Factors Influencing the Quality of American Grapes in Storage'

Home , Goethe (grape), Herbert (grape), Massasoit (grape), Requa (grape)

Technical Bulletin No. 606 ^'^W^y^^^'-^^^S»^ March 1938

UNITED STATES DEPARTMENT OF AGRICULTURl

FACTORS INFLUENCING THE QUALITY OF AMERICAN GRAPES IN STORAGE'

By J. M. LUTZ, assistant physiologist, Division of Fruit and Vegetable Crops and Diseases, Bureau of Plant Industry *

CONTENTS

Page Pas« Introduction 1 Handling and storage studies—Continued. Handling and storage studies 2 length of storage life of different varieties- 21 Materials and methods--- -_ 2 Physiological studies 22 Factors influencing shattering and decay of Respiration of Concord grapes------22 grapes in cold storage -- - 2 Changes in composition in storage 22 Loss of weight of grapes in storage--- 19 Influence of maturity on composition 24 Deterioration of flavor in storage 19 Summary --- 25 Influence of storage on behavior after Literature cited 26 removal from storage -_ 20

INTRODUCTION Although considerable experimental work has been done on the handling and storage of vinifera grapes by Carrick {2),^ Jacob (8), Mann (1^), Pentzer and associates {13, 14, 15), Stubenrauch {17) and others, there is little information available on the handling and storage of labrusca and muscadine grapes. Hedrick and his co- workers {6) and Husmann (7) briefly mention the storage and shipping qualities of a few varieties of American grapes. Thayer {18) reports the results of limited tests comparing the storage behavior of 22 varieties of grapes in a fruit cellar as well as in cold storage. Rose et al. {16) briefly discuss the storage of American grapes. The investigations reported herein were undertaken in an attempt to determine the influence of various factors on the storage Ufe, chemical composition, and physiological activity of American grapes. Information on these matters should be useful in the storage and transportation of table grapes. Storage may also be used as an ad- junct in the manufacture of grape juice or wine by prolonging the season in which fresh grapes are available. All of the storage studies were conducted in the experimental storage rooms at the cold-storage laboratory, Arlington Experiment Farm, Arlington, Va.

1 Received for publication July 28,1937. . J The writer gratefully acknowledges his indebtedness to D. F. Fisher for numerous suggestions in carrymg out this work; to M. H. Haller and P. L. Harding for assistance in making the respiration determinatlom; to R C Wright for suggestions and assistance in the determination of the rate of cooling in storage; and to I. W. Dix, J. R. Magness, and Charles Dearing for furnishing the fruit. ' Italic numbers in parentheses refer to Literature Cited, p. 28. 24922°—38 1 2 TECHNICAL BULLETIN 606, U. S. DEPT. OF AGRICULTURE

HANDLING AND STORAGE STUDIES

MATERIALS AND METHODS This work was conducted during the seasons of 1932, 1933, and 1934. With the exception of the Concord, Niagara, Delaware, Worden, and Moore Early varieties which were grown at Beltsville, Md., the grapes used in the comparison of the storage life of different varieties were grown less than 20 miles distant at the Arlington Experiment Farm, Arlington, Va. Preliminary tests showed no apparent difference in keeping quality of the fruit from these two sources. The muscadine grapes used in this work were secured from Willard, N. C. While it is realized that muscadine grapes are seldom if ever stored commercially, it was thought desirable to obtain some information on them. The fruit was picked at the market-ripe stage of maturity, which was about 10 days before the full-ripe stage. The fruit had developed full color and nearly full flavor but was not quite as ripe as fruit harvested for juice manufacture. The Moore Early harvested in 1934 and the second-picking grapes (table 13) were about 1 week beyond the market-ripe stage. Unless otherwise stated the fruit was stored in 4-quart baskets without washing, the containers being placed so as to permit free circulation of air around and over each one. It was usually placed in storage the day of harvesting, although occasionally it had to be held overnight at room temperature. Ordinary careful handling methods were practiced during harvesting and preparation for storage, except where variations in handling methods were being studied. A temperature range of 32° to 80° F. was used. The average relative humidity of the storage rooms for each of the 3 years is given in table 1.

TABLE 1.—Average relalivc humiditi/ of storage rooms uned in deierminiiig tlie effect of temperature on grapes

Relative humidity Belative humidity storage tempera- .Storage temperature (»F.) ture (°F.) 1932 1933 1934 1932 1933 1934

Percent Percent Percent Percent Percent Percent 32 79 80 76 60 83 96 36 87 88 80 70..._ 91 86 40 88 85 89 80 72 72 50 77 89 80

"Shattering" or dropping, or as it is sometimes called "shelling," of the berries from the pedicels was determined after shaking the bunches slightly. The shaking was apphed as uniformly as possible to all treatments.

FACTORS INFLUENCING SHATTERING AND DECAY OF GRAPES IN COLD STORAGE

TEMPERATURE The results obtained on the influence of temperature on shattering and decay are given in tables_2 to 7, inclusive, Some of these data are illustrated in figures 1 to 12, inclusive. QUALITY OF AMERICAK GRAPES IN STORAGE

•g ^ lOi 1 s ifS i i i i i i

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TABLE 3.—Effect of temperature on shattering and development of decay of Worden and Delaware grapes stored for various periods, 19S2 SHATTERING AFTER STOBAOE PERIODS INDICATED

Variety and storage tem- 1 week 2 weeks iwrature (*^ ¥.) 3 weeks 4 weeks 5 weeks 6" weeks 8 weeks

Worden: Percent Percent Percent Percent Percent Percent Percent 70 42.1 60 14.6 60 1.5 7.1 20.0 40 2.5 16.0 37.9 48.3 40' 62.5 32 4.0 l-i.C 38.6 60.7 32l__. , 56.7 Delaware: 70 20.00 60..-. .8 3.6 11.9 60-.- .0 2.1 4.7 9.7 40 2.8 7.0 36 4.2 7.4 36" 32.... .7 1.6

DECAY AFTER STORAOE PERIODS INDICATED

Worden: 70 1.1 60 1.5 60 .8 2.3 2.8 40.... .6 .9 1.5 2.1 401 7.1 32 .0 .3 .3 .3 321 _ 2.6 Delaware; 70 8.5 60 1.0 3.8 9. 1 60-.-. .0 .2 2.8 7.9 40 1.7 3.6 12 6 36 1.1 1.7 3 0 36' 7.9 32 .0 . 1 2

1 Inspected after 6 weeks' storage only. ' Inspected after 8 weeks' storage only.

TABLE 4.- -Effect of temperature on shattering and development of decay of different varieties of grapes, stored for various periods, 193S SHATTERING AFTER STORAOE PERIODS INDICATED

Variety and storage temperature (° F.) 1 week 2 weeks 4 weeks 6 weeks 7 weeks 8 weeks 10 weeks 12 weeks

Concord: Percent Percent Percent Percent Percent Percent Percera Percera 80 85.7 70 47.5 60 6.8 31.6 60 1.2 4.6 23.4 40 .8 3.2 9.5 38.4 36 .3 1.7 4.2 20.9 38,9 32 .3 1.2 2.7 5.6 18.4 38.9 321 16.7 32> 2.0 Niagara: 70 31.6 60 4.2 18.7 50 1.3 3.5 12.4 40 1.4 4.4 13.2 36 2.8 8.5 16.0 32 .8 6.2 13.6 19.6 Worden: 70 60 10.8 60 6.6 51.6 40 6.2 63.8 36 2.2 30 n m 6 32 .0 3 0 3Q fi 1 66.4 See footnotes at end of table. QUALITY OF AMERICAN GRAPES IN STORAGE 5

TABLE 4 —Effect of température on shattering and development of decay of different varieties of grapes, stored for various periods, 1933—Continued DECAY AFTER STORAOE PERIODS INDICATED

