NOVEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
Acknowledgment The authors thank the Roma Wine Company of Lodi for supplying the wine used in these tests and the Frigidaire Corporation for lending an ice cabinet.
Literature Cited (1) Assoc. Official Agr. Chem., Methods of Analyses. (2) Joslyn, M. A , and Marsh, G L., IXD ENG.CHEM.,27,33-5 (1938).
S
I S C E some low-alcohol wines are subject to spoilage by yeast and bacteria, it is important that a method of preserving the product be used. I n the past, wine has been pasteurized or a chemical preservative such as sulfur dioxide has been added, and in the last few years filtration has been used to some extent. The use of any chemical preservative is undesirable when other effective methods are available. Pasteurization usually has some deleterious effect upon wine, particularly if the temperature is high and the time is prolonged. Although little information is available as to the time and temperature required to pasteurize wines, the early work in France (4, 5 ) , particularly by Pasteur, and the work of Bioletti (1) and Cruess (f?) with California wines have indicated that lower temperatures or shorter .times than those in use might be entirely practical. This is particularly true of the wines of the eastern states which are more acid than those of other parts of the United States. The purpose of this work has been to determine the temperatures and time necessary to kill the microorganisms of low-alcohol wines of Kew York State.
1. Dry Wines' I n order to obtain an idea of the temperature necessary to paqteurize the wines of low alcohol content, several preliminary teqts were made: The methods were similar to those used in studying t'he pasteurization of grape juice (6). For this purpose, a pasteurizer consisting of a copper kettle, LO inches in diameter and 10 inches in height, was used. Bottles of approximately 1 quart and 1 pint capacity nwe filled with a sauterne wine No. 1 (Table I) furnished by one of the wineries. Two bottles of wine were pasteurized in each test; one bottle was used to obtain a record of the temperature and the other for sampling for plate counts. The temperatures were obtained from a standardized mercury thermometer placed xith the bulb at the center and near the bottom of the bottles, Samples of 1-cc. quantities of wine m-ere plated at short time intervals using a yeast extract-glucose-agar medium and incubating 4 days at 32" C. (89.6' F.). In the first two tests the water was heated to 140" to 142" F. and the wine was filled into the bottles at 100" F. In the third and fourth tests the bath was operated at 125" F. and the bottle: were filled at '78" F. In the last tests pasteurization was at 122 F., and filling at 43" F. The pasteurization was continued for 20 minutes after the temperature in the bottle was within 3: F. of the desired pasteurizing temperature. The results (Table I) show that the organisms in this wine were killed a t a relatively low temperature, since no organisms survived in the various tests after temperatures of 112.5", 128", 119", 112", 116", and 114" F. I n view of the fact that the various samplings were taken a t different time intervals, that each presented a relatively large increase in temperature, and that the wine represented but one sample of one type, too much significance could not be attached to the results. They merely indicated that pasteurizing temperatures considerably lower than those used in the industry might be practical. 1
Under the direction of Carl S Pederson.
1257
(3) Richert, P. H., J. Am. Chem. SOC.,52, 2241-4 (1930) (4) Seidell, Stherton, "Solubility of Inorganic and Organic Compounds," p. 564, New York, D. Van Nostrand Co., 1919. (5) Weimam, P. P. von, Chem. Rev., 2, 217-42 (1925); Gortner, R. A., "Outlines of Biochemistry," pp. 13-17, 1929. (6) TViley, H. W., U. S. Dept. Agr.. Bur. Chem. Bull. 72, 1-24 (1903). RECEIVED August 29, 1935.
Pasteurization of New York State Wines Experiments reported here show that Eew York State dry and sweet wines of low alcohol content can be effectively stabilized by pasteurizing at 130' F. for 20 minutes, and that this pasteurization can be carried out, under controlled conditions, in bulk, in closed bottles, or in open bottles. The microorganisms which occasionally survive the pasteurization at this temperature are not of the spoilage type and apparently have but little significance.
CARL S. PEDERSON New York State Agricultural Experiment Station, Geneva, N. Y. HARRY E. GORESLINE
AND
E. A. BE-kVENS
Bureau of Chemistry and Soils, U. S. Department of Agriculture, Washington, D. C.
Effect of Temperature and Time I n order to study more carefully the temperature and time necessary for pasteurization of commercial wines, various types of dry wines of low alcohol content were obtained from the wineries. I n order that comparatively large numbers of organisms would be present, these wines m-ere all obtained from the casks after complete fermentation had tJaken place, but beforesthey had been filtered. Naturally they were somewhat cloudy, and precipitates formed in the bottles
1258
IKDUSTRIAL AKD EKGIKEERIKG CHEMISTRY
J-OL. 27,
so. 11
oculated into tubes of broth in duplicate; I-cc. 4amples were used in each tube. The other bottles were removed, labeled, and incubated at 25" C. (77" F.) for 2 weeks and then held at room temperature for about 2 months. These bottles were then examined for signs of spoilage, and 1-cc. samples in duplicate were plated. The plates were counted and the colonie- as well as the broth in tubea showing growth were 5tudied. This was done to determine whether or not the more re-istant organisms were typical of the wine and if they ~i-ouldgroiv in wine.
