I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
March 1949 T a r acids T a r bases Paraffins Naphthenes Aliphatic olefins Cyclic olefins
Volume 0 5 6 6 21.2 8 2 26.9 15.1
93
Volume diomatics . 18 2 Sulfur compounds 3 4 Nitrogen compounds (other t h a n t a r bases) 0 Y Separation loss 0 i
LITERATURE CITED
93
-
Total
100 0
ACKNOWLEDGMENT This work was done under cooperative agreement between the United States Bureau of Mines, United States Department of the Interior, and the University of Wyoming. The writers wish t o thank H. N. Thorne, engineer in charge, oll-shale research and development, for his encouragement of the project.
582
(I) Ball, John S., U . 8. Bur. Mines Rept. Invest. 3591 (1941). (2) Dinneen, G. U., Bailey, C. W., Smith, J. R., and Ball, J. S., Anal. Chern., 19, 992 (1947). ( 3 ) Gavin, M . J., and Desmond, J. S., U. S. Bur. ,Wines B d l . 315 (1930). (4) Gooding, R. M., Adams, N. G., and Rall, H. T., IND.ENGI. CHEM.,ANAL.ED., 18, 2 (1946). ( 5 ) Guthrie, B., and Simmons, M. C., U . S. Bur. Mines Rept. Iflaeat. 3729 (1943). (6) Kraemer, A. J., and Buchan, F. E., C h e w Eng. News, 23, 1626 (1945).
(7) Staff Report, Zbid., p. 1242 (1945). R E C ~ I V EMarch D 8, 1948. Presented before the Division of Petroleum Chemistry &t t h e 113th Meeting of the A ~ E R I C A N CBEMICAL SOCIPJTY, Chicago, Ill.
CALIFORNIA WINES Oxidation-Reduction Potentials at Various Stages of Production and Aging M . A . JOSLYN University of California, Berkeley 4 , Calif. ing molecular oxygen; the NOWLEDGE of the other having a ,normal potenoxidation-reduction T h e oxidation-reduction potentials of wine during tial of Eh = -0.160 volt at pH potential offers a means for preparation, storage, and treatment in three representa9 and 20" C., which reacts the methodical study of the tive California wine districts were observed. As no corslewly and occurs in the reoxidatiosa factor in fermented relation was found between the age of the finished wine duced form only when it is not beverages, dairy products, and its oxidation-reduction potential, the latter could not mixed with another system and other foods. It has been be used as a criterion of age, although data from which can oxidize it. Geloso particularly useful in the inliterature indicate that the redox potential can be used believes that these systems vestigations of aeration, light as a measure of its state of oxidation. are identical with those that taste, and yeast turbidities in beer (2, Y, 16, 16,18); and of develop in a glucose solution nature and cause of oxidized stored out of contact with air, and suggests that they represent an enolic form of some sugar d e flavor in milk and other dairy products (6); and has been applied rivative. Such evidence as Joslyn has obtained would favor in the investigations of metallic hazes and aging in wine (3, 6, 10, Rib6reau-Gayon, but more data are needed before the redox 14, 17'). The nature of the systems involved in poising the redox potential a t a given level and the extent of change in redox posystems in wine can be characterized. tential upon the addition of a measured quantity of a n oxidizing It was suggested previously (11) that reduction plays aa or reducing agent, however, are more significant than the redox important a role in the aging of wine as it apparently does in the potential itself (10). aging of whisky (9). KrasinskiI and Pryakhina (14) recently reported that on aging in bottles the oxidation-reduction potential Oxidation by the oxygen of the air appears to play a n important of wine is lowered, and in consequence of this the body and role in the cask aging of wines, and this oxidation is a n important bouquet of the wine are improved. To accelerate this decrease factor in producing the desirable bouquet of old wines. Excessive they passed hydrogen gas through wine and produced a drop in oxidation, however, is known to cause decolorization and browning the oxidation-reduction potential from 0.4 to 0.25 volt or lower. of red wines, the browning of white wines, and the formation of colloidal iron deposits (17). Control of the rate and extent of After storage for 25 days, such treated wine was much improved oxidation is thus of great importance in the maturation of wines, in flavor, as compared with the untreated sample. This supports but too little is known, as yet, of the chemistry of autoxidation the well-known fact that freshly bottled wine improves in flavor of wines t o permit this. The only satisfactory method of conduring storage (1, 19). trolling oxidation in wines a t present is through the use of conSuch data as are available in the literature would indicate that tainers of desirable size (ratio of surface to volume is limiting the redox potential of wine can be used as a measure of its state of here) and of desirable porosity-Le., allowing a desirable rate of oxidation, but there is little evidence that it can be used as a n diffusion of oxygen from the air into the wine stored. objective measure of age. Some years ago investigations were RibBreau-Gayon ( l 7 ) ,as a result of his extensive investigations begun in the author's laboratory to debermine the degree of of oxidation and reduction in French wines, has concluded that the correlation between the redox potential of wine and its previous chief oxidizable constituents in wine are tannins, anthocyanins, treatment under existing commercial conditions. Data on the and sulfurous acid. He has shown that iron and copper salts redox potentials of wine during preparation, storage, and treatplay an important role as intermediary oxidants and catalysts of ment in three representative California wineries were obtained oxidation. More recently Gatet and Genevois (4) reported that during October and November 1940, including old and new wines, reduced ascorbic acid exists in wine and that iron salts catalyze and these are presented and discussed here. the oxidation of tartaric acid into dihydroxymaleic acid and dihydroxytartaric acid. Geloso (6) reported the existence of EXPERIMENTAL METHOD two oxidation-reduction systems in wine, one having a normal oxidation-reduction potentials of samples of wine withpotential of E,, = -0.115 vel$ a t p H 9 and 20" C., which reacts drawn at several points from the fermentation and storage vats p its hydrogen to various acceptors irp&& were nleasured in wide-mouthed, 500-ml. glass bottles fitted with 1
INDUSTRIAL AND ENGINEERING CHEMISTRY
588
TABLE I. OXIDATION-REDUCTION POTENTIALS AT VARIOUS POINTS IX
Wine 193.5 sherry
Containrr, Gallon Vat 32,000
Fill Full
1937 sherry
20,000
Full
1934 sherry
32,000
Fill1
1939 dry white 1935 muscat
20,000
Full
52,000
Full
1935 sherry
52,000
Bull
193F white port 1940 port
10,000
Full
52,000
Z/S
REDWOOD STORAGE VATS Time Filled 9 months
Full
Posi- Eobsvd., tion Mv. Cent,er -50 Bottom -5 Top +40 4 months Center 4-55 Bottom K$;& Top +7 9 months Center -13 Botiom Top +7.5 10months Cent,er +35 fS7 Top +33 2 weeks Center TOP +a0 Bottom +30 -+a0 U months Center +SO Bottom 'r op +60 5 months Center -7 -3 Top 2 weeks Bottom + l o 3 Top +l23
Tzmp.,
c.
