the pink color will disappear: Add NaOH to end reac- C a C 0 3 precipitate. tion, then another gram of mannite and if necessary more alkali CORNINGGLASS WORKS,CORNING,NEW YORK until a permanent pink color is obtained.” T h e method was first tried b y fusing 0 . j g. sand a n d THE COMPOSITION OF MILK AS SHOWN BY ANALYSES 0 . 2 g. boric acid with 3 g. soda. T h e melted mass f O F SAMPLES OF KNOWN PURITY MADE BY THE MASSACHUSETTS STATE BOARD OF HEALTH was t a k e n u p with water a n d 7 cc. conc. HC1 added B y HERMANNC. LYTHCOB after transfer t o a 2 j o cc. flask. T h e method was t h e n Received June 19, 1914 followed as described above except titration was hlilk, without d o u b t , is t h e most extensively adulmade with Ba(OH)2. T h e B203 content came from terated of a n y article of h u m a n food a n d , b y reason 2 t o I O per cent low, d u e t o retention of B203 b y t h e precipitate’ from C a C 0 3 . By using suction in filtering of its variable composition, t h e detection of this a n d washing this precipitate practically I O O per cent adulteration is difficult a n d in some cases impossible. of t h e Bz03 introduced was recovered. For 0 . 2 j g. For these reasons most legislative bodies, in addition B203 = 12.40 B a ( O H ) 2 we used r s . 3 j and 12.40 cc. t o prohibiting t h e sale of adulterated milk, prohibit t h e sale of milk, t h e composition of which falls below 1 J . A m Chcm. SOC.,SO (1908), 1687.
.
T H E J O U R N A L OF 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
900
specified standards a n d in some places, as in t h e S t a t e of Massachusetts, t h e penalty for t h e sale of milk which is adulterated is more severe t h a n t h a t for t h e sale of milk below t h e legal standard. T h e milk analyst in such localities must familiarize himself with t h e composition of natural milk in order t o detect a n d distinguish between milk which is adulterated and t h a t which is simply below t h e legal standard. T h e usual methods of adulterating milk are t h e addition of water, t h e removal of cream or performance of both acts, t h e ease of which as well as t h e resulting profit has considerable t o do with t h e extent of milk adulteration. As water is a natural component of milk, t h e detection of added water, as well as t h e removal of cream, can be accomplished only by showing abnormal chemical or physical constants which are consistent with t h e nature of t h e adulteration. Either or both of these forms of adulteration may be practised t o a limited extent a n d be impossible of detection. During t h e past six years, from 600 t o 7 0 0 samples of known purity milk have been examined in t h e laboratory of food a n d drug inspection of t h e Massachusetts State Board of Health of which nearly j o o samples have been subject t o a fairly complete analysis, 434 of which came from individual cows a n d t h e balance from herds. These samples were obtained from Jerseys, Guernsey, Ayrshire, Dutch Belt, a n d Holstein cows, as well as from cross-bred or socalled grade cows. The methods of analysis used were as follows: T O T A L S O L I D S , as used b y t h e Massachusetts S t a t e Board of Health for t h i r t y years: Evaporate 5 g. of milk in a flat-bottomed platinum dish over a boiling water b a t h for 2 hrs. a n d weigh t h e residue. ASH: Burn in a muffle t h e residue obtained as above, a n d weigh t h e ash. F A T : By t h e Babcock method. P R O T E I N S : From t h e percentage of nitrogen by t h e Gunning method using t h e factor 6.38. L A C T O S E : By t h e polariscopic method of t h e A. 0. A. C., mercuric nitrate being used as a clarifier. If lead is used as a clarifier, the results are low, owing t o t h e precipitation of lactose. MILK SERUM-(I) COPPER METHOD:' Add four volumes of milk t o one volume of copper sulfate solution (72.5 g. per liter adjusted t o read 36.0 a t 2 0 ' C. on t h e scale of t h e Zeiss Immersion Refractometer or t o a specific gravity of 1.0443 a t 2 0 / 4 O C.), shake well a n d filter. (2) ACETIC ACID METHOD:^ T o I O O cc. of milk a d d 2 cc. of 2 5 per cent acetic acid, heat for 20 minutes in a water b a t h a t 7 0 ° , cool I O minutes in ice water and filter. (3) MODIFICATION OF P F Y L A N D T U R N A U 3 called t e t r a serum I , giving t h e same serum which has been substituted in some instances for t h e acetic acid method. Shake jo cc. of milk with 5 cc. of carbon tetrachloride in a shaking machine for 5 minutes, a d d I cc. of 2 0 per cent acetic acid, shake again for j minutes, centrifuge and pour off t h e clear serum. 1 2 3
Lythgoe, Mass. State Board of Healfh Report, 1908, P. 594 Leach and Lythgoe, J Am, Chem. Soc , 1904, p. 1195. Arb. Kats. Ges 40, 247.
.
Vol. 6 , No.
II
(4) S O U R S E R U M : ' Allow t h e milk t o sour spontaneously and filter. ( 5 ) A S H O F S O U R SERUM:^ Measure 2 j cc. of t h e sour milk serum into a platinum dish, evaporate t o dryness a n d burn in a muffle a t a temperature not above j 5 o o C. Weigh t h e residual ash. The summary of t h e analyses of t h e samples arranged according t o breeds in t h e order of t h e average t o t a l solids is given in Table I. Determinations of solids, f a t , proteins, ash, a n d sugar were made upon all t h e samples, a n d t h e serum was prepared from nearly all t h e samples b y one or more methods. T h e variation' in t h e composition of milk is due primarily t o t h e breed of t h e cow b u t is more or less influenced by t h e period of lactation and the season of t h e year. I t is very generally known t h a t cows of the Jersey and Guernsey t y p e give better milk t h a n those of t h e Holstein variety, t h a t cows far along in lactation give richer milk t h a n just after calving a n d t h a t milk obtained in t h e summer is inferior in quality t o t h a t obtained in t h e winter although popular opinion is opposed t o this latter statement. The solids naturally show t h e highest numerical variation, from 17.17 t o 1 0 . 2 0 per cent in t h e milk from individual cows and from 14.57 t o 11.j6 per cent in herd milk. The constituents having t h e most influence upon this variation are first t h e f a t a n d t o a less extent t h e proteins, t h e former varying from 7.7 t o 2.4j per cent in milk from individual cows a n d from j . 4 0 t o 3.35 per cent in herd milk and t h e latter from 5.01 t o 2 per cent in milk from individual cows a n d from 4.02 t o 2.66 per cent in herd milk. T h e numerical variation of t h e , a s h is very slight a n d t h a t of t h e sugar is t h e least of t h e major constituents, the latter being from j.80 t o 3.91 per cent in milk from individual cows and from j.2 j t o 4.35 per cent in herd milk. T h e percentage variation is more marked t h a n t h e numerical variation, being t h e greatest in t h e f a t a n d least in t h e sugar. Owing t o t h e presence of a few samples of abnormally high concentration, t h e percentage variations above t h e average are greater t h a n those below t h e average. Solids vary from 32 per cent above to 21 per cent below the average Fat varies from 83 per cent above to 42 per cent below the average Proteins vary from 53 per cent above to 39 per cent below the average Sugar varies from 32 per cent above to 18 per cent below the average Minimum solids were 40 per cent below the maximum solids Minimum fat was 68 per cent below the maximum fat Minimum proteins were 50 per cent below the maximum proteins Minimum sugar was 32 per cent below the maximum sugar
,
Excluding some of t h e abnormally high figures these variations would be reduced. It is unusual t o find t h e solids above 1 7 or below 10.5 per cent, t h e f a t above 7 or below 2 . 5 per cent, t h e proteins above 4.5 or below 2.4 per cent, t h e solids-not-fat above I O or below 7.8 per cent, a n d t h e sugar above 5.5 or below 4.3 per cent. Using these limits, which eliminates 26 samples, t h e variations, f r o m t h e average are much ' less t h a n those calculated from all t h e samples. Solids would vary from 3 1 per cent above to 19 per cent below the average Fat would vary from 66 per cent above to 41 per cent below the average Proteins would vary from 38 per cent above to 27 per cent below the average Sugar would vary from 15 per cent above to 10 per cent below the average Minimum solids would be 38 per cent below the maximum solids Minimum fat would be 64 per cent below the maximum fat Minimum proteins would be 47 per cent below the maximum proteins Minimum sugar would be 22 per cent below the maximum Sugar 1 Matthes and Muller, Z . b f e n f l . Chem., 9 (1903). 173. 2 Burr and Berberich, Chem. Zfg., 32, 617. . .