Variety and storage temperature (° F.) 1 week 2 weeks 4 weeks 6 weeks 7 weeks 8 weeks 10 weeks 12 weeks

Concord: Percent Percent Percent Percent Percent Percent Percent Percent 80 9.2 70 6. 1 60 3.5 5.0 60 1.0 2.2 4.0 40 1.9 2.8 4.1 38 _ 5.2 .5 1.9 3.1 4.2 4.8 32 .3 .9 2.1 321 3.0 3.2 3.'8 4.4 32> 2.7 70 12.6 60.... 2.9 13.1 50 .9 3.7 9.3 40 1.6 .5.4 22.3 36 1.6 4.8 18.6 32 .2 1.8 5.7 13.3 Worden: 70 2.1 60- .7 50 1.5 2.0 40 .4 .4 36 .2 .4 13 32 .2 .8 1.6

1 Inspection after 12 weeks' storage only. ' Inspection after 8 weeks' storage only.

TABLE 5.—Effect of temperature and size of conta%ner on shattering and development of decay of different varieties of grapes, stored for various periods, 1934 SHATTERING AFTER STORAOE PERIODS INDICATED

1 week 2 weeks 6 4 weeks weeks 10 weeks 14 weeks Variety and storage temperature (°F.) 4-quart 8-quart 4-

Niagara: Pel. Pet. Pet. Pd. Pet. Pet. Pd. Pet. Pd. Pd. Pd. 70 1. 1 2.0 U. 1 60 .1 1.0 5.4 60 .8 4.4 40 .0 8.7 36 .3 1.0 8.6 17.7 32 .1 .6 2.8 1.3 9 1 Moore Early: 70 26.0 39.2 60 16.8 20.0 60.0 60 -. . 12.8 9.3 40 1.3 1.9 22.3 41.6 36 .9 .9 16.5 18.6 32 .0 .0 2.1 3.3 Concord: 70 15.9 37.1 75.0 9.1 10.7 40.9 60 .4 4.3 7.2 40 . - .0 .3 22.4 18.2 36 .0 .0 11.4 8.8 32 . .4 .0 5. 1 5.0 30.7 39.1 TECTTÎfICAL BULLETIN 6 0 6, XT. S. DEPT. OF AGRICULTURE

TABLE 5.—Effect of temperature and size of container on shattering and development of decoy of different varieties of grapes, stored for various periods, 1934—Con. JIECAY AFTER STORAGE PERIODS INDICATED

6 14 weeks 1 week 2 weeks 4 weeks weeks 10 weeks Variety and storage tcniperatiire (°F.) 4-quart 8-quart 4-quart 8-qiiart 4-quart 8-quart 4-quart 4-quart 8-quart 4-quart 8-quart basket baselit basket basket basket basket basket basket basket basket basket

Niagara: I'd. Pet. Pet. PeJ. Pet. Pet. Pet. Pet. Pel. Pd. Pd. 70 1.6 4. 1 5.6 60 .B 1.3 6.2 JO 2.5 1.6 40 - 1.2 6.6 36 1.1 1.4 6.6 6.7 32 .3 1.3 3.9 3.0 6.3 Moore Early: 70 5.9 5.6 60 2.4 1.7 10.5 50 3.7 3.9 40 1.6 2.1 6.6 6.5 36 1.1 4.4 4.6 32 .4 1.7 2.3 Concord: 70 2.0 2.7 6.0 60 1.4 1.8 3.4 60-- 1.6 2.8 4.8 40 .8 1.0 1.9 2.1 36 1.0 .8 1.8 2.6 32 .3 .7 .6 1.5 1.5 2 3

TABLE fi.—Effect of storage temperature on shattering and development of decay of Delaware grapes, 1934

Shattering and decay after storage tor—

storage tempera- 7 days 14 days 31 days 57 days 89 days ture (■>!".)

Shatter- Decay Shatter- Decay Shatter- Decay Shatter- Shatter- ing ing ing ing Decay ing Decay

Pereent Percent Percent Pereent Percent Percent Percent Percent Percent Pereent 70 .-- 4 7 1.0 24.7 2.9 60 3.2 4.0 15.7 7.9 .■iO . . . 8.6 4.1 40 1.7 3. 1 8.4 8.7 36 3.7 2.0 1.3.4 5.0 32 --- 1.6 1.0 3.1 2.6 7.1

TABLE 7.—Influence of teTnperafure on development of decay of muscadine grapes^ stored for various periods, 1934 [Average of P, varieties, Memory, Flowers, Scuppernong, Eden, James, and Tliomas, stored in 1-quart haske'ts]

Decay after storage for— Decay after storage for— storage tempera- Storage temperature (°r.) ture (°F.) 5 days 10 days .39 days 5 days 10 days 39 days

Percent Percent Percent Percent Percent Percera 80 -- 23.4 40-- ¡3.0 '6.0 70 17 3 36 Î 1.3 ¡2.7 10 4 60- 8 9 n.6 32 - .9 Î 1.7 60 1 ;).9 7.8

1 Calculated from 10-day data. 2 Calculated from ;i9-day data. QUALITY OF AMERICAN GEAPES IK STORAGE

TIME, IM STORJ^GC (kVccKs)

FIGURE 1.—Effect of temperature on shattering and the development of decay of Concord grapes during storage, 1932.

T/MC II* STOm^aE (IvtEKa) FlfiUKE 2 —Effect of temperature on shattering and the development of decay of Concord grapes during storage, IK«. 8 TIÎCHNICAt, BULLETIN 60 6, U. S. DEPT. OF AGRICULTURE

The data presented in the tables are in percentages of the original weight of fruit. Where more than one inspection was made, the decayed and shattered berries were discarded each time but were included in any later record of losses. In other words, the percentages given under each storage period represent all of the decay development or shattering that occurred after the fruit was placed in storage.

32 36 -iO STOfíAGC TEMPCRATURC: (°r.) FifiuRE 3.—Decay and shattering of Concord grapes after storage tor 1 week at various temperatures, 1933.

It can be noted from tables 2, 3, and 4, that making several inspec- tions during the storage period generally resulted in somewhat more shattering and less decay than when only a final inspection was made. The smaller amount of decay in the former case is perhaps due to removal of sources of infection at each inspection and the additional handling may account for the increased shattering under these conditions. Inspecting the fruit at intervals allowed a comparison of the effect of various temperatures after different periods of storage. QUALITY OF AMERICAN GRAPES IIST STORAGE

TiML IN STORAGE. (yVCCHs) FiciuRE 4.—Eiîect of temperature on shattering and the development of decay of Worden ^Tapes durinjç storage, 1933.

SH^TTCRING DECAY / /

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TiMC in ÖTORAGC (yV£c/

24922^—38 10 TECHNICAL BULLETIN 6 0 6, U. S. DEPT. OF AGRICULTURE

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1 y 1 / /y"^ ,,-'¿¿> >""" ^<^i^^;^^^ y ^, \Â f^ ;¿^^^I^1—— TIMO in 5JORAG£ (IVECKS) FKJURE (1.—Effect of temperature on shattering and thedevelopiiient of decay of Moore Karly {;raf)es duriniî storage, 1934. It can be readily noted from the data presented in tables 2 to 7, inclusive, and in figures 1 to 12, inclusive, that for all storage periods, both decay and shattering decreased in all varieties with lower temperature. The few minor exceptions are probably duo to experimental error. A temperature of 3 2 ° F. proved to be best, especially for long storage periods. However, 36° and 40° were used for storage periods of moderate length with fairly satisfactory results. For short periods, such as 1 or possibly 2 weeks, 50° is reasonably satisfactory. Wright and Taylor {20) found that the average freezing point of American-type grapes is 28.16° F. To avoid danger of freezing it is suggested that American grapes in commercial storage should sro....T...... ru.cCr.) not be held at temperatures Fir.uRE 7.—Decay and shattering of Moore Early Kriii)es i i ono T^ after storage ffir 1 week at various temperatures, 19:i4. DGIOW oU _r , QUALITY OF AMERICAN GRAPES IN STORAGE 11

SHATTERING DLCAY

4.20

TIME: IN STORAGE, fDAYS>) FIGURE 8.~Eflect of temperature on shattering and the development of decay of Delaware grapes during storage, 1934.

