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WSU-TFREC/Postharvest Information Network/Quality of Red and Golden Delicious Apples Shipped from Washington State-Progress Report for the 1989 and 1990 Crop

Quality of Red and Golden Delicious Apples Shipped from Washington State-Progress Report for the 1989 and 1990 Crop

Introduction and Justification

The Washington State apple industry is facing increasing competition in domestic and foreign markets from apple producers in other parts of the world. In order for Washington producers to keep their competitive edge, every fruit shipped must be tasty as well as have eye appeal.

Integration of many factors determines the condition and quality of fruit shipped from a single warehouse. The aggregation of lots shipped from all warehouses to a single market determines the consumers' perception of fruit quality from Washington State. Unfortunately there is a significant difference in the condition of fruit shipped from different warehouses.

This project uses a survey and education approach to pinpoint the reasons for these differences and then assists growers and warehouse managers in modifying practices to optimize fruit condition. The objectives of the project are to:

  1. Obtain information about packing practices followed by a number of Washington packinghouses
  2. Evaluate the quality and condition of fruit shipped from these warehouses
  3. Summarize this information to describe the condition and quality of apples shipped from sample warehouses
  4. Summarize this information to describe the condition and quality of apples shipped from Washington State at different times in the season
  5. Formulate plans for participating warehouses to improve fruit quality and condition for subsequent seasons.

The following is a summary of the results of the survey work done for both the 1989 and 1990 crop years. This report contains summary information of use to the general industry. This survey is being continued for the 1991 crop year. A second section contains information which is shared with only the management of the warehouse involved and is not included here.

Cooperating Warehouses

Technicians sampled fruit from 16 warehouses for the 1989 crop and 17 for the 1990 crop. There were many more packinglines sampled for the 1990 crop than for the 1989 crop since both Red and Golden Delicious apples were sampled in 1990 (Table 1).

Table 1. Location and number of packinglines sampled.

Red Delicious
Red Delicious
Golden Delicious
North of Wenatchee444

Each packingline was sampled on a regular basis throughout most of the packing season. In 1989-1990 Red Delicious apples were sampled from October 15 to May 31. In 1990-1991 Red Delicious were sampled from October 22 to May 31 and Golden Delicious were sampled from December 17 to May 31.


The technicians gathered information on fruit handling procedures at each warehouse each week. In addition they brought sample apples back to the laboratory for quality and condition testing.

At the warehouse the technician examined the packingline. In some warehouses fruit was presized prior to packing. In this case only the packingline was examined. The information gathered at the warehouse included:

  1. Fruit temperature prior to the dumper
  2. Water temperature in the dumper
  3. Fruit temperature before the dryer
  4. Air temperature inside the dryer
  5. Fruit temperature immediately after the dryer
  6. Fruit temperature at the box filler
  7. Air temperature in the packed box holding room
  8. Lighting on the sorting table

Half of the fruit brought back to the laboratory was examined the following day and half was held at 70°F for 7 days and examined. The fruit was evaluated on the following criteria:

  1. Fruit firmness
  2. Soluble solids
  3. Acidity
  4. Internal disorders
  5. Starch content

Firmness of Apples Shipped from Washington

Interim Summary and Conclusions

Firmness of Apples Shipped from Washington

1) Apple Firmness by Week

The following section describes the firmness of Red and Golden Delicious apples sampled from packinglines and analyzed as an industry aggregate throughout the packing season. The firmness of apples from individual packinglines has been reported to the warehouses involved and is not included here.

a) Red Delicious

The firmness of Red Delicious apples of the 1990 crop was significantly improved over that sampled in 1989 crop (Figure 1). This was true regardless of harvest date (data not shown) and packing date. In general, regular storage fruit was softer than CA-stored fruit. Red Delicious apples harvested in 1990 were of superior quality to those harvested in 1989.

b) Golden Delicious

We are not able to compare the firmness of Golden Delicious apples over the two crop years since we were not budgeted to sample Goldens from the 1989 crop. Golden Delicious apples sampled in December were softer than those sampled at any other time of the season (Figure 2).

2) Temperature Observations

Management of temperature is critical to preserving apple quality. Apple temperature can be raised by immersion in water in the dump tank or by being subjected to hot air in dryers. The temperature of Red Delicious (3/8 inch below the skin) was measured before and after the apples were floated out of the dump tank and measured again before and after the dryer. The temperature of the dump tank water has more of an effect on final fruit temperature than that of the air in the dryer.

a) Red Delicious Temperature Profiles

In the 1989 crop year, apples averaged 44.8°F immediately prior to being dumped. The dump tank water averaged 81.4°F. Apples sampled immediately before being waxed averaged 6l.5°F, for a total rise of 16.7°F (Figure 3). The apples were then passed through dryers in which the average temperature was 122°F. When the temperature was measured at the box filler it was the same as before the dryer. Total temperature rise was 16.2°F.

In the 1990 crop year, Red Delicious apples averaged 40.6°F immediately prior to being dumped. The dump tank water averaged 76.5°F and the apple temperature after waxing was 55.4°F, thus the rise in temperature was 14.8°F (Figure 4). The dryer temperature averaged 115.4°F and resulted in a fruit temperature rise averaging 3.8°F from the dryer. Total temperature rise in packing was 18.6°F.

There were only slight differences when temperature profiles of Red Delicious direct pack and presize packinglines are compared (Table 2). The dump tank water was 5°F warmer in direct packinglines than in presize packinglines; the air temperature in the dryer in direct packinglines was 10°F warmer. However, fruit temperature at the box filler was the same (Table 3).

