sorting and grading of fruits and vegetables pdf

Sorting And Grading Of Fruits And Vegetables Pdf

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Grading and sorting

Isaac Kojo Arah, Gerald K. Box HP , Ho, Ghana. Tomato production has increased in recent years due to the economic and nutritional importance of the crop. This increase is made possible by the numerous research advances made along the entire value chain. However, scientific research has been focussed mainly on production whilst neglecting postharvest issues.

Tomato producers have therefore enjoyed good harvests in recent times, though the good harvests of those from developing countries do not translate into profit as most are lost after harvest. From this study, it was revealed that the postharvest quality and shelf life of the fruit in part will depend on some postharvest handling practices and treatments carried out after harvest. Handling practices like harvesting, precooling, cleaning and disinfecting, sorting and grading, packaging, storing, and transportation played an important role in maintaining quality and extending shelf life.

Using appropriate postharvest treatments like refrigeration, heat treatment, modified atmosphere packaging MAP , and 1-methylcyclopropene 1-MCP and calcium chloride CaCl 2 application was also vital. It was concluded by this study that the quality of the harvested fruit can be maintained and shelf life extended by using appropriate postharvest handling practices and treatment methods.

Failure to adhere to these practices will result in a high amount of loss. Tomato Solanum lycopersicum L. Although the crop is believed to have been originated from the wild in Peru, Ecuador, and other parts of tropical Americas [ 2 ], the nutritional and economic importance of the crop has led to its global production.

By weight, tomatoes rank second only to potatoes in global production of all horticultural produce [ 3 ]. Tomato can be eaten in various ways and in a countless number of dishes. It can be eaten raw in salads or as an extract or sauce in many dishes and in drinks [ 4 ].

Tomato and tomato-based foods provide a wide variety of nutrients and many health-related benefits to the body [ 5 ]. Tomato contains higher amounts of lycopene, a type of carotenoid with antioxidant properties [ 6 ] which is beneficial in reducing the incidence of some chronic diseases [ 7 ] like cancer and many other cardiovascular disorders [ 8 ].

The numerous uses of tomatoes can be a contributing factor to its widespread production. Tomato production has increased in recent years to about million tonnes by [ 9 ] due to the economic and nutritional importance of the crop. This increase according to Alonso et al. However, scientific research has focussed on production mainly whilst neglecting postharvest issues. Research in the production aspect of the entire value chain in tomato production has resulted in improved cultivars or varieties which are high yielding and resistant to both diseases and drought.

This has made tomato producers enjoy good harvests in recent years; however, the good harvest of many producers in developing countries does not translate into profit as most are lost after harvest. Postharvest loss is a major challenge hampering tomatoes production in most developing countries [ 12 ].

Tomato being a perishable crop as a result of its high moisture content has short shelf life of about 48 hours [ 13 ] under tropical conditions. Specialised postharvest handling practices and treatment methods are needed in order to extend the shelf life of the crop after harvest.

Failure to adhere to these specialised handling practices and treatment methods will result in high amount of loss. It is therefore important to know the appropriate handling practices and treatment methods needed for harvested tomatoes in order to reduce postharvest losses thereby increasing profitability for handlers in developing countries. The purpose of this paper therefore is to look at some postharvest handling practices and treatment methods that can be used by handlers of developing countries and how they can affect the postharvest qualities and shelf life of harvested tomatoes.

Physical handling can have a drastic effect on the postharvest quality and shelf life of most harvested fruits and vegetables. For instance, rough handling during harvesting and after harvesting can cause mechanical injuries which can affect the postharvest quality and shelf life of harvested fruit like tomatoes [ 16 ]. It is therefore important to know suitable postharvest handling practices needed to maintain the quality and extend the shelf life of harvested tomatoes for producers in developing countries.

Some of the handling practices which include harvesting, precooling, cleaning and disinfecting, sorting and grading, packaging, transportation, and storage are discussed below.

The physiological maturity of any fruit at harvest has an important effect on postharvest quality of that fruit [ 17 ]. Therefore, care must be taken as to when to harvest the fruit in order to attain the best quality.

The shelf life of fruits and vegetables is described by postharvest physiologists in three stages: the maturation, ripening, and senescence stages. The maturation stage gives an indication of the fruit being ready for harvest [ 18 ]. Tomatoes can be harvested in either matured green, partially ripe, or ripe state.