TIME, in STO^Jtae (tvccKs) FIGURE 9.—Effect of temperature on shattering and the development of decay of Coneord grapes during storage, 1934. 12 TKCHNIOAL BULLETIN 606, U. S. DEPT. OF AGRICULTURE

It can be seen from the tables and illustrations that although decay generally developed rather uniformly during the storage period, shattering increased rather sharply toward the end of the storage period. This is well illustrated in table 8, which shows an increase in shattering in each succeeding storage period . HUMIDITY

jVtmospheric humidity is herein expressed in terms of relative humidity, i. e., the percentage of saturation at a specific temperature. It is also sometimes expressed in terms of the pressure of aqueous vapor existing at a specific temperature. The difference between this and the pressure of a saturated STOH^acTLMPdFtATunc (T.) atmosphere at the same FIUURE 10.—Decay and shattering of Concord grapes after temperature is termed the storage for 2 weeks at various temperatures 1»34. "v^por prCSSUrC deficit,"_0r the "saturation deficit," which can be used to express the evaporating power of the air.

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7 o I*J 10 ir y^ ,—- Q á^ ^ ^^^rrri--^^"^

i TIME: in STORAGE (O^ys) FIGURE 11.—Effect of temperature on the development of decay in muscadine grapes during storage, 1934.

In the storage of fruits and vegetables, which do not lose moisture from a free surface, it has been found * that the influence of atmos- ' Unpublished data by E. C. Wright, on file in the Bureau of Plant Industry. QUALITY OF AMERICAN GRAPES IN STORAGE 13 phenc humidity can be best expressed in terms of relative humidity rather than of vapor pressure deficit. Accordingly, the records pre- sentt-d herein were taken on the basis of relative humidity.

TABLE 8.—Development of decay and shattering of Concord grapes at different temperatures and during different storage periods,^ 1933

32° r. 36° F. 40° F. 50° F.

Shatter- Shatter- Decay Decay Shatter- Decay Shatter- ing ing ing ing Decay

Percent Percent Percent Percent Percent Percent Percent Percent VíTíil 2-\vock 0.3 0.3 0.3 0.5 0.8 1. 1 4« .Second 2-week .0 .() 1.4 1.4 2.4 18.8 T.S Third 2-week l.,s 1.5 2.5 1.2 0.3 l!3 Fourth 2-week . :).» .!! 16.7 1.1 2,S. 9 1.1 Fifth 2-week ___. _ _ 12.8 18.0 .6 Sixth 2-w6ek 20.5 .6

1 The figures given are the percentage of decay or shattering that occurred since the previous inspection and except at the first 2-week period do not represent the total shattering or decay since the fruit was stored.

The influence of humidity on shattering and decay is given in tables 9 to 11, inclusive. It can be seen that shattering usually increased with increasing humidity, although sometimes there was less shattering at the medium humidity than at the low. Humidity in storage did not seem to have any consistent effect on shattering after removal from storage. Decay seemed to be more prevalent at high humidities than at low- ones, but the effect of humidity was not as ÖC TcMPCfíATUfíC í^r", ) marked nor as consistent -Decay in muscadine grapes after storage for 5 days at with decay as with shat- various temperatures, 1934. tering. As might be expected, shriveling increased with decreasing humidity. This effect was considerably more marked however when fruit stored at 80 and 65 percent relative humidity was compared than when the comparison was made at 95 and 80 percent. Apparently grapes can lose some water without manifesting any appreciable shnveling; when more water is lost, shriveling becomes evident. On the basis of the results reported on the influence of hiunidity on shattering, decay, and shriveling, it appears that a relative humidity of about 80 to 85 percent is the most desirable for the storage of grapes. For short storage periods at low temperatures a relative humidity of 85 to 90 percent might be better, as there would be very Httle shattering and decay under these conditions, and shriveling would be reduced to a minimum. 14 TECHNICAL BULLETIN 6 0 6, U. S. UEPT. OF AGRICULTURE

TABLE 9 —Influence of humidily on shattering and decay of grapes during storage, 1932

('oncord I )elaware Worden Moore Early Stor- Rela- tem- tive Im- Length Shat- length Shat- pera- Length Shat- Length Shat- De- De- De- inid- De- of ter- of ter- of ter- ture of ter- cay cay cay cay (°F.) ity storage ing storage ing storage ing storage ing

Pet. Days Pet. Pet. Days Pet. Pet. Days Pet. Pet. Days Pet. Pel. 60 96 36 C5.1 4.7 35 7. 1 20.2 28 73.0 7.9 21 42.0 60 81 36 14.5 2.2 35 2.5 14.0 28 67.9 8.0 21 15.3 60 67 35 21.0 2.6 35 11.4 2.7 28 42.6 6.0 21 37. 1 40 »3 60 62.2 4.8 56 7.0 23.3 28 10.5 3.0 28 6.2 ""i.li 40 80 60 43.4 6.6 66 6.2 13.9 28 20.0 3.7 28 1.5 3. 5 40 05 60 39.9 2.3 56 2.5 9.4 28 10.0 2.3 ■ 28 3.0 1.3 32 96 63 20.3 4.6 56 2.5 1.5 63 80.0 1.6 42 13. 1 3.0 32 79 63 12.0 1.8 66 2.6 3.0 63 43.9 1.8 42 1.6 2.5 32 68 63 5.1 2.0 56 1.0 1.0 63 30.0 1.8 42 3.8 3.0 32 96 ■63 75.2 7.6 ¡42 40.6 1.3.7 32 79 1 63 68.4 6.4 M2 47, 5 9.3 32 68 ■63 64.7 9.0 ¡42 41.7 14.7

> Followed by 5 days at 70° F. ! Followed hy 7 days at 70° F.

TABLE W.-^Influence of humidily on shattering and decay of grapes during storage, 1933

Concord Worden llelative Storage temperature (° F.) htiniidity Length of Shatter- Decay Length of Shatter- Decay storage ing storage ing

Percent Days Percent Percent Days Percent Percent 50 95 28 13.9 3.3 60 80 28 8.8 2.7 60 66 28 6.7 3.2 40 95 67 20.9 3.6 40 80 57 7.8 3.2 40 68 67 17.4 1.4 94 87 11.1 3.0 42 23.3 0.9 79 87 4.6 .» 42 4.5 1.2 32 66 87 .6 .8 42 7.1 1.6 32 94 1 87 40.3 4.2 142 84.9 1.8 32 79 187 31.9 4.7 142 85.6 2.0 32 ., 66 187 36.1 3.8 142 79.8 3.0

1 Followed by 3 days at 70° F.

TABLE 1 \.—Influence of humidity on shattering and decay of grapes during storage, 1934.

