1252
INDUSTRIAL AND ENGINEERING CHEMISTRY
some of the earlier workers reported. Esau (6) has reported the production of formic acid by yeast. It was found that a sample of wine inoculated with burn6 bacteria after storage for 30 days contained appreciable amounts of formic acid but the latter was not found in the uninoculated control. Apparently formic acid may be produced both by bacteria and yeast. The sound wines contained only acetic acid with but traces of propionic. Declaux (2) reported that diseased wines contain more propionic than sound wines and that butyric acid is present in diseased wines. None of the samples analyzed contained any butyric acid. Of the seventy samples all the diseased wines showed formic acid in traces.
Acknowledgment The author acknowledges the valuable assistance of Lawrence Norton Quaccia in making a few of the distillations and of 31. A. Joslyn, of the Division of Fruit Products, University of California, for advice in conducting the investigation and preparing the manuscript.
Literature Cited (1) Assoc. Official Agr. Chem., Methods of Analysis, p. 140 (1930). (2) Declaux, E., Ann. Ecole Normale superieure, 2 (1865); J. Chem. Soc., 28, 188 (1865). (2a) Declaux, E., Compt. rend., 78,1160 (1872). (3) Dyer, D. C., J . BioZ. Chem., 28,445 (1916). (4) Eckenroth, H., Chem. Rundsehau, 6 , 103 (1897).
Precipitation Rate
of Cream of Tartar from Wine Effect of Temperature G. L. MARSH AND RI. A . JOSLYh-
University of California, Berkeley, Calif.
The precipitation of cream of tartar from new wines is hastened by cold storage, the rate of precipitation depending on the storage temperature and on the type of wine. The rate is more rapid during freezing storage than in cold storage. The actual amount of cream of tartar to be removed from wine for stabilization cannot be predicted from the data available since so many factors determine the actual solubility of cream of tartar in wine.
VOL. 27, NO. 11
( 5 ) Esau, P. J., M. S.thesis in bacteriology, Univ. Calif., 1933. (6) Fonxses-Diacon, H., and Jaulmes, P., Ann.faZs., 25, 149 (1929). (7) Gayon, U., Rev.nit. biere, 6,82; 7,97 (1899). (8) Grassi-Soncini, G. (tr. by Bioletti, F. T.), Biann. Rept. Calif. State Board Viticultural Commissioners, 1891 and 1892, Appendix E . (9) Grim, F., Ann. chim. pharm., 158, 117 (1871). (IO) Hortvet, J., J. IND.ESG. CHEM.,1, 31 (1909). (11) Jaulmes, P., Ann. fals., 21, 384 (1928). (12) Kayser, E . , BdZ. SOC. chim. biol., 6 , 345 (1924). (13) Kayser, E., BUZZ. SOC. encour., 94, 93, (1894). (14) Kayser, E., Rev. Bit., 47, 70 (1917). (la) Kulisch, P., 2. Nahr.-Genussm., 15, 663 (1907). (16) Laborde, J., Compt. rend., 138, 228 (1599). (17) Mach, E., and Portele, Land, Versuchs-Stats, 37, 303 (1889). (18) Malveain, P., Compt. rend., 148,784 (1909). (19) Marpurgo, Oesterr, Chern.-Ztg., 2, 209 (1899). (20) McNair, J. B., IND. ENG.CHmr., Anal. Ed., 5 , 62 (1933). (21) Osburn, 0. L., Wood, H. G., and Werkman, C. H., IWD. ENQ. CHEM..Anal. Ed.. 5 . 247 (1933). Richmon’d, H. D . , :4nalyst,’20, 1936 (1895); 31, 324 (1906); 33, 209, 305 (1908). Sielers, F., 2. Unter. 1Vahr.-Genussm., 47,135 (1924). Stein, A , J . prakt. Chena., 88,83 (1913). Thudichum, J. L. W.,“Treatise on Wine,” p. 68, London, George Bell &- Son, 1894. Thudichum, J. L. W., and Dupre, A , , “Origin, Nature and Use of Wine,” p. 184, London, Macmillan and Co., 1872. Wilson, J. A , J . Soc. Chem. Ind., 9, 18 (1800). Woodman and Burwell, Tech. &7rart., 1, 68 (1908). RECEIVED Aueuat 28, 1935.