Tomato being a climacteric fruit can be harvested at the matured green state allowing ripening and senescence to occur during the postharvest period of the fruit. Producers targeting distant markets must harvest their tomatoes in a matured green state [ 19 ]. Harvesting tomatoes in matured green state will not only give producers ample time to prepare the fruit for the market but also prevent mechanical injuries during harvesting.

Unfortunately, most producers from developing countries especially those in Africa harvest tomatoes when they are partially or fully ripened [ 20 ]. Fully ripened tomatoes are susceptible to mechanical injuries during harvesting resulting in shorter shelf life [ 21 , 22 ]. Care must therefore be taken when harvesting tomatoes in ripe state to avoid these injuries which will hasten deterioration.

Also, the use of harvesting and packaging containers with sharp edges must be discouraged to prevent bruising and puncturing of the fruits. Harvesting of fruits should be done in either early or late hours of the day to avoid excessive field heat generation.

The inability of producers to follow these simple but vital harvesting procedures coupled with some inefficiencies like lack of ready market and processing facilities in the entire value chain may explain the reasons why there are lots of losses in tomatoes harvested at fully ripened state in most developing countries. Access to ready market is a big challenge when dealing with highly perishable crops like tomatoes in most developing countries.

This challenge can be attributed to many factors but the major factor is the pattern of production resulting in high gluts. In most developing countries, a greater proportion of tomato production is rain fed. This causes high peaks in production during the raining seasons which is always more than the local consumption of the crop.

The problem is further compounded by the lack of processing facilities or equipment which can be used to process the crop into a more durable form for later use. Processing tomatoes into a more durable form will also serve as a means of value addition which will finally give a better market value for the crop.

Producers from developed countries always have supply contracts with multinational supermarkets to supply tomatoes. For instance, Blush Tomatoes, a tomato producing company in Australia, supplies Coles and Woolworth supermarkets with tomatoes making access to market already predetermined [ 12 ]. In the case of producers in many developing countries, there is lack of communication between producers and consumers and also lack of market information [ 11 ]. This could be the main reason for the mismatch between production and available markets.

Producers therefore have to sell their harvest at very low cost to prevent total loss. Field heat is usually high and undesirable at harvesting stage of many fruits and vegetables and should be removed as quickly as possible before any postharvest handling activity [ 23 ]. Excessive field heat gives rise to an undesirable increase in metabolic activity and immediate cooling after harvest is therefore important [ 24 ].

Precooling minimises the effect of microbial activity, metabolic activity, respiration rate, and ethylene production [ 25 ], whilst reducing the ripening rate, water loss, and decay, thereby preserving quality and extending shelf life of harvested tomatoes [ 26 ]. Harvested fruit must be precooled to remove excessive field heat if harvested at times other than the recommended periods. A cheap but effective way of precooling harvested tomatoes for producers of developing countries can be by dipping fruits in cold water hydrocooling mixed with disinfectants such as thiabendazole and sodium hypochlorite if availability of clean water is not a challenge.

This method is effective in removing field heat whilst reducing microbial loads on the harvested fruits. Tomato producers in developing countries especially those from Africa assemble their harvested produce under tree shade in an attempt to reduce field heat [ 29 ]. Tree shade, however, is not a reliable and effective way of reducing field heat in harvested produce.

Arah et al. Proper hygiene is a major concern to all produce handlers, because of not only postharvest diseases, but also incidence of food-borne illnesses that can be transmitted to consumers. According to a report by the Government of India [ 30 ], Salmonella , Cryptosporidium , Cyclospora, and hepatitis A virus are some examples of disease causing organisms that have been transmitted to consumers through fresh fruits and vegetables.

Unfortunately, cleaning or disinfecting tomatoes after harvest is not a common practice for most tomatoes handlers in developing countries especially those from Africa. This practice may be attributed to either the unavailability of portable water at the production sites or the sheer ignorance of the practice. However, in places where water is not a constraint, the use of disinfectants in water either for washing or for cooling can reduce both postharvest and food-borne diseases in fruits and vegetables.

The use of various disinfectants during postharvest treatment of tomatoes is well documented. For instance, sodium hypochlorite solution has been used to sterilise tomato fruits in order to reduce the incidence of fungal infection before any postharvest treatment was applied [ 31 ].