.KO\'.,191.1
T H E JOGRNAL OF I N D U S T R I A L A N D ENGINEERING CHEMISTRY TABLEI-SUMMARY
BREED h - U X B E R OF S A X P L E S . .
TOTAL SOLIDS-NO.
................
of samples between a n d 17.17 per c e n t . , , , , , , a n d 16 per c e n t . , , . . , , , , , a n d 15 per c e n t . , . , . , , , . , a n d 14 per c e n t . . . . . . . . . . a n d 13 per c e n t . . . . . . . . . . a n d 12 per c e n t . . . . . . . . . . 10.2 a n d 11 per c e n t . , , , , , . . , , Highest, per c e n t . . . . . . . . . . . . . . . . . Lowest, per c e n t . . . . . . . . . . . . . . . . . . Average, per c e n t . , . . . . . . . . . . . . . . . 16 I5 14 13 12 11
OF A N A L Y S E S OF S A M P L E S OF
MILK O F K X O W NP U R I T Y
Grade Grade - G r a d e Grade Grade Dutch All Jersey Guernsev -Tersev Holstein samnles . Guernsev D u r h a m Avrshire Avrshire Holstein belt 36 28 27 20 16 52 27 131 41 56 434 5 11 11 7 2
2 11 6 5 4
...
...
ii:i7
1+:00 12.15 14.60
12.43 14.75
of s a m d e s between 7 a n d 7 . 7 per c e n t . . . . . . . . . 2 14 6 a n d 7 per c e n t . . . . . . . . . . . 5 a n d 6 per c e n t . . . . . . . . . . . IO 4 a n d 5 per c e n t . . . . . . . . . . . IO 3 a n d 4 per c e n t . . . . . . . . . . . ... 2 . 4 5 a n d 3 per c e n t . . . . . . . . . . . ... Highest, per c e n t . . . . . . . . . . . . . . . . . 7.70 Lowest, per c e n t . . . . . . . . . . . . . . . . . . 4.20 Average, per c e n t . . . . . . . . . . . . . . . . . 5.65 PROTEINS-NO. of samples between 4 a n d 5 . 0 1 per c e n t . . . . . . . . . . . 3 3 a n d 4 per c e n t . . . . . . . . . . . . . . 28 2 a n d 3 per c e n t . . . . . . . . . . . . . . 5 Highest, per cent . . . 4.42 Lowest, per c e n t . . . . . . . . . . . . . . . . . . 2 . 7 9 Average, per c e n t . . . . . . . . . . . . . . . . . 3 . 4 6 ASH Highest, per c e n t . . . . . . . . . . . . . . . . . 0 . 8 4 Lowest, per c e n t . 0.64 Average, per cent 0.72 SOLIDS-NOT-FAT-NO. of samples between IO a n d 10.65 per cent.. . . . . 9 a n d 10 per cen 16 8 a n d 9 per cent 20 7 , 5 0 a n d 8 per cent ... Highest, per c e n t . . . . . . . . . . . . . . . . . 9 . 8 0 Lowest, per c e n t . . . . . . . . . . . . . . . . . . 8. I3 Average, per c e n t . . . . . . . . . . . . . . . . . 9 . 1 0 MILKS U G A R - N O . of samples between 5 a n d 5 . 8 0 per c e n t . . . . . . . . 20 4 a n d 5 per c e n t . . . . . . . . . . . 16 3 . 9 1 a n d 4 per c e n t . . . . . . . . . . . ... Highest, per c e n t . . . . . . . . . . . . . . . . . 5 . 8 0 Lowest. per c e n t . . . . . 4. IO Average, per c e n t . . . . 4.94 PROTEIN-FATRATIO Highest. . . . . . . . . . . . . . . . . . . . . . . . . 0.80 0.46 0.61 FAT-NO.
...
Highest, per c e n t . . . . . . . . . . . . . . . . . 4 7 . 4 Lowest, per c e n t . . . . . 33.1 Average, per c e n t . . . . . . . . . . . . . . . . . 3 8 . 3 REFRACTION OF COPPER SERUU AT 20° C. No. of samples between 40 a n d 4 0 . 4 . . . . . . . . . . . . . . . . . . ... 39 a n d 40 6 38 and 39 22 37 and 3 8 . . . . . . . . . . . . . . . . . . . . 3 36 and 3 7 . . . . . . . . . . . . . . . . . . . . . . ... TOTAL KO. OF SAMPLES. . . . . . . . . . . . . 31 Highest, szale reading. . . . . . . . . . . . . 3 9 . 5 Lowest, scale reading . . . . . . . 37.1 Average, scale readin . . . . . . . 38.1
, . .
2 8 12 4 1
... 1
4 5 8 2
...
...
...
... 1
1
9 3 3
...
3 7 5 1
... ... . . . . . . . . . . 16 Highest, scale reading. . . . . . . . . . . . . 4 5 . 2 Lowest, scale reading, . . . . . . . . . . . . . 4 2 . 4 Average, 'scale .reading. , .. , . 44.2 . TOTAL h-0.
OF S A M P L E S . .
,..
...
...
'2'
...
4 14 36 40 26 11 15.68 10.58 12.62
14.09 10.93 12.15
,..
'i'
... ...
...
13 44 67 6 6.30 2.45 3.95
'2'
21 19 3 1 15.32 I0.ii 12.98
14:68 11.44 12.64
...
...
i
11 7
4 14 20 1
1S:iS 11.40 13.74
5.45 1.46 3.20
l4:89 11.73 13.10
...
... 3 12 5
... ...
1
6 19 2 , . .
...
6.40 3.80 5.23
5.80 3.00 4.65
5.70 3.50 4.35
5.10 3.25 4.29
8 16 4 5.01 2.26 3.73
2 23 2 4.20 2.78 3,45
...
'41'
...
3.94 2.43 3.27
3 10 3 4.37 2.65 3.39
11 3.92 2.11 3.22
12 15 3.91 2.22 2.99
6 86 39 4.47 2.33 3.25
19 22 3.61 2.34 2.96
0.84 0.69 0.75
0.86 0.69 0.75
0.78 0.66 0.72
0.80 0.63 0.73
0.85 0.66 0.75
0.87 0.58 0.76
0.87 0.56 0.73
3 15
...
...
...
.I .6
...
3 42 68 18 10.24 7.50 8.67
16
40
11
90
... 5 14 8
...
IO
10:65 8.00 9.31
7
...
16
11
... 9.76 8.40 9.09 9 18
...
13
7
9 10 1
9.75 7.96 8.85
...
9 7
...
9.74 8.47 8.81
...
6.05 3.00 4.22
34 7
9T80 7.77 8.76
5.40 3.30 4.01
6 20 I 9.46 7.89 8.63
... 4 37
...
... ... ...
6 39 11 4.60 2.45 3.41
87
26 17.17 10.20 12.98 2 22 54 150 189 17
0.79 0.65 0.74
...
...
6 143 248 37 10.65 7.50 8.77
...