Delaware Concord Niagara Rela- Storage tempera- tive I-ength ture (° F.) humid- Length Shat- Length Shat- Shat- ity of Decay of tering Decay of tering Decay storage tering storage storage

Percent Days Percent Percent Days Percent Percent Days Percent Percent 70 ..- 88 10 8.8 2.1 8 36.9 7.1 10 10.5 4.4 70 . 66 10 2.2 2.2 8 9.2 6.0 10 1.5 ,5.2 50 85 36 8.3 3.7 36 30.6 6.3 36 3.6 7.6 50 - - 73 36 6.9 3.3 36 18.3 2.6 36 3.3 5.9 40 89 60 5.6 6.9 60 27.1 3.4 60 16.4 8,1 40 60 60 1.6 2.1 60 11.4 .0 00 6. 1 3,0 32 73 81 4.2 6.1 31 7.7 2,0 81 10.8 6,0 32 66 81 2.1 3.2 81 11. 1 1.0 81 3. 1 7.1 32 73 ' 81 17.1 7.1 181 41.0 3. 5 181 44. 1 11.1 32 66 1 81 8.2 4.8 181 il.2 1.9 1 81 47.9 13,5

I Followed by 3 days at 70° F QUALITY OF AMERICAN GRAPES IN STORAGE 15

TABLE 12.—Influence of delayed storage on shattering and decay in Delaware, Niagara, and Concord grapes

Delaware 1 (1932) Niagara " (1932) Concord ä (1933)

Days of delay at 70° F. Shattering Decay Shattering Decay Shattering Decay

Percent Percent Percent Percent Percent Percent 0 1.6 0.1 1.6 1.2 2.0 1 5.4 .6 2.7 2.5 11. 1 2 32.7 4.4 33.3 3. 34.2 3.8 44.8 7.1 48.6 4 0 4 84.8 8.3 5. 63.5 3.45

■ stored (i weeks at 32° F. ' Stored 4 weeks at 32° F. ' Stored 8 weeks at 32° F.

DELAYED STORAGE The importance of subjecting grapes to low temperatures immediately after harvesting is shown in table 12. It is evident that there is very marked increase in shattering with increased delay at 70° F. before storage at 32° F. A somewhat smaller increase in decay can be noted. Although conditions in the 70° room used in these investigations were probably more conducive to shattering than is the case under ordinai-y circumstances because of the relatively liigh humidity maintained there, this experiment does emphasize the importance of immediate cold storage. This particular room was used for the experiment because it furnished constant temperature and humidity conditions for comparing the effects of different periods of delay.

CARE IN HANDLING AND REMOVAL OF CRACKED BERRIES Table 13 shows the influence of rough handling and of repacking grapes. Repacking consisted in the careful removal of cracked and shriveled berries. When the fruit was washed, the repacking was done after washing. Rough handling caused a marked increase in both decay and shattering, especially the former; it also resulted in a very high percentage of decay when the fruit wa s washed. Repacking the fruit generally resulted" in a shghtly decreased percentage of shattering and decay. Similar results on the influence of careful handhng on Cahforma table grapes have been reported by Mann {12).

TABLE 13.'—Influence of size of container and washing and handling treatments on shattering and decay of grapes during storage, 1932 FIRST PICKING

Shattering Decay Size of Variety and storage contain- Method of handling temperature (° F.) Not Not washed washed

Quarts Percent Percent Percent Percent Concord: Weeks 3.6 10.0 1 32 Usual 50.0 44.0 70-.-. 33.0 26.0 3.3 6.0 70---- 1 16 do---, 4 do---. 33.0 50.0 3.0 4.0 70---. 1 16.0 36.0 1 4 Rough--- 55.0 60.0 70---- 18.0 20.0 2. 1 2.2 70---- 1 4 Repacked 4 Usual 7.9 4.3 2.8 4.3 50---. 2 9.7 22.0 2 4 Rough— 18.4 13.3 50- -. 1.9 2.7 2.1 1.2 50---. 2 4 Repacked, Usual 11.3 8.4 1.6 2.4 32---- 6 4 2.6 7.7 6 4 Rough— 16.1 26.4 32--- 2.9 14.1 .8 3,8 32 - 6 4 Repacked, 16 TECflNICAL BULLETIN 606, TT. S. DKPT. OF AGRICULTURE

TABLE 13.—Influence of size of container and washing and handling treatments on .■shattering anil decay of grapes during storage, 19S2—Continued FIRST PICKINO—Continued

Shattering Decay Length Size of of stor- contain- MetlKxl of handling temperature (° F.) age er Not Washed Not Washed washed washed

Niagara: Weeks Qiiaris Percent Percent Percent l^ercent 70 1 U-sual 42.0 38.0 8.0 11.0 70 1 Hough fin. 0 04.0 28.0 :!3. 0 70 1 Repacked .Vi. 0 43.0 9.4 12,2 60 -.- 3 VfWA\ . 33. 4 39. 1 8.2 16.3 50--- 3 Repacked 35. 0 .3(i. 1 11). 1 9. 1 32 1 I'sual l.(i 3.3 1.2 1. 1 32 t Rough 9. 1 8.9 4.9 1. 1 32 - - I Repacked 1.3 2. 1 .8 1.3 Worden; 70 1 I'sual 42. 1 30.1) 1. 1 5.8 70 1 Rough 57. 1 (i2. 8 U.O 20. 0 70 , I Repacked 54. 3 2fj. 5 1.8 2.8 50 _.- 7. 1 9.0 2.3 4. S 50 Rough 38. 1 26. 7 3.1 6.2 32 -. 3 15. 0 7.8 1.0 32 3 Repacked 5. 6 10.0 "5 .0 Delaware: 32 4 Usual 2.2 .0 32 4 Rough 7^8 9.3 3.7 3'. i

SECOND PICKING (PICKED WHEN NEARLY RIPE)

í^oncord: 70---- 1 4 Usual 83.6 45. 0 7.0 12.0 70-.-. 1 4 Rough,.. 70.0 55. 0 2:1.0 35. 0 70.... 1 4 Repacked .50 0 31.4 6.2 7.0 60-.-. 3 4 UsuaL___ 16.8 4.5 3. 1 :i. 7 50---. 3 4 Rough 17.1 14.0 5.4 12,8 50... 3 4 Repacked, 8. 1 1.2 1.9 32-... 6 4 Usual 4.0 3.2 1.8 4.3 32 8 4 Rough 3.3 2.6 5.8 8.0 32---- « 4 ]i.e packed. 4.0 .2 1.3 3.3 Delaware: 70 . - 2 4 Usual 37.4 46.4 10.2 9. 1 32 8 4 _--.do-.,. 5.9 4.7 1.5 1.8 Niagara: 70---- 1 4 -_._do.... 46.4 43.9 .5.0 7.3 32.... 8 4 __-.do__. 5.9 7.9 3.0 4.2

SIZE OF CONTAINER In comparing the effect of different-sized containers, the following types of baskets were used: For the 32-qiiart size, the ordinary tub Ijushel basket; for the 8- and 16-quart sizes, market bas- 70 kets; for the 12-qiiart size, k the climax or "jumbo" bas- \^ ket ; and for the 4-quart size, ^^ GO A the Georgia till. Experi- ^ 55 y \\ ments conducted earlier showed that there w^as no Sus HIZL BASKCT \ \ 1 apparent difference in the r K-V VJiRT MARKET BASKET storage behavior of grapes -/ III! I- í^^^ '^yi/ AfíT 3£OftO/A riLL B ASKe — stored in 4-quart Georgia tills 70M 35 Ä -A and 4-quart climax baskets. ■—/. •T— IX. ^^ Figure 13 illustrates the Í / 2 1 6 T,Mi 2 o ¡Houns)2 4 2 e 3 2 3 6 -f 0 -Í * fÉ rate of cooling at the cen- ,. ,„ , ters of three different sized IIGUIÍE 13.—Rate of cooling of Concord grapes in appioxi- i i . . • _, mateiy3i°to32°F, air temperature, 1932. baskets at an air tempera- QUALITY OF AMERICAN GKAPES IN STORAGE 17 tLire of approximately 31 ° to 32° F. The curves represent an average obtained from readings of two thermocouples surrounded by grapes at the centers of the containers. The packages were so placed that the sides and tops were exposed to cold air. The room was cooled by brine coils, but ah electric fan was used to provide a gentle air movement around the grapes. It required 22 hours to cool the center of the 4- quart Georgia-till basket from approximately 70° to the temperature of the cold-storage room, 29 hours to accomplish this amount of cooling in the 16-quart basket, and 39 hours in the bushel basket. It required 7,11, and 13 hours, respectively, to cool the fruit in the center of the 4-quart, 16-quart, and bushel baskets to 40° F. Tables 5, 13, and 14 show the influence of size of container on storage behavior of grapes. There was generallv an increase in decay and shattering with increasing size of basket.' On the basis of those results, it seems advisable to store grapes in baskets of 12-quart size or smaller, and preferably in the 4-quart size.

