Packin’ It Fresh

Quality for fresh produce such as vegetables peaks at harvest but deteriorates over time as these living organisms undergo pathological and physical changes. It is therefore important to reduce the time taken from harvest to consumption. Often, the main barrier to providing fresh produce to the consumer is distance and transport. Pre-cooling is often used to reduce temperatures in fresh produce to a level that prolongs the quality of the produce at harvest for as long as possible. However, it is not recommended to cool fresh produce below the recommended limits or the produce would be damaged from the chill. Ideal relative humidity must also be maintained during cooling. The fi ve methods of pre-cooling produce are:

• Room cooling

Produce is cooled in a cold room. This is a commonly used method but it is also the slowest cooling method.

• Ice cooling

Ice chips (or ice slush) are directly packed together with the produce. Alternatively, ice packs (or ice in containers) are used in the packing without direct contact with the produce.

• Hydro-cooling

Water is sprayed over fresh produce or the produce is immersed in water. This is a faster cooling method but it risks damaging produce that is susceptible to water damage.

• Forced-air cooling

There are a variety of ways to force cool air through packaged produce in order to rapidly reduce the core temperatures of the produce to recommended levels. While the produce does not get wet, the cost of handling and running a forced-air facility may discourage some producers from using this method.

• Vacuum-cooling

Vacuum coolers create a low-pressure environment, thereby reducing the temperatures of the produce as the surface water evaporates. This method is relatively expensive and producers often use it for cooling leafy vegetables that are considered to be sensitive to the

packaging environment.

Fresh packaging

Packaging helps to maintain fresh produce quality. Containers used for handling, pre-cooling and transporting produce from harvest to the packinghouse are typically cartons, crates, bags, sacks and bins.

A fresh produce container has three basic functions:

• To reduce injury or damage during handling and transport,

• To reduce water loss, and

• To offer ventilation when fresh produce release heat during respiration.

During harvesting, fresh produce such as apples, grapes and vegetables should be packed in ventilated containers to facilitate heat dissipation. These containers reduce the risk of the produce deteriorating due to heat that could be trapped in the container, as well as for use during pre-cooling.

Retail packaging such as biodegradable, recyclable, bulk packaging, trays and wraps would also be pre-cooled in order to minimize heat to maintain fresh produce temperatures.

Sanitation

Bacteria such as Salmonella, E. coli could be transferred to fresh produce by handlers, in water used washing, and through the reuse of containers without proper cleaning. Contamination and crosscontamination would be hazardous should an outbreak occur. Ozone technology could also be used to sanitize produce. It is more effective than chlorine as it destroys food-borne pathogens and microbes that cause spoilage.

Ethylene is a natural hormone produced by fruit (e.g. bananas) when they ripen. The hormone would stimulate fruit and vegetables that are packed around these fruit to ripen quickly, thereby reducing shelf life of the produce, losing of nutritional quality and even injuring the produce (e.g. softening of watermelons, yellowing of vegetables and bitter taste in carrots). This problem occurs when produce is stored or shipped in mixed loads, and when they are displayed near high ethylene producing fresh produce.

Packing different produce in mixed loads could also lead to the transfer of odors. Potatoes produce an earthy odor and taste to pears and apples when they are stored together, for example. Meat, dairy products and eggs absorb odors from apples and citrus fruit. It is therefore recommended to store produce such as citrus fruit, potatoes, nuts and onions separately from other produce.

These cold chain practices complement the existing good agricultural practices (GAP), as preserving fresh produce by reducing wastage due to contamination and poor handling and transporting are crucial

in providing quality fresh produce to the consumers.

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