Unripe fruits are difficult to harvest compared to completely ripened ones and are not easily damaged during harvesting and transportation but when fruits are completely ripened they get damaged is easily because of high content of sugar and water (Kereth et al, 2013:11). Fruits must be harvested firm enough to stand handling and to increase their shelf life and also to tolerate transportation to long distance if so required. Precaution must be taken during harvest in order to achieve the best quality. Post-harvest physiologists describe three stages in the life period of fruits and vegetables: maturation, ripening and senescence (Isaac et al, 2015:5). The maturity stage of tomato fruit at harvest is an important element of many quality traits. Tomato can be harvested when it is matured green, partly ripened or ripened state.
The stage of maturity at harvest contribute in quality, generally it means the fruits harvested at the progressive stage of maturity have increased fruits size, taste and aroma but decreased shelf life (Hassan, 2010). As tomato is a climacteric fruit it can be harvested at the matured green state allowing ripening and senescence to take place during the postharvest period of the fruit. Each stage at harvest has its own postharvest characteristic that the fruit will display. Fruit nutritional values and appearance maybe affected when harvested green. For instance, sugar transport to fruits in a vine-ripened tomato appears to increase during the last part of maturity and, therefore, when fruits are harvested unripe or in green state sugar transportation to fruits will be disturbed making postharvest degradation of starch, the main foundation of carbohydrates, which is both undesirable and inadequate( Isaac at al ,2015:5).
2.1.2 Lack of appropriate harvesting containers
SOURCE: (www.google.com/image. 2018)
Figure 2.1: Harvesting container
Tomatoes are picked in harvesting containers (nylon net bags or plastic buckets). Tomatoes are harvested by manual instead of mechanical in most countries. During harvesting, care should be taken to avoid mechanical damage which can be an entry point for disease causing pathogens. Most farmers use wooden crates and woven baskets with sharp surfaces which cause mechanical injuries to the picked fruits (Isaac et al, 2015:5). The use of even surface and shallow containers that will avoid overfilling will lessen both mechanical injuries and crushing of the harvested fruits. The ineffectiveness of using the wooden crate lies in the inadequate ventilations provided for cooling, tough surfaces and edges and depth of the package. The inside of the baskets have piercing edges which result in mechanical injuries. This results in bruising and crushing of the fruit which breaks the integrity of the fruits also in the introduction of disease causing pathogens.
2.1.3 Excessive field heats & lack of on-farm storage facilities
SOURCE: (www.google.com/image. 2018)
FIGURE 2.2: Tomatoes exposed to heat
Correct temperature management between harvesting and consumption has been found to be the most effective way to sustain quality. The field heat of harvested produce is commonly high particularly in the tropics, and should be removed as quickly as possible. The most favorable temperature for tomato harvesting of about 20 °C can be obtained either early in the morning or late in sunset. Harvested fruit must be pre-cooled to remove extreme field heat if harvested during the day while it was still hot (Isaac et al, 2015:5). If tomatoes are harvested during the day, they are exposed to high field temperature will develop sun scotch. If tomatoes we injured during harvesting process and get exposed to high temperature can result in decay of products.