ISOLATE AND IDENTIFY MICROORGANISMS ESPECIALLY BACTERIA AND FUNGI FROM STORED MAIZE

CHAPTER ONE

1.0       INTRODUCTION

Maize (Zea mays) is a cereal crop which is an important raw material in human diet (Amakoromo, 2011).  It is an annual grass in the family Poaceae and is a staple food crop grown all over the world. It is believed that maize originated from Mexico and Central America. Fermented maize starch is also known as “pap”. It is also known as “Ogi” in the western part of Nigeria by the Yoruba’s or Akamu in the Eastern or “Akassa” in the North by the Igbo’s and Hausas respectively (Parveen and Hafiz, 2003). It is a fermented maize product obtained as smooth gel or mixed with boiling water to form a porridge, which has a sour taste. Similar maize preparations are referred to as “Akana” and “Kenkey” in Ghana (Parveen and Hafiz, 2003). It is a popular staple and most popular traditional weaning food in West African countries (Adams and Moss, 1995; Amakoromo, 2011). It is used as weaning food by low income earners who cannot afford the more expensive imported weaning foods. (Ozoh and Kuyanabana, 1995; Amakoromo, 2011).

“Ogi” is mostly prepared using traditional fermenting and malting technologies which are simple but do not guarantee quality and lack of contaminations as well as lack of the appropriate nutritive value (Marero et al., 1989). It is prepared by soaking (steeping) in water for two to five days, grinding it (wet milling) and sieved to remove the husk. The main reason for fermenting maize grains is to convert starch contents in the cereals such that it does not require dilution. The fermenting process also removes the pathogens. Ogi provides about 20-26 kcal/kg per day to an infant who has an average density of 0.26 kcal/kg (Brown et al., 1998).

In most parts of Africa especially in Nigeria, children are fed with mashed adult foods. These foods are bulky and can cause malnutrition. The developments of nutritionally balanced calorie as dense weaning foods lead to the fermentation of maize to provide pap. The food must also be of the right quantity to satisfy the infant at one feeding. It is also a choice of meal for patients in need of soft and easily digestible foods (Jay, 2005). They are important energy food rich in carbohydrate with traces of vitamins, proteins and minerals (Achtenberg et al., 1994; FAO, 2009) and are natural antioxidants (Eaton and Nelson, 1991). Its reputation as the most popular traditional weaning food and its consumption by convalescent in the West African regions calls for a safe product, free of pathogen and any potentially hazardous microorganisms. The traditional fermentation processes of pap are usually spontaneous and uncontrolled (Odunfa, 1985) and have led to the loss of nutrients. The nutritive quality of maize porridge is very low resulting from low quality maize proteins and substantial loss of nutrients at the different stages of production (Nkama et al., 2000).

The Microbiology of pap and its related products has been studied (Odunfa and Adeyele, 1985; Adegoke and Babbola, 1988; Hountunigha, 1994). New attention is presently on the use of starter cultures, which is solving numerous problems associated with the product capable of prevention and treatment of many water borne disease using bacteriogenic lactic acid bacteria (LAB) (Olukoya et al., 1994). Olasupo et al. (1997) increased the shelf-life of “pap” using a bacteriocin producing lactobacillus isolate. “Ogi” is fairly acidic (pH 4.8), which tends to inhibit the growth of some bacteria. Despite the delicate health position of pap to some consumers, the role of spoilage microorganisms has not been investigated, nor has their potential to produce harmful metabolites. Its spoilage is however, enhanced by some extrinsic factors amongst which is storage. There are so many problems which can arise from fermentation of “Ogi” (i.e. spoilt ogi corn starch) and this may include; deriving complete sour taste which may result in over fermentation due to the conception of people. Also the length of fermentation can also affect the final product.

Pap as a fermented food contains bacteria and fungi as a result of the fermentation which takes place in the cereal starch (Odunfa 1985). Evaluation of the microbial quality of pap is to identify the contaminants associated with the improper storage for a relatively period of time. Improper storage is likely to develop other contaminants which can become harmful to consumers especially children; it could even lead to food poisoning or/and intoxication. Therefore, the study was carried out on the freshly prepared raw “Ogi” that was kept for seven days with one of the water been changed and the other not changed throughout the seven days.

1.1       AIM

The main of this study is to isolate and identify microorganisms especially bacteria and fungi from stored maize (Zea mays).

1.2       SPECIFIC OBJECTIVES

To isolate and identify bacterial contaminants from stored pap.

To isolate and identify fungal contaminants from stored pap.