Chill Fruit For Good Postharvest Management

As we  head into the summer months, it is useful to remember the importance of maintaining the cold chain to retain the quality of harvested fruits. The cold chain begins as soon after harvest as possible. For some highly perishable crops, like berries, delays of more than one hour can result in reductions in marketable fruit. Fruits should be protected from sunlight after harvest and during transportation to the packing area.

Importance Of Temperature Management

Why should you go to the effort to maintain the cold chain after harvest? It’s good economics. Holding fruit at the lowest safe temperature reduces physiological changes, decay development, water loss and shriveling, and growth of harmful pathogens. Low temperatures generally maintain the fruit at a higher standard of quality.

Pre-Cooling

Pre-cooling should be practiced whenever feasible to rapidly remove the field heat from products. Hydro-cooling and forced-air cooling are the most common pre-cooling methods for fruit. However, when neither of these methods is available, room cooling should be used. The method of choice depends on the type of fruit and length of storage desired.

Tender fruit such as berries are often packed directly in the field and, therefore, forced-air cooling or room-cooling are generally the only options. Forced-air cooling is highly recommended for these fruit due to their high perishability. Hydro-cooling can increase decay susceptibility in some fruit, such as table grapes and strawberries, due to the difficulty of removing moisture after cooling. Hydro-cooling is frequently used for apples, peaches, nectarines, and cherries, and sometimes used for pears.

Forced-Air Cooling

Forced-air cooling can be accomplished with fruit in bins, field lugs, or packed cartons. The important factor is the ability to move the cold air past the fruit within their container. Container ventilation and sufficient fan capacity are critical, as is sufficient refrigeration capacity. Fruit should not be left on the forced-air cooler beyond the time required to cool to seven-eighths, as the final one-eighth of cooling can take a long time. Lengthy cooling may lead to excessive dehydration. Seven-eighths cooling is calculated by the following formula:
(Starting fruit temperature – cool room air temperature) x 0.875

Fruit temperature should be monitored in the warmest location on the forced-air tunnel during cooling — usually the inside location on the pallet furthest from the fan — to determine when it reaches seven eighths cooling. It is simple to design a small forced-air cooler to cool a couple of bins or half a dozen cartons at one time in a cold room. All that is needed is a fan mounted in a piece of plywood and a tarp (see reference #1 below).

Hydro-Cooling

During hydro-cooling, fruit are passed through a cold water bath or a shower of cold water. Movement of water past the surface of the fruit during hydro-cooling will speed the rate of cooling, and the colder the water, the faster the cooling.

Care should be taken with shower systems not to damage the fragile fruit. For sweet cherry, a screen should be installed in the shower system no higher than 8 inches above the fruit surface to break the fall of the water droplets and avoid pitting injury. Hydro-cooler water must also be sanitized to prevent the spread of pathogens. A range of water sanitizers can be used, including sodium hypochlorite (liquid chlorine), ozone, peroxyacedic acid, and chlorine dioxide. When sodium hypochlorite is used, care should be taken to avoid accumulation of sodium from excessive reuse of water before the hydro-cooler water is changed. Build up of sodium has been shown to damage the skin of apples and pears.

Cold Storage, Transportation, And Distribution

After pre-cooling, fruits should be stored at their optimum temperature to extend the storage life (see reference #4 below). It is important to recognize that some fruit are chilling sensitive. This means they are damaged by exposure to temperatures above the freezing point. Many tropical fruit should not be stored at temperatures lower than 50°F or 55°F. Subtropical fruit such as citrus should be stored at temperatures between 32°F and 50°F. These optimum temperatures should be maintained throughout transportation and distribution, except in cases where fruit are being held at warmer temperatures to enhance ripening.

