T H E JOURYVAL O F I N D U S T R I A L A S D EZYGISEERIiVG C H E M I S T R Y
Xpr., 1914
TABLE 111-LA~EXDER, SWEETFEKNEL, ‘CARAWAY. CORIANDER,SWEET BIRCH A K D SASSAFRAS COMPARED ~ , ’ I B of a Fleischmann’s Yeast Cake in 50 Cc. of s y r u p Specific Gravity of Syrup. 1.1925 a t 20’ C. Temperature of Incubator, 3 2 O C.
Per cent oil
Oil
Lavender . . . . . . . . . . . . . . Sweet f e n n e l . . . . . . . . . . . . . Caraway., . . . . . . . . . . . Coriander.. . . . . . . . . . . . . Sweet birch.. . . . . . . . . . . Sassafras. . . . . . . . . .
Per cent gas 100 30 100 None 50 None
Time Days 1
0.2 0.2 0.2 0.2 0 .OS 0 . OS
7 1 7 7
coxcLr-sIoxs--I-Coriander is superior t o sweet fennel, which in t u r n is superior t o lavender a n d caraway. T h e latter tn-ooils have practically no value as preservatives when 0 . 2 per cent is used. 11-Sassafras is decidedly superior t o sweet birch. 111-Sassafras in these tests is superior t o a n y one of t h e above oils, with the possible exception of coriander TABLEIV-CLOVE,
JUSIPER BERRY,PEPPERMIKT, CASSIA, SASSAFRAS, \~IXTERGREES, AXISE, A N D S P E h R l l I N T COMPARED
1 / 3 2 of a Magic Yeast Cake in 5 0 Cc. of Syrup Specific Gravity of Syrup, 1.248. Temperature of Incubator, 3 2 O C.
Oil None. . . . . . . . . . . . . . . . Clove .......... Juniper b e r r y . . . . . . . . . . . . Peppermint.. . . . . . . . . . . . . Cassia.. . . . . . . . . . . . . . . . . Sassafras. . . . . . . . . . Wintergreen. . . . . . . . . . . . . Anise.. . . . . . . . . . . . . . . . . . Spearmint.. . . . . . . . . . . . . .
Per cent oil
.... 0.04 0.08 0.08 0.04 0.04 0.04 0.04 0.04
Time Days 1
2 7
3 4
4 2 3
2
_ .
Per cent gas 100 100 100 100 100 100 100 100
100
coNcLvsIom-I-In these tests, 0.03 per cent of cassia seems t o be equal t o t h e same a m o u n t of sassafras, a n d superior t o 0.04 per cent of anise, which in t u r n is superior t o 0.04 per cent of spearmint or wintergreen. 11-It will be noted t h a t these results differ somew h a t from similar tests made with Fleischmann’s yeast. PHILADELPHIA
ESTIMATION OF SUCROSE I N THE PRESENCE OF LACTOSE AND IN THE MILK PREPARATIONS1 By JITEXnRA NATH RAKSHIT Received December 21, 1913
T h e practical use a n d importance of t h e method of estimation of sucrose a n d lactose in their mixture, chiefly depend on t h e presence of t h e former in t h e sweetened condensed milks a n d other milk preparations. All t h e difficulty arises from t h e fact t h a t t h e milk sugar also undergoes hydrolysis during t h e iriversion of cane sugar b y mineral acids. Stokes 2nd Bodme? described a method, t h e principle involved in which is t h e titration of a portion with Pavy’s ammoniacal copper solution a n d t h a t of another p a r t after boiling with 2 per cent citric acid for t e n minutes a n d t h e n neutralizing. Boiling with citric acid was 1 T h e estimation of sucrose in presence of lactose, with special reference t o milk products, has also been thoroughly investigated b y the Association of Official Agricultural Chemists. See Proceedings, 1906, pp. 98-101 ; 1907, pp. 53-9: 1908, p p . 152-9. I n this connection should be mentioned t h e method of Bigelow and McElroy ( J . A m . Chem. SOL.,15, 6 6 8 ) , who determined sucrose in condensed milk b y polarization-before a n d after inversion with veast or invertase. rEDIToRs1 2 Analyst, 10, 62.