9 47
5.25 4.35 4.83 0.95 0.66 0.82
9 29 3 9.43 7.63 8.59
5 39 12 9.61 7.55 8.28
0.82 0.55 0.71
0.86 0.58 0.74
0.90 0.60 0.75
0.91 0.62 0.79
0.98 0.56 0.76
0.92 0.59 0.75
0.99 0.55 0.82
0.97 0.71 0.83
0.99 0.62 0.86
0.99 0.46 0.78
35.4 27.7 32.7
40.4 27,9 32.8
36.3 27.2 31.8
...
...
...
...
...
...
1
3 8
1 8 7
17 9
11
'27' 39.0 37.0 38.2
'22 39.3 37.2 38.0
16 39.0 36.6 38.0
'6' 4 1 11 38.8 36.6 38.0
4 11
'2'
2 4 10
... '?'
..
7 17 20 5 49 39.7 36.0 37.9
8 3 2
:1 1 1
'4' 6 5 6 2 23 44.4 40.2 42.5
28 47.5 41.3 43.9
20 44.1 41.3 42.9
'I" 45.5 41.: 43.,
3 1 1 12 43.6 40.7 42.7
...
...
...
...
1
...
5 5 4 2
...
...
1
1
40.0 25.0 31.3
...
7 5 3 15 38.8 36.0 37.7
... 3 5
.
10
2
...
20 44.5 41.5 42.8
2 4
39 32 23 100 40.4 36.0 37.6
2 4 12 12 12
4 46 46.6 40.0 42.5
...
0.87 0.56 0.76
5.20 4.08 4.70
35.9 30.6 33.0
6 16 25
0.84 0.64 0.72
5.35 4.20 4.93
38.8 30.1 33.9
... ...
0.77 0.63 0.70
5.58 3.91 4.65
38.6 31 .O 35.9
...
14.57 11.56 12.79
I 36 IO 4.02 2.66 3.31
5.30 4.05 4.88
1
8 27 4
23 269 142 5.01 2.00 3.27
1
5.75 4.20 4.85
...
'a'
21 34 4.03 2.00 2.93
...
5.29 4.36 4.86
...
...
5.40 3.35 4.03
5.34 4.50 4.94
...
Herd milk 47
7.70 2.45 4.21
4.75 3.00 3.56
5.46 4.35 4.87
...
17 35
2 10 15
7 11 25 13 13.96 10.20 11.69
i
30 55 113 116
5.22 4.46 4.84
...
4 12
2 5 2i 18
...
146 287 1 5.80 3.91 4.78
21
...
10 IO
1 10 5
REFRACTION OF ACETICSERUM AT 20° C.
No. of samples between 45 a n d 4 7 . 5 , . . . . . . . . . 44 a n d 4 5 . . . . . . . . . . . . 43 a n d 4 4 . . . . . . . . . . . . . . . . . . . . 42 a n d 4 3 . . . . . . . . . . . . . . . . 41 a n d 4 2 . . 40 and 4 1 . .
901
14 27
...
...
17 29 1 9.48 7.63 8.76
I1 36
...
31.8 26.3 30.9
33.5 25.0 29.2
47.4 25.0 32.5
37.1 a8.2 31.6
...
...
2 26 145 115 53 341 40.4 36.0 37.9
... ...
2 11 2
...
15 39.0 37.3 38.3
3 5 12 14 6
2 10 22 21 55 39.3 36.0 37.2
...
40 44.4 41.0 42.8
3 4 8 5 14 34 44.6 40.0 41.6
...
...
...
14 43 79 64 36 21 257 47.5 40.0 43.3
16 20 2 38 38.8 36.7 37.8
... 3 6 12 3
'24 44.6 41.8 42.7
c.
REFRACTION OF SOURMILKS E R ~ AT M 2OC' No. of samples. between 44 and 50.9 . . . . . . . . . . . . . . . . 1 43 and 44.. . . . . . . . . . . . . . . . . 5 42 and43 ...... 6 41 and 42.. , , . 2 40 and 41.. . . . . . . . . . . . . . . . . 1 39 and 4 0 . . . . . . . . . . . . . . . . . . ... 38.3 and 39.. . . . . . . . . . . . . . . . . ... TOTAL N o . OF SAM 15 .Highest, scale,read 44.2 Lowest, scale r e a d i n g . . , , , , . , , , , , . . 4 0 . 1 Average, scale reading. , , . . , , , , , , . . 4 2 . i ASH OF SOUR MILK SERUM' No. of samples between 0.9 a n d 0.932 g . per 100 c c , , , ... 0.8 a n d 0.9 g. per 100 c c . . . . . 7 0.730 a n d 0.8 g. per 100 c c . . . . . 8 15 T O T A L N o . OF S A M P L E S . . . . . . . . . . . . Highest, g. per 100 c c . . . . . . . . . . . . . 0.828 Lowest. g. per 100 c c . . . . . . . . . . . . . . 0.740 Average, g . per 100 c c . . . . . . . . . . . . . 0.786
... ... ...
... ... ...
... ... , . .
... ... ... ,..
...
...
... ...
2 3
... 2
...
...
... 1
... ...
7: 43. I 40.4 42.2
2 42.6 40.8 41.7
, . .
...
4 2 6 0.824 0.776 0.804
2 1 1 1
1
...
2 2 0.774 0.732 0,753
5'
I
...
43.5 40.5 42.1
24 44.4 39.4 41.9
, . . 7
'8'
'
1
3 0,836 0.790 0.811
IO
18 0.868 0,736 0.790
... ... 1
12 13 11
3
13
...
2 1 7 42.7 38.7 40.5
1 2 1 4 0.916 0.777 0.856
3 10 3 65 50.9 38.3 42.1
2 17 35 54 0.932 0 732 0.793
... ...
1
... ...
4 8 3 3 3 22 43.0 38.4 40.6
...
...
...
... ... ... ... ,..
...
... .,.
... ... ...
3 9 12 0.860 0.730 0.795
14 30 32 32 15 1-7 i
147 50.9 38.3 41.9 3 43 68 " 114 0.932 0.730 0.794
... 3
7
5
... ... ...
15 43,5 41.3 42.3
...
5 8 13 0.852 0,764 0.792
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
902
T h e variations calculated from t h e analyses of t h e herd milk are, of course, much less t h a n those obtained f r o m t h e milk of individual cows. Experience has shown i t t o be improbable t h a t cows giving a b normal milk will be present even in small herds of six or eight in sufficient numbers t o render t h e herd milk abnormal. Of t h e herd milk,
RELATION
T h e solids-not-fat (consisting of t h e proteins, lactose a n d ash) are much less variable t h a n t h e solids or t h e f a t a n d formerly was t h e only figure used in detecting added water, yet t h e variation here is considerable. A less variable figure, t h e soluble solids (consisting of t h e albumin, ash, a n d sugar varying between 5.95 a n d 6.45 per cent in herd milk a n d between j.80 a n d 6.60 per cent in milk from individual cows), has been suggested b y Cornalbal as a means of detecting added water, a n d this is substantially what is obtained when preparing t h e milk serum. It has been known t h a t t h e composition of milk is influenced b y t h e season a n d b y t h e time since calving. I n order t o show if these variations existed in t h e samples examined, t h e Grade Holstein, Grade Durham, Ayrshire a n d Grade Ayrshire milk were selected, thus excluding t h e exceptionally high Jersey a n d Guernsey a n d t h e exceptionally low Holstein a n d Dutch Belt figures. These 224 analyses were first arranged b y months a n d because of t h e small number of samples obtained in some months, t h e averages were not representative a n d t h e arrangement was therefore made by seasons. Of these samples, t h e period of lactation was h o w n in 194 cases a n d seasonal averages were made of these, together with averages of t h e same analyses arranged according t o t h e period of lactation. These figures, together with t h e variation according t o season of t h e herd milk, are shown in Table 11.
Fat
..
.........
. .. .
.. ,.
A n n . Fats., 2, 529.