TABLE 14.- -Influence of size of container mid loashing on shattering and development of decay of Concord grapes during storage, 19SS

Shattering Decay Storage Length Size of container (quarts) tempera- of ture storage Not Washed Not washeii washed Washed

'F. Weeks Percent Percent Percent Percent :í2_ 32 12 31.7 6.2 12 32 12 21.0 20. 6" 6.0 6.2 4 32 12 16.7 IS. U 4.4 7.0 12 70 1 66.8 49. 1 10.2 10.7 4,.. 70 1 50.0 37.2 2.1 8.6

WASHING Washing the grapes consisted of submerging the baskets in a 0.5- percent hydrochloric acid sohition for 5 minutes, allowing them to drain for 1 minute, and then submerging them in water for 5 minutes (10). The fruit was then stored wet. The influence of Washing on the storage quality of grapes is given in tables 2, 13, and 14. It can be seen from these tables that the washed fruit generally developed somewhat more decay than the unwashed when the usual careful methods of handling in baskets of 4- and 12-quart capacity were followed. This dift'erence between washed and unwashed fruit was lessened by repacking (removing cracked berries which are soon en- tered by decay organisms); the difference between washed and unwashed grapes was likewise increased by use of larger-sized baskets or by rough handling, treatments which increased the percentage of cracked berries and consequently the percentage of decay in both washed and unwashed fruit. The resultson shattering as influenced by washing showed no consistent effect in favor of washing or not washing. SULPHUR DIOXIDE TREATMENT The use of sulphur dioxide to reduce decay of California grapes in transit and storage is rather general {8, 13, 14, 15). Pentzer and his associates {15) report a slightly decreased rate of respiration with the concentration of sulphur dioxide ordinarily used. 18 TECHNICAL BULLETIN 60G, U. S. DEPÏ. OF AGRICIILTLIRK

Limited tests were made to determine tlie adaptability of this treatment to American grapes, in order to secure the liberation of a small amount of sulphur dioxide over a long period of time a method similar to that suggested by Pentzer and Asbury (14) was used. Sodium bisulphite Was scattered evenly on a layer of newspaper on the bottom of the basket and then covered with two thicknesses of newspaper. In 1933 Concord grapes treated in this manner and held at 32° F. for 81 days showed 11.1 percent of shattering and 0.4 percent of decay as compared with 21.1 percent of shattering and 1.9 percent of decay in an untreated check. Table 15 shows the results obtained in 1934. For a 4-quart basket 3 g of sodium bisulphite wore used; for an 8- quart basket 6 g, aiul for a 12-quart basket 10 g.

TABLE 1.').—Influence of sodium bisulphite on shattering and decay of grapes during storage, 19S4

Shattering Decay Length Size \':iri('tv jiiul storai:« temjiernture (°F.) of storage of con- period tainer Check Treated Check Treated

Toncord: Days Quarts Percent Percent Percent Percent 32 89 4 11.3 10.8 1.6 0.5 32.... ._ 96 12 33.0 6.7 3.6 1.9 60 36 4 32.3 11.8 3.7 4.8 60 3fi 8 49.3 24.3 4.3 4.5 70 8 4 19.4 5.3 4.8 5.7 70 8 12 52. 6 11.9 8.4 9.0 Niagara: 32.- 89 4 14.9 12.9 8.0 3.7 32 96 12 1.5.7 5. 1 7.6 4.2 60 :i(i 4 ,5.3 2.8 11.5 10.1 60 30 8 2.9 6.8 11.5 13.5 70 8 12 20.0 5.4 7.3 6.8 70.... 10 4 :i0.0 7. 5 11.3 11.4 Delaware: 32 89 4 5.5 3.3 3.3 2.3 32 96 12 8.2 1.9 5. 3 1.8 60 3fi 4 0.2 3. 1 3.0 2.0 60 ■M 8 6.2 3.6 3.4 2.1 70 10 4 18.« 2.8 3.0 2.6 70 10 12 18.2 6.5 2.9 1.8

Treating with sodium bisulphite generally resulted in a reduction in both decay and shattering. There was no injury to the appearance or flavor of the fruit with these quantities of sodium bisulphite at 32° F., but there was occasional slight mjury at 50° and 70°. Quan- tities of three times the amounts used above were also tried, but since this high concentration generally caused severe injury to the fruit, these results are not reported in detail. The data obtained on the use of sodium bisulphite are not extensive enough to warrant conclusions, but it might be desirable to try it out on a hmited commercial scale where especially long storage is desired. It would probably be advisable to use two-thirds or three-fourths the quantities used in these tests in order to safeguard against danger of injury to flavor or appearance of the fruit. In most cases the use of sodium bisulphite would probably not be necessary, storage at 32° F. probably proving satisfactory in itself. QUALITY OF AMERICAX GKAPK.S IN STORAGK 19

LOSS OF WEIGHT OF GRAPES IN STORAGE The loss of weight of grapes stored undoi' différent conditions for various lengths of time is given in tables 16, 17, and 18. These losses are expressed as percentages of the original weight. From these tables it is evident that loss of weight increased with decreasing humidity at any given tempei-ature, and that at any given temperature and humidity it increased with length of storage. Gen- erally, also, it increased with increasing temperature at any given humidity. DETERIORATION OF FLAVOR IN STORAGE

Very little if any deterioration in flavor was evident so long as the fruit remained marketable. With all varieties at all temperatures the fruit nearly always became unsalable as a result of shattering or decay before there was an appreciable loss in flavor, although occasionally at low humidities there was a rather marked loss in flavor before shattering or decay was serious. Under these circumstances the fruit was shriveled so badly that it was unmarketable. There seemed to be a decrease in acidity and sprightliness of flavor at high temperatures, which was not evident at low temperatures.

TABLE 10.—Influence o/ temperature and humidity on loss of weight of grapes in storage, 193°2

NIAGARA

Los.s of weiíílit after storage for Storaee temperature Reblive C F.) humidity 1 weeli 2 weeks .'Î weeliS 4 week.s 5 weeks fj weeks

Percent Percent Percent Percent Percent Percent Percent 32.. 73 0.94 1. .54 2.10 2.72 4.55 87 .50 1.21 1.90 2.61 3.92 88 .87 1. ,56 2.28 2.90 1.67 2.70 3.92 .5.06 60... ---- 83 2.05 3.95 6.47 91 2.14 4.28 80 5.01

CONCORD

32 79 1.03 2.34 2. 99 3.92 4.12 36 - 87 .15 .71 1.22 2.16 2.76 40 88 .63 1.31 1.96 3. 13 3. .53 1.51 2.97 4.09 83 1. 54 2.88 4.22 91 1.94 6.48 72 3.27 7.29 ..

