CHAPTER ONE
1.0                                 INTRODUCTION
Vegetables constitute commercially and nutritionally important indispensable food commodity. Vegetable naturally play a vital role in human nutrition by supplying the necessary growth factors such as vitamins and essential minerals in human daily diet and that can help to keep a good and normal health. Vegetables are widely distributed in nature. One of the limiting factors that influence the fruit economic value is the relatively short shelf-life period caused by pathogen’s attack (Droby, 2006: Zhu, 2006).
Tomato (Lycopersiconesculentum) pronounced Toh-MAH-to is the most important vegetable worldwide. Tomato is an annual plant which belongs to the Solanaceaefamily which includes other well-known species such as Potato, Tobacco, Pepper and Egg plants (aubergine) and can reach a height of over two meters. It’s a berry fruit, tomato is grown mainly in soil (Frazier and Westhoff,2004).
Tomato is essential mainly for its dietary needs and can be consumed in diverse ways. It can be cooked as vegetable, as an ingredient in many dishes and sauces; in the making of stew, fruit juices and can be eaten raw in salads(Masefield et al., 2002).
The modern day tomatowhich is a very popular fruitoriginated from South-Western Hemisphere, now the Peru-Euador area(Rick,2001).From here,it was distributed to many parts of tropical America. It possibly arrived the West African Ports via Portuguese traders or the Sudan (Tindall, 2004).
Tomato in West Africa is grown in gardens and irrigation schemes. In Nigeria, most tomatoes are grown in the northern parts of the country(Erinle,2007) and there is no record of any systematic or organized traditional storage method for vegetables and fruits. They are usually sold immediately after harvesting. They are packed in baskets, cardboard boxes, or wooden crates ready for transportation to the markets.
Tomato is the most perishable vegetable during handling, transportation and storage. This is because tomato contains large amount of water which makes them susceptible to spoilage by the action of microorganisms such as fungi, bacteria and protozoans (Ross, 1975). Estimates have shown that about one third of the produce is lost before reaching the consumer (Erinle, 2007), this loss has been attributed to a number of factors which include physical (mechanical breakage, bruises), physiological and also damages caused by pathological agents (Thompson and Kelly, 2000), market value of the tomato are mainly reduced by this factors.
Watt and Merrill, (2000) defined spoiled food as that which have been damaged or injured so as to render it undesirable for human consumption. Various activities may result in food spoilage: insect activities,causing physical injuries for example, bruisingand enzyme activity by microorganism causes change in colour, taste, smell, texture and quality of the food.
Pauland Sarisbury, (1981)  also referred to spoilage as any change in the condition of food in which the food becomes less palatable or even toxic: these changes may be accompanied by alteration in taste, smell, appearance or texture.
The spoilage of food by microorganisms should not be viewed as a sinister plot on the part of the microbes deliberately to destroy foods but as a normal function of these organisms in the total ecology of all living organisms (Watt and Merrill, 2000). It has also been estimated by Watt and Merrill (2000) that 20% of all fruits and vegetables harvested for human consumption are lost through microbial spoilage causing one or more of 250 market diseases. Spoilage of fresh tomato usually occurs during storage and transit and also while waiting to be processed.
Frazier and Westhoff,(2004) reported that fruits and vegetables after picking continue to respire and as a result heat is produced, this heat is known as ‘vital heat’, the amount which varies with particular amount of fruits and vegetables.
Vegetables that respire more thereby generating most heat are those that perish/spoil most rapidly (Wheeler, 2005). The resulting respiration of the fruits in addition to the normal ripening process complicates an independent discussion on microbiological spoilage of fruits in general and tomato in particular.