Pasteurization of Sauternes Three wines of the aauterne type (Table 11) were -tudied. sauterne S o . 2 contained 10.96 per cent alcoliol and 0.799 per cent acid as tartaric. Two pasteurization runs were made, one a t 119" and the other a t 132" F. (Table 111). Killing of organismb began somewhat above 100" F. but, in the 119" run, yeast colonies were obtained on material plated FIGURE 1. TEMPERATURE DIFFERENCES DURING THE PASTEUAI- a t the end of 31 minutes, when a temperature of 119" had been ZATION OF SAUTERNE WISE No. 2 AT 119O F. obtained. The majority of organisms were killed long before the 20-minute holding period began, but apparently a after pasteurization, particularly in the claret and Burfew resiatant individuals were present. However, no viable gundy. organisms were obtained from the ten bottles which had been heated for 43 minutes. I n pasteurizing a t 132" F., t'he All wines were bottled cold in green glass bottles of approximately 400-gram weight with a capacity of approximately 375 last yeast n-as obtained a t the end of 13.25 minutes wlieii a cc. Twenty-two bottles were used for each test; two were teniperature of only 123" F. had been attained. Initial killclosed and incubated for controls, ten mere used for temperature ing again started slightly above 100" F. .i spore-forniing measurements, nine for incubation after pasteurization, and one rod was found on t'he plate at the end of 30 minute?, hiit it for bacteriological plate counts. The bottles used for temperature measurements were corked with wine corks slit so that had little significance since spore-forming bacteria ordinarily thermocouples could be inserted into the bottles. In closing. do not grow in wine. some of the measuring junctions were forced towards the side so ;1study of temperature records (Figures 1 and 2) shun- a that they were in a different location in each bottle. These locauniform rise but quit'e a difference between records from \mitions were noted in each run so that a more accurate record of heat transmission might be obtained. The bottles in the next, 011s bott'les. The four thermocouples placed in the bath group were closed with wine corks, and the last bottle was plugged showed a uniform temperature throughout the bath. The with sterile cotton. most rapid attainment of the bath temperature was recorded Pasteurization was carried out in a copper water bat,h, 18 inches in the top of the upright bottles and the lewt rapid near the deep, 16 inches \vide, and 32 inches long, equipped with a removable rack capable of holding thirty-three bottles lying in a horibott,om of the same bottle (Figures 1 and 2). -111 other therzontal position. The water was heated by a common threemocouple. showed t'emperatures between t'hese two extremes, burner gas plate. This apparatus is illustrated and described by the differences being more or less dependent upon the location Walsh ( 7 ) . An ordinary Cenco turbine stirrer was placed in one of the t,herniocouple in reference to the center and side of the corner of the pasteurizer in order to circulate the water. The bottles of wine were placed in the rack on their sides with bottles. These results are in agreement wit11 results of Ford six bottles in a tier except for two bottles standing upright in and Osborne ( 3 ) who studied the rate of heat tranwiission in the middle of the rack resting on the middle tier; the bottles cider in bottles. with thermocouples were alternated with the others. Of the Since saniples for plating mere in all cases taken froiii the two upright bottles, one was used to obtain saniples for plate counts and the other for obtaining temperature records by means bottom of the sampling bottle, the curve representing the of two thermocouples; the measuring junction of one was near temperature a t t,he bottom of the upright hottle next to this the top and that of t,he other was near the bottom. Bottles bottle was used to estimate the temperature> recorded in filled with water were placed in all vacant spaces in the rack. Table 111. Likewise, throughout t'he tables to be preqented, The rack containing the bottles was placed in the 47" F. room until ready for pasteurization, thus giving a uniform teniperature in all experiments. The water in the pasteurizer was brought t o such a temperature that, when the rack of bottles was placed in it, the temperature of pasteurization was obtained without the adjustment of burners. Ordinarily the original bath temperature required vias about 8" F. higher than this pasteurizing temperature. Immediately before placing the rack in the pasteurizer, the thermocouples were connected through a sixteen-point rotary switch to an electropotentiometric thermometer eo that temperature readings could be made in all the bottles. -4sample was removed for a plate count at this time, and temperatures in the bottles were recorded. The rack was then placed in the bath for pasteurizing, and temperatures were recorded at all junctions about every 3 minutes. Time was recorded from R stop watch, and samples were withdrawn for plate counts at 1- or 2-minute intervals. Pasteurization was continued for 20 minutes after an average temperature at the various measuring junctions was within 2" to 3" F. of the desired pasteurization temperature. One-cc. samples of wine were plated immediately, using a yeast extract-glucose-peptone-agar medium. Plates were incubated I I a t 32' C. (89.6' F.) for 4 days. After the desired pasteurizing temperature was attained, one-cc. samples were also inoculated 24 ,?b 32 36 40 44 48 into tubes of sterile broth in duplicate. At the end of the pasTIME IN MINVTES teurization time the bath was cooled as rapidly as .possible with running tap water. After cooling, the contents of the bottles FIGURE 2. TEMPERATURE DIFFERENCES DPRIKG THE PAScontaining the thermocouples were plated in duplicate and inTEURIZATIOS OF SAUTERNE M'INE K O . 2 AT 132" F.
OVE $1BE R , 19.3j
-7 -
Time .ec 0 3.40 6:15 10.40 15:lO 19:36 22:40 24:40
JItr7.:
27:15 h
INDUSTHIkL A4ND ENGISEERIUG CHE3IISTRI TABLEI. PL.ATECOUSTSIS PASTEURIZATIOS OF S-AIUTERSE WINE No. 1
-
-
Pasteurization a t 142' F. Quart ---Pint Plate Plate Count count Temp per cc. Time Temp.= per cc. = F', 89 5 10; 112 5 119 5 1'5 3 181 9 154 6 I36 4 1.38 3 6,
. l I i i ~ . sec.
560 280 11
0 0
0
0 0
9,
1259
0 3.10 6:45 11:10 15:35 70:2j 34:15 26:4d
3o:oo h
F. 100 112 5 121 128 134 3 138 138 6 134
Plate count Time Temp "per r r . J f i j t , : sec.
960 860 6
14;
1
0 0 0 0
P
0 2305 3:45 7:47 11:35 l5:25 l7:25 '0:50 25::35 i
P. 78 89 95 104 112 118 114 124 124
,.
---
a t 125' -F. Pint---
---Pasteurization ------Quart--
il
Time
M i i ~ . sec. :
900 880
144 0 0 1
0 0
!
Plate D u nt Temp.a per cii.
0
2:30 4:oo 8:OO 11'45
l,5:40 li:-10 ?1:00 X F O
47 1.5 1-11' 7 0 10:10 142 0 4O:iO 145 0 3T 00 a Estimated from temperature-time curve. b Samples plated at regular intervals during these periods all showed n o colonie-.
O
100 5 112 118 5 123 12 5 .i 1 5 3 125 .i 12;
;i
Pasteurization a t 122' F.Quart Pin---Plate Plate count count Time Temp." per c c . Time Temp." per c c .
.Ucn.: se-.
F.
78 95
--~__--- ---
0 0
0 0
? (i
6
-'3 .,.I
-1;
lI~n.:sec.
-18 73 85
450 440 440
02 98 10; 111
RR_O
b0
118
1
4
11:30 16 18
F.
O
0
700 600 -150
121'
!
1;.
0
0 3:4: 6:40 8:40 11 : 2 0
15:m
17 21 '4
'
F.
4' x 79 !I 2 'I8 104 ill I14
117 1 lh9
36:;O
I?:?
