T H E J O C R N A L O F I N D C S T R I A L AiVD E N G I A T E E R I N G C H E M I S T R Y
334
in two varieties of t h e American species Vitis rotundi.folia, namely, Mish and Scuppernong, both of which a,re extensively cultivated southward from Virginia. The sample of Nish contained approximately 13 per cent of reducing sugar (invert sugar) and also there was found in it nearly z per cent of sucrose b y both the copper reduction and the Clerget polarization method of analysis. An estimation of sucrose in a sample of Scuppernong b y inversion with t h e enzyme invertase' showed 0.69 per cent of t h a t sugar. Two years later Alwoodl reported t h e presence of sucrose in the Hayes, T o r d e n , Illinois City, Pocklington and Xectar varieties of the American species V i t i s l a h r i ~ ~ c at,h e percentages of sucrose ranging from 1.23 per cent t o as high as 9.34 per cent. The sugar was estimated from copper reductions before and after acid hydrolysis. I n !dwood's report a description is also given of a very interesting chance seedling grape of unknown origin which was found b y Alwood and Eoff t o contain unusually large amounts of sucrose! the percentage ranging in different samples from 3.44 per cent t o 10.67 per cent. The presence of sucrose was inferred and the sugar estimated b y t h e same methods of analysis t h a t t h e writer used, namely, in\-ersion b y acid and b y t h e enzyme invertase. -41though sucrose has not been crystallized as yet from a n y varieties of grape, the results of Xlwood and Eoff and of t h e writer indicate with a fair degree of cert a i n t y t h a t i t occurs in two of t h e American species, r o t u t i d i f o l i a and l a b r u s c a . During the past four seasons the selected samples of grapes which have been received a t the Bureau of Chemistry from t h e Department's plantiiigs a t Tineland, N.J . , and from points in North Carolina, which f u r ni s h e d the Y O t u I I d Zfoli a varieties , have been examined for t h e presence of sucrose. The grapes were picked from the stems and pressed, in some cases without heating, in others after warming rapidly t o 9 j O in a steam kettle. The juices were analyzed immediately after pressing and sucrose was tested €or b y the usual reduction and polarization methods. The analytical d a t a were obtained by Llessrs. F. T. Anderson, 9.H. Bryan and S. F. Sherwood, of this Bureau. The 1-aricties in t h e following list: 43 in number, showed no sucrose a t any time. I t is not believed t h a t such heating causes a n y considerable inversion of sucrose in grape juice. ABSEXT James (Rotund ) Jefferson Lampasas Lindley Martha Massasoit Merrimac Mo. Riesling Ivlontefiore ( a ) Yiagara Noah I\'ortoils:u) Perkins Salem Ulster (a) Heated t o YJ0 heiore pressing; t h e others were pressed cold. TABLE I - V A R I E T I E S
Agawain Barry(e) Berckman5 Brighton Brilliant Canada(a) Catawba Centennial(a) Clinton(a) Concord(a) Cynthiana(a1 Delaware Diogene?(u) Dutchess
I S WHICIf S C C R O S E U'AS
Early Champion(a) Eaton(a) Elvira Eumelan(a) Flowers (Rotund.) Franklin(a) Gaertner Goethe Hartford(a) Herbemont Hybrid Seibel No. l ( a ) Hybrid Seibel No. 2 ( a ) Iona Ives(a)
I n Table I1 are recorded those varieties which a t times showed small amounts of sucrose, and those in which t h e sugar was found always present. 1
C . S. Dapt. Agric. Bur. Chem., Bull. 140.
