Postharvest decay can be due to both pre- and postharvest factors and can be the result of pre-harvest latent infections or contaminations and infections during harvesting. These infections can develop into disease symptoms during postharvest storage, transport or marketing of fleshy products. The postharvest life of fruits and the severity of postharvest decay depend partly on pre-harvest factors and harvest systems, partly on postharvest handling from field to market.The fruit quality starts in the field, thus the first step to reduce postharvest quality decay is harvesting safe produce, avoiding each contamination source, such as microbial contamination, heavy metals, and chemical residues, etc., this is possible following the Good Agriculture Practices (GAP). However, to slow the postharvest decay it is necessary to followi also the Good Postharvest Practices (GPP), such as temperature control, sanitizers use, Modified Atmosphere Packaging (MAP), etc. from harvesting to the table to guarantee product safety and quality also after many months storage from harvesting.
In the review on fruit postharvest of Michailides and Manganaris (2009), the authors have reported the effects of pre-harvest, harvest, and postharvest handling on postharvest quality decay of fruits, such as apricot, pear, kiwifruit, prune, nut, almond.
Harvest and storage
At harvesting, maturity stage, harvest systems, and climatic conditions can affect postharvest decay. The maturity stage of fleshy fruits is determined by fruit color, size, shape, soluble solids, sugars and acid content. In the last years, non-destructive methods have been developed to control and guarantee product quality. Harvest systems can be carried out by hand or by mechanical means. The first system is expensive because of the high level of labor involved, and it is carried out on small crops.
Mechanical harvesting is done on larger areas and when the harvest period is short. During harvesting, it is fundamental for the operators to follow the Good Hygiene Practices (GHP)in regards to, cutting tools, harvesting equipment, containers for harvest and for shipping, and it is necessary to manage the produce with care to avoid mechanical injuries.
Furthermore, fruits collected in the containers must be not mixed with fruits on the ground because they could be a source of microbial contamination, for example they could be contaminated by Mucor spp., Penicillium spp., Monilinia spp. that are responsible for rot during postharvest storage.
Also climatic conditions affect the incidence of latent infections or inoculum load potential during harvest., and the latent infections will occur during postharvest.
At harvesting, the raw material can be packaged directly in the field: this method is cheap, but the low costs do not justify the fast postharvest decay due to the mechanical injuries and the lack of temperature control. Thus, it is better to transport the raw material to the packinghouse as soon as possible after harvesting. The advantages of packinghouse are: fruits are transported more quickly to the cold storage facility and they are kept at lower temperatures, there is more control of the raw material by using high-tech automated equipment on the packing line.
Packaging is fundamental to preserve the quality and safety of the product, to protect the product against mechanical injuries and microbial contaminations, to manage and transport the product without damaging it. In the last years, Modified Atmosphere Packaging (MAP) combined with biological agents has improved and increased the shelf-life of fruits.
Post-harvest
During postharvest, fungicides, registered in USA, are very effective against natural incidence of rots causing fruit decay, but they are not authorized in Europe and in many other Countries. Thus, it has been shown that the use of biological products (= microbial antagonists) with heat treatments can control postharvest infections.
Ultimately, edible coatings on fruits is an innovative and interesting means for commercial application and an alternative to the use of chemical treatments. These coatings act as barriers against external agents during processing and storage. They have a natural biocide activity, good mechanical strength and adhesion, and biochemical stability. These coatings are safe for health, are low cost raw materials and require simple technology for production. A novel edible coating is a gel obtained from Aloe vera that is effective against Penicillium expansum, Penicillium digitatum, Botrytis cinerea, etc.
The authors have concluded that it should be necessary to study the latent infections that develop in the field before harvesting and whose symptoms occur during postharvest, consequently to study a system to quantify the infections severity. This information should be very useful for both the grower and packinghouse operators in decision making for pre- and postharvest treatments, longevity storage, and timing of marketing the fruit.
Original study. Michailides TJ, Manganaris GA. "Harvesting and handling effects on postharvest decay", 2009, Stewart Postharvest Review, pagg. 1-7. For more details: ucce.ucdavis.edu/files/datastore/234-1533.pdf