1.1 Introduction
Onion (Allium cepa L.) is one of the important vegetable crops grown globally, which belongs to the family Liliaceae. It is subdivided into three groups: Allium cepa, Allium aggregation, Allium prolilum, which are all diploids (Boukary, 2012). Onion is the common name for the herbaceous, cold season plant Allium cepa, which is characterized by a edible, rounded bulb composed of concentric, fleshy, tightly packed, and enlarged leaf bases. Onion is also the name of this edible bulb, which is commercially valuable and known for its pungent oil that departs a strong taste.
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
The diseases which are born by food are gradually becoming a dangerous risk to public health. People become infected with microbes or intoxicated with enterotoxins produced from microbes. Proper control of microbes and effective sanitation will help to reduce the rate at which people become sick from eating the food (Ortiz, 2015). Medicinal plants may be defined as any plant that can be put to culinary or medicinal use and include those we associate with orthodox drugs such as fox glove and opium poppy, as well as every day plants such as garlic. All the drugs from the past were substances with a particular therapeutic action extracted from plants. The use of herbs and medicinal plants as the first medicine is a universal phenomenon (Onyeagba et al., 2006). The increased usage of antibiotics has induced micro organism to acquire resistance factor which have become burning predicament (Abimbola et al.1993) as a result there is an urgent need to find the alternative of chemotherapeutic drugs in disease treatment particularly those of plants origin which are easily available and have less side effects (Khulbe and Sati, 2009). Spices in general show both antifungal and antioxidant characteristics, inhibiting the growth of bacteria and other pathogenic microbes. The antifungal activity of spices is due to specific phytochemicals or essential oils. The main factors that determine the antifungal activity are the type and composition of the spice, amount used, type of microorganism, composition of the food, ph value and temperature of the environment (Ali et al.,2008). It's antibacterial power is effective against preventing numerous intestinal problems that take place as a result of the alteration of the intestinal flora. This is ideal to avoid the formation of ulcers by eliminating the Helicobacter pyloria bacterium whose secretions of ammonia are responsible for many ulcers, especially those of the duodenum, and other gastric problem.
Onion (Alliumcepa) is native of Israel. This has been cultivated from the ancient times by all the nations of Asia and Middle East. Allium is the largest and important representative genus of the Liliaceae family. Onions are easily propagated, transported and stored. Onions are effective against common cold, heart disease, diabetes, osteoporosis, cough and sore throat. It is rich in proteins, carbohydrates, sodium, potassium and phosphorus. Onion consists of its flower part and edible bulb part. Flowers are greenish white or purplish white, the bulbs are white. The onion has both genetic and environmental components of relative pungency. Sulphur compounds in onion have also been shown to be anti-inflammatory both by inhibiting formation of Thromboxans and by inhibiting the action of platelet-a activating factor. Thiosulfinates condition antithrombotic benefit including; antioxidant activity, reduced serum cholesterol and enhance platelet activity in vitro. For cardiovascular health its later effect is very important by reducing the probability that platelets aggregate in the blood, a major cause of heart attacks and strokes. Flavonoids are the chemical compound found in onion are active against microorganism and in vitro condition it has been shown its activity against wide array of microrganism. Tannins, allicinalso possess antioxident and antifungal properties.
The main antifungal agent in onion is Quercetin and allicin (thio-2-propene-1-sulfinic acid-5-allyl-esters), quercetin binds to the bacterial DNAgyrase while allicin inhibits certain thiol containing enzymes in the microorganism by the rapid reaction of Thiosulfinates. Several authors have reported pharmaceutical activity of extracts of Onion including anti-tumor anti-diabetic, anti-oxidant, anti-allergic. In vitro studies have shown Onion to possess antibacterial, antiparasitic, and antifungal activity.
Therefore keeping in view the significance of Onion the present work was carried out to study antifungal effects of these spices against food borne pathogenic bacteria.
1.3 Statement of Problems
The study reveals the following problems associated with the antifungal activity of onion extract against some fungi pathogen;
- Lack proper investigation of the inhibition of pathogenic Fungi in onion oil extract,
- Inadequate information relating to the anti-fungal adverse effect of the onion oil extract,
- Lack of proper and precise information relating to the pathogenic fungi used and Preparation of onion oil.
1.4 Aim and Objectives of Study
The aim of the study is to identify and determine the antifungal activity of onion extract against some fungi pathogen. In achieving this aim, the following specific objectives were laid out as follows:
- To investigate the antifungal properties of onion spices;
- To investigate the inhibition of pathogenic Fungi in onion oil extract;
- Provision of information relating to the anti-fungal adverse effect of the onion oil extract; and
- To provide proper and precise information relating to the pathogenic fungi used, and Preparation of onion oil.
1.5 Significance of Study
This research work when completed and implemented it will help in the estimation of the inhibition of pathogenic Fungi in onion oil extract and proper and precise provision of information relating to the pathogenic fungi used, and Preparation of onion oil, which will be beneficial to lab scientist, and food technologist.
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.
1.6 Scope of Study
The scope of the research is focused on the antifungal activity of onion extract against some fungi pathogen.
1.7 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).
1.8 Definition of Technical Terms
Onion: The onion also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus Allium.
Oil: Oil is the remains of ancient plants and animals, compressed deep in the earth into liquid strings of hydrogen and carbon.
Activity: An activity is a phase, task, operation or other component within an activity group. Activities provide a framework for establishing and collecting budgets, costs, revenues and statistical information.
Effect: a change which is a result or consequence of an action or other cause.
E.coli: Is an acronym for Escherichia coli which is a bacterium commonly found in the intestines of humans and other animals, some strains of which can cause severe food poisoning.
Isolates: isolate simply means cause (a person or place) to be or remain alone or apart from others.
Antibacterial: Anything that destroys bacteria or suppresses their growth or their ability to reproduce. Heat, chemicals such as chlorine, and antibiotic drugs all have antibacterial properties.