AVERAGE OF 4 VARIETIES (CONCORD, DELAWARE, WORDEN, AND MOOBE EARLY)

32 05 0.95 32 7» 3.04 32 -. 68 4.45 40 93 2.00 40... 80 3.69 40 6« 5.86 50 05 1.48 .50 SI 6.42 50 67 7.12 20 ÏECHMICAL BULLKTIN 60Ö, U. S. DEPT. OF AtílUCULl'UKE

TABLE 17.—Influence of température und humidity on loss aj weight in storage of Concord grapes, 19S3

Loss of weight after storajie for— Relative Imniidity 87 (lays 57 days 28 days

Percent Percent Percent Percent 94 5.5 3'> _ 79 13.9 6S 16.0 95 7.9 W 80 9.8 68 ■ 14.0 1 96 2.(i \ 80 8.8 66 10.0

T.VBLE 18.—Influence of temperature and humidity on loss of weight in storage of muscadine grapes, 19S4

[.\vGriifïc of (i varieties, Memory, .Scupiwrnong, Thomas, James, Kden, and Flowers]

Loss of weiííht after storajje Loss of weifiht after storage Rela- Tempera- Heiii- for— Tempera- fi.r— tive ture tive i° F.) humid- CF.) humidity 5

Percent Percent Percent Percent Percent Percent Percent Percent :í2 . 76 1 1.6 1 2.7 10.7 60 . 83 4.2 liíi 80 ■ 1.0 1 1.9 7.5 70 . 89 3.6 4(1 89 1 1.4 1 2.9 11.4 80 75 13.6 r,{) 80 ¡3. I 6.2

' Calculated from 3ü-day data. 2 Calculated from lO-day data.

INFLUENCE OF STORAGE ON BEHAVIOR AFTER REMOVAL FROM STORAGE Table 19 shows tho effect of storage conditions on shattering and decay of Concord grapes after removal from storage. It can be seen that the fruit held for 8 weeks or less at 32° F., 6 weeks or less at 30°, and 4 weeks or less at 40° showed no significantly greater amount of shattering when held for 3 days at 70° after removal from storage than similar fruit held for the same length of time at 70° immediately after harvest. It can also be seen that there was no appreciable vari- ation in shattering among tho duplicate lots of fruit examined upon removal from storage without subjecting them to 70° when held foi- 8, 6, and 4 weeks at 32°, 36°, and 40°, respectively. When held longer than these periods at these tem¡)eriitures there was a marked increase in shattering. The ]}ei-centage of decay after 3 days at 70° increased slowly with increasing temperature and length of stoiago period. These results indicate that storage of Concord grapes does not influence their deterioration upon removal from storage provided the fruit has not been held at the storage temperature long enough to produce appreciable deterioration. As mentioned previously (p. 15), conditions in the 70° room used in these e.xperiments were more conducive to shattering than is normally the case, because of the relatively high humidity maintained therein. QUALITY OF AMEBICAN GRAPES IN STORAGE 21

TABLE 19.- -Influence of temperature and length of storage on shattering and decay of Concord grapes after removal from storage, 19S3 After 3 days at 70° F. TTpon removal from following removal Length storage Storage temperature (° F.) of .stor- from storage age Shattering Decay Shattering Decay

Percent Percent Percent Percent Week.i 1 18.4 12.7 4 13.2 1.8 « 14. 1 2.0 K 2.0 2.7 14. r> 4.1 12 10.7 4.4 37. 1 4.1 4 13.0 1.8 0 4.2 3. i 19.7 3.5 Sfi 8 20.9 4.2 33.3 4.7 12 46.9 7.5 4 3.2 2.8 17.2 2.6 40 --- - (i 9.6 4.1 43. 1 3.5 8 r.1.3 5.0 1 Held 3 days at 70° F. immediately after harvesting. LENGTH OF STORAGE LIFE OF DIFFERENT VARIETIES The grapes used in the length of storage-life experiments were carefully harvested in 4-qiiart baskets at the market-ripe stage and stored at 32° F. The humidity of the cold-storage room at this temperature for each of the 3 years is given in table 1. Notes were made on the condition of the fruit at intervals of 1 or 2 weeks. The number of weeks that different varieties of the labrusca, or euvitis, type remained in good condition at 32° is given in table 20. Storage life was nearly always limited by decay or shattering and occasionally by shriveling.

TABLE 20.—Number of weeks that various varieties of grapes remained in marketable condition at 32° F.

Variety Variety

Weeks Weeks Weeks Agawam 16 10 GoiT - Arkansas ñ Green Early... August Giant Hanover Bailey Hartford Banner..-. Herbert _ 12 Beacon Hicks 12 Beta - -■ Krause f> Bride Lindley 12 Brighton Lucile.. 4 Brilliant Lutie 4 Brocton Manito Brown Marsola Campbell Early Massasoit Capti vator Merrimac Catawba Monteflore Cayuga Moore Early... Caywood No. 50 Nectar.-- C hampanel Niagara Champion Noah Norwood 12 Charles A. Green 6 Chicago Olita Ontario--- 8 Cloeta 10 Cochee Oriental Peabody y Columbian Imperial. 4 Concord -- Portland President- 12 Creveling 12 Dakota . Requa Ripley Delaware '"8 Delawba Rock wood Rogers No. 13.- 12 Dunkirk 10 Early Concord Salem Early Daisy -. Shauman Early Dawn StudleyNo. 2.. Early Victor Torkawa Ellen Scott Urbana Empire State Wapauuka Eumedel WittelNo. If)-. Enmelan WittelNo. 31-- Eumetan WittelNo.42.. Fredonia Wittel No. 45-. Gaertner WittelNo. 61.. Goethe Worden. 22 TECHNICAL BULLETIN 606, U. S. DEPT. OF AGRICULTURE

Tho keeping quality of muscadine grapes was considerably inferior to that of the labrusca type. After 39 days' storage at 32° F. the Scuppernong and Thomas varieties were still in good condition, the Eden, James, and Flowers varieties in fair condition, and the Memory in poor condition. ^ PHYSIOLOGICAL STUDIES

BESPIRATION OF CONCORD GRAPES The rate of respiration of Concord grapes at various temperatures is given in table 21. The apparatus used in these determinations was that described by Haller and Rose (6). The fruit was grown at Beltsville, Md., and harvested at the market-ripe stage of maturity. It was placed in the respiration chamber the day of harvesting, but determinations were not begun until the following day, thus allowing the fruit to come to the storage temperature. The results presented are the average of duphcate determinations and of five successive runs of 48 hours each at 32°, 40°, 50°, and 60° F. ; of five runs of 24 hours each at 70°; and of three runs of 24 hours each at 80°. These data show the marked increase in respiration with increasing temperature. It is interesting to compare the rate of respiration of Concord grapes, as given in table 21, with that of several fruits given by Haller et al. Ù). Concord grapes respire much more slowly than straw- berries and peaches, more rapidly than lemons and grapefruit, and, except at 70° and 80° F., more slowly than Washington Navel oranges. Concord grapes respiro slightly faster than apples (11), and usually somewhat more so than Emperor grapes (16). The rate of respiration of Concord grapes as given in table 21 is somewhat slower than that reported by Gore (3) for this variety, possibly because of differ- ences in maturity of the fruit used.

