NEWSLETTER ARTICLES

Small Farms and Specialty Crops

IMPROVING PRODUCTION AND POSTHARVEST HANDLING OF ORGANIC FRUITS AND VEGETABLES FOR DISTANT MARKETS

Most organic growers and shippers recognize that they can no longer apologize for the quality or appearance of organic produce and must ship product that is comparable in every way to conventionally grown produce. The marketing chain has also become accustomed to expecting organic fruits and vegetables with the appearance of conventional product. This is a new area for many organic growers who are accustomed to selling through direct marketing or shipping short distances. Many of these growers are used to shipping to customers with a relatively short field-to-table shelf life period. Even more experienced conventional growers/shippers, who have recently initiated organic production, are learning some of the limitations of postharvest handling of organic product.

Organic producers are limited with respect to the options available for preserving fresh fruits and vegetable quality in the marketing chain. Special care should be taken with the permissible aspects with an eye on compensating for other prohibited practices. Most organic certifying agencies, for example, limit the concentration of free chlorine which can be used in dump tank water. Long a key aspect of sanitation and surface cleansing of hydro-cooled product, conventional growers will commonly use 50 to 200 ppm of free chlorine in dump tanks. Organic producers may be limited to as little as 4 ppm. The surface cleansing and disinfestation which comes from free chlorine is directly related to concentration, and free chlorine is rapidly tied up by organic matter and soil arriving on fruit from the field. The pH of the water is also important in the effectiveness of the chlorination and a pH of 6.5 to 7.5 should be maintained.

Organic growers must monitor chlorine levels in hydro-coolers and dump tanks regularly or even continuously to be certain that they get the most from the little they are permitted to use. A more vigorous pre-wash may also be advisable with many products, and the pre-wash water should also be chlorinated. It may be possible with many products to add brushes, sponges, or high pressure spray as an additional measure in cleaning product from the field. Conventional growers are encouraged to empty and refill their dump tanks daily and use self-cleaning residue screens in hydro-coolers to keep out organic residue. These recommendations are especially important for organic growers, and they may wish to empty and replace water more frequently depending upon the circumstances. Higher levels of chlorine are permitted for cleaning equipment in organic operations and more frequent cleaning may be helpful.

Ozone is emerging as a new potential postharvest treatment for fruits and vegetables. It is widely used in many countries to purify drinking water, and new postharvest applications have been developed. It is approved for organic production by many certifiers although cost and effectiveness are still limiting factors in many situations.

Some organic certifying agencies permit the application of food grade waxes or oils to products. Fungicides which are often mixed with waxes in conventional packing operations are prohibited, however, and surface infestations of fungal organisms may be a problem for organic producers in some circumstances.

Some products, which are traditionally hydro-cooled, may also be effectively pre-cooled with forced air. Often this may involve special considerations in the design or management of the system to assure adequate pre-cooling and to compensate for humidity requirements of the specific product.

Cold room designs and efficiency is an area where special attention will also help organic growers improve postharvest quality. Many growers frequently fool themselves about the cooling power and temperature of their pre-cooling and cold room facilities. It is important to design the system to actually cool a specific volume of product to a specific temperature. And it is important to operate the cooling system to actually obtain and hold those temperatures. It may be desirable, for example, to operate at the lower end of recommended storage temperature ranges to compensate some for lost effectiveness from limitations on free chlorine concentrations.

Many aspects of pre-harvest production management affect postharvest shelf life. Irrigation and fertility management may have a dramatic effect on postharvest quality of products as diverse as cantaloupes and onions, for example. A great deal is known about pre- and postharvest management of most fresh fruits and vegetables. Pre-harvest management practices should be carefully reviewed for each product with attention directed toward potential impact on shelf life.

Physical handling of the product throughout the harvest and postharvest handling chain can dramatically affect shelf life. Many postharvest decay organisms enter through bruised or scratched product and more careful handling will limit this kind of damage. There are various types of new plastic containers in a multitude of sizes and shapes for all aspects of the harvest packing operation. These containers permit "unitizing" of the harvested product into larger packages and are readily palletized. These containers can also be cleaned and sanitized easily. This will limit repeated handling of individual or small volumes of fruit which can aggravate physical damage.

In summary, it would be valuable for organic growers who are having arrival or quality problems to review in detail the handling stream for each product shipped. The following are some of the general areas which organic growers and shippers may wish to review with each specific product:

• Pre-harvest Management
• Harvest Management
• Temperature Maintenance
• Water Quality
• Pre-wash?/Scrub?
• Cooling Equipment Design
• Frequent Equipment Cleaning
• Storage Temperature
• Transport Temperature
• Dedicated Packing Facilities
• General Sanitation