MICROBIAL FOOD SPOILAGE DISORDERS AND ITS CONTROL

1.1 Introduction

Foods and microorganisms have long and interesting associations which developed long before the beginning of recorded history. Foods are not only nutritious to consumers, but are also excellent sources of nutrients for microbial growth. Depending on the microorganisms present, foods may spoil or be preserved by fermentation. Food spoilage is a metabolic process that causes foods to be undesirable or unacceptable for human consumption due to changes in sensory characteristics. Spoiled foods may be safe to eat, i.e. they may not cause illness because there are no pathogens or a toxin present, but changes in texture, smell, taste, or appearance cause them to be rejected. Some ecologists have suggested these noxious smells are produced by microbes to repulse large animals, thereby keeping the food resource for themselves.

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, Research hypothesis and questions, Limitations of the Study and Definition of technical terms.

1.2 Background of Study

Bacterial are group of microorganism all of which lack a distinct nuclear membrane (and hence are considered more primitive than animal and plant cells) and most of which have a cell wall of unique composition. Most bacterial are unicellular; the cells may be spherical (coccu) rod – shaped (bacillus), spiral (spirillum), comma – shaped (vibrio) or corkscrew-shaped (spierocheate). Generally, they range in size between 0.5 and 5um (Elizabeth and Martin, 2003).

Food is any substance that people or animal eat or drink or that plants absorb to maintain life and growth. Food is any substance consumed for nutritional support for the body; it is usually of plant or animal origin (Ezeronye, 2007). Food consists of chemical compounds which heterophilic living thing consumes in order to carry out metabolic processed. They are also substances which when introduced to the digestive system under normal circumstances contribute to growth, repair and production of energy (Ezeronye, 2007). Foods are classified into six essential nutrients known as protein, carbohydrate, vitamin mineral, fat and oil, water.

PROTEIN: One of a group of organic compounds of carbon, hydrogen, oxygen and nitrogen (sulphur and phosphorus may also be present). The protein molecule is a complex structure made up of one or more chains of amino acid, which are linked by peptide bonds. Proteins are essential constituents of the body; they form the structural material of muscles, tissues, organs, etc. and are equally important as regulators of function, as enzymes and hormones, proteins are synthesized in the body from their constituent amino acids, which are obtained from the digestion of protein in the diet (Elizabeth and Martin, 2003).

CARBOHYDRATE: One of a large group of compounds, including the sugar and starch, that contain carbon, hydrogen and oxygen and have the general formula CX (H20) Y- Carbohydrates are important as a source of energy: they are manufactured by plants and obtained by animals from the diet, being one of the three main constituent of food. All carbohydrates are eventually broken down in the body to the simple sugar glucose which can then take part in energy producing metabolic processes. Excess carbohydrate, not immediately required by the body is stored in the liver and muscles in the form of glycogen. In plants carbohydrate are important structural materials (e.g. cellulose and storage products (commonly in the form of starch) (Elizabeth and Martin, 2003).

VITAMIN: Any of a group of substances that are required in very small amounts, for healthy growth and development: they cannot be synthesized by the body and are therefore essential constituents of the diet. Vitamins are divided into two groups, according to whether they are soluble in water or fat. The water soluble groups include the vitamin C; the fat soluble vitamins are vitamins A, D, E and K. Lack of sufficient quantities of any of the vitamins in the diet results in specific vitamin deficiency diseased (Elizabeth and Martin, 2003).

FAT: A substance that contains one or more fatty acids (in the form of triglyceride) and is the principal form in which energy is stored by the body (in adipose tissue). It also serves as an insulating material beneath the skin (in the subcutaneous tissue) and around certain organs (including the kidney). Fat is one of the three main constituents of food; it is necessary in the diet to provide an adequate supply of essential fatty acid and from the efficient absorption of fat –soluble vitamins from the intestine. Excessive deposition of fat in the body leads to obesity (Elizabeth and Martin, 2003).

Therefore, in Nigeria where the research was carried out, the activity that was conducted is to know the Microbial Food Spoilage Disorders (Diseases) and It’s Control.

1.3 Statement of Problem

Poor sanitary condition in most of the local markets and the environment being highly polluted and charged with spoilage and pathogenic flora is likely the source of contamination of food items sold by such sellers (Oweghe et al., 2001). It is known that poor hygienic conditions in a food environment may encourage the multiplication of pathogenic organisms in food (Egeonu, 2002). It has been observed that Bacillus cereus and Staphylococcus aureus grow to oxygenic levels in food at 300c (Egeonu, 2003). Therefore microbiological examination of foods and food contact surfaces may provide information concerning the quality of the raw food, and the sanitary conditions under which the food is processed (Michael et al; 2004). Microorganisms live throughout the kitchen and can easily move around by attaching themselves to people easily move around by attaching themselves to people, food and equipment. Bacteria may pass from equipment to food which has not been properly cleaned and sanitized before being used to prepare another food. This implies that the food to be consumed by humans should be pure and free from contamination especially by pathogenic and spoilage microorganisms. Failure to ensure the safety and wholesomeness of the food consumed by the public might lead to some illness. To reduce contamination by microorganisms to a minimum level, and obtain good keeping quality of the products, the raw materials should regularly be monitored and examined.

Food contacts surfaces are a major concern for food service facilities in controlling the spread of food-borne pathogens, surfaces such as bench tops, table, etc. may have bacterial on them from contact with people, raw foods, dirty equipment or other things such as cartons that have been stored on the floor. If the bench tops are not properly cleaned, any food on them will be contaminated by the bacterial (Kamil, 2005).

1.4 Aim and Objectives of Study

The aim of the study is to assess the Microbial Food Spoilage Disorders (Diseases) and Its Control. In achieving this aim, the following specific objectives were laid out as follows:

1. To isolate and identify bacterial species associated with food contamination;
2. To determine the microbial load of isolated bacteria; and
3. To establish the public health implication of consumption of such foods.

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:

• What are the bacterial species associated with food contamination?
• What is the microbial load of isolated bacteria?
• What is the public health implication of consumption of such foods?

1.6 Significance of Study

Food is very important for the sustenance of the human health. However, the preparation of foods is often associated with inadvertent contamination by microorganisms. Food contamination by antimicrobial resistant organisms has become a serious problem in public health. The emergence of resistant organisms has been observed to be as a result of inappropriate use of antibiotics. Evidence has shown that the use of antibiotics in animal has resulted to resistance food borne pathogens that may be transmitted to humans as food contaminants. This study was designed with a view to ascertain the diversity of bacterial and fungal contaminants in foods. The microbial contaminants are to be isolated, identified, and their susceptibilities to commonly available antibiotics determined. For resistant isolates, the possible resistance gene(s) involved will be identified. The findings will be discussed in relation to the potential public health implications of eating microbial contaminated foods and will be of immense benefit to the public as well as food related organisations.

1.7 Scope of Study

The study focuses on the Microbial Food Spoilage Disorders (Diseases) and Its Control.

1.8 Limitations of the Study

During the course of this study, many things militated against its completion, some of which are:

1. 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.
2. Research material: availability of research material is a major setback to the scope of the study.
3. Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
4. 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).