ASH-AS
R E L A T I O N BETYVEEN T H E T O T A L S O L I D S A N D SCGAR-
Like t h e ash t h e sugar is nearly constant a n d t h e percentage of sugar in t h e solids increases as t h e solids decrease. I n Jersey milk t h e average figure is 30 a n d in Holstein milk 40 per cent. RELATION BETWEEN THE DIFFERENT MILK CONSTITUENTS
PROTEIN-FAT
RATIO-This
has been extremely studied
-
LACTATION
8.92 8.72 8.59 8.82 8.73
4.80 4.78 4.55 4.84 4.77
38.2 37.7 37.3 37.9 37.7
43.7 42.5 41.9 42.4 42.5
43.1 42.0 39.8 40.4 41.3
0.778 0.811 0.803 0.801 0.809
0.79 0.80 0.83 0.80
32.2 31.4 31.8 31.1 31.6
2.93 3.19 3.43 3.43 3.29
0.73 0.74 0.75 0.76 0.75
8.72 8.79 8.89 8.93 8.83
4.90 4.86 4.71 4.75 4.81
38.1 37.7 37.7 37.7 37.7
42.1 42.6 42.3 43.4 42.6
42.6 41.8 42.0 42.2 42.1
0.785 0,779 0.817 0.788 0.793
0.74 0.78 0.83 0.81 0.81
31.3 31.1 31.7 32.1 31.6
3.39 3.19 3.18 3.27
0.75 0.75 0.75 0.76
8.92 8.73 8.45 8.84
4.80 4.78 4.55 4.87
38.2 37.7 37.3 37.9
43.7 42.5 41.9 42.4
43.1 42.0 39.8 40.4
0.778 0.811 0.803 0.801
0.80 0.82 0.80 0.82
32.2 31.0 32.0 31.2
not fat
A perusal of this table concerning t h e seasonal variation shows t h a t milk obtained in t h e winter is t h e best, t h a t obtained in t h e summer is t h e worst, while milk obtained in t h e spring a n d fall is a mean of t h e summer a n d winter samples. These differences. however, are 1
SOLIDS A N D T H E
0.75 0.75 0.77 0.73 0.74
4.24 3.92 3.99 4.00
TIMES I ~ C ECALVING
THE
42.2 42.5 42.2 41.7 42.3
3.98 3.97 4.14 4.22 4.06
...
BETWEEP;
9.03 8.74 8.66 8.91 8.76
1 m o n t h . . . . . , . .. , , .. 25 1 2 . 7 0 2 to 5 months.., , . , ., ., 82 12.76 6 t o 9 months 58 13.03 10 t o 15 mont 29 13.15 A v e r a g e , . . , . , , , , ... .. . 194 12.89 ABOVESAMPLES ACCORDING TO SEASONS 39 13.16 W i n t e r , , , . , .. , , . , . . , ... . Spring , ,. . , , 70 1 2 . 6 5 31 12.44 Summer. . , , ., Fall., , . . . ,,.. 54 12.84
,
RELATIOX
t h e ash is nearly constant, t h e percentage of ash in t h e solids increases as t h e solids diminish, being 3.9 in Jersey milk a n d 6.7 per cent in Holstein milk.
Sour
3.39 3.16 3.18 3.28 3.23
88 36 60 224
1.34
T S equals t o t a l solids.
Acetic 44.3 43.3 42.3 42.8 42.7
4.24 4.00 3.97 3.97 4.03
40
R E L A T I O N B E T W E E N T H E S O L I D S A N D PROTEINS-The amount of proteins in t h e solids is fairly constant a t about z j per cent. Olson1 has given for t h e approxim a t e calculation of t h e protein from t h e solids t h e forT S where P equals proteins and mula P = T S - -
Copper 37.9 38.3 37.5 37.7 37.8
13.16 12.72 12.46 12.79 12.76
,
R E L A T I O N B E T W E . E K T H E S O L I D S A N D T H E PAT-The percentage of f a t in t h e solids decreases y i t h t h e solids; in t h e Jersey milk, it averages 38 a n d in t h e Holstein milk 2 7 per cent. T h e highest figure was 47.4 obtained from a sample of Jersey milk a n d t h e lowest 2 5 . 0 per cent. from a sample of Holstein milk.
Lactose 4.88 4.92 4.71 4.80 4.83
4.20 4.14 3.73 3.94 4.03
Summer Fall.. . . . Average..
S O L I D S A X D ITS C O N -
Per Ash Protein- ' cent of sour fat fat in serum ratio solids 0,779 0.81 31.7 0.789 0.76 32.2 0.853 0.84 30.1 0.775 0.86 30.7 0.792 0.82 31.6
Ash 0.76 0.73 0.75 0.74 0.74
.. .. ... ... Winter (Dec.) . . .. , . .. ... Spring . . . . . . . . . . . . . . . . . . .
MILK
STIT UE NTS
Solids Proteins 3.41 3.13 3.15 3.37 3.31
INDIVIDUAL Cows
B E T W E E K THE
P U R I T Y MILK SAMPLES ARRANGED A C C O R D I N G TO SEASONS AND PERIOD OF
No. of T o t a l HERDS samples solids Winter (Dee.-Feb.) ,....... 9 13.23 Spring (Mar.-May). , , . ... 15 12.87 Summer (June-Aug.) ..... . 8 12.39 Fall (Sept.-Nor.).. . , , . 13 12.85 Average.., , .., . 45 12.79
11
b y no means as marked a s those observed between t h e different breeds. T h e period of lactation appears t o have no influence upon t h e variation by season for in t h e series of 194 samples arranged by seasons, t h e average period of lactation was practically t h e same in each season. All t h e results are affected b y t h e seasonal variation a n d all b u t t h e sugar a n d serum figures are affected by t h e period of lactation. The' protein-fat ratio a n d t h e percentage of f a t in t h e solids of these samples were not materially affected either by t h e season or by t h e period of lactation.
Solids varied from 14 per cent above t o 10 per cent below t h e average F a t varied from 3 4 per cent above t o 17 per cent below t h e average Proteins varied f r o m 21 per cent above t o 20 per cent below t h e average Sugar varied f r o m 9 per cent above t o 10 per cent below t h e average Minimum solids were 21 per cent below t h e maximum M i n i m u m fat was 38 per c e n t below t h e maximum M i n i m u m proteins were 3 4 per cent below t h e maximum M i n i m u m sugar was 18 per cent below t h e maximum
TABLE11-KNOWN
Vol. 6 , No.
Refraction of serum
.
0.80
Average period of lactation
.. .. .. .. .. .. ..
.. .. ..
3 weeks 3 . 4 months 7.5months 10.6 months 5 . 4 months 5.1 5.6 5.6 4.7
months months months months
b y \Tan Slyke2 a n d his average ratios being based upon several thousand analyses are of more value t h a n those shown in Table 1. T h e figures f o r t h e protein-fat ratio for t h e different breeds are as follows: 1
THIS JOURXAL
2
J. Am. Chcm. SOC.,SO, 1166.
1, 256.
S o y . , I914
T H E J O U R N A L O F I N D l i S T R I A L A N D E N G I N E E R I N G CH E M I S T R Y
Protein-fat ratio From Breed Van Slyke Table I Holstein-Friesan. . . . . 1 : 0.87 1 : 0.86 Dutch B e l t . . . . . , . . . . . . . . . 1 : 0.83 Ayrshire. . . . . , . . . , . . 1 : 0 . 8 2 1 : 0 . 7 5 American Holderness. 1 : 0.83 . . ...
