1.1 Introduction
Tomato (Solanum lycopersicon) is a major horticultural crop with an estimated global production of over 153 million metric tons. It is the most important fruit vegetable and the second most widely cultivated crop in the world after potato, with a total production of about 141 million tons (Faostat, 2009). Tomato is highly perishable and one of the most widely produced and consumed fresh vegetables in the world for fresh fruit market and the processed food industry (Costa and Heuvelink, 2006). It is used in the preparation of sauces, stews, soups, salads and other dishes which are taken with most staple food crops (Issahaku, 2012; Adu-Dapaah and Oppong Konadu, 2002). It is also the most common vegetable in the Mediterranean diet and is known to be beneficial for health, especially with regards to the prevention of chronic degenerative diseases (Herna´ndez Sua´rez et al., 2007; Leonardi et al., 2000).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
1.2 Background of Study
Tomato (lycopersicumesculentum) is an animal plant, having a weak woody stem covered with glistering red iscultivated in many parts of the world. The tomato plant is widely cultivated in many parts of the world and also has a smooth stain. It is green when immature but becomes bright red or yellow as it ripens. These products are considered important worldwide (Robins et al; 1994).
Tomato fruit is a well vegetable eaten raw as salad or for garnishing various foods in Nigeria as well as in many part of the world. The fruit contains high amount of carbohydrate, fat, organic acid, water, minerals, vitamins and pigments (Reddy, 2009). When spoilt as a result of life process of bacteria, yeast and molds, the sugar are rapidly used up being changes into acetic acid lactic acid, alcohol and carbondioxide, the amount of these substances depending on their types of organism which are most activities particular sample in question.
In generally, adequate heat processing is given to tomato paste to achieve commercial sterility (speck 1994), but subsequent abusive post process handling /storage may lead to understand microbiological changes. It is public knowledge that can of tomato paste often show external evidence of spoilage under tropical retail condition (Anon, 1980).
Tomato fruit contains a lot of water which makes them susceptible to spoilage by microorganism. Also, the high water content makes storage and transportation of vegetable difficult. The microorganism reduces not only the nutritional values but also the market value s of tomato fruit. Micro organisms also affect the seller due to the spoilage of tomato. Hazard analysis and critical control point − HACCP identifies evaluate and control hazards that control or significant for food safety (De Rover, C. 1998)food safety (De Rover, C 1998). The control of parameter include various factors such as time of harvesting, temperature and moisture during storage, selection of agricultural product prior to processing, decontamination conditions, addition of chemicals at final product storage (Sango, 1995).
Tomatoes were chosen for this study because they are referred to as ready-to-eat food since they are manually processed and many people take tomatoes raw directly or via meals of salad usually served cold. Microbial spoilage and contaminating pathogens on this product poses a serious problem in food safety. Ecological factors influencing survival and growth of human pathogens or raw growth of human pathogen on raw fruit and vegetables. There are vew reports of studies on micro-organism associated with spoilage of tomato fruit in Nigeria. Similar research cost of test ripened tomato fruits sold in local markets in Benue State has tended to turn the worry public to patronize spoilt tomato fruit because they are relatively cheap. (Benchat, L.R.:2002).
Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Effect of Irradiation on Nutritional Quality and Shelf Life of Tomato Powder.
1.3 Statement of Problems
Tomatoes are an attractive cash crop for small scale farmers and provide potential source of employment to many rural and urban people. The tomato fruits have been marketed freshly picked from the field and is the best selling fresh market vegetable crop (AVRDC, 2006).
Despite the human need of tomato, damage as a result of post-bacteria spoilage micro-organisms has been of serious concern. Microbial decay is one of the main factors that determine losses and compromises the quality of the produce. The extent of the losses especially through microbial decay has not been quantified in most areas and on this has been quantified the result are short lived.
Periodic surveys may help to understanding the seventy of losses in a specific place and at a specific time. Estimates of post harvest losses in Benue State have of been established. Therefore, the study aims at establishing estimates of post harvest losses in Nigeria, identify pathogens involved in post a harvest decay of tomato fruits and evaluate ways of managing them using crude plant extracts.
One key means of preserving tomato fruit is drying. It is the oldest method of preserving agricultural products. Drying is a form of processing that ensures the availability of perishable products all year round (Grabowski et al., 2003; Habou et al., 2003). Drying is a process of food preservation and management which appears to be suitable and satisfactory under most conditions in developing economies (Idah and Aderibigbe, 2007; Ali and Sakr, 1981). Dehydration of perishable commodities like tomatoes with very high moisture content results in substantial reduction in weight with consequent savings in storage and distribution (Mepba et al., 2007). Conventional drying has been used in most developing countries including Nigeria to preserve most food stuffs (Kolawole et al., 2010).
1.4 Aim and Objectives of Study
The aim of the study is to determine the Effect of Irradiation on Nutritional Quality and Shelf Life of Tomato Powder. In achieving this aim, the following specific objectives were laid out as follows to:
- Determine the effects of radiation on the physico-chemical properties of tomato powder.
- Evaluate the effect of drying method on three tomato varieties and the packaging material for dried tomato powder.
- Study the effect of radiation on microbial load in dried tomato powder.
- Compare and determine the most efficient method of drying tomatoes using solar and freeze drying techniques in a tomato variety.
- Assess the effect of radiation on the phytochemical properties of tomato powder.
- Use radiation to extend the shelf life of dried tomato powder.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- Is there effect of radiation on microbial load in dried tomato powder?
- What is the packaging material for dried tomato powder?
- To what extent is radiation used in shelf life of dried tomato powder?
- What are the effects of radiation on the physico-chemical properties of tomato powder?
1.6 Significance of Study
This study provides important information on the current status, causes of post-harvest losses of tomatoes in Benue State and their management using crude plant extracts. The output is this study will be important in reducing tomato post-harvest losses by improving the efficiency of post-harvest handling due to better post-harvest management strategies.
Natural plant products and their analogues have been foud as important source of agricultural bio-pesticides which serve as anti-microbial properties of the plant extracts (Cardelina, 1995), reported that plant are sources of natural pesticide that leads to new pesticide development.
This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.
1.7 Scope of Study
The Study focuses on the Effect of Irradiation on Nutritional Quality and Shelf Life of Tomato (Solanum Lycopersicon L.) Powder.
1.8 Limitations of the Study
During the course of this study, many things militated against its completion, some of which are:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Research material: availability of research material is a major setback to the scope of the study.
- Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
1.9 Definition of Terms
Irradiation: Irradiation is the process of exposing fresh foods to low amounts of x-rays to sterilize and prolong its life.
Food Preservation: Food Preservation is any number of methods by which food is kept from spoilage after harvest or slaughter.
Preservation: the activity or process of keeping something valued alive, intact, or free from damage or decay.
