The source of a large outbreak of food borne disease related to Salmonella-contaminated tomatoes has been traced to Nigeria. Although the microbiological quality of tomatoes sampled was similar to that found in markets from developed countries, the presence of pathogens causes a risk of infection for consumers.
There are many ways to sterilize surfaces and materials to kill bacteria and other harmful organisms that attack tomatoes. One way is through the use of ultraviolet, or UV radiation, also called UV light. UV light is a form of electromagnetic radiation.
The objective of this work was to evaluate the microbiological quality of tomatoes using UV light.
CHAPTER ONE
1.1 INTRODUCTION
Tomatoes are part of a nutritious diet and are a great source of vitamins and minerals sold and consumed all over Nigeria. Tomatoes are commonly red but also come in a variety of other colours, such as yellow, pink, and purple. Tomatoes are often eaten fresh or used as an ingredient in recipes. Popular types of tomatoes include beefsteak, plum, and cherry tomatoes.
By making sure they are properly handled, washed, prepared, and stored, you can enjoy the health benefits of tomatoes and help prevent food poisoning for yourself and your family.
While fresh field tomatoes do not naturally contain bacteria that can make you sick, they can become contaminated because they are grown close to the ground.
Eating tomatoes that have been contaminated with harmful bacteria can make one sick. Contaminated tomatoes have been linked to incidents of food poisoning caused by Salmonella. Salmonella is a particular problem for tomato growers in Nigeria. And the tomato industry is eager for a way to reduce salmonella contamination and regain consumer confidence.
Salmonella has become a leading cause of food-borne illness in the Nigeria. Once largely associated with poultry and eggs, the bacteria live in the intestines of animals. But recently, the bacteria are increasingly in fresh fruit and vegetables, for unknown reasons. Of nine nationwide salmonella illness outbreaks since 2007, just one was linked to a meat product, according to the Centers for Disease Control and Prevention. The rest were associated with vegetables, fruit, nuts or cereal.
Salmonella causes about 1.4 million cases of food-borne illnesses and more than 500 deaths a year in the United States, according to the CDC. While most people recover without treatment, young children, the elderly and those with weakened immune systems can become severely ill.
Salmonella, which describes a group of 2,600 strains of related bacteria, can survive outside living organisms and has lived as long as 18 months in soil.
"Salmonella is turning out to be a far more challenging environmental bug than we ever thought it would be or could be," Brown said. "It's very difficult to get rid of, and we don't even know where it comes from."
Fruit and vegetable farmers face a particular challenge because produce is often eaten fresh; there is no "kill step," such as cooking. Most produce is not packaged, which increases the chances for contamination. And some pathogens such as salmonella and E. coli burrow inside the fruits and vegetables, making it impossible to wash them away. In fact, Brown has found that his microorganisms are not effective against salmonella when the battle takes place inside the tomato, only on the surface.
1.2 AIM/OBJECTIVE OF THE STUDY
The objective of this study is to discuss how ultraviolet could be used to sterilized microorganism in tomatoes. At the end of this work student will be able to:
- Understand different types of sterilization
- Understand the full meaning, uses, application and operation of UV light
- Understand the types of microorganism that attacks tomatoes.
This method employed to minimize the growth of organisms and transmission of disease consumers of tomatoes. In the environment the use of UV-light techniques decreases the growth of bacteria on surfaces, which leads to the decrease in transmission of organisms amongst the population. It does penetrate air, effectively reducing the number of airborne microorganism and killing them on surfaces on operating rooms and rooms that will contain caged animals. To help sanitize the air without irradiation humans, these lights can be turned on when there rooms are not in use. . Hanging laundry outdoors on bright, sunny days takes advantage of the ultraviolet light present in sunlight. Although the quantity of UV rays in sunlight is small, these rays may help kill bacteria on clothing, especially diapers.
1.4 LIMITATION OF THE STUDY
A major disadvantage of UV light as a disinfectant is that the radiation is not very penetrating, so the organism to be killed must be directly exposed to the rays. It is noteworthy microorganisms in the air and upper layers of the soil, but it may not the effective against all bacterial spores. Organisms protected by solids and such coverings as paper, glass, and textiles are not affected. Another potential problem is that UV light can damage human eyes, and prolonged exposure can cause burns and skin cancer in humans. And it may cause damage in human skin cells and permanent damage the eyes.
1.5 SUN--FREE SOURCE OF UV
Sunlight contains some UV radiation, but the shorter wavelengths – those most effective against bacteria – are screened out by the ozone layer of the atmosphere. The antimicrobial effect of sunlight is due almost entirely to the formation of singlet oxygen on the cytoplasm. Many pigments produced by bacteria provide protection from sunlight.
There are a variety of ways we put ultraviolet (UV) radiation to good use.
OUR SKIN AND UV: When we expose our skin to UVB, it stimulates the production of vitamin D, which our bodies need. Window glass absorbs UVB, so people need to go outside to gain the benefit. However, too much exposure to UVB can cause skin cancers, so the aim is to find the optimum amount of exposure. UV lamps are used in sun beds to give the users a sun tan, but this use of UV is controversial.
STERILIZATION AND DISINFECTION: UVB also helps us when we hang washing outside to dry, as some of the bacteria present in the washing are inactivated by exposure to UVB. This helps to protect us from infection and is another reason to dry washing outside rather than in an energy-hungry dryer.
The ability of UV to inactivate bacteria and viruses is taken further by using artificially produced UVC to sterilize surfaces of things such as medical equipment. Auckland’s sewage treatment plant uses UVC to inactivate bacteria and viruses just before discharging the clear effluent into the Manukau Harbour.
Often UVC is called “germicidal UV” because it is able to directly disable the strands of DNA in bacteria and viruses and make them inert. Inactivated bacteria and viruses are as good as dead because they are not able to reproduce and multiply.
ASTRONOMY: Very hot objects emit some amount of UV radiation. The hotter the object, the more UV is emitted. Observing and recording the UV from astronomical objects such as planets in our solar system, stars, nebulae and galaxies enables us to gain extra information such as the temperature and chemical composition of these objects. The only problem is that our Earth’s ozone layer absorbs much of the UV and so these observations need to be made outside the Earth’s atmosphere. On board the Hubble Space Telescope, the Faint Object Spectrograph (FOS) and the Goddard High Resolution Spectrograph (GHRS) are used to collect and analyse UV light from interesting targets.
The Solar and Heliospheric Observatory (SOHO) is a spacecraft that was launched in 1995 to study the Sun. It is a joint project of international cooperation between the European Space Agency (ESA) and NASA. Two of SOHO’s twelve instruments are used to record and analyse UV radiation from the Sun.
We can use UV and fluorescence to make efficient lighting for offices, workshops and our own homes.
CURING: UV radiation used to be called “chemical rays” after it was first discovered in the early 19th century. This was because UV could make certain substances change chemically. This effect is put to use in a number of ways, one of which is to harden special glues quickly. This process is called “curing”.
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