Topics: ,

Leave a Reply

Berries Stories
Berries
May 2, 2017
Southeastern Strawberry Growers Advised to Prepare for Disease Pressure
Recent rain is conducive to the main strawberry fruit rot diseases, according to the chief of the Southern Region IPM Center. Read More
Berries
April 26, 2017
Tips To Manage Winter-Damaged Blueberries
While low-chill varieties in Southern states may have experienced freeze damage for the second year in a row, giving those plants extra care will help ensure a good start to the 2018 growing season. Read More
The Hill family of Southern Hill Farms in Florida
Berries
April 13, 2017
Florida Farming Family Staying on Top of the Blueberry Game
The Hill family of Southern Hill Farms continues to up their efforts to diversify business and stay out ahead of a competitive market. Read More
Berries
April 10, 2017
North Carolina Blueberry Crop Still Kicking
Thanks to pruning cuts and a diverse mix of cultivars, the majority of the crop survived a series of March freezes. Read More
Closeup of Florida blueberries
Berries
April 6, 2017
Study Shows Bumblebees Can Boost Blueberry Yield Big Time
UF/IFAS researchers find placing hives of the distinct pollinator in the field pumps up output by 70%. Read More
Berries
March 30, 2017
Chateau Herbicide SW Now Registered for Use in Citrus, Caneberries
Broad spectrum preemergent herbicide to control broadleaf and grasses. Read More
SWD On Raspberry
Berries
March 26, 2017
Outsmarting SWD with Social Media
Entomologist in Kentucky uses social media for pest updates, trap catches. Read More
Freeze protected blueberry bushes in Florida
Berries
March 25, 2017
Florida Blueberry Crop Escapes Slap from Late-Season Cold Snap
Freeze protection tactics prove fruitful as local producers look to gain from Georgia’s loss. Read More
Frozen blueberries
Berries
March 15, 2017
Arctic Blast Gives Southern Fruit Growers the Chills
Peaches and berries in bloom most at risk from freezing temperatures. Read More
Growers boot up drone technology on the farm
Berries
March 3, 2017
Specialty Crops Primed for Precision Agriculture
Employing the latest horticultural technology tools could have substantial financial benefits for producers of hand-picked specialty crops, according to a new research paper. Read More
Berries
March 2, 2017
Pruning Pointers for Dormant Care of Berries
If you haven’t started pruning your berries, it’s time you do. Read More
Berries
February 26, 2017
Advantages to Growing Southern Highbush Blueberries
Growers in some regions where temperatures don’t get too low could consider the benefits of Southern highbush varieties. Read More
Berries
February 23, 2017
Primocane: A Major Innovation in Berry Production
I’ve witnessed the rise of primocane-fruiting blackberries, from first selections to integration in the market. Read More
2017 Florida Strawberry Picking Challenge winners
Berries
February 22, 2017
Florida Strawberry Picking Contest a Big Winner for Charity
Fourth-annual fundraising event brings in more than $100,000 to benefit children of local farmworkers. Read More
Registration area at the 2017 Florida Blueberry Growers Association Spring Meeting
Berries
February 17, 2017
Florida Blueberry Growers Counting on a Comeback
With last season's disaster in the rear view, all eyes are searching for bluer skies. Read More
The Latest
Berries
May 23, 2017
Researchers Examining Potential for Long…
Team at Penn State University using low and high tunnels and plastic coverings to extend raspberry and strawberry seasons. Read More
Berries
May 15, 2017
Grower Comments on Pyrethroids Being Sou…
Comment period on popular class of insecticides opens today. Read More
Berries
May 4, 2017
Florida Farming Pioneer Still Making the…
Alto Straughn presented with University of Florida’s Distinguished Alumnus Award. Read More
Berries
May 2, 2017
Southeastern Strawberry Growers Advised …
Recent rain is conducive to the main strawberry fruit rot diseases, according to the chief of the Southern Region IPM Center. Read More
Berries
April 26, 2017
Tips To Manage Winter-Damaged Blueberrie…
While low-chill varieties in Southern states may have experienced freeze damage for the second year in a row, giving those plants extra care will help ensure a good start to the 2018 growing season. Read More
Berries
April 13, 2017
Florida Farming Family Staying on Top of…
The Hill family of Southern Hill Farms continues to up their efforts to diversify business and stay out ahead of a competitive market. Read More
Berries
April 10, 2017
North Carolina Blueberry Crop Still Kick…
Thanks to pruning cuts and a diverse mix of cultivars, the majority of the crop survived a series of March freezes. Read More
Berries
April 6, 2017
Study Shows Bumblebees Can Boost Blueber…
UF/IFAS researchers find placing hives of the distinct pollinator in the field pumps up output by 70%. Read More
Berries
March 30, 2017
Chateau Herbicide SW Now Registered for …
Broad spectrum preemergent herbicide to control broadleaf and grasses. Read More
Berries
March 26, 2017
Outsmarting SWD with Social Media
Entomologist in Kentucky uses social media for pest updates, trap catches. Read More
Berries
March 25, 2017
Florida Blueberry Crop Escapes Slap from…
Freeze protection tactics prove fruitful as local producers look to gain from Georgia’s loss. Read More
Berries
March 15, 2017
Arctic Blast Gives Southern Fruit Grower…
Peaches and berries in bloom most at risk from freezing temperatures. Read More
Berries
March 3, 2017
Specialty Crops Primed for Precision Agr…
Employing the latest horticultural technology tools could have substantial financial benefits for producers of hand-picked specialty crops, according to a new research paper. Read More
Berries
March 2, 2017
Pruning Pointers for Dormant Care of Ber…
If you haven’t started pruning your berries, it’s time you do. Read More
Berries
February 26, 2017
Advantages to Growing Southern Highbush …
Growers in some regions where temperatures don’t get too low could consider the benefits of Southern highbush varieties. Read More
Berries
February 23, 2017
Primocane: A Major Innovation in Berry P…
I’ve witnessed the rise of primocane-fruiting blackberries, from first selections to integration in the market. Read More
Berries
February 22, 2017
Florida Strawberry Picking Contest a Big…
Fourth-annual fundraising event brings in more than $100,000 to benefit children of local farmworkers. Read More
Berries
February 17, 2017
Florida Blueberry Growers Counting on a …
With last season's disaster in the rear view, all eyes are searching for bluer skies. Read More