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CONTROLLED ATMOSPHERE STORAGE OF APPLES

ae By Ben H. Pubols Economic and Statistical Analysis Division Economic Research Service

APPLES IN COLD STORAGE, 1964-65

MIL. BU.

50 —__U. §. total

ae

Regular

NOV. FEB.

END-OF-MONTH DATA. % CONTROLLED ATMOSPHERE STORAGE.

U. S. DEPARTMENT OF AGRICULTURE NEG. ERS 4168-66(1) ECONOMIC RESEARCH SERVICE

More than a fifth of the apples in regular cold storage declined in cold storage on October 31, in with shipments therefrom, There- both 1964 and 1965, were in after, stocks in and shipments from controlled atmosphere(CA)storage, both types of storage followed Over the next 4 months of 1964- similar courses. The storage 65, the volume sealed in CA stor- pattern for 1965-66 appears to be age changed little while the volume close to that for 1964-65,

Reprinted from the Fruit Situation, TFS-158, January 1966, by the Economic and Statistical Analysis Division, Economic Research Service

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TFS-158 - 18 - JANUARY 1966 CONTROLLED ATMOSPHERE STORAGE OF APPLES

By Ben H. Pubols Economic and Statistical Analysis Division ' _Eeonomie Research Service

Nature of Controlled Atmosphere Storage

Modification and control of the atmosphere in fruit storage plants is a method used increasingly in recent years to hold the condition and extend the storage life of fruit, especially apples. This is in addition to the main- tenance of artificially cooled temperatures and high relative humidity, basis requirements for regular cold storage.

All fresh fruits continue to respire after harvest--that is, they take in oxygen and give off carbon dioxide. Many fruits, including apples, ripen after harvest. This ripening process may be greatly retarded by the usual cold storage methods, which reduce fruit metabolism including the rate of respiration. Under controlled atmosphere (CA) methods, respiration and ripening may be reduced further by lowering the oxygen content of the air, which normally consists of 21 percent oxygen, 78 percent nitrogen, and 1 percent other elements.

Two principal techniques are employed to reduce the percentage of oxygen in the apple storage rooms. The first involves the use of oxygen, and its displacement by carbon dioxide, in natural respiration of the fruit. In this process, however, provision must be made to prevent excess accumulation of carbon dioxide, which could be harmful. The second method involves the circulation of atmosphere of the desired composition (produced by commercial generators) through the storage rooms to replace normal air. By this method the oxygen content may be lowered sufficiently in a matter of hours, or at most a few days, much faster than by the first method.

Many fruits have been tested in CA storage to determine the most suitable atmospheric conditions and temperatures for prolonging their life. They include apples, pears, peaches, grapes, strawberries, bananas, and oranges. Results have been most successful with apples. For apples in CA storage, levels of 2 to 3 percent oxygen and 1 to 7 percent carbon dioxide together with the appropriate minimum temperature, usually 30 to 38 degrees (depending on the variety), and 95 percent relative humidity, are the most satisfactory for minimizing respira- tion and the ripening process. Each apple variety differs slightly in requirements for oxygen and carbon dioxide, temperature, and relative humidity for optimum results.

CA storage has been unusually successful with McIntosh apples, allow- ing storage for 7 to 8 months at 38 degrees F. When held under 38 degrees in regular storage, McIntosh are susceptible to internal breakdown, particu- larly "brown core”. But at 38 degrees in CA storage, internal breakdown is avoided and storage life is prolonged. Other varieties in regular storage

TFS-158 -19 - JANUARY 1966

can be safely held at temperatures of 30 to 32 degrees. Even for these apples, CA storage has been reported as beneficial in prolonging storage life when held in such storage beyond a 60- to 90-day period.

Essentials for CA storages include practically air-tight rooms and special equipment to achieve and maintain satisfactorily the desired atmospheric conditions. This is in addition to the requirements for adequate refrigeration and air circulation for regular cold storage. Accordingly, construction and operating costs are somewhat higher for CA storage than for regular cold storage. Over time, the additional costs should be recovered through increased revenues resulting from superior quality fruit.

To maximize results from CA storage, several precautions should be ob- served. The apples to be stored should be picked at the proper stage of maturity censistent with the desired color. CA storage cannot correct over-maturity; it ean only aid in holding the firmness or condition of the fruit as it is at the time of storage. Once picked, the apples should be quickly placed in the CA rooms, the oxygen content lowered within the required 20 to 30 days, and then the apples kept under optimum atmospheric control until the rooms are opened for movement of the fruit. For these apples to be in the best possible condition when they reach consumers, the fruit should be kept under refrigeration, insofar as practicable, during transportation, handling, and display by retailers.

Extent of CA Apple Storage

The commerical application of controlled atmosphere in the storage of apples in the United States began over a quarter century ago. Growth of this kind of apple storage has been rapid over the past 5 to 10 years, and further gains are in prospect. The location and capacity of such storage was surveyed for the first time by the U. S. Department of Agriculture in 1963, covering data for October 1, 1963. A like survey on CA storages for October 1, 1965, was started last fall and is still underway. Monthly data on apples in CA storage were collected initially for the volume so stored at the end of January 1963. Since then, similar data have been collected monthly and published in the Department's Cold Storage Report.

