Fruits and vegetables are very susceptible to mechanical injury. This can occur at all stages of the marketing chain and can result from poor harvesting practices, such as the use of dirty knives; unsuitable containers used at harvest or during the marketing process, e.g. containers that can be easily crushed or made of splintered boards, with sharp edges or faulty nailing; over-packing or improper filling of containers; careless handling of containers Damage resulting from these practices may include cutting of fruit, internal bruising, superficial scratches and crushing of soft products. Improper handling can create entry points for mold and bacteria, increase water loss, and increase the rate of respiration.
Products can be damaged when exposed to extreme temperatures. The level of tolerance to low temperatures is important when considering cold storage. All products freeze at temperatures between 0 and -2 degrees Celsius. Although some commodities tolerate slight freezing, poor temperature control in storage can lead to significant losses.
Some fruits and vegetables are also susceptible to post-harvest contaminants introduced through the use of contaminated pallet boxes; dirty water used to wash produce prior to packing; decaying produce left around packing houses, and contamination between unhealthy and healthy produce in the same package.
Losses directly attributable to transport can be high, particularly in developing countries. Damage occurs as a result of careless handling of packaged products during loading and unloading; vibration (shaking) of vehicles, especially on poor roads; and improper loading, with packages often being jammed into the vehicle to maximize the carrier’s revenue. Overheating leads to rot, and increases the rate of water loss. In transportation, this can result from the use of closed vehicles without ventilation; from stacking patterns that block air circulation; or from the use of vehicles that offer no protection from the sun. Vehicle breakdowns can be a major cause of loss in some countries, as perishable products may be left exposed to the sun for a day or more while repairs are made.
At the retail marketing stage, losses can be significant, especially in the poorest countries. Poor quality markets often offer little protection of products from the elements, leading to rapid deterioration of products. Sorting produce to separate the saleable from the unsaleable can result in large percentage deviations, and there can be high weight losses due to the purification of leafy vegetables. The arrival of fresh produce in a market may cause existing stock to be discarded, or sold at very low prices.
Source: wikipedia.org