TABLE 11-VARIETIES I X VARIETIES
VOI. 8, KO. 4
SDCROSE WASFOUND 1912 1913 I914 Campbell's Early(e). . . . . . . . . . . . 0.36 0.61 Absent Clevener(a) . . . . . . . . . . . . . . . . . . . . . . . . 1.40 Absent Absent 4.22 3.82 Absent Colerain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Absent Absent Ahsent 0.50 Diana . . . . . . . . . . . . . . . . . . . . . . . . . Absent Absent Absent 0.52 Early Daisy(a). . . . . . . . . . . . . . . . . . Absent Absent 0.65 Absent E a r l y V i c t o r ( a ) .. . . . . . . . . . . . . 1 . 0 1 0.88 1.23 Eden (Rotundifolia). . . . . . . . . . . . 0 . 6 1 0.59 Absent Herbert(a). . . . . . . . . . . . . . . . . . . . Absent 0.47 1.45' Absent Isabella(a). . . . . . . . . . . . . . . . . . . . . Absent Absent Absent 0.35 Lady... . . . . . . . . . . . . . . . . . . . . . . 4.57 4.54 5.01 Absent L e n o i r ( a ) . .. . . . . . . . . . . . . . . . . . . . 4.32 Absent 1.0~5 Absent Moore's E a r l y ( a ) . . . . . . . . . . . . . 2 . 2 9 2.6i 2.25 Absent K e c t a r ( a ) .. . . . . . . . . . . . . . . . 3 . 0 6 3.28 4.12 2.02 Pocklinzton.. . . . . . . . . . . . . . . . . . . 2.81 I .88 0.62 1.97 RommeT. . . . . . . . . . . . . . . . . . . . -4hsent Absent 0.33 Absent Scuppernong (Rotund.) . . . . . . . . 0.91 1.18 Absent 1.14 2.97 2.91 3.36 Thomas ( R o t u n d . ) , , . , . , , , , , , 2.39 Vergennes . . . . . . . . . . . . . . . . Absent Absent 0.34 Absent Wilder(a) . . . . . . . . . . . 1 . 2 2 Absent Absent Winchell, . . . . . . . . . . . . . . . . 0.44 Absent Absent Aisent Woodruff . . . . . . . . . . . . . . . . . . . . Absent 1.00 0.95 0.34 Worden ( a ) . . . . . . . . . . . . . . . . . . . Absent Absent 0.80 Absent (a) Prepared b y cooking the grapes and then pressing: t h e others were cold-pressed. WHICH
1911 Absent
-n summary, a n examination of these 66 varieties during four successive seasons shows t h a t 43 of them contained no sucrose, I O contained sucrose occasionally, and in 13 varieties it was frequently present. I t is evident, therefore, t h a t sucrose should be regarded as a normal constituent of many varieties of grapes of American origin. FRDIT A N D VEGETABLE UTILIZATION LABORATORY BUREAUOF CHEMISTRY,
WASHINGTON
THE OCCURRENCE OF SUCROSE IN RELATIVELY LARGE AMOUNTS IN A NEW SEEDLING GRAPE By U'. B. ALWOODAND J. R .
EOFF,J R . '
Received August 30, 19 15
Although sucrose has never been found in European grapes, it has been shown b y Gore2 t h a t many varieties of American origin! including representatives of both the Iritis r o t u n d i f o l i a and labrusca species, contain this sugar. The presence of sucrose in several varieties of the labrztsca species was also reported b y one of ~ 1 s . ~ I n that bulletin there was described a seedling grape of unknown origin, the fruit of which had attracted the attention of one of us (Eoff) during a visit t o t h e market in Sandusky, Ohio, in the fall of 1909. This grape was found t o contain larger amounts of sucrose than had been reported previously from a n y American grapes. Although t h e origin of this seedling is u n certain, it appears t o belong t o t h e Iabrusctr group. I t was suggested in B u l l e t i n 140 t h a t the seedling might be useful for cross-pollenizing some of our strong-growing grapes, rich in acid and flavor, like the Catawba, because t h e flavor of the new grape is very mild-entirely without foxiness-and its acidity is very low. Seedlings from such crosses might result in improving t h e character of vintage grapes in the direction of milder flavor and lower acid content. h further examination of this seedling was carried on for a period of 60 days during t h e season of 1911 so that t h e d a t a might be very conclusive. This grape is characterized b y fairly large bunches, well filled! berries large and beautiful, color darker when fully ripe t h a n Delaware. The flavor is peculiar, 1 The work described in this paper was performed while the authors were connected with t h e Enological Laboratory (now closed), Bureau of Chemistry, United States Department of Agriculture. 2 THISJOURNAL, 1 (19091, 436. 3 Alwood. U. S. Dept. Agric., Bur. Chem.. Bull. 140 (1911).