26 26 26 25 25 25 25 25 25 26 26 24 24 24 24 24 24 24 24. 24 24
Eh,
pH 4.00 4.00 4.00 3.82 3.82 3.82 4.00 4.09 4.09 3.83 3.53 3.80 3.80 3.80 3.80 3.80 3.80 4.00 4.00 3.70 3.70
MV.
105 240 285 301 286 280 252 230 320 280 332 279 296 276 276 326 306 239 243 351 371
Vol. 41, No. 3
glass clectrode assembly. The measurements were made at, the wine temperaturos prevailing during the survcy, and reported as &bsv& and as Eh (corrected for the voltage of the saturated calomel electrode at the temperature observed). T o test the reproducibility of the potential measurement, samples of a 1939 port were withdrawn from a 38,000-gallon redwood vat in the >It. Tivy Winery on December 6, 1940, in various ways. This port wine had been clarified, chilled, and filtered into the vat on July 23, 1940, and a t the time of observation the vat, was practically full--37,242 gallons of wine in a 38,566-gallon vat. The observed potential on samples of winc carefully siphoned out under nitrogen gas with t'welve different electrodes varied from 25 to 45 mv., the average being 33. Using the same two electrodes, the potential of thc wine so transfcrrctl was 43 mv.; the potential of the wine transfcrrcd without using a blanket of nitrogen gas was 55; that of the wine allowed to fall through the air in the sampling vessel was 65, and through nitrogen 45. OXIDATION-REDUCTION POTENTIAL AT U l l A l l
TABLE11. EFFECTOF AERATION OX OXIDATION-RIGDCCTION CREEK F I N E R Y POTENTIALS A complete survey of the wines in storage a t the Bear Clcck Position 1939 sherry 1939 sherry 1940 port 1938 port
;::$g:':
&ubsvd.,
165 200 73
Tup Bottom Center Center
265
7';
Before Aeration Temp., 22 22 22 22
3,93 3.93 3.83 3.70
ig "3;:
After Aeration
hf::
~ ";"~ ,;
413 448 321 603
180 235 190 260
ii!
428 483 438 508
:!i
TABLE111. OXIDATION-REDCCTION PoTENTIALs OF T O K A Y GRAPEJUICE AT VARIOUSSTAGES OF FERNENTATION Condition
Freshly filled fermentor Free run juice into sump Incipient fermentation Incipient fermentation Aetive fermentation End fermentation
~
~
j
Eobavd.,
.l ~ i ~ ~i d ~ ill, ~.,~
o,540
Temp., 0
c.