307
expected t o invert t h e cane sugar without affecting t h e other. T h e difference in reducing power would account for t h e cane sugar. E. ST’. T . Jones,I in a modification of t h e above process of inversion, recommended t h a t i t should be k e p t in boiling water 7%-ith 1.6 per cent citric acid for half a n hour. F. W a t t s a n d H. A. Tempany2 have shown t h a t t h e inversion of cane sugar is fairly complete in t e n minutes when only t h e t w o sugars are present, b u t is very greatly retarded in t h e presence of milk constituents. These authors have suggested t h a t t o obtain satisfactory results t h e boiling should be’ continued for forty minutes. I n analyzing several samples of condensed milks i t was observed t h a t even boiling for t h a t period was not always sufficient for complete inversion-the results obtained were too low. I n addition t o t h e inconrenience of t h e lengthy time of boiling the metlwd does not yield reliable results in all cases in t h e presence of milk constituents. T h e principle of t h e following method is simple, 2nd works well for practical purposes. T h e percentage of lactose in t h e solution is first determined by titration with Fehling’s solution, t h e n a measured quantity of Fehling’s solution is boiled with a calculated quant i t y of sugar solution so t h a t all t h e copper may be thrown out of solution with t h e simultaneous consequent decomposition of all lactose when cane sugar alone v d l be left in solution, which can be readily estimated after t h e usual inversion a n d neutralization. X solution was prepared containing I a n d 2 . 5 per cent of lactose a n d sucrose respectively. I n titrating I O cc. Fehling’s solution, 6.9 cc. sugar solution (equivalent t o 0.98 per cent lactose) were required. Twenty cc. Fehling’s solution were placed in a n Erlenmeyer flask, a n d 13.8 cc. sugar solution a n d 60 cc. water were added. T h e solution was heated t o boiling for j minutes or until t h e reduced copper coagulated. I t was t h e n filtered hot through fine filter paper t o another similar flask. T h e filtrate should be perfectly clear; no copper should remain either in solution or in suspension. Kest: I O cc. of strong hydrochloric acid were added and gently boiled for I O minutes, cooled, neutralized with sodium carbonate a n d made u p t o zoo cc. Ten cc. Fehling’s required 2 j . 6 cc. of t h e above sugar solution, which is equivalent t o 2.49 per cent sucrose in t h e original solution. Similarly t h e following estimations were made: Percentage found -*__7
Sucrose
Lactose
8.10 20.08 3.00 15.04
4.00 4.00
5.95 5.95
-Percentage taken
Sucrose 8.10 20.00 3.00 15.00
Lactose 4.00
4.00 6.00 6.00
It is t h u s seen t h a t the method is quite satisfactory in t h e case of mixtures of pure sugars. I n t h e examination of milks a n d milk preparations, t h e y are usually coagulated first b y cautious addition of dilute citric acid, adding drop b y drop and shaking alternately. An excess of citric acid makes t h e subsequent filtration difficult, otherwise it is very easy a n d 1 2
Analvst. 14. 81. I b i d . , 30, 119
T H E J O C R N A L O F I N D r S T R I d L A-VD E S G I N E E R I X G C H E M I S T R Y
308
rapid. T h e filtrate after neutralization is examined for sugars as before. A sample of milk was t a k e n which was found t o contain 4.64 per cent milk sugar. Four flasks of 2 5 0 cc. capacity were filled with I O O grams of t h e above milk a n d 5, I O , 2 0 a n d jo grams of pure cane sugar were added t o t h e m , respectively. Ten grams of each of t h e above prepared solutions were t a k e n in I O O cc. flasks, a n d made up t o I O O cc. F r o m each, 50 cc. were t a k e n , placed in four other 100cc. flasks, a n d coagulated with 2 per cent citric acid solution added drop b y drop, shaking all t h e while b y a r o t a t o r y motion. These were filtered a n d t h e filtrates made u p t o I O O cc. a n d t h e sugars were estimated as before. Percentage of lactose
Percentage of sucrose
r-.