600 550 480 280 4 :3 1 1 0
2
0"
the siniilai curve obtained film temperature; iecorded in the particular expermient was u-ed to obtain the eqtiniated temperature-. Theye curves are not presented since they are practically a repetition of those given. Katurally. the >tirriiig incidental to taking +ample- would cause a more rapid heat
per cent alcohol :ind 0.646 per cent acid was pasteurized a t 121" and 130" F. Three sampling bottles were used at 130" and two at 121" E'. Bottle A (Table IV) contained the wine done and was representative of the wine in all of the bottles; B contained the wine with 25 p. p. m. sulfur dioxide; and bottle C, used only a t 130" F., contained 50 p. p. m. sulfur dioxide. During pasteurization, plate counts were obtained from samples of bottles of wine containing the sulfur dioxide as T ~ R L11. E CHEMICAL AXALYSIS OF PASTEURIZED WIXES well as the normal product. I n pasteurization a t 121O F. no Acidity as -Alcohol-Wine Xumher Tartaric B y volume B y xeiglit organisms were obtained after 108" had been attained. In Per cent Per cent Per c e n t the sample that contained 25 p. p. m . of sulfur dioxide, orSauterne 2 0.799 10.96 8.77 Sauterne 4 0.646 13.36 10.70 ganisms were killed at still lower temperatures. On the Claret 1 0.714 14.16 11.33 other hand, a t 130' F. a yeast \vas obtained on the plate a t Burgundy 2 0.885 11.28 9.02 34 minutes, 9 minutes before the end of the holding period. TABLE111. PLATECOUKTSOBTAIXEDIS P.~STE:URIZING SeT-eral bacterial colonies had developed on platings pre1-iously,but after the large majority of organisms were killed. SAUTERNE W I N E N O . 2 Othemise, all organisms in the normal wine had been killed Pasteurization a t 1 1 9 O F,-Pasteurization a t 132' F.-Plate count Plate count when a temperature of 109" F. had been abtained, and in Time Temp.* per cc. Time Temp." per cc those bottles containing 25 and 50 p. p. m . of sulfur dioxide Min, F. Min.: sec ' F. when 105" had been attained. It is difficult to decide how 6500 50 0 52 5900 much significance to attach to most of these more resistant 1 56 -59I 0 5500 3:15 80 organisms since usually they will not grow in the wine and i t 85 5000 5:15 96 90 io00 8:15 102 is not certain that they might not be chance contaminations. 94 8000 i:17 1Oi Similar conditions have been found in the study on the pas9 98 3800 8:15 111 1800 10 101 5700 9:15 115 1000 teurization of grape juice (6) in that occasional organisms, 11 104 2000 10:15 117 240 present in the juice and sometimes surviving the majority of 13 108 930 11:15 190 94 14 109.5 950 c 12315 121 5 40 niicroijrganisms, would not grow in the juice. 15 110 5 630 13:15 123 1 16 111 5 In both of the sauternes no organisms were found in the ,330' 14:15b 124 0 17 112 5 370C 15:15 125.5 0 fully pasteurized samples plated a t the end of the run; but 18 113 280 16:15 126 0 19 114 104 c 18:15 128 0 after incubating bott'les of wine for 2 months, 1200 organisms 20 116 Si 20:15 129 0 21 115.3 -14 22:15 per cc. were obbained from one of the bottles of sauterne No. 2 130 0 22 24 116 24:15 130.5 and from 1 to 17 organisms per cc. in five of the bottles of 13 ~. 23 b 116.5 26:15 131
--
7-
. 1
(.
3
C
5
26 27 29 31 33
35 37
117 i 118 118 i 11!2 114
114 119 11')
rj 7
4
38:16 30:15 32:l.s 34.15
131. ,5
131.5 I32 13'
0
1
4 119 5 4:1 119 0 a Recorded near die bottoin of t h e upright bott!e, b Beginning of 20-minute holding period. e .-it least one of tubed samples lermented, other remained >rerile 39 41
tranwiis-ion; therefore in the tables, teiiiperatures recorded may actually be slightly low during the period of rapidly increasing temperature. A third sample of sauterne wine (Xo. 3) containing 12.98 per cent alcohol and 0.691 per cent acid was pasteurized a t 120" F. Enough sulfur dioxide was present so that organisms apparently had been killed, since no colonies appeared on the plates. This sample was discarded. A fourth sample of sauterne wine (No. 4) containing 13.30
551 0
FIGURE 3.
5
IO
I
I5
I
20
25
1
30
TIME IN MINUTES
1___1_Li 35
40
45
50
TIME-TEMPERATURE CURVES OBTAINED I N THE PASTEGRIZlTION OF A PORT TYPE OF W I N E AT 130' F. FOR 20 MINUTES
INDUSTRIAL AND ENGINEERING CHEMISTRY
1260
TABLEIV. PLATECOUNTSOBTAIXEDIN PASTEURIZING SAUTERNE WISE No. 4 at 121' F.--Plate count per cc. A B 24 31 25 26 21 18 28 8 16 10 4 8 2 8 6 0 1 0
-Pasteurization Time
Min.
F. 53 68 82 92 96 100 103 106 10s
10 11 b
b
'b8'
b
0
l1Z 121.5
38
b
0
b
b
0
0
--Pasteurization a t 130' F.-Time Temp.Q Plate count per cc. Min. O F. A B C 50 14 13 18 57 19 11 20 65 21 19 24 25 7 76 11 12 83 15 9 90 2 19 13 95 4 8 13 101 10 5 2 105 6 0 0 9 109 0 0 0 10 112 0 0 0 11 114 0 0 0 12 116 0 13 118 0 14 119 1
;
b
Recorded near the bottom of the upright bottle. b Samples plated a t intervals during these periods showed no colonies. 6 Beginning of 20-minute holding period. a
123.5
22 23 24 25
126 126.5 127 127
v.
b
Time
Min. 0
3 5 7 10 11 12 13 14 15 16 17 -.
Temp.5 F. 66 87 96 102 109 111 112 113 114 115 116 117 117 118
at 120' F.Plate count per cc.
9 C 8 C O C
2 1 0
o
120 0 0 23 120 2 24 120 1 26 120 1 28 120 30 120 2 32 120 2c 0 34 120 0 36 120 2 38 120 40 120 2 Recorded near the bottom of the upright bottle. b Start of 20-minute holding period. 6 At least one of sample tubes fermented. (1
PASTEURIZING CLSRET
--Pasteurization Time
Min. 17,900 8,500 4,800 19 39 5 22
0
130
IN
0
1 3 5
7
8 9 10 11 12 13 14 15 16 19 20 21 22 23 b 24 25 27 29 31 33 35 37 39 41 43
preheating period. Yeasts were entirely killed off a t the end of 17 minutes a t 117" F., and the organisms appearing after this time were cocci- and spore-forming bacteria. These organisms were isolated and reinoculated into wine, but in no case was growth obtained. A t 128" F. similar results were obtained in that the large majority of organisms were killed before a temperature of 100" F. was attained. Nevertheless, a few organisms persisted even after the temperature of 128" F. was attained. The surviving types mere again iqolated and inoculated into wine, but they failed to grow. Organisms were found in the fully pasteurized wine but no yeasts were obtained after 14 minutes or after a temperature of 117" F. was attained. All organisms surviving were bacteria. At the end of 2 months of incubation one yeast was obtained on plates from one bottle of claret pasteurized a t 120" F. but no organisms were obtained in any of the bottles pasteurized a t 130" F.