The 1963 survey disclosed that 265 storage plants had CA rooms on October 1, 1963, with a capacity of more than 11 million bushels of apples. This was 12 percent of the total usable space of the 1,612 apple houses in the United States. Although substantial increases in CA storage capacity have been made since October 1, 1963, capacity data from the 1965 survey are not yet available to show the gains. However, over 12 million bushels of apples were reported in CA storage on November 30, 1965. Furthermore, not all available CA space was filled. It is estimated that present capacity slightly exceeds 13 million bushels.

Of the 265 plants having controlled atmosphere storage rooms on October 1, 1963, 159 plants (60 percent) were in the Eastern States. The other 106 plants were nearly equally divided between the Central and Western States. ‘The total

TFS-158 - 20 - JANUARY 1966

capacity of all plants CHISW25 , 000 bushels) was divided among these 3 regions as follows: Eastern, 48 percent; Western 34 percent; and Central, 18 percent. Capacity per plant in the Western States (77,612 bushels) was more than twice that in each of the other 2 regions. Among States, New York, Washington, and Michigan (in that order) led in capacity (table 2).

The quantities of apples in storage--CA, regular, and total--by months, 1963-65, are shown in table 3. Total U. S. stocks build up rapidly during late summer and early fall when harvesting is most active, reach a peak usually by the end of October, then decline over the rest of the marketing season ending the following midyear.

Total apples handled by apple houses in a season is greater than the top volume reported at the end of October. During harvest, apples move out of, as well as into, apple houses. This applies particularly to regular cold storage operations, because apples sealed in CA rooms usually are held a minimum of 90 days to qualify for CA sales. This time period accounts mainly for the small increase in CA stocks at the end of November and the slight change over the next few months. Meanwhile, apples from regular storage account for most of the sales. Stocks of apples in the 2 types of storage at the end of each month of the 1964-65 season are shown in the cover chart.

Of total stocks of apples in cold storage at the end of October 1964, apples in CA rooms comprised about 21 percent and those in regular storage the other 79 percent. By the end of March, when CA rooms were opened in increasing numbers, CA apples constituted about half of total stocks, because of the large reductions in regular storage over the preceding months. Movement and stocks of both types of apples followed similar pathways over the next few months.

Total cold storage stocks of apples on October 31, 1965, were approxi- mately 56 million bushels, about 1 percent larger than a year earlier. CA stocks again comprised about 21 percent of the total. For the entire 1965-66 season, the pattern of stocks probably will fairly closely match that of 1964-65.

State Regulation of CA Apple Storage

State storage regulations for CA apples are in force in at least 12 States: Maine, New Hampshire, Massachusetts, Connecticut, New York, New Jersey, Pennsylvania, Virginia, Michigan, Washington, Idaho, and California. For CA- stored apples to be certified for marketing as "CA apples", all 12 States except Michigan require that the oxygen in the storage rooms be reduced to a maximum of 5 percent within 20 days after the rooms are sealed. In Michigan, the period is 30 days. Moreover, all 12 States require that most varieties of apples be kept a minimum of 90 days with the oxygen level no higher than 5 percent. Michigan, New Jersey, and Virginia allow a minimum of 60 days for Jonathans.

All le States require that daily records be kept of temperature and of oxygen and carbon dioxide percentages. They also require annual registration or licensing of storage facilities, and registration or license number stamped

TFS-158 =O a= JANUARY 1966 Table 2.--Controlled atmosphere storage: Number and capacity of plants with controlled atmosphere storage rooms, United States, October 1, 1963

Plants : Capacit

Reet pe cas) Bemor ’ Quantity ‘Percentage ' Volume ‘Percentage ° per plant 1,000

Number Percent Bushels Percent Bushels Eastern States ; 159 60.0 5,376 48.3 33, 811 Central States 3 57 Pies 1,946 17.5 34,140 Western States ; 9 18.5 3,803 34.2 Ti ,0Le United States : 265 100.0 dalesales 100.0 41,981

Data derived from "Capacity of Refrigerated Warehouses in the United States, October 1, 1963’. SRS, USDA, August 1964.

on all CA apple containers. In addition, some States specify inspection to assure that U. S. condition standards and other requirements are met.

Economic Importance of CA Apple Storage

Apples properly stored in CA rooms hold their condition well from fall until the following summer. This allows growers and others engaged in storing and selling the apples an extended period for marketing their fruit. Moreover, it permits more orderly marketing, especially at harvest time. Flexibility in choice of time to market is perhaps the greatest after January 1. During late winter and spring, when stocks of both types of apples are about equal, both types are highly competitive for the buyers' dollar. In the past, CA apples, especially the McIntosh, have usually brought premimum prices. The CA method of storing permits increased opportunities for apple marketers to maximize their returns from the fruit.

Consumers also benefit from CA apple storage. It provides them with increased quantities of firm, crisp, juicy apples late in the season. They have shown their preference for such apples by paying top or premimum prices.