Protein-fat ratio From Breed Van Slyke Table I Shorthorn. 1 : 0 . 8 0 ..... Devon.. . . 1 : 0.80 .. . . . Guernsey . 1 : 0 . 6 6 1 ; 0 . 7 1 Jersey.. . . 1 : 0 . 6 4 1 ; 0 . 6 1
There seem t o be three groups of cows according t o t h e protein-fat ratio, those of t h e Jersey t y p e with t h e protein-fat ratio below 0 . 7 , those of t h e Holstein t y F e with t h e protein-fat ratio above 0 . 8 j , a n d t h e balance of t h e breeds with a protein-fat rctio a b o u t 0.8. Van Slyke has given for t h e approximate calculation of t h e proteins from t h e f a t , t h e formula P = o . 4 ( F - 3 ) 2 . 8 where P equals proteins a n d F equals t h e fat.
+
903
where S equals t h e milk sugar, T S t h e total solids, F t h e f a t , a n d 0.7 t h e ash. I t was found t h a t t h e values of S obtained b y both formulas were nearly t h e same when t h e milk was pure a n d varied from 4 . j t o j per cent. I n skimmed or watered samples, t h e values disagreed a n d were above A j in t h e former a n d below 4 per cent in t h e latter. table was t h e n prepared, using t h e above formulas for milk with solids from IO.j t o 1 2 . 5 per cent a n d f a t from This table has been in constant use 2 . j t o 4 per cent. for j years for t h e purpose of distinguishing between skimmed milk, whole milk a n d watered milk. From
TABLE 111-CALCULATEDSUGAR
Shortly after t h e Olson formula was published. it occurred t o t h e writer t h a t since Olson's formula a n d t h a t of Van Slyke were correct only when applied t o pure milk, a combination of both formulas might be used in distinguishing between pure a n d adulterated milk. T h e sugar was chosen as the possible index a n d calculations were made upon m a n y samples of milk, using t h e following formulas: I.
11.
S = T S-
S
=
[F
T S - [F
+ 0 . 7 + ( T S-
+ 0.7 +
TS
)]
1.34 (0.4(F- 3 ) )
+ 2.81
a n extension of this table a list of t h e maximum a n d minimum f a t corresponding t o t h e total solids from 1 0 . j t o 4 per cent was prepared a n d published in t h e 1909 report of t h e Massachusetts S t a t e Board of Health. Subsequent experience, however. has shown t h a t for practical purposes, t h e maximum a n d minimum values could be placed f a r t h e r a p a r t . I n Table I11 of calculated sugar, t h e upper values for t h e sugar were obtained by Formula I, t h e lower values by Formula 11. T h e positions of t h e heavy lines were detetmined b y allowing t h e variations of not more t h a n
904
T H E J O U R N A L O F I N D U S T R I A L , 4 N D E,VGINEERINC; C H E M I S T R Y
one-tenth in t h e calculated sugar values. T h e samples falling above t h e other heavy lines m a y be suspected of being skimmed, those falling below t h e lower line m a y be watered, a n d those falling between these lines are probably normal milk. If a sample is both skimmed a n d watered, i t m a y be classed in this table as normal milk, b u t usually, when both such acts are performed, either one or t h e other preponderates t o such a n extent t h a t t h e sample will appear adulterated. F i v e h u n d r e d a n d seventy-four samples of milk of known purity a n d 2 1 6 8 commercial samples which could not be declared adulterated with a variat i o n in solids from 1 1 t o 13.6 per cent have been t a b u l a t e d with reference t o t h e relation between t h e solids a n d t h e fat a n d t h e results of this tabulation are shown
Vol. 6 , No. I T
sample is either watered or skimmed as t h e case m a y be. Considerable more work m u s t be done, however, involving t h e tabulation of several thousand analyses of samples of known purity milk from individual cows in order t o establish t h e accuracyof t h e above statement. MILE; SERUM-hIilk serum has been extensively used for t h e detection of added water in milk1 a n d its value for this purpose is d u e t o t h e fact t h a t in t h e preparation of serum t h e most variable components of t h e milk, t h e f a t a n d casein, have been removed. Of t h e various methods for t h e preparation of t h e serum, t h e writer prefers t h e copper method o n account of t h e simplicity a n d rapidity of i t s preparation, because i t can be prepared without h e a t a n d requires b u t a small quantity of milk. With t h e small beakers now in use with t h e
TABLEI V RELATIONBETWEEN THE TOTAL SOLIDS A N D FATOF 2168 SAMPLES OF MILK WHICHWERRNOTDECLARED ADULTERATED
i n Tables I V a n d V . I n both of these tables t h e zone of pure milk is indicated as in Table 111. I t appears from these tables t h a t t h e methods in use for t h e detection of added water are efficient b u t t h a t those for t h e detection of skimming are not so reliable. A larger percentage of known milk purity fell below t h e lower heavy line t h a n of t h e commercial samples not declared adulterated. T h e samples above t h e upper h e a v y line which m a y be suspected of being skimmed, constituted 1 7 per cent of t h e known purity samples a n d 4 7 per cent of t h e commercial samples. Of t h e samples containing less t h a n 3.3 per cent of fat, j per cent of t h e known purity samples a n d 6 8 per cent of t h e commercial samples were above t h e upper heavy line. Table I11 is intended solely for t h e purpose of selecting t h e particular samples which are t o be subjected t o other tests for adulteration a n d t o give a positive indication of t h e character a n d possible extension of t h e adulteration. F r o m Table V it would seem t h a t i f a sarpple was 0 . 4 above or 0.4 below t h e maximum or minimum f a t figure corresponding t o t h e solids t h e
Zeiss immersion refractometer, i t is possible t o obtain sufficient filtrate from a I O cc. sample a n d if one is in a h u r r y 17.6 cc. of milk will give sufficient filtrate in a few minutes. This method has been criticized b y t h e a u t h o r 2 a n d subsequently b y Ackermann3 on acCount of t h e dilution necessary i n t h e preparation of t h e serum, b u t this is offset b y less variation in t h e serum from different samples. It has another disadvantage, t h a t i t is n o t possible t o use t h e values of t h e ash of t h e copper serum in detecting added water because t h e amoun't of copper in t h e serum is higher in watered milk t h a n in unwatered milk a n d consequently t h e ash in t h e serum of watered samples is b u t little less t h a n in t h e serum of t h e original milk before watering. This objectionisalso applicable t o the calcium chloride serum of Ackerman, owing t o t h e precipitation of t h e calcium phosphate i n t h e p r e p a r a t i o n o f t h e ~ e r u m . ~ 1 For an extensive and complete review of the literature on this subject, see Arb. Kais. Gesundheits., 40, Heft. 3 . 2 Eighth Intern. Congr. of Appl. Chem., 1, p. 308. 3 Z . X a h r . Genussm., 24 (1912), 612. 4 A r b . K a i s . Gesundheits.'. 40, pp. 248, 255 and 256.
K'oV,, 1914
T H E J O U R N A L O F IiVDUSTR124L 4 W D E N G I N E E R I N G C H E M I S T R Y
90.5
hibits signs of becoming sour, t h e only serum t h a t should be prepared is t h e spontaneously obtained sour serum.
T h e acetic method as modified b y Pfyl a n d T u r n a u is fairly rapid when only a few samples are examined. I t can be prepared at t h e room temperature, t h e dilut i o n is b u t 2 per cent a n d t h e ash figures increased b y 2.21 per cent are comparable with those obtained
BETWEEN
RELATION
THE
COKSTITUEKTS
MILK
OF
serum consists of water, sugar, lactic
SERUhl-h~ilk
TABLEV RELATION B E T W E E N THE TOTAL SOLIDS
AKD
FATOF 574
Ash of sour serum 0.730 0.750
O.7iO 0,790 0.810 0.830
0.850 0.870 0.890 0.910
TOTALS ....
16
-
0.7 2.1 1.4 2.8 1.4 1.4 0.7 0.7 0.7
_
..
11.9
-
37 38 39 Per cent of samvles
40
1.4 6.4 6.4 5.6 2.1 2.i
0.7
i.8 6.3 9.9 9.2 5.6 0.7 2.8 0.7 1.4
0.i 0.7
.. .. _
25.4
_
..