Pasteurization of Burgundy
12;
PLATE COLXTS OBTAINED WINE
-Pasteurization
1
b
43
TABLE
b
b
18
VOL. 27. NO. 11
Temp.a F. 57 61 74 88 98 102 106 109 111 113 115 117 119
124 124 125 125 126 126 126 126.5 127 127 127.5 128 128 12s 12s
at 128' F.Plate count per cc. 17,500 17,300 11,800 100 8 6 5 2 1
OC O C
2
0 2 OC
0 0 10 0 1
0 0 2 1C 2 0 0
sauterne No. 4 pasteurized a t 120", but from none of the bottles pasteurized a t 130" F. The controls naturally contained living organisms.
Pasteurization of Claret A claret wine of 14.16 per cent alcohol by volume and 0.714 per cent acid (Table 11)was pasteurized a t 120" and 130" F. The wine was very cloudy and heavily seeded with yeasts and bacteria. I n both runs considerable reduction in count had occurred before a temperature of 100" was attained in the bottom of the bottles (Table V). I n spite of this, a few organisms persisted even to the end of the pasteurizing period but no colonies were obtained on plates prepared from the ten bottles of wine containing the thermocouples. I n the 120" F. run the last tube of broth showing grox-th was the one inoculated with the wine 8 minutes before the end of the
TKO samples of Burgundy wine were studied, but the first contained sulfur dioxide and as a result no colonies appeared on plates and the sample was discarded. The second sample ( S o . 2) contained 11.28 per cent alcohol, 0.885 per cent acidity, and a large number of bacteria (apparently one of the acetic acid types). These produced such small colonies on plates that it was necessary to count them with the low power of the microscope. Their presence could be detected only by the fact that their growth on plates produced a haziness in the medium. Because of the nature of the growth of the bacteria, it was easy to make a separate count of the bacteria and yeasts. I n these runs the effect of sulfur dioxide upon the rate of killing was again tried. Three sampling bottles were used a t 131" and two a t 120" F. Bottle A (Table VI) contained the wine without additional sulfur dioxide; bottle B contained the mine with 25 p. p. m. of sulfur dioxide; and bottle C (used only a t 131" F.) contained wine with 50 p. p. m. of sulfur dioxide. All yeasts had been killed when a temperature of 114" F. in the 131" run, and of 116" in the 120" run had been attained. The bacteria persisted somewhat longer but were killed even before the start of the 20-minute holding period in the 120" run. The small quantity of sulfur dioxide, as in the case of sauterne wine, had a marked effect on the killing of the yeast as well as the bacteria. This is particularly marked in the pasteurization a t 131" F. in that organisms were not obtained in the wine with 50 p. p. m. sulfur dioxide after 6 minutes when a temperature of only 99" had been attained in the bottom of the upright bottles, while organisms were obtained on plates from the normal wine when 114" was attained. In spite of this apparently rapid killing of microorganisms a t 120" and 130" F., it is of interest that at the end of 2 months of incubation, six bottles pasteurized a t 120" F. contained from 1 to 18 living organisms per cc. The majority of those organisms were molds. Bottles pasteurized at 130" did not show mold.
Pasteurization of Abnormal Sauterne It has not been the purpose of this work to study the pasteurization of abnormal wines, but two tests were made on bottles of sauterne wine inoculated with a culture of a top yeast from a winery and with a so-called tourn& wine obtained froni a winery. In pasteurizing this material, no bacteria were obtained on plates even though a few could be found in the wine by microscopic examination. They were either killed off a t low temperatures or they were not in a living condition. The latter explanation seems more logical since they could not be cultured later. The top yeasts were
INDUSTRIAL AND ENGINEERING CHEMISTRY
NOVEMBER, 1935
1261
Results shown in Table T'III indicate that a rapid killing of organisms occurred before 121.3' F. was reached, or 7 minutes before the 20-minute hold--------Pasteurization a t 120' F,--Pasteurization a Plate t 131'count F.-ing period was started. After most of the organYeast count Bacterial count Time Temp.* per cc. per cc. Time Temp.a per cc. isms had been killed, occasional living cells mere .Win. ' F. A B 9 B .Win. 17. A B C found. Cultures from these organisms failed 0 49 560 340 6OOOd 6000d 0 53" 960 470 460 to grow when inoculated into sterile wine. Du2 57 560 560 6000d 6000d 1 62 820 800 880 plicat'e platings of the bottles fitted with t'hermo2 73 1100 720 620 4 67 740 840 60006 6000d 5 72 650 560 6000d 6OOOd 6000d 3 81 520 720 350 520 400 570 couples showed no living organisms after heating 6 79 780 560 6000d 4 888 7 84 720 430 6000d 6000d 5 94 660 310 125 for 39 minutes. 8 89 490 100 6000d 6OOOd 6 99 560 25 2 SHERRY.A sherry type of \Tine containing 9 93 560 6 6000d 6000d 7 104 630 1 0 10 97 480 1 6000d 6OOOd 8 108 190 0 0 4.43 per cent sugar and 13.68 per cent alcohol 11 100 77 0 6000d 6000d 9 111 5 0 0 12 103 54 0 6000d 3000d 10 114 1 0 0 was pasteurized a t 130" F. (54.4" C.). As shown 11 116 0 0 0 13 105 6000d 5OOd 20 0 in Table VI11 similar results were obtained with 12 11!2 0 30006 . . . . 14 107 4 0 62d 13 121 22 the exception that most of the organisms were 250d 15 109 1 0 16 110 1 1 IOOOd 37d 14 122 0 killed at lower t'emperatures-that is, below 110' 17 111 0 1 25Od 5d 15 113 0 18 112 0 0 60 250 16 124 0 F. or 11 minutes before the beginning of the 2019 113 1 0 1000 2 17 126 3 minute holding period. The bottles of wine con20 114 1 0 0 0 18b 126 c ! taining the thermocouples showed no living or21 115 0 0 1 0 22b 116 1 0 1 0 2: 130 1 c ganisms when plated after pasteurization, with 22 112.5 0, 39 d . 