T H E J O C R N A L OF I N D C S T R I A L A N D ENGINEERING CHEMISTRY
Apr., 1916
TABLEI-DATA
LAB.
No. 3054 3060 3066 3073 3081 3103 3112 3132 3148 3179 3201 3220 3244 3255 3284 3298 3308
Date analyzed 1911 Aug. 23 Aug. 27 Aug. 30 Sept. 3 Sept. 6 Sept. 10 Sept. 13 Sept. 17 Sept. 20 Sept. . 2 4 Sept. 27 Oct. 1 Oct. 4 Oct. 8 Oct. 15 Oct. 18 Oct. 22
ON
Specific gravity 1.0648 1.0662 1.0670 1.0721 1.0731 1.0746 1.0817 1.0824 1.0724 1,0827 1.0831 1,0737 1,0690 1,0626 1.0750 1,0726 1,0741
THE OCCURRENCE O F SUCROSE IN A SEEDLING GRAPE(J. R . RESULTSIN GRAMSPER 100 Cc. OF JUICE Total solids 16.80 17.17 17.38 18.71 18.97 19.31 21.23 21.41 18.79 21.49 21.59 19.13 17.90 16.23 19.47 18.84 19.23
Sugarfree solids 2.24 1.86 1.87 2.04 1.95 2.00 1.96 2.36 2.08 2.02 1.83 1.95 2.21 2.08 2.30 2.28 2.32
Invert sugar 7.90 8.56 7.91 8.27 8.32 7.97 8.91 9.15 8.99 9.52 9.51 8.96 9.31 8.92 9.72 9.43 9.40
Sucrose Total Total by sugar acid as inversion a s invert tartaric 6.66 14.91 0.56 6.75 15.67 0.50 15.91 7.60 0.42 8.40 17.11 0.39 17.48 8.70 0.42 9.34 17.80 0.47 0.30 10.36 19.82 19.57 0.34 9.90 17.12 0.26 7.72 0.30 9.95 19.99 0.26 10.25 20.29 0.21 8.22 17.61 0.31 6.38 16.03 0.29 5.23 14.43 0.29 7.45 17.56 0.24 7.13 16.93 17.31 0.25 7.51
mild, honey-sweet, not exactly grape-like in character, yet many persons have pron.ounced it as very pleasant and desirable for table use. I t can be harvested for market over a long period b y selecting t h e bunches. Table I gives the chemical d a t a in full, with notes on t h e character and condition of the fruit when analyzed. Our thanks are extended t o Dr. B. G. H a r t m a n n who has aided us in this investigation. The d a t a herewith published complete three years’ examination of this peculiar grape and quite fully cover the question of its composition. The further question of its practical value belongs t o students of horticulture. BUKEALJ OF CHEMISTRY,
\vASHINGTON
A COMPARISON OF METHODS FOR’l’HE DETERMINA-
TlON OF CASEIN IN MILK By C . B. HERSEY Received October 20, 1915
Xs a part of a. milk study’ which was ComPletedbY t h e author during the past year a t the VniL’ersitY of California three methods for the determination of casein in milk were compared. T h e folloking rGsum6 of t h e work is now submitted with results: Ever since Dr. Babcock introduced his remarkably simple and accurate method for fat determination in milk, much effort has been spent on devising Some equally simple and accurate determination for casein in milk b y which t h e cheese maker could more carefully Control his product and b y which the dairyman could receiye a more equitable return for his milk. From among the SeVeral methods thus evols’ed t h e ones chosen for this comparison were t h e T‘an Slyke t h e H a r t Centrifugal3 and the Official Nitrogen or Kjeldahl m e t h ~ d . A ~ systematic comparison of t h e above methods had n o t been made, though the Shutts and ~~~~6 each made a few tests H a r t and t h e Nitrogen method, Literature 1 “-4 S t u d y of Milk from Individual Cowsshowing DailyandSeasonal Variations in Composition and a Comparison of Methods f o r the Determination of Casein in Milk,” being a thesis on which with other work the author was granted t h e M . S. degree in Food Chemistry, Univ. California Library, Berkeley. 2 L. L. Van Slyke a n d A. W. Bosworth, “A Volumetric Method for Casein Determination in Milk,” N.Y . Exp. S t a . , Tech. Bull. 10, 231-241. E . B. H a r t , “ A Simple Test For Casein in Milk a n d Its Relation t o t h e Dairy Industry,” Wis. Exp. S a . , Bull. 166, 22. 4 “Methods of Analysis of t h e Association of Official Agricultural Chemists.” U. S. Dept. of Agr., Bur. of Chem., Bull. 107 (Revised), 1 1 7 . 5 F. T. Shutt, “ H a r t ’ s Casein Test.” Canada E x p . F a r m . Rpt., 1909, p . 192. H . H. Dean, “Comparison of H a r t ’ s Method,” A n n . R e p t . of Onl. A g r i . Col. and E x $ . F a r m s , 34 (1908). 97-127.