_
44.4
2.1 3.5 5.0 3.5 2.i 0.)
..
.. ., . .~ 16.9
ASH Refraction of sour serum
SERUM REFRACTION
38
39
AND S O U R SERUM
40
Totals
...
...
...
... 0.7
...
... ...
... _ _ 1.4
12.7 18.: 22.i 21.1 11.2 5.6 4.2 2.1 2.1
...
100.0
. . . . . . 0:s 0.7
0.8 1.5 2.3
. . . . . . . . . . .
0.8
, . .
. . . . . .
. . . . . . .., 0.8 2.3
tially soured. Under such circumstances, t h e copper serum so prepared will give a higher reading a n d t h e acetic serum a lower reading t h a n would be given b y t h e same sample before souring. m h e n a sample ex-
MILKO F KNOWN PURITY
acid, more or less protein, a n d mineral matter depending upon t h e mode of preparation. T h e acetic serum contains sugar, coagulable albumen, protein precipit a t e d b y tannic acid a n d all t h e mineral m a t t e r . T h e sour serum contains t h e same substances in addition t o lactic acid formed from t h e sugar. The copper serum contains t h e sugar, coagulable albumen. protein precipitated b y tannic acid, a n d some of t h e mineral matter. T h e calcium chloride serum contains t h e sugar, proteins precipitated b y tannic acid. a n d a portion of t h e mineral m a t t e r , b u t no coagulable albumin. T h e refractive index of milk serum is a n additive property consisting of t h e s u m of t h e refractiye indices of its constituents, a n d except in t h e case of t h e calcium chloride serum. bears no absolute relation t o t h e com-
from the sour serurr. Tke greatest value of t h e sour serum is in t h e preparaticn of the ash. Using z j cc. of sour milk serum there is less t h a n 2 g. of organic m a t t e r t o be burned a n d t h e influence of t h e combustion of this upon the 190 milligrams of ash is slight. I t is advisable t o apply this test in addition t o t h e refraction or specific gravity of the serum t o all samples suspected of containing added water, for both figures depend upon different milk constituents a n d , furthermore, if milk is declared adulterated b y both methods, i t eliminates t h e possibility of t h e samples being naturally abnormal milk obtained from a sick cow. It will be noticed in Table I t h a t t h e refraction of t h e sour serum is midway between t h a t of t h e copper serum and t h e acetic serum. This should be borne in mind when making examinations of milk which have parTABLEVI-RELATION BETWEEN Refraction of copper serum
SAMPLES OF
5.4
2.3 2.3 3.1 2.3
..
0:i 0.8 0.8 ,
.
12.3
41 42 43 Per cent of samples
0.8 2.3 3.8 3.8 1.5
0:s 017
..
13.7
3.1 4.6 6.2 3.9 4.6 1:s 1.5
0.8 0.8 27.0
44
15
2.3 2.3 0.8 0.8
2.i
0.8
2.3
1.5
0:s
..
h:s
0:s _.
. . . . . . .. ...
3.1 4.6
$:+ ..
24.6
1.5
10.0
.
Totals 13.9 16.9 23.1 21
...
0.8
4.7
.s
10.7
...
4.6 4 6
,3 I I 6
__
100.0
position of t h e milk from mhich i t was made. I n t h e calcium chloride serum, t h e refractive indices follow very closely t h e percentage of sugar in t h e milk. There is no specific relation between t h e ash of t h e
s
906
T H E J O C R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
sour serum a n d t h e other properties of t h e serum of pure milk, as shown i n Table VI, computed from t h e refractions of copper serums of 142 samples, t h e refraction of t h e sour serum of 130 samples, a n d t h e ash of t h e sour serums of t h e same samples. I t is possible, however, if one knows t h e refractive indices of t h e milk serum t o calculate with accuracy t h e specific gravity or t h e solids of t h e same serum. n2-I
T h e Lorenz a n d Lorentz formula ___
n 2 + 2
.
I - =
d
K where
F ~ I TN S O L I D S
IT
n o difference in t h e value of K , provided t h a t t h e refractive index a n d specific gravity are determined a t t h e same temperature a n d t h e l a t t e r referred t o water a t 4' C. Where t h e values of ?t a n d d are obtained at different temperatures, t h e value of K varies with t h e temperature.
I n t h e formula
?I
- It' ~
C
= A , n a n d n1
must be determined a t t h e same temperature. T h e value of K in t h e copper serum is slightly less in watered milk t h a n in whole milk, due t o t h e fact t h a t while ACE
...
Vol. 6, No.
7,c
5-6
73 Y e t
SOUR SERUM
PER C E N T
n equals t h e refractive index, d t h e specific gravity,
a n d K a constant, is uniform for various concentrations of milk serum a n d m a y be used t o calculate t h e specific gravity from t h e refractive index. T h e formula n-n1 evolved b y Walter a n d Robertson' ~= A where c
equals t h e refractive index of t h e solution, the refractive index of t h e solvent, c t h e concentration of t h e solution, a n d A a constant, is applicable for t h e calculation of solids of t h e milk serum. T h e values of these constants are given below. I n t h e Lorenz a n d Lorentz formula, t h e difference i n temperature makes IZ
'
1
Wicd Ann., 18 (1889). 107; J . Phys. Chcm , 13 (1909). 469.
t h e refraction of t h e copper solution is a b o u t t h e s a m e as t h a t of t h e milk serum, i t s specific gravity is higher. T h e variation, however, is too slight to have a n y marked effect upon t h e calculation of t h e specific gravity from t h e refractions. Table VI11 gives t h e value of t h e specific gravity a n d solids calculated from t h e refraction figures of t h e acetic a n d copper serums a n d of t h e specific gravity calculated from t h e sour serum. R E L A T I O N O F T H E PROTEIhT-FAT R A T I O T O S E R U M REFRAcTIox-It will be seen from Table I t h a t in t h e samples obtained from Jersey a n d Guernsey cows, n o figures for copper refraction were obtained below 37.0 a n d t h e figures for t h e protein-fat ratio were all less
Nov.,
T H E J O U R N A L OF 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
I914
TABLEVII-RELATION
BETWEEN
SERUMCOXSTANTS
_._=
n2-1 d R n2+2 1 K = 0.2056 ( a ) Calcium chloride n at 17.6' C. d a t 1 5 / 1 j 0 C. n a t X o C. K = 0.2058 (a) d a t X 0 / 4 0 C. n a t 20° C. Acetic A = 0.00158 ( b ) d a t 15°/150 C. K = 0,20554 ( b ) n a t X o C. K = 0.20592 ( b ) d a t X 0 / 4 ' C. n at 20' C. Copper IC = 0,20484 A = 0.00158 ( b ) d a t 15O/15'C. n a t X oC . K = 0.20526 ( h ) d a t X0/4' C. n a t 20' C. sour d at 15'/15' C. K = 0.20581 n a t X o C. K = 0,20607 ( b ) d a t X' ,'4' C . ( a ) XYeigner a n d Yakuwa Milchmertsch. Zenlr., 6 (1909). 473. (b) Lythgoe, Proc. Eighth'lnlein. Conn?'. Appl. Chem., 1, 309.