QT
HAT the freshly expressed juice of the grape and new wine contain cream of tartar in concentrations greater than saturation is well known. I n order to avoid the undesirable precipitation of cream of tartar in the bottled wine, the excess cream of tartar is removed by prolonged storage a t room temperature or by cold storage for shorter intervals. According to the accepted laws of precipitation, the rate of precipitation of cream of tartar should depend on the velocity of formation of nuclei and on the rate of crystal growth, both of which are functions of the absolute supersaturation ( 5 ) . Since substances other than cream of tartar present in wine may serve as nuclei for crystal formation and since the solubility of cream of tartar in wine is influenced by a large number of factors, it is difficult to apply the simple precipitation laws to the study of removal of excess cream of tartar from wine. Thus, as shown in Figure 1, although there is a tendency for the cream of tartar content of California exposition wines of 1900 to decrease with increase in alcohol content, other factors are involved in determining the actual solubility. Since the solubility of cream of tartar decreases with decrease in temperature, it is to be expected that the rate of precipitation of cream of tartar should be faster a t lower temperatures. However, as shown later, the type of wine also influences the results. Continuing the study reported previously on the effect of cold and freezing storage on wine composition (g), the writers have determined the amount of cream of tartar precipitated from four typical wines stored a t various temperatures for different intervals of time, and the data observed are presented here.
Storage Tests Freshly made untreated wines of the vintage of 1934 from a winery in Lodi in the San Joaquin Valley district mere used in these tests: These consisted of a dry white wine made from Toka grape juice, a dry red wine made from a blend of Carignane and Jlicante Bouschet grapes, a port wine from a blend of about half Alicante Bouschet and half Carignane, Cornichon, and Mission, and a sherry material from fermented Tokay juice. Before use the
NOVEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
1253
wines were filtered brilliantly clear through a small Cellulo pulp filter. The composition of the wines is given in Table I. TABLE I. COMPOSITION O F WINES USED Sp. gr. ( 2 0 ° / 2 0 0 C.) Composition. grams/100 cc. n.1
Dry \5 hite 0.9919
Dry Red 0,9951
12.15 0.051 0.418 1.96 0.030
13.62 0.048 0.600 3.22 0.050
Sherry Material 0.9893
Port 1.0229 02
".
n0 '
alcohol^
21.59
21.61 0.021 0.413 12.65 0.034
Volatile acid 0,030 Total acid 0.473 4.11 Extract Total nitrogen 0.029 Reducing sugars as dextrose 0.100 0.228 2.03 9.60 Tannin and coloring matter .... 0.198 ..... 0.147 .ish 0.418 0.510 0.301 0.347 Alkalinity a s h b Water-sol. 28.7 25.3 20.3 18.5 9.6 15.5 \vater-insoi. 13.5 13.5 Total tartaric acid 0 269 0 272 0.178 0.199 0.341 0.223 0.250 IiHCpH4Oa 0.337 Refractive index (20' C . ) 1.3419 1.3457 1.3515 1.3632 p H (25' C.1, 3.86 3.71 3.70 3.74 Freezing point, ' C. ( " F . I -5.6 (22) - 6 . 7 (20) -11.7 (10) -13.9 ( 7 ) a Per cent b y volume. b Cc. of 0.1 ,V eodium hydroxide per 100 cc. nine.
In order to avoid the complication of oxidative changes, the wines were stored in completely filled, hermetically sealed glass bottles in the tests at temperatures above the congeriling point. The filled bottles were stored at 25', loo, 4.4", O', and -3.9' C., and the zero time was taken as that necessary for the wine a t the center of the container to reach storage temperature. This interval was about 10 hours. Samples were removed from storage a t frequent intervals, immediately filtered cold, and the filtered wine vas analyzed for cream of tartar, specific gravity, and pH. The methods of analysis of the A. 0. A. C. ( 1 ) were used. No free tartaric acid was present in any of the samples of wine tested so that the total tartaric acid content was expressed directly as cream of tartar in accordance with the official procedure. The results obtained are presented in Tables I1 to V, inclusive; typical results are shown in Figures 2 and 3. rlfter the completion of the storage tests the final sample was analyzed in more detail with the results shown in Table VI. In the studies on the effect of freezing storage on mt,e of deposition of cream of tartar, 100-cc. portions of the wine were stored in beakers in air at -17.8" C.; about 3 hours were required for the complete separation of ice from the wine and 6 hours for the wine to reach storage temperature. Four samples of the frozen wine, after storage for various lengths of time, were removed for analysis. Duplicates were thawed in air a t room temperature, and in a running water bath, to 10" C. The length of time to reach this temperature varied with type of wine, and was faster for the sweet wines than for the dry. The samples were then filtered and the cream of tartar precipitate, aft,er washing with 20 cc. of potassium chloride-alcohol mixture, was washed back into the original beaker with hot water; the solution was brought to a boil and titrated directly. The results obtained when the samples were thawed in air for 90 minutes are shown in Table VI1 and Figure 4. The initial cream of tartar content of the wines when used was: dry white, 0.291 gram per 100 cc: dry red, 0.342; sherry material, 0.164; and port, 0.210. Ali the results reported are the averages of closely agreeing duplicate or triplicate determination.
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FIGURE 2. RATE
O F DEPOSITION OF CRE.4M OF T.4RT.4R FROM W I K E STORED AT -3.9' C.