5 0 bhe exception of one bott'le in which a few living 1 :3 120 c o , c 0 , : cells were found. The occasional organisms sur;3 l2Y.5 t ; ; viving during and after pasteurization failed to 42 120.5 0 0 0 0 grow when cultures of them were inoculated into sterile wine. Recorded near the bottom of t h e upright bottle. b Start of 20-minute holding period. TOKAY.A Tokay type of wine cont,aining9.14 c Sample plated a t regular intervals during these periods showed no colonies. d Indicates 1000 in plate count. per cent sugar and 13.82 per cent alcohol was pasteurized a t 130" F. The results in Table TI11 shorn that t'he rapid killing of organisms again occurred a t a comparatively low t e m p e r a t u r e i n this killed off a t a relatively low temperature-that is, approxicase below 110.5" F. or 9 minutes before the beginning mately 112' F. of the 20-minute holding period. S o living organisms were 2. Sweet Wines2 found in the wine after heating to 113.3' F. or after pasteurizaPort, sherry, muscatel, and Tokay wines ordinarily contion. tain 18 or more per cent alcohol by volume; however, wines MUSCATEL.A muscatel type of wine containing 8.28 per of these types can be sold without being fortified to 18 per cent sugar and 13.80 per cent alcohol was pasteurized a t 130' cent alcohol. This offers the opportunity for developing new F. The initial contamination in this tvine was corrlparatioely types of purely domestic wines ( 2 ) . These sffeet wines, low since i t had not been inoculated, and, as shown in Table having less than 18 per cent alcohol, have a tendency to spoil VIII, the rate of killing was more gradual than in precedand "blow up" after bottling unless properly stabilized. Exing samples. Practically all the organisms had been killed periments were therefore undertaken to determine whether whell 118' F. was reached, or 6 minutes before the start of such Kew York State wines could be stabilized against mithe 20-minute holding period. All bottles examined after crobial spoilage by pasteurization in the bottle. Samples of pasteurization showed no living cells. five types of wine were secured from commercial wineries HAUTSAUTERKE. A sample of Haut Sauterne wine conand consisted of a port type of wine, a sherry type, a muscatel taining 6.27 per cent sugar and 13.36 per cent alcohol Fas type, a Tokay, and a Haut Sauterne. The chemical composipasteurized a t 130" F. This t.ype of wine ordinarily has tions of these wines are shown in Table VII. Since the numa lower sugar content than the heavier wines already nienbers of microorganisms in each wine, with the exception of the tioned. The results in Table \TI11 indicate that a temperamuscatel type, were extremely low, a small amount of actively ture of 115" F. was sufficient to sterilize the wine; this t,emfermenting wine was added to each sample before bottling in order to provide sufficient organisms to follow the rate of 135 killing during pasteurization. TABLEVI.
PLATE COUNTS OBTAINED IX PASTEl2RIZING I3URGUXDY W I N E
-.
:
: :
0
tI25
TABLE
VII. CHEMICAL COMPOSITIONS O F E E W YORK SWEET WINESOF Low ALCOHOLCOXTENT
W
STATE
2
3115 I
Type of Wine Port Sherry Tokay Muscatel H a u t Sauterne
Percentage b y Volume 13.44 13.68 13.82 13.80 13.36
Alcohol by Weight 10.77 10.98 11.08 11.06 10.70
Percentage Percentage Sugar a8 Acidity a s Dextrose Tartaric 17.70 0.690 0.72~ 4.43 9.14 0.562 8.28 0.547 6.27 0.646
E pH 2.996 3.245 2.975 2.984 3.047
V) 105
i 8 z
3
95
85
3
Pasteurization, temperature recording, and sampling were carried out in the same manner as for dry wines.
Results of Pasteurization PORT. A port type of wine containing 17.7 per cent sugar and 13.44 per cent alcohol was Pasteurized a t 130' F. 2
Under t h e direction of E. A . Beavens.
5
75
2
65
2
V
55~-5
'
FIGURE 4. TEURIZATIOS
I
IO
15
20 25 30 TIME IN MINUTES
I
3
7
-
V
4
7
J
0
TIME-TEMPERATURE CURVESO B T ~ I N E D IN THE PASHAUTSAUTERNE WIVE AT 130' F. FOR 30 MINUTES
OF
ISDUSTRIAL 1 S D ENGINEERING CHEMISTRY
1262
VOL. 27, NO. 11
termined in tlie laboratory without danger of spoilage, and to trace the rate of killing of the microorganisms present in the wine.
Pasteurization in Bulk
ELECTRIC HEATER
PYREX CHIMNEY
POSITION or THERMOCOUPLE: AT DIFFERENT L E V E L a
FIGURE5.
PAsTEURIZIXG
TANKSHOWIVG THE P o s I T I o Y s THERMOCOUPLES
OF H E I T E R S A N D
perature was reached 9 minutes before the pasteurizing temperature was attained. The bottles examined after pasteurization were apparently sterile. Figures 3 and 4 show graphically two typical time-temperature curves recorded from the thermocouples inserted in the bottles of wine during pasteurization runs. Figure 3 represents curves obtained from a wine of high sugar content and Figure 4 a wine of low sugar content. The curves show uniform rises in temperature with only slight differences between individual bottles. The most rapid rise was recorded from the top thermocouples located in the upright bottles in all experiments. This is shown in curves 11 and 12, Figures 3 and 4. The bottles of pasteurized wine of each type incubated at 77" F. for 2 weeks and additionally a t room temperature for 2 months appeared to be well stabilized, and 1 cc. samples plated in duplicat,e contained no microorganism with the exception of the port and muscatel types in which a few micrococci were found. The unpasteurized control samples showed clouding and sedimentation, and when plated they were shown to contain many yeast cells.
3. Commercial Pasteurization of Wines3 Pasteurization is a n important step in the manufacture of wine. Commercial wines have a tendency to spoil or become hazy unless stored under ideal conditions or unless steps are taken to stabilize them, and one of the means of accomplishing this is by pasteurization. There is some change in character and flavor produced by all methods of rendering wines sterile. and it was to bring the effect of pasteurization to a minimum that this work was undertaken; unless pasteurization i\ carried out under controlled conditions, serious impairment of character and flavor may result. Laboratory tests on small lots had shown that wine> could be pasteurized at temperatures as low as 130" F. and remain in good condition for long periods of time even under adverse conditions. Three general methods of pasteurization are in use in the wineries of Kew York State-pasteurization in bulk, pasteurization in sealed bottles, and pasteurization in open bottles. It was the purpose of this work to pasteurize mines under commercial conditions by these three methods to see if a stable product could be produced, to determine whether the pasteurizing temperature in use could be lowered to that dea Under t h e direction of Harry E. Coresline.
