Maintaining the Quality of Your Vegetables
By Harriet Behar

This article was first printed in the Sept/Oct 2008 issue of the Organic Broadcaster, published by the Midwest Organic and Sustainable Education Service.

Vegetable growers know the hard work that goes into planting, weeding and harvesting vegetables throughout the season. However, not all growers know how best to harvest, clean, pack and store your produce so you present and deliver high quality, nutritious and attractive vegetables. Considering the various needs of your markets is the first place to start, since produce put into a CSA box meant for consumption within a week is a different animal from a vegetable to be sold into the wholesale market where it may be more than a week until the vegetables are put into a consumer’s grocery basket.   Selling vegetables at an open air farmer’s market requires different handling than delivering vegetables directly to a retailer’s or restaurant’s cooler. 

If you are novice grower and are unsure of what your market may be looking for, take a trip to the grocery store!  If your produce does not look as good as what is already on the racks, then it is probably not good enough to sell to retailers.  You can get away with “uglier” produce at a farmer’s market or to your CSA, but over-ripe, heavily insect damaged, diseased and otherwise unsavory produce should not be sold.  You don’t want to build a reputation as a poor quality grower, this label will follow you for years to come, even if your produce quality improves over time. If your plan was to sell beets with tops, and the greens have insect damage or other flaws, then clip those tops and sell beet roots rather than a poor looking product.  If the vegetable is not intact, such as the end of cucumber was damaged when harvesting, sort this out.

Before You Plant
If long shelf life is one criterion for the vegetables you grow, remember to consider this when ordering seeds for next year, paying special attention to those varieties with the description “holds well in the field”.  Harvesting “over-mature” vegetables will cause problems when you plan to hold them in storage for any length of time, so purchasing seed varieties that will hold their quality longer is a good plan.  If you are growing veggies that are more perishable, such as heirloom tomatoes and melons, be aware of their special harvest and handling needs.  All crops need to harvested in the cool of the day, kept out of the sun and put into optimum storage conditions quickly, in order to retain quality for as long as possible. 

Harvest With Care
Harvesting should be handled by workers who know what a quality product looks like. It is better to just leave the poor quality produce in the field than to harvest and haul it back to the packing shed, only to have to toss it out into the compost.  Make sure everyone knows how many leaves in a bunch of kale you want, or what sized cabbage heads your retailer prefers so your boxes are uniform and your customers get what they want consistently week after week.  Speaking of customers, don’t be afraid to ask them what they want……a restaurant making gazpacho may be willing to take larger cucumbers than the retailer down the street, and you can make better use of your harvest time if you know how much of each type of veggie you can sell.  For farmer’s markets, keep good records from week to week and year to year so you can plan for the type of vegetables that sell. As you probably know, there is not as big a market for mid season zucchinis as there is for early and late season zucchinis, and you can plan your succession plantings accordingly.  It is quite frustrating to have to till in a nice crop of any type of produce, but even the most successful fresh market growers do this with a vegetable planting once in a while.

Setting up a good system for harvesting which recognizes the special requirements of what you are growing is also a good idea.  For instance, young zucchinis have a very thin skin. They should be picked wearing smooth cotton gloves and handled as little as possible to keep the skin in good condition.  Winter squash should be harvested with clippers, cutting the stem as close as possible to the squash without leaving a sharp point that could cut into a neighboring squash in the box.  These are two examples where quality could be damaged during harvest and packing and is very vegetable specific.  No matter what vegetable you are working with, it is always a good idea to harvest with trimmed nails.

Know What and How to Clean
Knowing the best method of cleaning the produce once harvested is also important. Should the product be chilled in ice water, or should it be cleaned using a damp cloth?  Can you submerge it in water for a period of time (i.e. spinach) or should you avoid contact with water at all (i.e. basil)?  All water in contact with organic produce must be clean enough to drink, do not use water from creeks or springs.  Don’t sell ready to eat salad mixes unless you are certain that you have a system in place which does multiple rinses and you are confident that it is absolutely clean and safe.  It would probably be best to have your washing and packaging area licensed as a formal kitchen by your state food licensing authority. They can help you put all of the necessary safeguards in place if you wish to sell ready-to-eat products, but it is probably safer to sell all of your produce as field washed and that is all.  The liability risk for ready-to-eat raw foods is one that most market gardeners should not take.  The USDA has a series of guidelines focused on food safety for fresh produce, www.cfsan.fda.gov/~dms/prodgui4.html or search online for “Guide to Minimize Microbial Food Safety Hazards of Fresh-cut Fruits and Vegetables”.