Serum
t h a n 0.82 a n d from t h e average figures i t appears t h a t a s t h e protein-fat ratio increases, t h e concentration of t h e serum diminishes. All t h e refraction figures corresponding t o protein-fat ratio above 0 . j o have been TABLEVIII-COMPARISON
B E T N ~ E N REFRACTIVE I I D I C E S A N D OTHER MILKS E R U M (CALCULATED FROM FORMULAS GIVEKI X TABLE VII) ACETICS E R U M COPPER S E R U M S O U R SERUM
CONSTANTS OF
-_
Scale Solids Sp. gr. Solids S p . gr. reading n~ Per Per 2OoC. 20° C . cent 15°/150 20°/4" cent 15°i150 2Oo14O 28.0 1.33820 3.30 1.0149 1.0131 3.30 1.0184 1.0163 29.0 1.33861 3.55 1.0160 1.0141 3.55 1.0194 1.0173 30.0 1.33896 3.78 1,0170 1.0151 3.78 1.0205 1.0184 31.0 1.33934 4.02 1.0180 1.0161 4.02 1.0215 1.0194 32.0 1.33972 4.26 1.0190 1.0172 4.26 1.0225 1.0204 33.0 1.34010 4.5 1 1.0200 1.0181 4.5 1 1.0235 1.0214 34.0 1.34048 4.74 1.0211 1.0193 4.74 1.0246 1.0225 35.0 1.34086 4.98 1.0221 1.0203 4.98 1.0256 1,0235 36.0 1.34124 5.22 1.0231 1.0213 5.22 1.0267 1.0246 3i.O 1.34162 5.46 1.0242 1.0223 5.46 1.0277 1.0256 38.0 1.34199 5.70 1.0252 1.0233 5.70 1,0288 1.0266 39.0 1.34237 5.94 1.0262 1.0243 5.94 1.0298 1.0276 40.0 1.34275 6.18 1.0273 1.0254 6.18 1.0308 1.0287 ...... ...... 41.0 1.34313 6.42 1.0283 1.0264 42.0 1.34350 6.66 1.0293 1.0274 . . . . . . . . . . . . . . . ...... ...... 6.90 1.0303 1.0284 43.0 1.34388 44.0 1.34426 7.14 1.0313 1.0295 . . . . . . . . . . . . . . . . . . . . ...... 7.38 1.0323 1.0305 1.34463 45.0
.... ....
--
Sp. gr.
15°)150 20°14' 1.0136 1.0121 1.0146 1.0134 1.0157 1.0144 1.0167 1.0154 1.0177 1.0164 1.0187 1.0173 1.0198 1.0185 1.0208 1.0195 1.0218 1.0205 1.0229 1.0215 1.0239 1.0225 1.0249 1.0236 1.0259 1.0246 1.0269 1.0256 1.0279 1.0266 1.0290 1.0277 1.0300 1.0287 1.0310 1.0297
plotted 2nd the results are shown in t h e c h a r t on page 9 0 6 . F r o m this c h a r t , i t is a p p a r e n t t h a t normal milk with a protein-fat ratio less t h a n 0 . 7 0 , should give sera with refractive indices above 3 7 b y t h e copper s e r u m , 40 b y t h e sour method, a n d 4 1 b y t h e acetic m e t h o d . T h e relation between t h e protein-fat ratio a n d t h e percentage of f a t i n t h e solids is shown in t h e plot. T h e protein-fat ratio increases as t h e percentage of f a t in t h e solids decreases; therefore, if t h e per cent of f a t in t h e solids is high (above 3 5 ) , t h e sample should give 2, sertirr with a high refraction. T h e consideration
907
year, t h e milk of a large number of herds has been examined in connection with another investigation. F r o m these, sixteen have been chosen, including t h e samples from which t h e highest a n d lowest figures have been obtained; t h e analyses are recorded in Table I X . T h e character of t h e herds, t h e n u m b e r of COWS a n d t h e a m o u n t of milk obtained at t h e milking, is given i n Table X. None of these analyses were used in t h e preparation of Table I. Sample No. 1 2 was obtained from a celebrated,herd of thoroughbred Holstein Fresian cows, t h e majority of which were in t h e last stages of lactation. Sample TABLEX-CHARACTER OF HERDSPRODUCING THE MILK RECORDED IN TABLE IX Grade Grade AyrJersey shire a n d and Grade Guern- Guern- Dur- Ayr- Holh*o. Jersey sey sey h a m shire stein Number of cows 1 20 . . . . . . . . 2 , , 35 ,. 2 .. 2 . . . . 5 4 3 .. , . 8 8 4 4 .. . . . 12 5 8 5 4 8 14 6 .. 4 7 'i .. 10 3 '4 8 .. 4 4 . 20 9 .. .. . . . . 13 10 .. 2 . . . . . . 11 .. .. , , ., , , 12 .. .. 1 . . . . 13 .. 9
Holstein
.
.
.
.. ..
.. ..
13 3
..
..
39 25 36
10 24 12
W t . of milk Total _*_ no. Av. per cows Lbs cow 20 39 13 22
27 30 29 25 28 15 39 25 46 10 24 12
. . . . . . . 450
11.6
250 329 400 240 260 273 180 500 217 580
12.2 13.3 12.6 10.4 9.7 12.0 12.9 8.7 12.6
325 167
14.3
ii:i
ij:s
No. I j was obtained from t h e same herd t w o months later, m a n y of t h e cows having freshened since t h e previous sample was t a k e n . T h e analyses of these t w o samples show t h a t while the solids a n d t h e f a t were both much lower in t h e second sample taken, there was practically no difference between t h e figures obtained from t h e milk serum. All t h e other samples were taken from different herds. T h e milks from herds Nos. 14, I j a n d 1 6 are not sold a t retail until after being mixed with milk of good quality, in order t o bring i t u p t o t h e requirements of t h e Massachusetts law. SUMMARY
Variations in t h e composition of milk are due primarily t o t h e breed, a n d t o a less extent t o t h e season of t h e year a n d t o t h e t i m e since calving. TABLEIX-ANALYSES OB HERD MILKOF KNOWNPURITY T h e. least variable milk constituents are t h e lactose SolirlsFat Refraction Sour -.in _ . ~ ~ ~ _._. ~ ~ ~ . ~ Total PronotPro- total of serum serum a n d ash, both of which are of value in detecting added f a t Lactose tein solids & ash solids Fat tein Ash water. Per Per P e r Per Per Per f a t Per Copper Sour G. per N o . cent cent cent cent cent cent ratio cent 2 O o C . 2 0 ° C. lOOcc. It is possible, within reasonable limits, t o indicate 1 14.18 4.70 3.46 0.73 9.48 5.03 0.74 33.2 38.5 42.8 0.790 2 13.96 4.70 3.25 0.78 9.26 5.16 0.69 33.6 38.6 42.2 0.802 from t h e percentage of solids 2nd f a t , whether or not 3 13.34 4.30 3.20 0.70 9.04 5.05 0.74 32.2 38.3 42.2 0,762 4 13.10 4.20 3.22 0.75 8.90 5.12 0.77 32.1 38.8 42.7 0.812 a sample has been watered, skimmed, or is normal 5 12.97 4.40 3.07 0.76 8.57 4.80 0.70 33.9 38.0 42.1 0.772 milk. 6 12.85 4.10 3.17 0.66 8.75 5.04 0.77 31.9 38.6 42.0 0.772 7 12.80 3.85 3.35 0.74 8.95 4.85 0.87 30.1 38.2 42.2 0.788 K O relation exists between t h e refraction of t h e serum 8 12.76 4.10 2.98 0.76 8.66 4.60 0.73 32.1 37.7 40.8 0.768 9 12.58 3.60 3.38 0.74 8.98 4.64 0.94 28.6 38.0 42.0 0.812 a n d t h e sour serum a s h ; therefore, if both figures are LO 12.44 3.70 2.98 0.66 8.74 4.93 0.81 29.8 38.0 42.0 0.762 I1 12.30 3.80 3.01 0.72 8.50 4.96 0.79 30.8 37.6 41.0 0.764 below t h e minimum for pure milk i t is positive indica12 12.26 3.70 3.03 0.74 8.46 4.56 0.82 30.3 37.5 40.7 0.820 13 12.19 3.65 2.94 0.70 8.54 4.63 0.81 29.9 37.7 41.3 0.762 tion of t h e presence of added water. 14 12.14 3.40 3.15 0.75 8.74 4.70 0.93 28.0 37.8 41.7 0.796 15 11.74 3.30 2.96 0.78 8.44 4.59 0.90 28.1 37.4 40.3 0.786 T h e protein f a t ratios in all cases have been less t h a n 16 11.28 3.20 2.83 0.74 8.08 4.35 0.89 28.5 37.1 39.5 0.752 I. If this figure exceeds I, skimming is indicated, of these relations should be studied in connection with t h e a m o u n t being greatest in samples possessing t h e t h e other figures obtained from t h e same sample, highest ratio. particularly with t h e sour serum ash, before t h e s a m If t h e protein-fat ratio is less t h a n 0 . 7 or t h e perple is called watered. centage of fat in t h e solids is above 3 j.0, samples m a y During t h e m o n t h s of M a r c h , April a n d M a y of this be declared watered by a low refraction of t h e serum, not ~
~~~
908
THE JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
necessarily below t h e minimum for all samples of known purity. This is particularly so when dealing with herd milk. I n t h e absence of a refractometer, . t h e specific gravity or t h e per cent of solids of t h e serum is just a s valuable as t h e refractive index i n detecting added water. T h e writer wishes t o acknowledge his t h a n k s t o his assistants, Messrs. Charles H . Hickey, Louis I . Xurenberg, a n d Clarence E. Marsh, t o whom he is greatly indebted for their valuable cooperation in making t h e analyses of t h e samples.
