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Saturday, February 16, 2019

WSU-TFREC/Postharvest Information Network/Monitoring the Quality of Apples in Long-Term CA Storage

Monitoring the Quality of Apples in Long-Term CA Storage


Timing for harvest of Washington apples has improved, principally as a result of the Apple Maturity Program. Proper harvest timing permits late season marketing of apples of high quality and superior condition.

Each year in some orchards harvesting is delayed because of lack of color development or size. If this late- picked fruit is placed in CA storage for spring or summer marketing, fruit condition problems may arise. Although this fruit may have good firmness directly out of CA storage, it softens rapidly, resulting in an undesirable product arriving on the retail shelf.

Here is a simple technique to evaluate fruit condition and detect potential problems. It is useful in determining lots suitable for export shipment as opposed to local sales. It also can assist in determining the sequence of rooms to be opened.

Testing Procedure

  1. At harvest, select uniform fruit of an average size for that lot. Use fruit of similar sizes to minimize fruit size effects on firmness.

  2. Place about 80 fruit per lot in a polyliner leaving a 2" opening on top. The liner is used to prevent shrivel. It may, however, increase the amount of scald in Red Delicious above that seen on fruit in the bin.

  3. Sample several lots of fruit in each room.

  4. Place the samples close to the door for easy access.

  5. Perform the following test twice during the storage season on each lot of fruit. For example, in a long-term CA room (June opening) test each lot in February and again in April.

    Special Note: Due to the later harvest this season, some fruit was picked from certain locations which experienced night temperatures below 32°F. Repeated examination of this fruit while in storage should be undertaken at monthly intervals to ensure the continued arrival of quality fruit at retail markets.

  6. At each testing date, remove 40 fruit from each lot. Place 30 fruit in a box with a polyliner open (about 2 inches) on top. Set this box in a room with fairly constant temperature of 70° F.

  7. Test the other 10 fruit on the day the sample is taken from the CA room. Pressure test each apple twice, avoiding the sunny side. Visually inspect the apple both externally and internally. Record the average firmness of the 10 apples.

  8. Repeat the firmness test and visual inspection of 10 fruit from each lot at intervals of 3-4 days. For example, if the samples are taken from the CA room on Thursday (Day 1), then test the next 10 apples the following Monday (Day 4), and 10 more the next Friday (Day 8). For export shipments test the fruit on the following Thursday (Day 14).

  9. Graph the average firmness values for each lot of fruit as shown in the figure.


The firmness test of apples is currently the most consistent indicator of fruit quality after storage. Unfortunately, testing fruit immediately upon removal from the storage room only provides an indication of fruit firmness out of storage. It does not indicate how well fruit will maintain its firmness in the marketing channels.

For example, see the accompanying graph in which two lots of Red Delicious were tested. When the fruit was tested the day the sample was taken from storage, both lots tested about 15½ pounds. After repeated tests, Lot 1 proved to be the better choice for long distance marketing.

Differences of less than ½ pound are probable within the error of the method and are not significant.

Warehouses are urged to work with this method, to provide markets with fruit of high quality and excellent condition.

Dr. Ken Olsen(1) and Dr. Eugene Kupferman(2)

(1)USDA-SEA; Tree Fruit Research Laboratory; Wenatchee, WA
(2)WSU Tree Fruit Research and Extension Center
1100 N. Western Ave., Wenatchee, WA 98801

Post Harvest Pomology Newsletter, 2(4): 3-4
November 1984

Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us