Selected References on Controlled Atmosphere Storage

1. Hardenburg, R. E. 1964. Developments on Postharvest Use of Controlled or Modified Atmosphere for Quality Retention of Horticultural Crops. (Speech) ARS, U. S. Dept. Agr., Beltsville, Md.

2. Olsen, Kenneth L., and Schomer, Harold A. 1964. Oxygen and Carbon Dioxide Levels for Controlled Atmosphere Storage of Starking and Golden Delicious Apples. Mktg. Res. Rpt. No. 653. U.S. Dept. of Agr., Washington, D. C.

Agricultural Research Service. 1965. A Review of Literature on Harvesting, Handling, Storage, and Transportation of Apples. ARS 51-4. U.S. Dept. of Agr., Washington, D. C.

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TFS-158 = 23 - JANUARY 1966 Table 4.--Apples, commercial crop: Production, average 1959-63, annual 1964 and indicated 1965 1/ : Average’ “Indicatea’* : Average : * Indicated State and area * 1959-63: 1964 1965 State and area + 1959-63 ° 1964. 1965 1,000 1,000 1,000 *: 1,000 1,000 1,000 bu. bu. bie. 2: bu. bu. bu. Maine 1,818 1,950 2,200: : Minnesota 332 430 290 New Hampshire 1,380 1,180 1,370: : Iowa 274 300 370 Vermont 1,036 920 900; : Missouri : 1,248 1,600 1,600 Massachusetts 2,820 2,800 3,150; : Kansas : 206 290 280 Rhode Island 172 180 200:: : Connecticut 1.312 1,280 1,370:: WN. Central S23, 98ChE 2950s wie 5 100 New York 20,860 21,500 23,500: ; : New Jersey : 2,760 2,800 2,600; ; Kentucky 336 00 450 Pennsylvania : 8,940 11,500 _11,000; ; Tennessee : 316 400 320 : , Arkansas A PAIS 205 N. Atlantic : 41,0 Lu. ,110 46.290: : : : —_ 2 :; S+ Central ;____867__1,105___—-980_ Delaware 296 2h0 280:: ; Maryland 1,422 1,560 1,450:: Total Central 2 2,682. 30,875 28.770 Virginia : 10,090 9,800 10,5005 : West Virginia 3; 5,260 5,700 5,100: : Montana 33 30 20 North Carolina eS (29) 2,400 4.200: : Idaho 1,090 1,450 1,350 : :: Colorado alpsis{o) 1,600 1,600 S. Atlantic :_19,428 19,700 21,530: :New Mexico 481 1,200 650 : sUtan 348 430 310 Total Eastern > 60,526 63,810 67,820: : Washington 22,280 25,500 24,000 _ SSS! Oreson : 2,086 1,920 2,200 Ohio 3,260 4,200 3,600°* California : 786__ 12,400 000 Indiana 1,726 2,300 nee5077 Illinois 22llo, 9,500 S,50078 aveerens ee Michigan * 13,160 16,500 16 ,000* * : ee Wisconsin 1,542 1,650 1,300'* United States '2/122,641 139,215 135,720

1/ Estimates of the commercial crop refer to the total production of apples in the commercial apple areas of each State. For some States in certain years, production includes some quantities unharvested on account of economic conditions.

oy Average includes States for which estimates have been discontinued.

Table 5.--Apples, commercial crops 1/: Production by varieties,

United States, average 1959-63, annual 1964-65

Variety Ay 1964 1965 ¢° Variety : eee 1964: 1965 1,000 1,000 1,000 :: > 1,000 1,000 1,000

bu. bu. bu. =: : bu. bu. bu.

Summer: : *+Winter, cont'd: :

Gravenstein > 2,419 Sis 1,110 *: Cortland > 3,608 3,622 4,194 Other summer > 2, 44h 2,820 2,382 *: Delicious ey tion 33,938 33,332 Total : I 863 6,154 3,492 *+ Golden delicious: 2/8,252 11,222 812,142 a eee sem MOTT LOS). Fly llores 17,479 18,335 Fall: : >: Northern Spy > 2,912 3,436 3,510 Grimes Golden Sap alpalicfe) 1,156 1,059 R.I. Greening Pcie 3,591 3, 42h Jonathan > 8,292 9,768 10,078 :: Rome Beauty 8,781 11,061 10,762 Wealthy He Wasi 1,28 1,217 *: Stayman 6,604 reratene [5,032 Other fall + {9D 1,686 1,939 *: Winesap > 8,187 7,539 DA (Ale Total oe 12905: a d5, 09 14,293? Yellow Newtow3/? 4,054 4, Ou6 4,114 LE ae nL noes > 9 VORKeinpertal! 6,483 7,487 6,522

Winter: Baldwin Ben Davis and Gano Black Twig (Paragon)

25655 1,158 279

2,084 862 180

++ Other winter 2,033 :: Total

765 +3

153 ??Total all varieties: 122,641

*__ 45793 22939 9,105 *"105,196 119,203 117,935

139,215 135,720

1/ Estimates of commercial crop refer to the total production of apples in the commercial areas of each

State. 3/ Albemarle Pippin.

2/ Golden Delicious included with "other winter varieties" prior to 1960 in Colorado.