*H
$$, f409 +315 +200 +260
22 22
0.690
20
0 . 5 ~ ~ -45
24 24 24
+15
24
3.g3 3.78 3.65 3,6j
-256 -205
24 24
3.78
19 9 0
0.608
0.578
+70
3.65
-10
4-40
two platinum \\-ire electrodes, potassium chloride-agar bridge, and two glass-stoppered tubes, one of which, the inlet tube, reached to the bottom; the other, used as an owrflow tube, reached just to t,he neck. The electrode vessels were 7 cm. in dialneter and cm, high, The were made of bright plat,inum \Tire, 26 gage, spirally wound, and carefully sealed into 3-mm. diameter Pyrex glass tubes filled with pure mercury. The potassium chloride-agar bridge was made of a rounded capillary E-tube 1.5 mm. in diameter and filled wit,h saturated potajsium chloride and 3% agar; the inlet and outlet tubes \%-ere5 mm. in diameter. Electrical contact with the potentiometer assembly was made with copper wires, the ends of which n-ere thoroughly cleaned and amalgamated before dipping into the mercury. A s report,ed by Hewitt ( 8 ) , Joslyn give results in mell-poised systelns found that such ~~rhich \yere reproducible xvith a high degree of precision ( 1 3 ) . In wines the electrodes usually agreed within 5 mv., and only the average of two readings agreeing within 10 mv. is given in the tabulations. The electrodes were periodically cleaned with nitric acid, and stored distilled ,vater, The air in the electrode vessels the ,?,ith oxygen-free nitrogell gas prior to \vas \vine into it through alltali-treated and washed rubber tubing. Subsequent tests, however, indicated that redox potentials mea@ured in wine carefully siphoned into the electrode vessels without Ilitrogen treatInentu.ere identical within error to those obtained by the above procedure. All transfey of wine from bottles or similar containers was done under a blanket of nitrogen gas. The potential of the syst'emplatinum Tvire/wine/saturated pot,assium chloride agar/saturated potassium c,lloride solut,ion/saturated calomel cell-bvas measured assembly \,,ith a research model Leeds & xorthrup No. 7661-81. The pH of the wine was measured by the same
Vineyard Association winery at Lodi, Calif., representative of \vinc?s produced in the coolest region of the great interior valleys, was made during Oct'ober 22 to October 29, 1940. The data obtained are given in Tables I to I X . At this winery the wine was produced by the methods in usc in the larger table and dessert wineries (I, 12). The fermollt,ations were conducted in concrete fermeiitors of about 6000gallon capacity, and after fermentation the wine was pumped iri1.u large redwood vats for coinplct,ion of fermentation and st,oragc. After fermentation the wine mas usually racked off thc lees, heated t o 105' F. and clarified IThilc warm with bentonitc, thcii racked and filtcred with diatomaceous earih through a Liltcr press, pasteurized by heating for 2 to 3 minutes a t 185" F., ehillctl in a tubular wins cooler, filtered cold, stored, chilled again, and stored cold and filtered. During this sequence of operation> for shbilizing the wine, sulfite, tannin, and citric acid xere adtiml where necessary. Wincs at various stages of this treatment, TWIT tested. The effect of position in vat is shown in Table I, in which ai'e given data for the oxidalion-reduction potentials taker1 1 foot from the bott'oni, t,he center, and 1 foot from the top of the large redwood storage vats widely- used for dessert vvincs in tho largor California wineries (12). Since the potential would be affcctcd by aeration a t the time of filling, t2le period of storage airlcc the vats were last filled is given. I n gcneral, the centcr where the mass Of !vine is protected from direct contact with air diffusing through the porca of the wooden staves is a t a lower potential, but the differences observed were not large, particularly for \rats last filled 5 months or less ago. In vat's in which the winc ha-; remained quiet for about 9 months, the wine a t the bottom is usually at a significantly lower potential in spite of being c l o x r t o the wood. Apparently diffusion through the 3-inch rccj\Tood staves used is too slow to materially affect the potential. In subsequent tables only the data for wine siphoned out of the center of the vat are given. The degree of aeration the Rine received in handling, rathor than its age or type, affected the oxidation-reduction potential. Typical dat'a are shown in Table 11 in which the Eh of sevcral wines before and after the aeration is given. These wines were aerated by pouring into large beakers and stirring and bubbling air t'hrough them for minutes. The fib the aerated wines was dctermined immediately aftcr aeration. In some wines there is little or no increase in Eh under such trcatmerit, and in others a large increase, The Eh of the 1939 sherry that Of the 1938 port practically not at aplr increased very and of the other ports markedly. I n general the lower thc initial redox potential the greater is its increase on aeration.
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
March 1949
TABLE IV.
OX~BATION-REDUCTION POTENTIALS IN SHERRY AT REDWOOD VATS
VARIOUS STAGES IN 20,000-GALLON Condition Sherry material Before fortification - 1.8O Balling 13.1% alcdhol, 1% reduding sugar After aeration t o mix for gaging After addition of brandy and aeration, -4.5’ Balling, 20.5% alcohol 1940 sherry material 1 month after fortification , Pasteurized and clarified Clarified Pasteurized and clarified Pasteurized, clarified, and filtered 1940 Carignane sherry material heated 3 weeks
Vat
Mv.
Temp C.”
58 --122
24 24
3.85 3.85
188 124
24 24 24 24
3.88 3.85 4.00 4.00
312 230 290 301
25 25 25 25 25 25 25 25 25 25 25 25 25
3.97 3.88 3.98 4.00 4.00 3.89 3.88 3.83 3.83 3.83 3.73 3.78 3.90
281 301 256 231 346 236 346 349 324 311 336 316 276
25
3.90
300
25 25 25
3.90 3.85 4.23
294 291 322
++35 220
25 25 23
3.87 3.89 3.92
233 281 466
85 +300 +45 45 $7
24 24 25 25 25
3.83 3.87 3.82 4.00 4.09
331 546 291 201 253
Eobavd.,
1 2
+-6616 ++4455
1 2 1 2 19 21 24 27 44 30 14a 3 4 5 12 68 7
+35 55 10 - 15
++
+-10010 + 100 ++78 103 +65 +4-70 90 +30 +54 +1 4485 +78
1939 Mission sherry material heated 2 months and 3 weeks 1939 Tokay sherry material heated 9 2 months and 3 weeks 1939 Carignane sherry material 10 heated 2 months And 3 weeks 11 1939 Mission sherry material 18 cooked and filtered 69 1939 sweel port heated 2 months 1939 sherry finished 222 1939 dry sherry finished 279 4938 sherry 221 Finished 214 Being cooled. 22 I937 sherry finished 1935 sherry finished 35 b 1934 sherry 39 b
- 13
+ -
pH
Eh, Mv.
