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Inagriculture,postharvest handling is the stage ofcrop production immediately followingharvest, including cooling, cleaning, sorting and packing. The instant a crop is removed from theground, or separated from its parentplant, it begins to deteriorate. Postharvest treatment largely determines final quality, whether a crop is sold forfresh consumption, or used as an ingredient in aprocessed food product.
The most important goals of post-harvest handling are to keep the product cool and safe, to avoid moisture loss and slow down undesirablechemical changes, and avoiding physical damage such asbruising, to delayspoilage.[1]Sanitation is also an important factor, to reduce the possibility ofpathogens that could be carried by fresh produce, for example, as residue fromcontaminated washing water.
After the field, post-harvest processing is usually continued in apacking house. This can be a simple shed, providing shade and running water, or a large-scale, sophisticated,mechanised facility, withconveyor belts,automated sorting and packing stations, walk-incoolers and the like. In mechanised harvesting, processing may also begin as part of the actual harvest process, with initial cleaning and sorting performed by the harvesting machinery.
Initial post-harvest storage conditions are critical to maintaining quality. Each crop has an optimum range of storage temperature and humidity. Also, certain crops cannot be effectively stored together, as unwanted chemical interactions can result. Various methods of high-speed cooling, and sophisticatedrefrigerated and atmosphere-controlled environments, are employed to prolong freshness, particularly in large-scale operations.
Once harvested, vegetables and fruits are subject to the active process of degradation. Numerousbiochemical processes continuously change the original composition of thecrop until it becomes unmarketable. The period during which consumption is considered acceptable is defined as the time of "postharvest shelf life".[citation needed]
Postharvest shelf life is typically determined by objective methods that determine the overall appearance, taste, flavor, and texture of the commodity. These methods usually include a combination ofsensorial,biochemical, mechanical, andcolorimetric (optical) measurements. A recent study attempted (and failed) to discover a biochemicalmarker andfingerprint methods as indices for freshness.[citation needed]
Postharvest physiology is the scientific study of theplant physiology of living plant tissues after picking. It has direct applications to postharvest handling in establishing the storage and transport conditions that best prolong shelf life.
An example of the importance of the field to post-harvest handling is the discovery that ripening of fruit can be delayed, and thus their storage prolonged, by preventing fruit tissue respiration. This insight allowed scientists to bring to bear their knowledge of the fundamental principles and mechanisms of respiration, leading to post-harvest storage techniques such as cold storage, gaseous storage, and waxy skin coatings.[citation needed]