The commercial equipment used for bulk paoteurization consisted of a 500-gallon steel tank equipped with three 500-watt electric heaters. Thebe stood upright in the bottom of the tank and vere covered with Pyrex glass chimneys open at the top and bottom. The circulation of material in the tank was due to the thermal stirring caused by the rising of the heated wine through the chimneys. The only opening in the tank was a hatch at the bottoni through xhich the various pipe lines and gages passed. This hatch was removed and sixteen thermocouples were installed at Trarious points inside the tank. The thirty-two thermocouple wires were brought out of the tank through a small opening, and the wires were laid in slits cut in the sides of a rubber stopper which 11-as then driven into the hole. The wires and stopper were treated xith heavy shellac to obtain a tight joint. The positions of the thermocouples and heaters are shown in Figure 5 . The thermocouples were distributed in such a manner that accurate readings of temperature could be obtained in all parts of the tank and in close proximity to the heaters. These thermocouples were attached to an electropotentiometric thermometer through a sixteen-point switch, and temperature readings \yere taken every 30 minutes throughout the pasteurizing run. The tank was first filled with water to test the seals and, after draining, was filled with 500 gallons of sauterne wine of t,he following composition: Alcohol % Total a h d i t y ,
%
11.56 0.99
Sugar, %
PH
5.37 3.01
The heaters were then turned on and the pasteurizing run started. The set of three thermocouples which mere on the same horizontal level gave almost the same readings, and in plotting curves the average temperature was used. The plotted temperatures are shown in Figure 6. Since too many curves would detract from the value of Figure 6, only the readings for the thermocouples in the hottest and the coldest parts of the heaters and the averages of the top, middle, and bottom of the tank are shown. There was a difference between the bottom and the top of the tank of about 12" F. after the pasteurizing temperature was reached, whereas the difference between the middle and the top was only about 2" F. It was therefore reasonable to assume that at least one-half of the tank was above 140" F. during the holding time. The colder wine remained in the bottom since the limited circulation due to the heaters was not enough to mix the wine to bring all of i t to the same temperature. The coldest spot in the tank was in the bottom of the chimney where the wine was entering and passing u p through the heater, and no hot spots existed in the tank which would tend to burn the wine. It m-as necessary to reduce the pressure in the tank from time to time as t#hewine expanded, and for this purpose the overflow valve was opened and enough wine removed to reduce the pressure to below 20 pounds per square inch. This had to be done about every 20 minutes throughout the pasteurization. The second purpose of this experiment was to deterniiiie the rate of killing of the microorganisms by the pasteurizing process, and samples of wine were drawn from the tank a t set intervals. The sampling valve was located in the same relative position as the thermocouple by which the pasteurizing temperature m-as being controlled. The wine samples were plated in the customary manner for bacterial counting, using a yeast extract-glucose-peptoneagar medium and incubating for four days a t 32" C. (89.6" F,). The total count a t the various time intervals is recorded in Table IX. The count decreased slowly for the first 3 hours and then decreased rapidly, dropping from 2500 to 3 per cc. in one hour. The curve in Figure 6 shows that the
ISDUSTRIAL AND ENGINEERING CHEMISTRk-
NOVEMBER, 1935
1263
r
TABLE TrIII. PLATE COUSTS OBT.4ISED I 3 PASTEURIZINQ LOW-ALCOHOL SIi'EEr
--
--Port
Type Plate count per ICC.
Time .TIL 11.
O
LI
9 10 11 12 18 I4 i5 16
17 18 I9b 20
Type--
Plate count per CC.
-Nuscatel Type-Plate c o u n t Temp." per cc.
97 107 106 3 110 113 115 E; 118 2 120 122 123 5 1 2 4 ,E 126 127 12E 12b.i
30,000 30,000 20,000 9,000 4.000
1
20,000 20,000 6,000 44 0 0 0 0
0 0
129 ?
...
c
37 1x1 ' 1 130::3 38 131 0 130.5 0 130.5 39 131 Recorded near t h e top of t h e upright bottle. b Beginning of 20-minute holding period. C Samples were sterile during this interval.
. .
0
0
0
TABLEIx. PLATE
Start 8:40 9:oo
A. M.
1o:oo 11:oo
12:oo 12:30 P. M.
l:oo
1:30 2:oo 2:15 2:30
60.6 61.9 70.6 84.3 98.3 105.6 113.8 119.8 126,6
2 :45
3:oo
3:15 3:30 3:45 4:oo 4:15 4:30 4:45 5:oo Cooled wine
--
Plate Count---
Bacteria and yeasts
,\fold
Total per cc.
200 20 10
4480
'
F.
1i0:5 13615 129: 6
...
131.6 iii:4
... . .. . I .
Tokay-Plate count per cc.
Temp.Y
FOR
20 MINUTES
--H a u t Sauterne -Plate count per cc.
Teinp.0
245
130.'5 130.5 130.5
6
93.5 98.5 103 107 110.5 113.3 115.8 118 120 121.8 123.5 124.5 125.6 126 5 127 127.8
106
41 IF 6 > 1
0 11.
95 100 105 108 112
20,000 10,000 8.000
166 3 0
5
8 2
115
0 0 0
7 U
1
iii
(1
9,000 9,000 6.600 2.600 18
7
115 , 121 :i 122 8
0 0 0
124 125 i 26 126 S 12; 5
n
1%
130 130
0
130
0
il
IJ
120
0
IJ
130
0
12K5
0
the niaxinlum precipitation was reached just as the 130" F. pasteurizing temperature was reached, 5 hours and 50 minutes after the heaters had been turned on. These samples were incubated for 3 weeks at 25' C. (?To F.), and spoilage took place in all samples taken under 11i" F., but no spoilage occurred in samples taken above this temperature.
Pasteurization in Sealed Bottles S.4MPLES TAKESD U R I S C PASTEURIZATIOS COGST OF
Appro\-. Temp. 0
130" F.
F.
90 95 101 101 110 113 115.5 118 120 121.5 123 124.5 125.5 126.5 127.5 128
rapid killing of microorganism took place Rhile the temperature in the bottom of the tank was between 98" and 113" F., and that all of the cells had been killed by the time the temperature reached approximately 115" F. There were three mold colonies on each of the laqt three plates poured but there can be no doubt that they were air contaminants.
Time of Sampling
--
F.
F.