33 5
EOFFA N D S . F. SHERWOOD,ANALYSTS)
CONDITIONOF FRUIT Berrieslarge, fine condition, not fully colored Aboutsamecondition Maturesunevenly. some bunches appear fullyvipe Aboutsamecondition Continues t o develop very unevenly Condition holds as for previous d a t e Ripeningunevenly S o m e b u n c h e s p a s t best condition Condition holds, some bunchesnot fully colored Crop picked for market Flavor becoming peculiar, not vinous Fruitholdingwellonvines Fruit h o l d i n g w e l l o n v i n e s Fruitholdingwellonvines F r u i t h o l d i n g w e l l o n vines Fruit falling Fruitfallinghadly
paring t h e Van Slyke and Official or t h e Van Slyke and t h e H a r t method seems t o be lacking. METHODS OF ANALYSIS M E T H O D was performed exactly as given in the bulletin,’ using t h e chemist’s modification, t h a t is, N / I O acid a n d base instead of acid of an arbitrary strength. H A R T METHOD-The details of procedure were followed exactly as given in t h e bulletin with the exception t h a t instead of using hand power t h e centrifuge was electrically driven ”with rheostat for speed control, which feature is greatly to be desired not only from a muscular point of view b u t because of t h e greater uniformity of speed attainable which is essential t o t h e success of the test. NITROGEN M E T H O D was carried out according t o the Official Kjeldahl-Gunning method. In t h e latter part of the work j per cent of CuSOd was added t o t h e K2SO4 (Hibbard’s mixture)* which expedited greatly the time required for the decomposition with the strong sulfuric acid with exact117 the same result. as f a r as nitrogen is concerned, Throughout the work all directions and precautions were carefully observed. Frequently full duplicate analyses were made,
VAN
SLYKE
RESULTS
Table I shoL?Ts t h e average for each method of 1 4 3 , samples of fresh each analyzed by the three methods, with a maximum and minimum f o r each method. ~h~ close check of the ~~~t and official b y the average and the corresponding doubt. ful check of t h e v a n Slyke and Official are t o be noted, TABLEI Official Average.. . . . . . 2,477, Maximum . . . . . 3 . 3 1 Minimum. . . . . . 1 . 7 1
Hart 2,52VC 3.4 1.81
Van Slyke 3.077, 3.70 1.05
Table 11 gives in detail the variation of the two methods from t h e Official method which is considered for t h e Comparison t o be t h e standard of accuracy. T h e variations are given in percentages of casein, showing t h e number and percentage of determinations which differed b y various amounts both more and less or higher and lower for each method t h a n b y t h e Official method. Cnless this “higher and lower” factor be determined it might be possible t o arrive a t a series of averages which would give an erroneous impression of t h e true condition; i. e., in any individual 1 LOG.
Cil.
P . L. Hibbard, “ATotes on t h e Determination of Nitrogen b y the Kjeldahl Method,” THISJ O U R N A L , 2 (1910). 463-6. 2