TABLE VI. Wine Angelica Port
Drysherry Tokay Muscat
Container 52,000-gallon vat 50-gallon barrel 60-gallon barrel Bottle
Condition Last refilled 2 weeks prior Being pumped into barrel I n siphon barrel Freshly filled
Wine Angelica Port Sherry Sherry, dry Tokay
C. 24
pH 3 89
Eh, Mv. 446
$270
25
3 89
516
+165 +150
25 25
3 89 3 89
411 396
Eobsvd.,
Mv. +ZOO
O
At the time this survey was made the fermentation season was almost over, but some free run Tokay must was being fermented. A series of six vats representing various stages of fermentation was selected, and the Eh observed for these is given in Table 111. As is well known, the Eh of the unfermented must, even after sulfiting, is high, and it drops during fermentation from over 400 mv. to about 0 or slightly below. The oxidation-reduction potential of the fermenting wine was a t its lowest during the stage of most rapid fermentation-i.e., when the sugar content has dropped to about half its original value. The particular low level reached is :determined by the composition of the must, condition of fermentation, and characteristics of the yeast used (IS). Following this initial decrease the potential begins to rise, the rate and extent of rise being determined by the degree of aeration and the poising capacity of the wine. I n the production of California sherry, the sherry stock is fortified with brandy, clarified, filtered, and aged for some time before heating (11, 13). At the Bear Crcek Winery, sherry was prepared from clear sherry material, preferably aged for about one year, by heating with steam coils in 10,000-gallon redwood vats. The rate of heating was so adjusted that it takes about 2 weeks for the wine to come t o 130’ F., and this temperature is ’ then maintained for 2 t o 3 months, depending on the wine-the wine of higher sugar content usually requiring a shorter heating period. The oxidation-reduction potentials observed at various stages of sherry production and aging are shown in Table IV. ‘The oxidation-reduction potential of the freshly fermented wine
Vintage 1935 1936 1937 1934 1935 1936 1937 1934 1935 1936 1937 1935 1936 1937 1935 1936 1937 1935 1937
TABLE VII.
a
POTEYTIALS IN 1939 TOKAY TABLE V. OXIDATION-REDUCTION SHERRY DURING BOTTLING
OXIDATION-REDUCTION POTENTIALS I N
OLD W I N E S
STOREDIN OAK PUNCHEONS AND OVALS FOR FIVE MONTHS
Sherry
Shermat. 30 immediately after filtration. b 32,000 gallon vats.
589
Container Oval Puncheon Puncheon Puncheon Puncheon Puncheon Puncheon Oval Puncheon Puncheon Puncheon Oval Puncheon Puncheon Oval Oval Puncheon Oval Oval
Capacity 180 110 110 140 140 110 110 180 132 132 132 180 132 132 180 110 180 180
Eobnvd., MV.
Temp., C.
PH
Eh M;.
25 26 26 26 26 26 26 26 26 26 26 26 26 26
3.65 4.00 3.90 3.95 3.80 3.85 3.80 4.05 3.83 3.97 3.76 3.80 3.97 3.83
404 365 370 395 380 375 405 350 315 325 398 406 360 400
26 26 26 26 25
3.80 3.93 3.83 3.72 3.72
330 257 365 355 378
158 120 125 150 135 130 160 105 70 +80 +153 160 115 +155 85
$io” 110 133
OXIDATIOS-REDUCTION POTENTIALS IN BOTTLED DLSSERT WINESAT LODI Vintage 1937 1934 1936 1937 1935 1936 1937 1935 1936 1937 1935 1936 1937
Eobavd.,
Mv.
Temp.,
c.
++ 145 140 +176 + 170 +215 + 155 +253 185 + 176 +zoo
P 1-I 3.70 3.70 3.61 3.60 3.56 3.77 3.56 3.53 3.78 3.62 3.53 3.68 3.70
27 27 27 26 27 26 26 27 26 26 26 26 26
160 137 155
Eh
M vl 4-392 387 422 416 462 40 1 43 1 500 422 446 406 383 40 1
TABLE VIII. OXIDATIOK-REDUCTION POTENTIALS IN MISCELLANEOUS DESSERT WIXES Vintage Condition 1940 2 weeks after fortification Whiteport 1940 3 weeks after fortification Port 1940 1 month after fortification Port 1940 3 weeks after fortification Port 1940 1 month after fortification Muscat 1936 8 months after transfer Port 1940 6 weeks after fortification Port 1940 1 month after fortification Port 1940 2 weeks after fortification Port 1936 8 months after transfer * White port 1940 2 weeks after clsrification Port 1940 2 weeks after fortification Port 1940 3 weeks after fortification Port 1940 1 week after fortifioation Wine Port
Eobsvd.,
Mv. -40
Temp.,
C.
