How To Ensure Proper Handling And Display At Markets

Fresh vegetables that have been harvested, handled, packed, stored, and transported using the best procedures and materials are ultimately delivered to grocery stores or other destination markets for sale to consumers. At this point, the vegetables may be stored an additional day or two before being displayed for a few hours to a few days until purchase. If not purchased, the vegetables are discarded as part of the display rotation.

Preventing Problems

While the vegetables are at the destination market, there are key practices that need to be implemented to prevent all of the good handling that came before from being for naught. 

The keys to maintaining vegetable quality at destination markets are:
    • Careful handling to minimize mechanical injuries;
    • Storage and display within the optimum temperature range;
    • Maintenance of adequate relative humidity; and
    • Proper sanitation of the storage and display areas.

Additionally, expedited handling and effective rotation is critical for reducing shrink and providing the best quality vegetables to the consumer.

Distribution center and produce department managers need to have a very good idea of the condition of the perishables in their care, and they must work together so that only those vegetables that are at the peak of freshness are placed on display. This does not necessarily mean FIFO (first in, first out), but rather in some cases, a product received today should go out to the store or out on display before a product received yesterday!

Ideally, vegetables should be delivered to the destination market at their optimum temperature and quickly unloaded and transferred to a storage room that is also at the optimum product temperature. For most vegetables, the optimum temperature is 32ºF to 36ºF (as low as possible without risk of freezing the product). Other vegetables are chilling sensitive and should not be held below a critical temperature that ranges from about 45ºF to 60ºF, depending on the product. Chilling injury may not occur if the product is briefly exposed to a temperature below its critical limit, but the effect of low temperature exposure is cumulative, which still makes even brief exposure to chilling temperatures a risk. (Information on the temperature requirements for vegetables can be found online in USDA Handbook 66 located here: www.ba.ars.usda.gov/hb66/contents.html).

Vegetables that are not chilling sensitive should definitely be displayed in a refrigerated display merchandiser, and even chilling-sensitive vegetables benefit greatly from being displayed at their optimum temperature. Unfortunately, the design and management of refrigerated display merchandisers often leaves much to be desired. As shown in the figure above, the temperature within most display cases is not very uniform. We have measured air and product temperatures in many supermarket display cases and found the temperatures to range from about 45ºF to 63ºF. 

The refrigerated air typically flows from the back of the case to the front before returning to the refrigeration unit. We often see display cases that have been overfilled, or even modified to raise the level of the product on display (as shown in the figure on page 30). The result of these practices is that the flow of refrigerated air is either blocked by the mounded produce or the cold air is diverted over the top of the displayed produce, over the front edge of the case, and spills out onto the floor in front of the display!

Ice is sometimes used for vegetable displays at destination markets. It may seem that setting the product in ice is an ideal way to achieve the optimum temperature for most vegetables, but ice displays are actually very inefficient at removing heat from vegetables. Only that part of the vegetable contacting the ice is cooled to 32ºF, while the rest of the vegetable is at about the same temperature as the surrounding air.

A Critical Factor

Maintaining proper relative humidity (usually 90% to 95%) around vegetables at destination markets is one of the most critical factors in maintaining optimum quality.

In our experience, more vegetables on retail displays actually become unsalable due to shrivel caused by water loss than any other reason. Protecting vegetables from excessive air movement, packaging in semipermeable or perforated plastic films, and periodic misting with clean, sanitized water are all ways to reduce water loss and shrivel. Keep in mind though, that not all vegetables tolerate direct contact with water. We recommend only using misting for the vegetables that benefit from the practice (See “Keep It Cold”).

Beware Of Contaminants

During handling of vegetables at destination markets, consideration must also be given to minimizing the potential for contamination of product by chemical or microbial agents of food safety concern. The storage room, preparation tables, display cases, and any other surfaces that come in contact with fresh vegetables must be cleaned and sanitized on a regular basis and personnel must be well aware of and practice good hygiene. Unmarketable produce that is culled before display or collected from the displays during rotation must be properly disposed and kept separate from sound produce.

A few things that vegetable growers, packers, and shippers can do to help assure that their product will maintain its quality during the retail portion of its postharvest life include adequately cleaning and trimming vegetables after harvest, following precooling and storage recommendations for optimum temperature management, and using consumer packages with moisture barriers.