Proper Containers are Key
Plan to have acceptable harvest containers for the type of produce you are handling.  Plastic tubs and buckets work well, but be careful to not overfill them to the point where they crush the produce in the bottom.  A variety of deep and shallow containers will come in handy.  If you use second-hand waxed cardboard boxes, make sure they never contained nonorganic produce, since these may have been fumigated and are not allowed under organic regulations.  Wooden crates should only be used for crops with thick skins to avoid damage.  Take care when putting the produce in the tubs or boxes. Depending on the type of produce, you may want to align them so all of the butt ends are facing one way or you may alternate, whatever works to protect the skin and leaves of the vegetable from damage caused by the neighboring vegetable.  Experiment with packing the vegetable in your containers before you send a whole crew out to harvest. 

Some items can be field packed, such as kale, broccoli and cabbage.  Don’t pack the boxes directly on the ground so they get dirty and leave a muddy mess when you stack them.  You can bunch, trim and pack with either one person doing all three jobs or splitting the work up in a crew with someone bunching and another person trimming and packing.  Field packed produce should be transferred to a cooler as soon as possible to remove the field heat.  If you can, pack the pallets or arrange the boxes so there is cool air circulation all around the boxes when they come directly from the field.  Harvesting in the early part of the day, or even in the evening with lights is an option as well.  It would be nice if every day before market day it was 55 degrees and cloudy……but we all know that doesn’t happen.  Only field pack produce that is clean and not dusty or dirty. 

Some growers have hauled old milk bulk tanks or stock tanks out into the field to do a quick dip to wash off dirt before putting the produce in the waxed box, but again this would be only for fairly clean produce. The water would quickly get too dirty to use for something like radishes, for instance.  Also, the water may start getting warm if you are out in the field for a long period of time, which would be exactly the opposite of what you want.  Some vegetables such as string beans benefit from not having any contact with water, and are an excellent candidate for packing in the field.  Remember, a tidily packed box, rather than one that has the produce packed in it chaotically, will make a better impression on the buyer, can be packed tighter, and protects the quality of the produce better during storage and shipment.

Cooling for Longer Life
Plan ahead to get the produce into a shady area as quickly as possible and a cooled area very soon after that.  Removing the “field heat” from produce quickly will go a long way to increasing the shelf life and maintaining the nutritional quality of your produce for the consumer. Hydro cooling in a tank of water is one way to remove field heat from certain types of vegetables, but does offer some risk of spreading pathogens in the water. Depending on the size of the tank and how much produce you run through it, you might want to consider adding chlorine or peroxyacetic acid to the wash water.  For certified organic growers, make sure you contact your certification agency before you add anything to the water. They can help you understand the concentrations you are allowed to use.  A low tech method of washing greens can be a tank of water with a perforated pvc pipe running through it horizontally, connected to a solid pvc coming in vertically into the tank with a fan that blows air through, making bubbles and gently agitating the water to help you with washing.  Mesh bags can also be used. There is a tip sheet available from the UW on this method. (http://www.hort.wisc.edu/freshveg/Healthy%20Farmers.htm) Sweet corn can be hydrocooled in the husk by putting in mesh bag and dunking in cold water, and then draining and top icing with crushed ice if available.

Another method of hydrocooling is with a cold water spray, either with a hand hose or in a vegetable washing tunnel.  There are numerous types of tunnels and washers on the market, and many you can find used, or make your own.  Check out the internet for more ideas.  If you are harvesting a lot of veggies, you may want to have a dedicated crew out in the field and another crew in the packing shed, ready to receive the freshly picked produce for washing and packing.  The UW Madison has a handy tip sheet on how to build a simple hands-free washer that allows you to wash produce with two hands, which is less stressful on your body and allows you to wash more quickly.  The hands-free washer tip sheet is also available at http://www.hort.wisc.edu/freshveg/Healthy%20Farmers.htm, along with numerous other good ideas for small-scale growers, including setting up a packing shed floor plan.