Found
Calculated
Pound
Calculated
4.40 4.24 3.86 3.12
4.41 4.22 3.86 3.09
4.73 9.03 16.60 33.40
4.76 9.09 16.67 33.33
Some sweetened condensed milks were examined a n d t h e sugars estimated b y t h e above method, starting with a I O per cent solution. T h e following results were obtained: Brand
Ash proteid f a t lactose sucrose
1. Best skimmed condensed m i l k , , . . . . . . . . . . . 2. Nestle’s condensed milk, “ S e s t Brand” . . . . . 3. Milk-maid b r a n d . , . . . . . . . . . . . . . . . . . . . . . . . 4. Best skimmed condensed milk, cow and calf brand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vol. 6 , N o . 4
constant. After suffidient solvent has been added t o dissolve t h e whole of t h e soluble substance, further addition will dilute t h e solution without increasing t h e a m o u n t dissolved. I n t h e case of dextrin, however, no matter how small a n a m o u n t of water be employed, under no condition does t h e concentration of t h e solution obtained remain constant, while on t h e other h a n d t h e addition of further solvent never fails t o dissolve additional dextrin, although t h e use of no amount of water, however large, will dissolve t h e whole of t h e sample. This unexpected behavior seemed worthy of quantitative s t u d y , a n d a large number of dextrins were examined in t h e folloving way: Weighed samples were introduced & t h known a m o u n t s of water i n t o well stoppered bottles a n d shaken in a thermostat, After a certain time a p a r t of t h e mixture was whizzed in a centrifuge, and t h e water-soluble m a t t e r determined b y evaporation of a n aliquot p a r t of t h e solution. This was repeated until no further change in t h e concentration of the solution occurred, requiring a t no time over twenty-four hours. Characteristic results are shown graphically b y t h e following curves, t h e soluble frac-
Totai solids by evaporation
70.7 74.2 70.8
i0.2 74.8 io.1
i5,l
75.6
D
u >
I n conclusion, I h a r e much pleasure in expressing b y best t h a n k s t o A h . R. L. Jenks, Chemical Examiner for Customs a n d Excise, for his kindly allowing me t o analyze several samples of condensed milks. CUSTOMS A N D EXCISECHEMICAL LABORATORY CUSTOM HOUSE.CALCUTTA, INDIA
THE SOLUBILITY OF DEXTRIN’ By W. K. LEWIS Received December 26, 1913
I n a n a t t e m p t t o find a rapid method of determining t h e proportion of dextrin soluble in cold water, t h e a u t h o r some time ago t r e a t e d weighed dextrin samples with known amounts of water in t h e tubes of a centrifuge, a n d after thorough agitation separated t h e suspended insoluble m a t t e r b y whizzing. The soluble portion was determined b y t h e evaporation of a n aliq u o t p a r t of t h e clear solution. T h e ratio of water t o sample was varied t o insure sufficient solvent so t h a t t h e solution should not be s a t u r a t e d with respect t o a n y of t h e soluble constituents of t h e original dextrin. It was surprising t o find t h a t t h e soluble fraction increased rapidly with dilution. If a physical mixture of a soluble a n d a n insoluble substance b e treated with increasing a m o u n t s of a solvent, we shall first obtain a s a t u r a t e d solution of t h e solute a t t h e temperature employed, t h e excess solute remaining undissolved. During t h i s stage t h e concentration of t h e solution obtained mill remain 1 All d a t a quoted in this article are taken from a thesis by C. W.Hobson, submitted in partlal fulfilment of the requirements for the S B. degree a t the Massachusetts Institute of Technology.
CONCENTRATION
-
G R A M S PER L I T E R
tion of t h e dextrins being plotted as ordinates, abscissae being t h e concentration of t h e solutions obt ained. With t h e idea in mind t h a t t h e insoluble portion of t h e dextrins might serve as a body on which t h e soluble portion could be adsorbed, these quantitative results were studied in t h e following way: Call t h e fraction of t h e dextrin insoluble in water, however great in a m o u n t . a t t h e temperature in question, I -~i. It follows t h a t a n indefinitely large a m o u n t of water will dissolve t h e fraction A . The fraction actually dissolved, as determined b y experiment, is designated b y x . T h e fraction soluble in water infinite in a m o u n t , b u t retained on t h e insoluble portion under t h e conditions i n question, is A - x. T h e concentration of t h e solution, expressed in a n y suitable way, call c. If t h e
*
