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- Post-harvest needs of growing peppers should not be ignored
- By Karen Gentry
Associate Editor
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- Growers need to remember that the post harvest part of growing peppers is really important and shouldn’t be ignored.
That was the message Bob Herner, professor of horticulture at Michigan State University, gave at this year’s Great Lakes Vegetable Growers Convention in Grand Rapids, Mich.
“Probably the most important thing is temperature control,” said Herner.
Cooling methods come into play when it comes to controlling temperature. When peppers come into contact with water and then the peppers aren’t dried and the temperature warms up, there’s more decay, Herner said.
“It’s critical to dry peppers if there’s any contact with water,” Herner said. There’s trouble with decay when there’s warm, humid weather when the peppers are harvested and then shipped. Herner said temperatures need to be maintained about 50 degrees F or a little bit lower.
He advises growers to find reputable trucking companies, as things are out of growers’ hands once the peppers are on the truck. Herner said a lot of time commodities will be mixed on loads on trucks and the needed temperatures are not necessarily compatible. When peppers are shipped to their destination within two or three days, post-harvest considerations are not as critical compared to when longer periods are involved.
Many shippers are getting away from using water to cool peppers, through the use of forced air cooling, according to Herner. Air is forced through the package causing a pressure differential from one side of package to another. “This draws air right through the package rather than around it,” Herner said.
Herner said Michigan growers use a lot of different ways to handle peppers. Some growers have their own cooling facilities, some will take to a packing shed while some pack peppers in the field.
Listed below are post-harvest, pepper recommendations, distributed by Herner.
Harvesting
Harvesting by hand results in less injury than mechanical harvesting and should be used for peppers for the fresh market.
Time of day to harvest
Research suggests that harvesting after the fruit temperatures are at least 60 degrees F will result in less mechanical injury during harvesting and handling with less decay likely.
Packing in the field vs. packing shed
Field packing results in less injury but may be difficult to control quality, including size, going into the container unless the harvesting crew is very well trained. There is also the problem of how to clean dirty fruit.
- Packing in a shed can result in more injury than field packing but it may be easier to control quality.
- Take care when dumping from buckets into large field containers.
- Keep harvested peppers in the shade.
Dry vs. water dumping
Dry dumping may cause more injury but may result in less microbial contamination because of lack of water contact.
- Water dump causes less injury and can help clean soil from the fruit. Microbial contamination may be a problem and dump water should be chlorinated. Dry fruit thoroughly after any contact with water. This can be done by drying rollers and/or air flow.
Chlorination recommendations
Maintain 100 to 150 ppm free chlorine.
- Maintain a pH of 6.5 to 7.5.
-Clean dump tanks, hydrocoolers and packing lines and sterilize with chlorine at least once a day.
Packing shed recommendations
Lower drop heights or eliminate drops.
- Cushion all hard surfaces.
- Make sure any brushes used are recommended for peppers as stiff brushes can cause surface damage.
- Match rotational speed of brushes with line flow.
- Do not run cold fruit over packing line.
- Make sure there is adequate light and comfortable stations so workers can do a good job of eliminating culls.
Prevention of water loss
Use high relative humidity of 90-95%.
- Wax peppers with a thin layer to prevent water loss, to enhance appearance and to decrease vibrational injury during shipment.
- Shrink-wrap film extends shelf-life by about one week.
Container
Make sure the container has at least 5% venting on ends and sides for best air flow and temperature management.
- Larger elongated slots are better than a larger number of smaller holes.
Pre-cooling
Forced air cooling is the best choice.
- Room cooling is a poor second choice as it takes too long to cool.
- Hydro-cooling can cause problems with later infection if the peppers are not dried after cooling and the peppers are maintained at low temperatures. Water should be chlorinated. This method is capital intensive.
- Vacuum cooling is expensive but could be used.
Temperature and relative humidity
Optimum temperatures are 45-55 degrees F and relative humidity should be 90-95%.
Modified or controlled atmospheres - not recommended.
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