Estimation of Sucrose in the Presence of Lactose and in the Milk

Table III—Lavender,. Sweet Fennel, Caraway, Coriander,. Sweet. Birch and. Sassafras Compared. Vie of a. Fleischmann's Yeast Cake in 50 Cc. of Syrup...
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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

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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

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