Table 2. Temperature comparison between Red Delicious packed on lines with and without a dryer for the 1990 crop year (degrees F).

 # of packing linesFruit prior to dumpDump tempFruit prior to waxerDryerFruit exiting dryerFruit at box filler
Direct Pack839.7379.8055.09120.8859.8358.67
Presized 1841.3074.2455.56109.7760.3259.67


Table 3. Temperature profile for Red Delicious 1990 crop by packingline (degrees F).

Packing lineFruit at
Temp rise at
box filler

In summary, the dump tank water temperature had more of an effect on fruit temperature (rise of 16.7°F in 1989: 14.8°F in 1990) than the dryer temperature (rise of 0.0°F in 1989: 3.7°F in 1990).

b) Golden Delicious Temperature Profiles

There are major differences in the manner in which Golden Delicious apples are packed within the industry. Some firms use a separate packingline for Goldens while others use the same equipment as with Red Delicious. Some firms wax some or all of their Goldens while others do not wax Goldens. Goldens may be presized or packed directly. It was expected that these differences would lead to differences in fruit temperatures. However, the temperature profile of Golden Delicious sampled from the 1990 crop year was very similar to that of Red Delicious.

Golden Delicious apples were sampled starting in December 1991 and for the rest of the packing season for the 1990 crop year (Figure 5).

Average fruit temperature prior to dumping was 40.4°F; dump tank water averaged 63.7°F and the fruit temperature was 51.8°F immediately before the dryer. Thus Goldens averaged a temperature rise of 11.4°F from being immersed in the dump tank. Average temperature of the dryer was 117.5°F which increased the temperature of the apples by 3.4°F. Three of the Golden Delicious packinglines sampled do not have dryers. Fruit sampled prior to dumping was the same (Table 4). The dump tank water averaged 52.5°F on lines without dryers and 60.8°F on lines with dryers. The average fruit temperature immediately before the dryer was 47.6°F and 52.4°F, respectively. Golden Delicious dryer temperature was 111.4°F and fruit temperature rise was 3.0°F. Goldens run on lines with dryers experienced higher dump tank water and dryer temperatures. Goldens run on lines with dryers averaged 8.0°F warmer than those run on lines without dryers (Table 5).

Table 4. Temperature comparison between Golden Delicious packed onlines with and without a dryer for the 1990 crop year.

Fruit prior
to dump
Dump temperatureFruit prior to waxerDryerDryer exitFruit at box filler
No dryer40.7952.5447.6347.25


Table 5. Temperature profile for Golden Delicious 1990 crop by packing line (degrees F).

Packing line Fruit at dumper Dump water Dryer air Final temp Temp rise at
box filler
O239.4044.70 120.0063.6024.20

The temperature of Red Delicious apples sampled as they were being placed in boxes averaged 61.0°F during the 1989 crop year and 60.0°F for the 1990 crop year. The temperature of Golden Delicious at the box filler averaged 55.4°F when a hot air dryer was not used. All of these temperatures are well above optimum levels.

The differences in fruit temperature vary greatly among packinghouses (Figure 6). For example, one packingline for Goldens which does not dry the fruit had the dump tank water at 104°F while the other two held the dump tank water in the high 40s and low 50s°F. This resulted in fruit temperatures in the box of 56.0°F for the packingline with high-temperature dump tank water. The other two lines which do not use a dryer had fruit at 49.0° and 44.0°F.


1) Red Delicious

The quality of Red Delicious grown in 1990 was far superior to that grown in 1989. This was true regardless of maturity at harvest or the time of packing. Washington simply had superior fruit in 1990. It was ironic that this fruit came from trees that bloomed early and were harvested comparatively later, thus allowing the fruit to hang on the tree for a long period of time. It is logical that ambient temperature and not time on the tree had a great deal to do with fruit quality.

The survey of temperatures on the packinglines has shown that the major point at which fruit temperature rises is in the dump tank and not the dryer. In 1989 the average rise from the dump tank averaged 17.0°F while there was no rise from the dryer. In 1990 this was slightly different, although the relationship stayed the same. Red Delicious temperatures rose 15.0°F in the dump tank and another 4.0°F in the dryer.

In both years the temperature of the fruit going into the box averaged 60.0°F 3/8 inch below the skin.

2) Golden Delicious

Sampling of Golden Delicious was done solely for the 1990 crop. Fruit firmness of Goldens sampled was about 1.5-2.0 pounds lower in December than in any other time of year. We will be watching to see if this is a trend.

Most of the packers of Golden Delicious included within this study use warm air to dry the fruit. Three packinglines did not have dryers on their Golden lines. The temperatures of fruit going into the box were 44.0, 49.0, and 56.0°F. The majority of the packers used a drying tunnel. Their fruit averaged 57.0°F. There is quite an impressive difference in temperature between packinglines using dryers and those not drying Goldens.

The great difference between fruit quality and condition between years is illustrated in the Red Delicious data. Studies like this must be repeated over several years in order to include differences in fruit quality.

The key to reducing fruit temperatures appears to be reducing the temperature of the dump tank water. Water in the dump tank is far more effective than air in the dryer in raising fruit temperatures.

This study raises questions concerning the rate of cooling of apples in boxes and what effect this temperature profile has on fruit condition and shelf life. We have done a series of experiments to begin to address these questions. These data are presented in a separate report.

Dr. Eugene Kupferman, Ken Miller, and Lori Kutch

WSU Tree Fruit Research and Extension Center
1100 N. Western Ave., Wenatchee, WA 98801

Tree Fruit Postharvest Journal 2(4):4-11
December 1991

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