TABLE 21.'—Respiration of Concord grapes as influenced hy temperature, 1932

Oiper storage temperature (" F.) COs per kilogram-hour kilogram- C0,/0i hour ratio

Cubic centi- Cubic centi- Afilligrams meters Tneters 32 -- -- 2.74 1.39 1.53 0.91 40 ------5.32 2.69 2.60 1.03 50 - -- -.- --- 10.75 6.44 6.18 1.05 60 _ - -.. 15.85 8.02 6.34 1.26 32.70 16.50 13.70 1.20 38.55 19.60 16. 66 1.25

CHANGES IN COMPOSITION IN STORAGE In 1932 a number of samples of juice were taken from grapes stored for varying periods at different temperatures to determine the influence of storage on the chemical composition of the juice ; also to ascertain the suitabihty of the refractometer for obtaining approximation of the sugar content of grape juice. The berries were removed from the stems and the jidce was extracted through 12-ounce canvas with a hydrauhc press using a pressure of 500 pounds per square inch for 5 minutes. The acidity was determined essentialljr by the method described by Caldwell (Í). Twenty-five cubic centimeters of grape juice was QUALITY OF AMERICAN GRAPES IN STORAGE 23 diluted with 250 cubic centimeters of water and titrated in an 8-inch evaporating dish with O.lN sodium hydroxide using phenolphthalein as an indicator. Blank determinations on the 250 cubic centimeters of water were subtracted from the final readings. Soluble soUds were determined by three methods, (1) the Abbe refractometer, (2) the Brix hydrometer, and (3) by drying to constant weight in a vacuum oven at 65° C. Sugar analyses were made on samples preserved in alcohol. Twenty- five cubic centimeters of juice was preserved with 50 cubic centimeters of 95-percent alcohol. The alcohol was evaporated on a steam bath and the residue made up to volume. A suitable aliquot was clarified with neutral lead acetate and deleaded with sodium oxalate. Reducing sugar was determined by Bertrand's modification of the Munson and Walker method. Total sugar was determined after in- version of a part of the clarified solution by the same method. The method of extracting the juice, described above, did not prove satisfactory in determining the influence of various storage conditions on the composition of the juice. Although duplicate analyses of the same lot of juice checked very closely with each other, they did not show consistently the effects of different storage treatments. How- ever, the results (table 22) show that the percentage of soluble solids in the juice as determined by the refractometer is very close to that determined by drying in a vacuum oven. By applying a corrective factor for each variety a close approximation to the sugar content of the juice can be determined rapidly on a very small sample by means of the refractometer. From the results obtained it appears that determinations of sugar by means of a refractometer would probably be satisfactory for use where extreme accuracy is not essential. The Brix hydrometer can also be used under similar circumstances as recommended by Winkler (19) as a maturity test for vinifera grapes. In 1934, samples of grapes were taken at intervals from the various storage temperatures and preserved for analysis by freezing. The berries were removed from the stems and were frozen and thawed in sealed glass jars. After thawing the juice was extracted as_ described above. Soluble solids (by refractometer) and titratable acidity were determined on this juice. The results are given in table 23.

TABLE 22.'—Comparison of soluble solids as determined by various methods with sugar analyses in grape juice

Soluble solids by— Sugar Difference between soluble solids as deter- Variety Samples Reduc- mined by re- Refrac- Brix Drying Total fractometer tometer ing and total sugars

Number Percent Percent Percent Percent Percent Percent 18 24.43 24.65 21.87 21.06 2. .56 Do 5 24.49 24.22 24.42 22.01 20.84 2.48 16.36 16.31 16.38 14 16.94 15.93 14.16 13.61 1.78 11 16.16 16.89 15.78 14.02 13.68 2.13 11 16.86 16.65 15.89 20 . 17.22 16.91 17.07 5 16.26 13.04 11.42 2.21 24 TECHNICAL BULLETIN 60 6, XT. S. DEPT. OF AGRICULTURE

TABLE 23.- -Composition of grape juice as influenced by length and temperature of storage of grapes, 1934

Concord Delaware Niagara

Storage tem- Acid Acid Solids/ Acid Solids/ Length Solu- Solids/ perature (° F.) Length Solu- (as Length Solu- (as (as of ble acid of ble acid of ble tar- acid solids tar- ratio storage ,solids tar- ratio storage solids ratio storage taric) taric) taric)

Days Pel. Pet. Dnv.t Pet. Pet. Pays Pet. Pet. 0 13.95 0.63 26.4 0 22.70 0.42 54.0 0 16.20 0.41 39.5 80 7 15. 30 .40 38.2 7 22.90 .38 60.3 7 10.80 .37 46.4 15 22.80 .38 60.0 15 18.45 .34 64.3 7 14.76 .44 33.5 7 16.90 .37 46.7 70— 15 15. 16 .42 36. I 15 22.80 .40 57.0 16 16.90 .36 46.9 60 15 14.95 .61 29.3 15 22.80 .38 60.0 15 16.95 .38 44.6 60 - - 31 15.90 .60 31.8 33 23.60 .,30 65.3 33 17.40 .34 61.2 60... 16 15.40 .62 29.6 15 22.80 .42 ,54.3 15 16.70 .41 40.7 50 31 15.65 .55 28.4 33 23.40 .44 53.2 33 16.70 .37 45.1 60 50 10.30 .,58 28.1 52 24. 55 .42 58.5 62 18.00 .37 48.6 40 21 15.80 .60 26.3 23 22.45 .48 46.8 23 17.10 .39 43.8 40 07 15.80 .62 2,5.5 69 23.20 .42 55.2 69 15.70 .47 33.4 32 31 IB. 26 ..59 27.5 33 21.70 .46 47.2 33 17.10 .42 40.7 32 07 16. 15 .,55 29.4 69 23.65 .43 55.0 69 17.66 .44 39.9 32 SO 16.60 .57 28.9 91 24.45 .47 52.0 91 17. 45 .45 38.8

Freezing the fruit gave results for acidity probably somewhat lower than those obtained on unfrozen juice (9). It is believed however that since all fruit was treated in the same manner the results are compar- able. It was found that there was a sHght increase in soluble solids with storage. This was apparently due to loss of moisture increasing the concentration of sugar in the juice more than respiration decreased it. The most significant change however was the decrease in acidity in Concordgrapes at temperatures of 40° F. or above and an increase in solids/acid ratio. This decrease w^as nearly in direct relation to the temperature of storage and the length of time the fruit was held. There was a loss in sprightliness or "flattening out" in flavor of all three varieties at the higher temperatures. The higher CO2/O2 ratio at the higher temperatures in table 21 indicates a greater respiration of acids under these conditions. At low temperatures there was apparently a slight increase in acidity, but this is probably due to loss of moisture as previously mentioned, so that there was also a slight increase in solids \vith the resultant solids/acid ratio remaining fairly constant. INFLUENCE OF MATURITY ON COMPOSITION The influence of maturity on the composition of grapes is clearly illustrated in table 24. The fruit on August 24 was nearly fully colored, but was still immature. It was considered market ripe from August 29 to September 5 and full ripe on September 12. These analyses were made on juice e-xtracted from unfrozen grapes. Similar results on the influence of maturity on composition have been reported by several investigators. TABLE 24. —Influence of maturity on composition of Concord grapes, 1933

Acid (as Soluble Solids/acid Date of harvesting Date of harvesting Acid (as Soluble Solids/acid tartaric) solids ratio tartaric) solids ratio

Pereent Percent Pereent Percent Aug. 24 0.71 14.65 20.6 Sept. 5 0.67 17. 25 30.3 Aug. 29 .67 15. 30 22.8 Sept. 12 .45 17.60 39.1 QUALITY UF AMElUCA>i URAPES IN STORAGE 25

SUMMARY The amount of shattering and decay of grapes in storage was least at 32° F. and increased with increasing temperature. Decay seemed to develop more or less imiformly throughout the storage period. Shattering became especially marked near the end of the storage period. More shattering and decay occurred at high than at low relative humidities, while shriveling, as would be expected, was most serious at low humidities. A relative humidity of 80 to 85 percent seems to be most desirable for grapes. Delayed storage adversely influenced the storage life of grapes in proportion to the amotmt of delay. Careful handling and removal of cracked berries at time of storage improved the keeping quality of grapes. When the containers were placed so as to allow free air circulation around and above each one it required 22, 29, and 39 hours, respectively, to cool the centers of 4-quart, 16-quart, and bushel baskets of grapes from 70° to 31° F., the latter being the temperature of the storage room. There was usually an increase in the percentage of decay and shattering with increasing size of basket. For the storage of the varieties of grapes used in these experiments, baskets of 12-quart size or less are recommended. Washing the grapes generally caused a slight increase in decay during storage even when the fruit was carefully handled in baskets of 12-quart size or less. Careless handling or the use of larger baskets augmented the injurious effects of washing, whereas careful handling minimized it. The use of sodium bisulphite seemed to cause some reduction in the percentage of decay and shattering, but it is doubtful whether it would be commercially practicable with American grapes except possibly to a limited extent, because of danger of injury and also because satisfactory results can generally be obtained by storing at 32° F. without using the bisulphite. Loss of weight was correlated directly with temperature and in- versely with relative humidity. Grapes removed from cold storage while still in good condition did not develop appreciably more mold or shattering in 3 days at 70° F. than similar fruit not stored. The comparative storage quahties of 84 varieties of labrusca, or euvitis, type grapes and six varieties of muscadine grapes are given. The respiration of Concord grapes increased from 2.74 mg of car- bon dioxide per kilogram-hour at 32° F. to 38.55 mg at 80° F. The refractometer proved to be a satisfactory means of obtaining a close approximation of the sugar content of grape juice. The most significant effect of storage iipon the composition of grapes is a loss in acidity with corresponding loss in sprightliness of flavor at Idgh temperatures. There is a slight increase of solids and acids at low temperatures apparently due to loss of water. Grapes increase in content of solids and decrease in acid content during maturation on the vine. The solids/acid ratio was almost doubled in a period of 19 days. 26 TECHNICAL BULLETIN 60 6, U. ,S. DEPT. OF AGRICULTUllE