Important Storage Issues
Be aware that many vegetables respire and release an ethylene gas.  This gas can cause other susceptible vegetables in the same cooler to ripen quicker than you may wish, such as causing the leaves on broccoli to yellow and drop off, potatoes to sprout, and yellowing of items such as cucumbers, broccoli, kale and spinach.  In order to lessen this damage, you should avoid storing green leafy vegetables with ripening fruits such as apples or tomatoes.  Keeping the produce at a low temperature also slows the production of ethylene.  There is also the risk of odors from one produce item affecting a different item if kept in a tight storage area for any length of time.  Onions are the main culprit, so store them separately from other items, especially cabbage, celery, potatoes and carrots.

Humidity is also an issue, so have a gauge in your cooler so you know where you stand and if you need to provide some ventilation or add humidity.  Having water on the floor in the cooler is an easy way to add humidity, but squeegee it out on a regular basis so it doesn’t begin to harbor pathogens. Just a small amount of water can add humidity so experiment to figure out what you might need.  The produce itself will also add some humidity as it respires, so check the humidity regularly with produce in the cooler and adjust as necessary.

Prepare an area where you can sort and remove any diseased or damaged produce, since these will decay faster. We all know that one bad apple can spoil the whole bushel.  For larger growers, having a conveyor belt is a good investment, but for smaller growers, this may not be what you need.  In either case, have good lighting and comfortable seating in your sorting area, for obvious reasons.  If you are selling into a variety of markets, you may sort for size as well as quality, striving for uniformity in a retailer’s case while giving the restaurant the larger peppers for stuffing. Again, know your market.

Some sort of cooler is necessary if you are going to keep veggies for any period of time.  An inexpensive cooler using an air conditioner can be made with plans for this available at www.storeitcold.com/how.php. You can also achieve a variety of temperatures in the cooler by putting up plastic sheeting between zones, with the colder areas closer to the cooling source and the warmer areas near the door.  It really does make a difference when you keep the vegetables in their optimum storage temperatures, so try to set up these temps for each type of crop you grow. 

Temperature and Humidity Needs Vary
The following is a guideline for the temps and humidity needs for a variety of vegetables:
32F-36F and 90-98% humidity- Green onion, sprouts, greens, turnips, peas, shallots, rhubarb, rutabaga, radish, parsnip, leeks, kohlrabi, horseradish, all herbs except basil, fresh garlic, fennel, corn, celery, celeriac, cauliflower, carrots, cabbage, brussel sprouts, broccoli, beets and asparagus.
32F-36F and 85-95% humidity- berries, apples and other tree fruits, muskmelon.
45-50F and 85-95% humidity- summer squash, peppers, okra, beans, eggplant, cucumber, watermelon, potatoes
55F-65F and 85-95% humidity- basil, tomatoes and sweet potatoes.
55-65F and 65-70% humidity- pumpkins and winter squash.
34-36F with less than 65% humidity- onions, shallots and potatoes.

Successful Transport
Shipping the cooled produce is another consideration, and depending on your size, you may have a refrigerated truck or not.  If not, damp blankets over the produce can be helpful. Putting a wrapped frozen jug of water in the middle of boxes while you are selling at farmer’s market can keep the produce fresher until the end of the selling day.  Obtaining an ice machine (crushed ice) for putting on items such as sweet corn and broccoli is essential if you are planning on selling quantity to wholesale markets.  If you are harvesting items such as blackberries, have a beverage cooler with some ice packs out in the field and put each pint or quart you pick in the cooler as soon as it is full to give this very perishable product a longer shelf life.

Wholesale markets have a specific size of box and produce size requirements, which can be found by searching the web for the specific vegetable or in a new book recently published by www.FamilyFarmed.org entitled "Wholesale Success". 

Lastly, consider long term storage for your fall harvested crops such as beet roots, carrots, onions, potatoes and even cabbage and leeks.  Good ventilation is very important for long-term storage as well as maintenance of cool temperatures at the lower end of the humidity needs for the crop.  MOSES will be sponsoring a field day at the John and Jane Fischer-Merritt farm near Duluth MN on September 20th, highlighting their large, multi-roomed energy efficient root cellar, where they provide their CSA members and local stores high quality, local produce throughout the winter months at a minimum of cost to them for cooling and ventilation. I hope to see you there. Happy harvesting!

Harriet Behar is the MOSES Outreach Specialist. She was an organic inspector and inspector trainer for many years and has an organic bedding plant and vegetable operation with her husband in Southwest WI.