Eh M;. 206
25
pH 4.054
3-20
25
3.93
266
-15
25
3.90
231
-40
25
3.97
106
-43
25
3.97
203
-13
25
4.12
233
-27
26
3.99
218
-70
25
4.01
146
-30
25
4.08
216
O
0
26
3.98
245
4-30
26
3.93
275
-50
26
3.98
195
-35
26
4.00
210
+l5
25
4.22
260
increases from about 100 to 200 to about 200 to 300 mv. during the aeration with compressed air used to mix it for gaging. After the addition of brandy and mixing, the potential is about 300 mv. This then remains a t about 300 mv. during aging, but may rise slightly, depending on the degree of aeration during clarification and filtration. During heating there is a decrease in the higher the sugar content, the greater is this decrease. Following this the Eo rises, particularly during the chilling operation, but then drops again. The final Eh depends on the period of storage following any treatment leading t o absorption of oxygen and is independent of age of the wine. The lowest potential, for example, wa9
INDUSTRIAL AND ENGINEERING CHEMISTRY
590
TABLE IX. OXIDATION-REDUCTION POTEXTIALS IN TABLE WINES Wine 15 Claret 23 Red 34 White 40 Claret 43 White 47 White 51 65 56 61 70 71 72 73
W-hite Rhite Red White Red Red Red White
\'intage Condit,ion 1940 1 month after fermentation 1940 3 weeks after fermentation 1940 Clarified right after fermentation 1940 1 month after fermentation 1940 Clarified right after fermentation 1940 Six weeks after fermentatation 1940 1 week after fermentation 1940 1 week after fermentation 1940 2 weeks after fermentation 1940 1 month after first racking 1936 2 manth after transfer 1934 2 month after transfer 1936 3 weeks after transfer 1939 1 year after transfer
Temp., a. C. pH 25 3.85 25 4.00 25 3.85
Eohrvd.,
Vat
Mv.
20,000
20,000 32,000
-100 -61
+35
Eh I
Mv. 146 185 281
-I-? 0
-42
25 25
3.80 3.85
4,700
-58
25
3.75
188
4,700 4,700 2,300 500 2,700 2,700 2,700 2,700
-13 -35 -91 -22 +48 -30 0 +Si
26
3.90 3.93 4 22 3 72 3.75 3 68 3 68 3.63
233 211 154 224 294 216 245 332
32,000 32,000
25
26 25 25 25 26 26
204 256
POTENTIALS IN RED TABLE WIXES TABLE X. OXIDATION-REDUCTION STORED IN OAKOVALS Wine Barbera
Burgundy Cabernet Gamag Carignane Grand Noir Petite Pinot Val de Pirio Zinfandel
Petite Sirah
Vintage 1934 1937 1937 1938 1938 1936 1936 1935 1937 1939 1938 1940 1938 1940 1940 1940 1940 1937 1939 1936 1936 1937 1937 1936 1935 1940 1940
Last Treatment Filtered 3/31/37 9/21/38 9/21/38 8/25/39 8/25/39 3/1/40 4/3/40 Clarified 5/8/40 2/28/40 10/14/40 9/11/39 10/7/40 4/3/40 10/10/40 Racked 11/21/40 10/22/40 10/14/40 4/2/40 10/ 18/40 4/9/38 4/19/38 8/13/40 9/21/38 1/18/38 3/8/39 9/22/40 10/10/40
Eobavd.,
317, +ljO
- 00 - 13 -50
Temp., O C. 19 16 16 16
- 14
15
15 16 15
-33 ..
- 13
+- 4710 +11 - 11: -18 -70 +72
- 65
+48 -48 +13 - 40 - 28 -7 -25 - 68
-GO
- 140 - 50
15 15 16 15 16 16 13 15 16 16 16 16 16
15
15 15
16 16
15
POTESTIALS I N TABLE X I . OXIDATION-REDUCTION WINESSTOREDIX OAKOVALS
Kine Sauvignon Vert Semillon
Green Hungarian White Pinot Riesling
Traminer
Vintage 1938 1940 1937 1938 1939 1940 1940 1940 1940 1936 1938 1935 1937 1937 1937 1936 1936 1938 1936 1937 1938 1936 1935 1938 1938 1938 1939 1936 1935 1936 1935 1938 1937 1940
Last Treatment 11/20/40 Racked 11/25/40 Filtered 7/25/39 Racked 6/5/40 9,9/40 10122 '40 11/20/40 Filtered
11/23/41 9/11/40 11/8/40 8/21/40 9/27/39 7/9/39 9/11/40
10/18/40 9111/40 Clarified 7/13/39 10/18/40 1/24/39 11/8/40 Racked 4/25/39 10/18/40 9/18/40 7/18/40 Clarified 1/21/39 1/26/39 1/24/39 8/30/40 10/18/40 1/9/40 Racked 11/26/40
fiobsvd.,
MV. +130 +40
f 5 - 10
- 50
- 14
C.