100 104 108 111 5 114.5 117 119 5 121 3 123 124 3 125.5 126 5 127,5 128 128.2 128.,
3
;
---Sherry
W I N E S .%T
4800 4460 4850 3700 2500 35 0 0 0 0
5000
u
0
4860 3701 250i 39 3 0 0 0
0
0
0 0 0 0 0 0 0 0 0 0 0
0 0 0 0
0 0 0 0 0 0 0 0 3 3 3
1
4 3
0 0
U
0 0 0 3 3 3
The wine was heated for 2 hours and 23 minutes after the pasteurizing temperature of 130" F. had been reached, and a t the end of the pasteurizing period the tank was cooled rapidly by circulating cold water through the jacket; one hour was required to bring the middle position of the tank below 100" F. When such a wine is heated under pressure for a considerable length of time, a heavy precipitate is formed and probably some aging effect is obtained. The samples which were removed for bacterial counting were allowed to settle, and
These experiments \yere conducted a t a commercial winery equipped with a Barry-Wehmiller conveyor type pasteurizer. This pasteurizer consists of a large rectangular tank divided into three vertical compartments, through which the bottled wine passes in baskets att,ached to a chain conveyor. A sketch of this apparatus is shown in Figure 7 . This large tank was filled with water; the first compartment (or preheater) wits held at a temperature of about 100" F., the center compartment at the pasteurizing temperature, and the third conipartment at cold water temperature. These temperatures were automat,ically maintained, and the chain conveyor moved at such EL speed that the bottles were held in the pasteurizer compartment for approxi-
i
aog
-
I IO
I/
AM
FIGURE 6. IKFLUENCE
1
11
L
I2 NOON TIME
2
3
4
___
5
8 PM ,
O F THE T E M P E R 4 T U R E IN THE P.4sTEORIZIXG T . 4 x K ON THE B.4CTERIAL COCNT
VOL. 27, NO. 11
INDUSTRIAL AND ENGINEERING CHEMISTRY
1264
mately 20 minutes. The time of passage through the entire apparatus was about 50 minutes. The wine for these studies was prepared for bottling by passage through a Seitz filter and was then passed to the automatic bottling machine. After bottling, a cap was placed on the bottles by the roll-on-thread process in which the cap was rolled into the thread on the neck of the bottle by a special machine. The closed bottles of wine were placed in the baskets of the pasteurizer, and the pasteurizer run was started. Owing to the construction of the machine it was impossible to remove sample bottles for examination except where the conveyor traveled from the preheater over into the pasteurizer section. In this way the effect of preheating could be traced, but there was no n a y to trace the rate of killing of microorganisms during the actual pasteurization. Bottles were removed as they came from the preheater and a t the end of the process, and were cultured for microorganisms by plating with yeast extract-glucose-peptoneagar. The plates were counted after 4 days of incubation at 32" C . (89.6" F.); the results are shown in Table X.
contamination as possible. The tanks were then filled with water until about 1 inch of the neck of the bottles protruded above the surface, at which point thermocouples were inserted in the bath and in bottles located at various points in the pasteurizer, to record the rise in temperature during pasteurization. When all was in readiness, a steam hose was inserted into the water and the pasteurizing bath was gradually heated by moving the steam hose from place t o place. When the pasteurizing temperature was reached, the flow of steam was cut down until it would just maintain the temperature. The pasteurization was continued for 20 minutes, and then the bottles were removed from the bath and allowed to cool spontaneously. After cooling for perhaps 30 minutes, the wine had contracted sufficiently to permit the introduction of a nine cork.
It was customary in this plant to pasteurize under commercial conditions a t 140" F. It was decided, in the light of previous experience, to lower the temperature for these experiments to about 130" F. The first pasteurization was with a sauterne wine of the following composition:
TABLE X. EFFECT OF PASTEURIZATION ON PLATE COUXT OF WINE Count before pasteurisation Count from preheater Preheater temp. F. Count after padeurization Max. temp. of pasteurization,
Claret 71
0 111
' F.
0 147
--Burgundy? Quart 3150 765 98.5 0 140
Alcohol % Total alfid,
%
Sugar, PH
11.90 0.693
%
0.695 3.22
The rise in temperature a t the various points in the pasteurizer during the run are plotted in Figure 8. Even though the heating was accomplished by moving a steam hose from place to place in the bath, the temperature in the bottles did not fluctuate widely. This same procedure mas employed in the pasteurization of a claret wine of the following composition:
Fifth 2600 1730 98.5 0 140
The first run made was with a claret wine in quart bottles. Alcohol, % 9.88 0.655 Sugar, % This wine had an average count of 71 per cc. when it entered Total acidity, % 0.993 3.37 PH the pasteurizer, but when samples were removed from the This wine was pasteurized a t a lower temperature than the preheater the wine was sterile. The bottle temperature at this point was 111" F., and the highest temperature reached sauterne; the temperature a t the beginning of the holding during pasteurization was 147" F. After 2 months of incuperiod was 113" F. and at the end 132' F. The general character of the rate of heating was the same as that plotted bation all bottles of wine were found to be sterile. in Figure 8 for the sauterne wine. A Burgundy wine was pasteurized in the same manner in Since the bottles in these experiments were open, it was quart bottles. This mine had a n average count of 3150 per possible to trace the rate of killing of the microorganisms cc. when it entered the pasteurizer, but when samples were throughout the pasteurization. I n each experiment two removed from the preheater a t 98.5" F. the average count was bottles of wine were plugged with cotton, and from these 765 per cc. Samples removed after the pasteurization showed bottles 1-cc. portions of wine were plated a t regular intervals one bacterial colony in four samples. After 2 months of incubation bottles of this wine were found to be sterile. This exusing a yeast extract-glucose-peptone-agar medium. One of periment was repeated with the same mine in which fifththe bottles contained the filtered wine while the other held gallon bottles were used instead of quarts. The wine had an unfiltered mine. This latter sample was used as a precaution average count of 2600 per cc. upon entering the pasteurizer, against the filter's having removed the microorganisms to a and after passage through the preheater a count of 1740; bottles cultured after pasteurization were found to be sterile. I n both cases the maximum TABLE XI. EFFECTOF PASTEURIZATION os PLATE COUNTSIN SAUTERNE A N D CLARET WISES temperature reached during the pasteurization was Unfiltered Sauterne, Unfiltered Claret 140" F. 7 -
Sample
Pasteurization in Open Bottles
It is customary in plants of small size or where the volume of business does not justify the installation of expensive automatic pasteurizing equipment to pasteurize in small vats by placing the filled bottles in water and then heating to the desired temperature with steam. Since the wine is filled into the bottles a t room or cellar temperature, it is impossible to insert a wine cork before the pasteurizing because the expansion of the wine during the heating forces the cork from the bottle. It is necessary therefore under these conditions to pasteurize the wine and cork after i t has cooled somewhat. The equipment used in these experiments consisted of two wooden tanks approximately 5 feet long, 3 feet wide, and 2 feet deep. The wine was filtered through a K5 Seitz filter sheet, and the bottles were filled directly from the filter. They were then placed in the pasteurizing vats, and a tapered cork was inserted loosely in the bottle in order to eliminate as much air
No.