Vol. 6, No.
II
(ether was used) a n d t h e latter evaporated. A small a m o u n t of oil remains. A piece of copper wire is heated in a colorless gas flame until i t is black a n d n o longer colors t h e flame green. T h e hot e n d of t h e wire is dipped into t h e oil a n d again brought into t h e flame. If chlorine or bromine has been used as a bleaching agent a green or blue coloration is produced.” RIoisture determinations were made by drying t h e samples for five hours in a steam oven a t t h e temperat u r e of boiling water. The determinations of acidity were made in accordance with Method j in Bull. 152, of t h e Bureau of LABORATORY OB FOOD A N D DRUGINSPECTION Chemistry, U. S. Department of Agriculture. rvhich M A S S A C H U S E T T S S T A T E BOARDOF HEALTH is as follows: T o 20 grams of flour in a 500 cc. E r BOSTON lenmeyer flask a d d zoo cc. freshly boiled water. Digest at 40’ C. for t w o hours, shaking a t Io-minute intervals. SOME CHARACTERISTICS OF CHLO RINE-BLEACHED Decant t h e clear liquid through a folded filter a n d tiFLOUR t r a t e jo cc. N / z o K a O H . B y c. A A. UTT Table I indicates t h e results obtained on inspecReceived July 3, 19 14 tion samples. I t will be noted t h a t t h e moisture does Since t h e Government ruled against flour treated with t h e oxides of nitrogen (F. I . D. 100;S. T. 7 2 2 , not v a r y any more between t h e bleached a n d unU . S. D e p t . of Agr.), chlorine-bleached flour has made bleached flour t h a n might be expected in duplicate its appearance. United States P a t e n t I , O ~1 ~ 9 7 7 , determinations. An increase in acidity in t h e bleached TABLE I-SOME C H A R A C T E R I S T I C S O F C H L O R I X E - B L E A C H E D FLOLR September 2 9 , 1913, deals with a process in which “flour is treated with anhydrous chlorine (diluted with a n inactive gas) in order t o mature a n d whiten it.” This process a n d a few others in which chlorine is t h e active agent are used. By this means, i t is claimed, 13.36 0.126 484. - 1870 43 1 12.99 94 95 46-47 Unbleached patent t h e flour is whitened a n d aged. Bleached p a t e n t L3.68 0.144 764 + 1860 4 2 8 13.07 93 94 14.22 0.198 532 - 1780 47 5 T h a t chlorine w.il1 bleach flour has been known for 48-45 Unbleached, clear 16.10 , 83 14.18 0.288 916 f 1800 48 6 16.07 . , 85 Bleached, clear m a n y years, b u t its activity a n d difficulty of control 5 2-5 4 P a t e n t unbleached 10.70 0.162 442 - 1940 38 87 12.67’ 93 92 11.12 0.18 881 + 1950 39 16 12.87 93 89 a t e n t bleached have caused its use t o be viewed with suspicion. 65-66 PUnbleached 12.66 0.126 556 - 2020 3 9 3 4 12.40 94 92 patent 12.88 0.126 648 f 1980 39 98 12.92 93 89 Bleached patent I n connection with t h e pure food work of Kansas i t 95-96 Unbleached 12.20 0.144 494 - 1920 41 83 14.05 94 94 12.24 716 f 1970 41 78 13 67 93 94 Bleached was found necessary t o collect some information on 9 1-92 P a t e n t unbleached 13.10 0.189 0.126 540 13.12 0.135 844 + P a t e n t bleached chlorine-treated flour. T h e results of this investiga12.44 0.216 504 51-55 Unbleached, clear 12.32 0.252 928 + Bleached. clear tion are presented in this paper. 11.46 0.189 544 97-98 Unbleached Samples were obtained directly from t h e mills b y 11.40 0.198 868 f Bleached 10.99 0.198 736 f 70299 Bleached t h e Kansas food inspectors, of t h e same flour before 70300 Bleached 11.22 0.207 900 + 12.88 0.306 576 a n d after bleaching. These were placed i n screw- 65-63 Unbleached 12.69 0.324 667 f Bleached 12.56 0.18 501 t o p glass jars, sealed a n d shipped t o t h e laboratory. 70-72 Unbleached 12.68 0.234 972 + Bleached 12.42 0.216 496 T h e following determinations were made: ( I ) Chlorine 73-7 1 Unbleached 12.42 0.270 855 + Bleached qualitatively a n d quantitatively; ( 2 ) moisture; (3) acidity. A number of gluten a n d baking tests were flour as compared with t h e corresponding unbleached sample is noted in nearly every instance. The chlorine also made. Chlorine was determined b y Jacobs’ method as content varies from 442 parts per million t o 576 p a r t s used in t h e Plant Chemistry Laboratory of t h e U. S. per million in t h e unbleached flour; when bleached Department of Agriculture. It is as follows: “TO t h e variation is 648 t o 9 7 2 p a r t s per million. All bleached samples reacted positively with the copper 2 5 grams of flour in a platinum dish, a d d z j cc. of a solution containing 2 5 grams of K O H a n d 2 5 grams wire reaction for chlorine. T h e differences i n loaf volume are not much greater K N 0 3 per liter. Evaporate t o dryness on a steam b a t h , a n d ignite in a muffle a t a dull red heat until t h a n one would expect t o find in individual loaves thoroughly charred. Extract t h e charred mass with from t h e same flour. Loaf volume favors t h e unbleached 2 j cc. j per cent “ 0 3 ; filter. R e t u r n residue t o t h e flour in some cases, in others t h e bleached flour. All platinum dish, char further a n d extract again with loaves were graded against a standard loaf made from hard wheat flour under t h e same conditions, as is t h e z j cc. 5 per cent H N 0 3 ; filter, wash with h o t water, a n d ignite t o a n ash. Dissolve t h e ash in j per cent custom. I t will be noted t h a t in nearly every case HNO,, filter a n d wash. Combine t h e filtrates a n d de- t h e bread made from t h e unbleached flour grades better. T h e bleached flour gives a loaf having a n objectionable termine t h e chlorine with silver nitrate.” Qualitative determinations of chlorine were made color a n d texture. T h e gluten tests r u n practically uniform for t h e b y t h e copper wire method as given b y Alway (Bull. bleached a n d unbleached flour. there being no more 102, Nebraska Experiment Station, page 5 3 ) as follows: “One ounce (30 grams) of flour is extracted with benzene difference t h a n on duplicates. However, physically