13
15 15 16 13
T 52
15 15
+
15 15 15
- 50 +27 T 32 - 30 98 +I1 +8 +lj
+33 ,45 1.69 +30 -I- 10 +65 - 42 +95 T 18 +95 +25 - 38 +22 33
15 15
15 1;
15 15 15 15 15 15 15 15 16 16 16 16 15
+
15
+25
15 16 16 15
+5
+io
- 15
+ 50
3.60
3.71 3.73 3.46 3.92 3.65 3.71 3.71 3.82 3.63 3.76 3.63 3.80 3.81
E6
hlv. 403 203 240 203 239 220 240 263 206 264 241 128 235 183 325 188 301 205 266 213 225
246 228 185 193 113 203
ltrHITE T.4BLE
Temp., e
pH 3.74 3.75 3.77 3.70 3.82 3.83 3.92 3.65 3.70 3.68 3,57 3.85 3.48
15 15
Eh,
pH 3.70 3.85 3.63 3.55
AIv. 383 293 298 243
4.03 3.95 3.68 3.78 3.72 3.63 3.73 3.54 3.54 3.60 3.84 3.63 1.62 3.31 3.60 3.31 3.31 3.58 3.48 3.46 3.24 3.37 3.87 3.78 3.52 3.58 3.50 3.55 3.53 3.82
203 239 305 203 280 285
223 351 264 261 268 286 298 322 283 263 318 212 348 271 348 278 215 275 286 258 278 323 238 303
Vol. 41, No. 3
observed in a vat of 1935 sherry. This drop in Eh following the recovery of thr \Tine after being subjectcd to oxygen absorption is well illustratd in Table V, showing the changes occurring in sherry during bottling. The redox potentials of dessert wines stored in oak for a period of five months after the last transfer or treatment are given in Table VI. The Eh obtained varied from 257 to 405 mv., the low& in a 1936 Tokay, and liighest in a 1937 port, but the value.3 observed could not be correlated either with previous treatment, age, or size of storage container. The E* of these wines, after drawing off int,o pint bottles and stored for a month, are shown in Table VII. I n general, the potential in bottled S than those in cask, owing to wines T ~ higher absorption of oxygen during transfer. The storage period was too short ,for the wines t o recover and t o reach the l o m r Eh values characterist,ic of bott,led wines. The oxidation-reduction potentials of niiscellaneous dessert wines are shown in Table VIII, and of the table wines in Table I S , when stored in vats of 20,000 gallons or over in size. These wines were lowx iii E A value than the others reported above, arid in new wines in general the Eh was loiver than in older wines. The red wines in general viere a t a 1071-er Eh value than the white. OXIDATION-REDUCTIOS POTESTIALS IN TABLE WINES AT INGLENOOK WINERY
This winery was selected as representittive of the smaller wineries in the cool north coast region of California where the better white wine grapes (largely Riesling) and red vine grapes are gronn. The fermentation a t the Inglenook Vineyard Company a t Rutherford is conducted in sniall redwood vats, care being taken to segregate the grapes as to vmi(ity, and the wines are allowed t o agc in 1000-gallon oak ovals and oak puncheons in cool cellars. The aging is not, rushed, and the \vines are racked and clarified with gelatin or isinglass as they finish. Measurements of the oxidationreduction potentials a t the center of the ovals were made during the period of November 23 to 27, 1940. The Eh of t,he red table n-ines as shown in Table X generally varied from 190 to 250 mv., although values as high as 403 and as low as 113 \?ere observed. The Eh of the xhite table wines in general were somewhat higher, 200 t o 300 mv. for the older u-ines. Wines shortly after fermentation are lower in Eh and rise in Eh value with racking, filtration, and transfer. Even old wines stored in mall containers tend t u become more reducing during storage. OXIDATION-REDUCTION POTENTIALS IN WINES AT IMT. TIVY WINERY
The Mt. Tivy Winery a t Reedley, located near t'he center of the San Joaquin valley, was selected a2 typical of thc 1argc.r 1vinc:ries producing wincs from grapes g r o w l with abundant heat. Thc data obtained there
INDUSTRIAL AND ENGINEERING CHEMISTRY
March 1949
591
during December 3 t o 7, 1940, are presented in part in Tables XI1 t o OF PORTWINE XVI. Since exposure to air was found to After Aeration, Mv. E ~ , Directly after, 1.5 hr. after 20 hr. after influence Eh, samples of port wine were Eobsvd., Temp., Vintage Mv. C. PH Mv. Eobsvd., E h ' Eobavd. Eh Eobvd. ah withdrawn from the center of large 147 395 358 110 143 391 117 1940 30 22 3 68 278 (l0,OOO- to 30,000-gallon) redwood vats, 428 483 180 235 503 255 308 60 22 3.78 118 1940 240 488 478 230 423 175 3.84 277 22 236 1939 29 their Eh measured, and then vigorously 200 448 493 245 493 245 408 22 3.69 135 383 398 aerated. The potential was then deter150 378 130 365 228 202 1939 117 160 22 3.89 393 368 145 120 105 353 258 22 3.75 105 1939 mined immediately after aeration, 1.5 135 383 413 165 433 185 4.00 377 lo 22 13 1940 129 14 1940 123 22 4 00 371 195 443 150 398 130 378 and 20 hours later. As shown in Table 125 373 318 70 328 80 238 4.08 -10 22 110 1936 155 403 XII, the Eh value increased from 100 t o 160 408 433 185 408 3.84 160 22 124 1939 393 328 146 80 353 105 241 22 4.14 -7 143 1940 200 mv. immediately after aeration, 100 348 308 60 308 60 237 3.71 -11 22 156 1939 except for those wines whose Eh was initially high. The lowest increase was 25 mv. for a 1939 port which had been POTENTIALS IN M U S C A T ~ L TABLE XIII. OXIDATION-REDUCTION chilled, acidified, and filtered into the storage vat about 2 WINES months prior to testing, and the highest increase was 195 mv. Eobsvd., Temp., Eh, Vintage & V. I c. BH Mv. for a 1940 port which had been pasteurized and clarified about 4.00 22 1940 4-6 one month prior to testing. -4bout 2 hours later the Eh value 3.98 22 1935 f20 3.89 22 108 in general remained essentially unaltered, the variations amount1935 3 . 