FIGURE3. RATE OF DEPOSITIONOF CREAM OF TARTAR FROM DRYWINE STORED AT VARIOUS TEMPERATURES
Deposition of Cream of Tartar EFFECTOF TEMPERATURE. The data show that merely cooling the wine to a temperature just above freezing, as is done in some current installations in California wineries, is not sufficient to cause the separation of appreciable amounts of cream of tartar. T o remove a considerable portion of the cream of tartar, the wine must be stored a t the cool temperature for a period mhioh depends upon the nature of the wine and the temperature of storage. Thus, for dry white wine, storage for 3 days a t 10' C., between 1 and 3 days :it 4.4"and 0" C., and less than 1 a t 0' C., reduced the cream of tartar content of the wine to that of the sample stored a t room temperature for 225 days. The rate of precipitation of cream of tartar was quite rapid in the initial period and then decreased, becoming very slow after 12 days at practically all temperatures used. This action was t o be expected since the degree
FIGURE 4. RATEOF DEPOSITION OF CREAMOF TARTAR FROM WINE STORED AT -17.8' C.
1hDUSTRIAL ASD ESGINEERISG CHERIISTR1-
1254
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(CESTER) DIRECT-EXy s I o N T U Bu L A R COOLER FOR CHILLING WINE PA
Courtesy, Frigidaire C o r p o rnfion
(BELOW) HEFHIGERATING
s Y S T E M AND
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STEELWINE COOLERINSTALLED AT CAMEOVINEYARDS COMPAKY, FRERXO, CALIF. Courtesy,. B a k e r Ice Machine C o m p a n y , Inc.
of supersaturation decreased culltinually owing to separation of the cream of tartar. However, the decrease in rate of separation appeared to be more rapid than would be accounted for by decrease in cream of tartar concentration in the wine. The rate of precipitation increased with decrease in temperature; thus 30 per cent of the cream of tartar p r e s e n t was removed after storage for 5 days a t 10°C., about 3 days a t O'and 4.4O, and after storage for but 2 days a t -3.9O. EFFECT OF TYPE OF WINE. Figures 2 and 3 show the effect of type
\ OL. 27, NO. 11
It u w ~ l dappear that the presence of t a n n i n sild coloring matter in tlie red wine niay have i n t e r f e r e d with either the formatiuu of nuclei or the growth of crystals since the h i g h e r sugar and e x t r a c t c o n t e n t wuld have the opposite effect. TIIIE, Richert (3) has shown that invert sugar decreases the s o l u b i l i t y of creamof tartar, b u t h y n o t as great an extent as would he accounted for merely ( m the haai* of deerease
ciiloride to the oxidized port increased tile amount of creamof tartar precipitated t o that found in tlie original port. It is hard to believe that the separation of coloring matter distiirbed tire salt balance in the wine, and some other factors are probably involved. If the molecules of the coloring matter served as nuclei for crystal formation, then it is reasonable that their removal should decrease the rate of precipitation of cream of tartar. If thin is the case, aome other constituent or constituents in the red wines are responsible Sor delayed crystallization of cream of tartar when compared with white wines. As sliown in Table VI1 and Figure 4, tile rate of removal of cream of tartar from wine on frecziug storage at -17.8" C. is much more rapid than during storage at temporatures above freezing. Thus, 30 per cent of the cream of tartnr present in dry red wine was deposited after about 4 days storage at -3.9" C., and the same amount was deposited in the time taken for the wine to reach -17.8' C . (about 6 hours); the
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iu aiiiOiiiit OS w t e r asnilahle Sor s o l u t i u i i That the c o l o r i n g matter does not have 4 simple retarding effwt on the rate of cream of tartar separation brit may acttially increasc the rate of precipitation was &own in an interesting experience wit,h p r t wine. About S literaof port tml been stored a t room t.einperatiire in a 20-liter carboy for about 8 montlis. This wine was foirnti to lie extremely cloudy m r l to liare precipitated most of its coloring matter a i d n p r t i o n of its cre:~niof t a r t a r c o n t e r i t . On warining the wine at 140" F. for an hour or two, the cream of tartar reilissdved but the precipitated coloring matter did not, being apparently converted t o an insoluble oxidized form. The surprising finding was that no cream of tartar separated from a sample OS t,he wine wlien frozen under conditions such that an RpprccinMe amount of cream of tartar precipitated in the original port. The freezing test was repeated with t h e r c s u l t s s h a m in Table VIII. After removal of readily oxidizable 1:oloring material, t.he rate of precipitation of cream or t a r t a r a n d t h e a m o u n t participated were both markedly less tlian in the origiinn.1 sample, even though tlie creiim o f tartar mnt,ent \vas the sitme: Iliiginni
c.
Stwed at
10" c.
0.9916 0 . 9 9 1 4 3.86 3.90 0 . 2 8 8 0.228 0.9817 0.9914 3.87 L9l 0.283 0.228 0.9916 0.9914 3.87 3.92 0.250 0.200 0.9918 0 9913 8.89 398
storwt at 4.4" c.
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