Dipping of tomato fruits in thiabendazole solution reduced the microbial load on the fruits [ 32 ]. Fruits and vegetables are usually treated with chlorinated water after washing to reduce the microbial load prior to packaging.

Workneh et al. Disinfection can be used in conjunction with hydrocooling to achieve the purpose of reducing excessive field heat and reducing microbial infection at the same time. One of the most important processes in packaging and marketing of fruit and vegetables is sorting [ 34 ] and grading. Sorting is the removal of rotten, damaged, or diseased fruits from the healthy and clean ones. The damaged or diseased fruits can produce ethylene in substantial amounts which can affect the adjacent fruits [ 35 ].

Grading is also the process of categorising fruits and vegetables on the basis of colour, size, stage of maturity, or degree of ripening. The two processes are vital in maintaining postharvest shelf life and quality of harvested tomatoes. Sorting limits the spread of infectious microorganisms from bad fruits to other healthy fruits during postharvest handling of tomatoes. Grading also helps handlers to categorise fruits and vegetables in a given common parameter which enables easy handling.

For instance, grading on the basis of colour or maturity stage will help eliminate overripe fruits which will easily produce ethylene to hasten the ripening process in the whole batch. Commercial tomato producers normally use sophisticated systems that require precise sorting and grading standards for their produce. Small-scale producers and retailers in developing countries in contrast may not use written down grading and sorting standards; however, the produce must still be sorted and sized to some degree before selling or processing it.

Packaging is also one of the important aspects to consider in addressing postharvest losses in fruits and vegetables. It is enclosing food produce or product to protect it from mechanical injuries, tampering, and contamination from physical, chemical, and biological sources [ 36 ].

Packaging as a postharvest handling practice in tomato production is essential in putting the produce into sizeable portions for easy handling. However, using unsuitable packaging can cause fruit damage resulting in losses [ 37 ]. Some common packaging materials used in most developing countries include wooden crates, cardboard boxes, woven palm baskets, plastic crates, nylon sacks, jute sacks, and polythene bags [ 37 ].

Most of the abovementioned packaging materials do not give all the protection needed by the commodity. Whilst the majority of these packaging materials like the nylon sacks do not allow good aeration within the packaged commodity causing a build-up of heat due to respiration, others like the woven basket have rough surfaces and edges which cause mechanical injuries to the produce.

The wooden crate and the woven palm basket are some of the common packaging materials used in many developing countries especially those in Africa for packaging tomatoes. The major shortcoming of the wooden crate is in its height which creates a lot of compressive forces on fruits located at the base of the crate [ 38 ]. These undesirable compressive forces cause internal injuries which finally result in reduced postharvest quality of the tomatoes [ 20 ].

Food grading

Show all documents Fruits Sorting and Grading using Fuzzy Logic This work presents a new technique for sorting and grading of fruits. The features are efficiently extracted from the query image. The fuzzy logic technique is used for both classification and grading of fruits, as it also involves decision making by humans. The proposed technique accurately classifies and grades the fruits. The results are good for the five chosen fruits of same color and sizes.

Mechanical sorters are machines, usually integrated to a conveyor belt , over which agriculture products are sorted by external criteria like dimensions and weight. Such equipment is based on mechanical apparatus triggered by these criteria. For example, a product, be it fruit or vegetable, is dropped into a bucket when its weight or diameter are measured at higher values than a given threshold. When values are lower, it simply travels on the conveyor belt towards the following test. Mechanical sorters are fast and reliable. However, they are limited in that they test only generic criteria.


Grading of agricultural produce especially the fruits and vegetables has become a and grader used in the processing of sorting and grading.


Farm Machinery and Equipment-II

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The purpose of sorting is grading fruit according to parameters such as dimensions diameter, length and shape , thus defining sorting classes for the many varieties of fruit. Unitec innovative technology applied to fruit sorting and packing guarantees that the product quality features are safeguarded. This is possible because Unitec has designed specifically dedicated sorter for each single type of fruit, thus safeguarding the total quality level of each piece of fruit. Unitec sorting machines and electronic sorting equipment as a whole are a distinctive feature of the innovative capacity of Unitec.

Post harvest Management of Horticultural Crops (2+1)

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