9 8 22 24 1940 ing to about ~ 3 mv., 0 increasing in some and decreasing in 3.98 22 140 1937 22 3.98 28 1940 others. Even 20 hours later the wine had not recovered from its 3.98 22 15 1940 4.00 22 120 aeration, the new wines decreasing in Eh value and older wines 1939 3.99 22 137 1939 still increasing. 4.02 22 118 1937 3.96 22 148 1935 The Eh values of a number of muscatel wines in storage in 4.02 22 129 1935 3.45 23 113 large redwood vats, as shown in Table XIII, varied from 257 23 3.92 137 1940 to 396 mv., the new wines having a potential below 275 mv. and 3.94 23 - 28 1940 23 3.88 33 the older ones, with one exception, over 350 mv. Here again 4.04 23 158 1939 23 4 .OB 120 there was no correlation of E h with age of wine or even period of 1939 3.98 23 10 1940 quiescent storage. The Eh value of sherry material as shown in Table XIV in general decreased during cooking and then increased on storage. TABLEXIV. OXIDATION-REDUCTION POTENTIALS I N SHERRY The En of the table wines stored in large redwood vats were AND SHERRY MATERIAL much higher here than those observed in Napa Valley, varying Vin- Eobsvd., Temp., 6h, from 292 to 420 mv. as shown in Table XV. Wine tage Mv. C. p H Mv. Finished 1937 55 22 3.96 303 The Eh value of a representative sample of 1940 white port which had been decolorized with activated carbon, clarified with 22 3.82 438 190 1936 3.72 368 22 120 1939 bentonite, filtered, and chilled, was 393 mv. a t 23" C. and pH 3.74 393 22 145 1938 3.82 298 22 50 3.93. That of a 1940 white port stock, after mixing with carbon, Sherry mate- 1940 22 3.74 178 - 70 1940 rial was 373 mv. under the same conditions. 3.93 317 (Into sherry house on) 24 1939 Partially 4- 70 11/29/40 cooked The potentials observed in several bottled wines are shown in 9/16/40 3 . 8 8 277 24 1940 sherry +30 Sjii)So 24 3.92 261 1940 Table XVI. I t is interesting that the angelica and white port +I3 10/23/40 24 3.95 273 1940 +25 samples which had been bottled for two years were relatively 10/28/40 24 3 . 8 3 281 1940 f33 reducing in comparison with freshly bottled wines. TABLEXII.
EFFECTOF AERATION OXIDATION-REDUCTION POTENTIALS
POTENTIAL IN TABLE WINE TABLE XV. OXIDATION-REDUCTION STOCKS
SUMMARY AND CONCLUSIONS
The oxidation-reduction potentials of over 250 lots of California wine prepared from grapes grown in three viticultural regions 373 20 Dry were observed under a variety of conditions. They were meas358 20 108 Sauterne 373 20 123 Dry muscat ured a t various stages of fermentation, clarification, and stabili356 20 106 H. sauterne zation during storage in containers varying from small oak pun333 20 83 Sauterne 348 20 98 Dry muscat cheons, oak ovals, and small redwood vats to 50,000-gallon redwood 420 3.75 20 170 Tokay 352 3.94 20 102 vats. No correlation was found between the age of the finished 340 3.25 20 90 Sauterne wine and its oxidation-reduction potential, so that the latter 371 3 . 2 5 20 121 Claret 292 3.59 20 42 Dry muscat could not be used as a criterion of age. The treatment previous 3.28 360 20 110 Claret to measurement, particularly if it led to absorption of oxygen, had a greater effect than age. During production of wine, the oxidation-reduction potential drops during fermentation t o a low level TABWXVI. OXIDATION-REDUCTION P O ~ N T I AINLBOTTLED S characteristic of the yeast and method of fermentation, then WINES rises during transfer, racking, filtration or clarification, and then VinEobavd., Temp., Eh , Wine tage Time in Bottle Mv. pH pH Mv. falls again. Wine, whether stored in large or small containers or Angelicaa 1937 Two years -20 20 4.21 230 bottles, tends to become more reducing in oxidation-reduction Angelica . . 11 year 3 months 46 21 4.08 256 Muscatel year 3 months 4-10 21 4 12 260 potential. The potential of table wines, particularly red wines, Port 1935 30 days +157 21 3 98 407 is generally lower than that of dessert wines. White portQ 1935 Two years f17 21 3.88 267 Sherry 1935 30 days 4-207 21 3.81 457 The oxidation-reduction potential changes during the production of California sherry indicate that the oxidation-reduction a Exposed to sunlight for 6 months prior t o observation. potential rises during fortification, falls somewhat during aging Wine
Vin-
tage 1940 1940 1940 1939 1940 1940 1940 1940 1940 1940 1939 1940
Eobsvd.,
Mv. 123
Temp.,
=
c.
PH 3.68 3.52 3.68 3.30 3.60 3.60
Eh,
Mv.
592
INDUSTRIAL AND ENGINEERING CHEMISTRY
of the unheated sherry material, and falls further during the heating process. The drop in oxidation-reduction potential during heating in general is greatest with sherries of the higher sugar - content. On aeration the potential rises immediately and then generally falls, the fall being greater with new wines than with old wines. ACKNOW LEDGMEKT
The data reported here was obtained with the assistance of Ray Dunn, who at the time was working on Works Progress Administration Project KO.5456, under which this investigation a a s carried out. The coopelation of the managements and chemists at the several California wineries v, here measurements were made is gratefully acknowledged. The writer particularly acknowledges the assistance rendered by hl. W. Turbovsky of the Bear Creek Rincry a t Lodi, John Daniels of the Inglenook Wineiy at St. Helena, and Tom Scott of the Mt. Tivy Finery a t Fresno, California. LITERATURE CITED
Amerine, M. A., and Joslyn, M. A., Calif. Agr. Erpt. Sta. (Berkeley), Bull. 639, 1-143 (1940). (2) Clerck, J., de, Wochschr. Brau., 51, 196-200, 204-7, 378-81 (1934) ; Bull. assoc. Btud. &cole sup&. brasserie unit. Lowain,
34, 55-87 (1934); 35, 23-30 (1933); J . 407-19 (1934).