Time
Min.
1 2 3 4 5 6 7
Temp. O
Sample
1600 1600 1600 1600 1600 1600 1600 1500 388 68
1 2 3 4 5 6 7 8
So.
I".
9 10
0 3 5 7 9 11 13 15 17 19
62 62 63 66 69 76 83 91 97 102
16 17 18 19 20 21 22 23 24 25 26 27 28
31 33 35 37 39 41 43 45 47 49 51 53 55
123 126 129 131 133 134 134.5 135.5 137 138 139 139.5 140
8
Plate count
5 5 5
5 5
3 0
0 1 1 0 1
2 2 3 5 0 0
Time
Temp.
.Win.
' F.
10
0 4 6 8 10 12 14 16 18 20
73 75 78 80 84 88 91 95 100 107
16 17 18 19 20
32 34 36 38 40
123.5 126 127.5 130 131.5
9
5 5 5 5
5
Plate count Pinpointa Others
2000 2000 2000 2000 6000 6000 6000 1400 6000 2200
712 712 712 712 576 576 576 108 190 4
0 0 0
0 0 0 0 0
0
0
NOVEMBER, 1935
INDUSTRIAL AND ENGINEERING CHEMISTRY
point where satisfactory counts could not be obtained to trace the killing rate. This precaution proved to be n e c e s s a r y since the filtered wine was found to be sterile when cultured direct from the f i l t e r . The killing r a t e is therefore s h o w n LPREHEATER LPASTEURIZER COOLER for the unfiltered FIGURE 7. BARRY-WEHMILLER products in Table PASTEURIZER XI. I n the c a s e of the sauterne wine -the count decreased rapidly between 91 " and 102" F., but a few survivors were cultured on plates during the entire run. This was found to be due to a contamination from the bottles and consisted of almost a pure culture of a mold-like microorganism. I n commercial practice the bottles were not sterilized, and they were found to be heavily contaminated. Cultures of these sunriving forms were inoculated into sterile wine, but in no case could any growth be demonstrated. It was concluded that they were of but little importance as far as causing spoilage was concerned. The claret wine was found to have a heavy contamination of bacteria which grew in extremely small colonies on the plates, and it was necessary t o count them with a lens. All of these bacteria were killed by the time the temperature had reached 115" F., and the wine was rendered sterile between 115" and 119" F.
Summary Studies were made on the pasteurization of New York State dry and sweet wines of low alcohol content. Temperatures attained in the bottles were carefully determined by means of thermocouples, and the rate of killing of microorganisms was followed by frequent platings of the wine and culturing into broth tubes. No appreciable difference was noted between the rate of heat transmission in the various types of wine; the rate was approximately the same as that found by previous workers on various fruit juices. Samples of sauterne, claret, and Burgundy types of wines with a high initial contamination of microorganisms more or less normal to wine were pasteurized a t approximately 120" and 130" F. for 20 minutes. The microorganisms in these wines were killed off a t relatively low temperatures, only a few surviving the 120" F. temperature. The addition of small quantities of sulfur dioxide t o the wine (25 and 50 p. p. m.) had an appreciable effect in lowering the temperature (approximately 5" F.) or shortening the time necessary for successful pasteurization. Sweet wines, as represented by a port type, a sherry type, a muscatel type, a Tokay, and a Haut Sauterne, were pasteurized a t approximately 120" and 130" F. for 20 minutes; in general, the results indicated that a rapid killing of micro-
1265
organisms took place between 110" and 121' F., depending on the type of wine. Studies mere made on the commercial pasteurization of New York State wines to obtain information as to the lowest effective temperature a t which these wines could be stabilized. Three different methods of pasteurization gave satisfactory results in each case-pasteurization in bulk, in closed bottles, and in open bottles. I n the first method the heating was accomplished by means of electric heaters inserted directly into the wine, and in the latter two hot water was used. The temperature rise during pasteurization was followed by means of thermocouples which mere placed in the wine and in the water baths. The rate of killing of the microorganisms was
!
!
'
I
! I I
1
1
1
I
I
70
80
-1
1
I I
20
30
40 50 W3 TIME IN MINUTES
W
100
FIGURE 8. TIME-TEMPERATURE CURVES OBTAINED IN THE PASTEURIZATION OF SAUTERNE WINE followed during the experiments by plating portions of wine on yeast extract-glucose-peptone-agar medium a t regular intervals. Two sauterne wines, two claret wines, and one Burgundy wine were pasteurized under commercial conditions a t approximately 130' F. for 20 minutes, and subsequent examinations showed these wines t o be free from spoilage organisms. In certain cases spore-forming bacteria, coccus forms, small rod forms, and molds, which were more resistant to heat than the yeasts, were isolated from the pasteurized wine. These forms could not be induced t o grow in sterile wine and mere apparently not significant from the standpoint of pasteurization and stabilization of the wine. Samples of the pasteurized wines of the various types used mere examined after 2 weeks of incubation a t 77" F. and storage for 2 months a t room temperature, and were found to be well stabilized and free from spoilage organisms.
Literature Cited (1) Bioletti, F. T., Calif. Agr. Expt. Sta., Berkeley, Bull. 213 (1911). (2) Cruess, W. V., Fruit Products J . , 14 [7], 198 (1935) (3) Ford, K. L., and Osborne, A. G., Glass Container, 8, 7 (1928). (4) Pacottet, P., "Vinification," 4th ed., Paris, 1921. ( 5 ) Pasteur, L., "Etudes sur le vin," Paris, 1st ed., 1866,2nd ed., 1873: also in "Oeuvres de Pasteur," Vol. 3, p. 203 (1921). (6) Pederson, C. S.,N. Y. State Agr. Expt. Sta., in manuscript. (7) Walsh, W. F., N. Y. State Agr. Expt. Sta., Circ. 149 (1934). RECEIVED August 29, 1935. Approved by t h e Director of t h e New York S t a t e Agricultural Experiment Station for publication as Journal Paper 95. Food Research Division Contrib. tion No. 262.
No.