LITERATURE CITED (1) CALDWELL, J. S. 1925. SOME EFFECTS OP SEASONAL CONDITIONS UPON THE CHEMICAL COM- POSITION OF AMERICAN GRAPE JUICES. Jour. Agr. Research 30: 1133-1176, illus. (2) CARRICK, D. B. 1930. SOME COLD-STORAGE AND FREEZING STUDIES ON THE FRUIT OF THE VINIFERA GRAPE. N. Y. (Cornell) Agr. Expt. Sta. Mem. 131, 37 pp., illus. (3) GORE, H. C. 1911. STUDIES ON FRUIT RESPIRATION... U. S. Bur. Chem. Bull. 142, 40 pp., illus. (4) HALLER, M. H., HARDING, P. L., LUTZ, J. M., and ROSE, D. H. 1932. THE REPSIRATION OF SOME FRUITS IN RELATION TO TEMPERATUBE. Amer. Soc. Hort. Sei. Proc. (1931) 28: 583-589. (.5) and ROSE, D. H. 1932. APPARATUS FOR DETERMINATION OF CO2 AND O2 OF RESPIRATION. Science (N. S.) 75: 439-440, illus. (6) HEDRICK, U. P., BOOTH, N. O., TAYLOR, O. N., WELLINGTON, R., and DORSEY, M. J. 1908. THE GRAPES OF NEW YORK. 564 pp., iUus. Albany (N. Y. Agr. E.xpt. Sta. Rept. 1907, pt. 2). (7) HusMANN, G. c. 1932. GRAPE DISTRICTS AND VARIETIES IN THE UNITED STATES. U. S. Dept. Agr. Farmers' Bull. 1689, 33 pp., illus. (8) JACOB, H. E. 1929. THE USE OF SULFUR DIOXIDE IN SHIPPING GRAPES. Calif. Agr. Expt. Sta. Bull. 471, 24 pp., illus. (9) JosLYN, M. A., and MARSH, G. L. 1935. EFFECT OF COLD AND FREEZING STORAGE ON WINE COMPOSITION. Indus, and Engin. Chem. 27: 33-35. (10) LUTZ, J. M., and RUNNER, G. A. 1933. STUDIES ON THE REMOVAL OF ARSENICAL SPRAY RESIDUE FROM GRAPES. Amer. Soc. Hort. Sei. Proc. (1932) 29: 345-349. (11) MAGNESS, J. R., and DIEHL, H. C. 1924. PHYSIOLOGICAL STUDIES ON APPLES IN STORAGE. JüUr. Agr. Research 27: 1-38, illus. (12) MANN, C. W. 1929. THE HANDLING OF CALIFORNIA TABLE GRAPES. U. S. Dejlt. Agr. Cir. 83, 14 pp., illus. (13) PENTZER, W. T. 1931. THE COLD STORAGE OF GRAPES. Icc and Rofrig. 81: 84. (14) and ASBURY, C. E. 1934. SULPHUR DIOXIDE AS AN AID IN THE PRESERVATION OF GRAPES IN TRANSIT AND STORAGE. Blue Anchor 11 (8): 2-4, 23, illus. (15) , AsBURY, C. E., and HAMNER, K. C. 1934. THE EFFECT OF SULPHUR DIOXIDE FUMIGATION ON THE RESPIRATION OP EMPEROR GRAPES. Amer. Soc. Hort. Sei. Proc. (1933) 30: 258-260. (16) ROSE, D. H., WRIGHT, R. C, and WHITEMAN, T. M. 1933. THE COMMERCIAL STORAGE OF FRUITS, VEGETABLES, AND FLORISTs' STOCKS. U. S. Dept. Agr. Cir. 278, 40 pp. (17) STUBENRAUCH, A. V. 1909. [HANDLING AND STORAGE OP CITRUS FRUITS AND GRAPES.] Ice and Refrig. 36: 8-9. (18) THAYER, P. 1918. STORAGE OF GRAPES. VARIETIES THAT STAND UP UNDER ARTIFICIAL CONDITIONS. Ohio Agr. Expt. Sta. Monthly Bull. 3: 315-317. (19) WiNKLER, A. J. 1932. MATURITY TESTS FOR TABLE GRAPES. Calif. Agr. Expt. Sta Bull 529, 35 pp., illus. (20) WRIGHT, R. C. 1937. THE FREEZING TEMPERATURES OF SOME FRUITS, VEGETABLES AND FLORISTS' STOCKS. U. S. Dept. Agr. Cir. 447, 10 pp. (Revised, 1929.) ORGANIZATION OF THE UNITED STATES DEPARTMENT OF AGRICULTURE WHEN THIS PUBLICATION WAS LAST PRINTED

Secretary of Agriculture HENRY A. WALLACE. Undersecretary M. L. WILSON. Assistant Secretary HARRY L. BROWN. Director of Extension Work C. W. WARBUBTON. Director ef Finance W. A. JUMP. Director of Information M. S. EISENHOWER. Director of Personnel W. W. STOCKBEEGER. Director of Research JAMES T. JARDINE. Solicitor MASTíN G. WHITE. Agricultural Adjustment Administration H. R. TOLLEY, Administrator. Bureau of Agricultural Economics A. G. BLACK, Chief. Bureau of Agricultural Engineering S. H. MCCRORY, Chief. Bureau of Animal Industry JOHîî R. MOHLER, Chief. Bureau of Biological Survey IRA N. GABRIELSON, Chief. Bureau of Chemistry and Soils HENRY G. KNIGHT, Chief. Commodity Exchange Administration J. W. T. DUVEL, Chief. Bureau of Dairy Industry O.E. REED, Chief. Bureau of Entomology and Plant Quarantine^ LEE A. STRONG, Chief. Office of Experiment Stations JAMES T. JARDINE, Chief. Farm Security Administration W. W. ALEXANDER, Administrator. Food and Drug Administration WALTER G. CAMPBELL, Chief. Forest Service FERDINAND A. SILCOX, Chief. Bureau of Home Economics LOUISE STANLEY, Chief. Library 1 CLARIBEL R. BARNETT, Librarian. Bureau of Plant Industry E.G. AUCHTER, Chief. Bureau of Public Roads THOMAS H. MACDONALD, Chief. Soil Conservation Service H.H. BENNETT, Chief. Weather Bureau WILLIS R. GREGG, Chief.

This bulletin is a contribution from

Bureau of Plant Industry E.G. AUCHTER, Chief. Division of Fruit and Vegetable Crops H. P. GOULD, Senior Pomologist, and Diseases. Acting, in Charge. 27

. S, GOVERNMENT PRINTING OFFICE: 1938

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