Vol. 41, No. 3 Inst. Brewing, 40,
Garino-Canina, H., Ann. chim. applicata, 25, 209-17 (1935). Gat&, L., and Genevois, L., Bull. sac. chinz. France, 8, 485--7
(3) (4)
(19411.
( 5 ) Geloso, J., Ann. brass. dist., 29, 177-81, 193-97, 257-63, 273-9 (1931); Chimie R: industrie, 27, 430-1 (1931). (6) Greenbank, G. R., J . Dairu Sci., 23,725-44 (1940). (7) Hartong, B. D., Wochschr. Brau.. 51, 409-11 (1934). (8) Hewitt, L. F., “Oxidation-Reduction Potentials in Bacteriology (9)
and Biochemistry,” 4 t h ed.. London County Council, 1936. Hochwait, C. A., Thomas, C. A., and Dybdal, S . C., IND. E m .
(10) (11) (12)
Joslyn, M ..4., Fruit Products J . , 20,277433, 288,294 (1 941). Joslyn, M.A., IKD. ENG.Cmm., 30, 568-77 (1938). Joslyn, M.A., and Amerine, 35. A., Calif. Agr. Ezpt. 6ta. (Berke-
(13)
Joslyn, M. A., and Dunn, I?., J . Am. Chem. Soc., 60,
CHEM.,27, 1404-7 (1935).
ley), Bull. 651, 1-186 (1941). 1137-41
(1938).
Krasinskii. N. P.? and Pryakhina, E. A . , Vinodelie i T’inogradarstro S.S.S.R., 6, NO.2, 7-11 (1946). (15) Laufer, S., Am. Brewer, 69, KO.1, 15-22, 24-5 (1936). (16) Mendlik, F., Wockschr.Brau., 51, 305-7 (1934). (17) RibOreau-Gayon, J., “Contribution B 1’Btude des oxydations e t rQductionsdans les vins,” 2nd ed., Bordeaux, Dolmas, 1933. (1s) Siebel, F. F., Jr., and Ringruen, l3~, IND. ENG.CHEM.,27, 1042(14)
5 (1935).
(1)
RECEIVEDSeptember 26, 1947. Presented before the Division of .4gricultural and Food Chemistry at t h e 1 1 2 t h Meeting of the AXERICANC n s ~ r r C A L SOCIETY, Xew York, N.Y.
0
ariations R . A. CRAWFORD B . F. Goodrich Company, Akron, Ohio
G. J.TIGER G o z e r n m e n t Laboratories, The L’nicersity of Akron, Akron, Ohio
! Icompounding
study was made in an attempt to prepare a stock having the excellent processing properties of divinylbenzene cross-linked polymer (GR-S-60) and the stress-strain properties of standard GR-S. Investigation of Banbury mixing of stocks containing GR-S-60 and blends of GR-S-60 and GR-S indicated that mastication a t high dump temperatures (in the vicinity of 380” F.) would seriously degrade both the processing and stress-strain properties of these compounds. Banbury treatment of GR-S a t 380’ F. for 5 minutes in the presence of 0.5 part of sulfur, 1.5 parts of 2-mercaptobenzothiazole, and 50 parts of carbon black, prior t o mixing with other materials, gave an easy-processing stock that was superior to Banbury-mixed GR-S-60 in both processing and stress-strain properties, as judged bq laboratory methods, including the Garvey die extrusion test. In addition, the processing properties of this compound closely approached, and the stress-strain properties excelled, those of GR-S-60 that had been mixed on a mill a t lower processing temperatures. With other combinations of cross-linking agents, the best results were obtained from 5-minute mixing a t 380” F. with Amberol ST-137; Butyl Eight, sulfur, and Captax; Durez resin 12687 and Captax; Telloy or Vandex, zinc oxide, and sulfur; ethyl Tuads; thio-p-naphthol and sulfur; or Polyac. Applied on a commercial scale, this
treatment would involve little, if any, additional processing in the preparation of tread stocks, and no new compounding materials would be required. The ktock would be completely compounded and prepared for the extruders in a single Banbury cycle.
URIKG 1946 a considerable amount of work was done in attempting to improve the processihility of GR-S. b ~ n o n g the variations tried were the blending of high-gel high-&looneyviscosity polymers with polymers of very low Mooney viscosity, the preparation of high-gel polymers by the intioduction (if divinylbenzene into the polymerization charge, the production of high-gel polymers by means of normal and tertiaiy mercaptan modification and additional butadiene in high conversion polymers, and finally the changes in compounding and processing reported here. GR-S cross-linked by means of 0.5 part of divinylbenzene per 100 parts of monomer xvas produced as X-285 of the Office of Rubber Reserve series, and was later designated GR-S-60. Previous work on similar polymer (80% gel content and 55-60 Mooney viscosity), alone or blended with regular G R S in amounts up to about 75Yc,showed this type of polymer to exhibit less shrinkage and superior extrusion, surface appearance, and general processibility in calendered, extruded, and molded stocks Blending of the CR-S-60 with GR-8 was expected to produce LL
