Direct Marketing and Quality Control

Adapted by Robert Kasmire, Vegetable Specialist, UC Davis Cooperative Extension, and Christie Wyman, Coordinator, Small Farm Center, UC Davis Cooperative Extension, from Florida Cooperative Extension publication "Vegetable Crop Fact Sheet" by Mark Sherman.

One reason consumers shop at farmers markets, fruit stands, and other direct marketing outlets is because they know the products are freshly picked and the quality of the produce is higher.

Poor postharvest handling practices can cause extensive loss of market quality, resulting in lower prices. Fresh produce is alive, and after harvest it depends upon its own food reserves for the energy needed to remain alive. We want to manipulate postharvest conditions so that product deterioration is minimized and the quality delivered to the consumer is maximized. We can do this by providing favorable:

Harvesting practices
Packaging
Postharvest environment

Harvesting Procedures

1. Harvest at optimum maturity for best eating quality. Immaturity increases water loss and shrivel. Some fruits (e.g., strawberries and tomatoes) may never ripen satisfactorily; others (melons, sweet corn) may be low in sugars. Overmature products such as beans, corn, and celery become tough. Overmature sweet corn will be low in sugars and starchy. Both immature and overmature produce are more susceptible to decay.
2. Harvest during the coolest part of the day. This is most important for highly perishable products, because high temperatures lead to rapid deterioration. To minimize the spread of certain diseases, harvest should begin as soon as the foliage has dried.
3. Harvest frequently for roadside marketing. Harvesting throughout the day to replace produce that has been sold will prevent quality deterioration between harvest and sale.
4. Handle all produce gently. Cuts, punctures, abrasions, crushing, and bruising happen in every handling step. Fruits and vegetables may appear undamaged, but internal bruising may have occurred. Most decay and much of the water loss (shriveling) develops on fruits or vegetables where damage has occurred. You can reduce this by eliminating as many steps as possible between harvesting and marketing. The simplest and most effective way is to pack products directly into merchandizing containers. If this can't be done, pack products directly from field containers into merchandizing containers. Handle products carefully, and don't underpack or overpack your containers.
5. Keep containers clean. Use water containing about 70 ppm chlorine (or one teaspoon of household bleach mixed with one gallon of water) to kill decay-causing organisms on the container surface and to remove sand or other trash that could injure the produce. (Plastic containers are easier to keep clean than wooden ones.)
6. Keep harvested products out of the sun. This will minimize wilting, sunburn, and prevent unnecessary heating of produce. On a sunny, hot day, tomatoes held in the sun for one hour can be as much as 25°F hotter than fruit held in the shade.
7. Avoid rough roads. Vibrations can cause considerable damage to produce. Grading field roads may be worthwhile. Tie or wedge the load securely to help reduce damage. Most small farm operators ship or haul their produce in nonrefrigerated trucks. If the weather is very hot or very cold, this can cause noticeable quality loss. Even refrigerated trucks can only maintain temperatures--they can't cool products during transit. If you have a refrigerated truck, keep the refrigeration units, doors, walls, and air delivery ducts in good operating condition to maintain adequate refrigeration.

Packaging

1. Don't overpack or underpack your containers. Packing too tightly causes compression bruises. If packed too loosely, the individual pieces vibrate against each other and sustain vibration bruises.
2. Use new or sterilized containers. Residue from old produce can infect new produce.
3. Make sure containers are not damaged. For instance, 80% of the stacking strength of fibreboard cartons is at the corners. If corners are damaged, much of the strength is lost. Carton strength is also reduced by bulge packing, wetting, and poor stacking in loads.
4. Containers need adequate ventilation to permit cooling and temperature maintenance.

Strawberries, when covered with polyethylene film wrap and kept at 10°C, have 22 percent less dehydration and 33 percent less decay than those stored uncovered at 26.7°C after 3 days storage.

Postharvest Environment

Temperature, water loss, and atmosphere composition

Temperature is the most important factor available for controlling product deterioration. Optimum temperatures increase shelflife and help maintain quality. (See Table 1) Temperatures that are too high increase water loss and encourage decay. Temperatures that are too low can cause chilling injury to sensitive products (decay, discoloration, pitting, and loss of flavor and ripening ability). If you do not have refrigeration you can help maintain the shelf-life of products by harvesting frequently, keeping them out of the sun, and stacking them so that they have sufficient air circulation.

Intermittent warming can be used to reduce or prevent chilling injury. Peaches can be stored for six weeks or more at 0°C if they are warmed for two days at 180°C after three weeks.

Water loss from fresh produce causes wilting in leafy vegetables and shriveling in fruits, tubers, and roots. Sprinkling or misting some vegetables (see Table 1) with fresh water, trimming tops from root crops and shanks from corn, and using protective plastic packaging will help reduce water loss.

TABLE 1. Handling Information for Vegetables