LACTIC ACID BACTERIAL SPECIES ASSOCIATED WITH LOCALLY FERMENTED MAIZE

ABSTRACT

Lactic Acid Bacteria play key roles in the fermentation of maize to akamu. The lactic acid bacterial species associated with the local fermentation of maize were isolated, characterized and identified. The isolation of the lactic acid bacteria was done by culturing of the sample after serial dilution on MRS agar for 24hrs at 37oC. The isolates obtained were subcultured on a nutrient agar to obtain a pure culture of the lactic acid bacteria. The occurrences of the lactic acid bacteria were determined. The characterization and identification of the lactic acid bacteria was achieved by the different biochemical tests that were carried out such as the, sugar fermentation, catalase. The morphology, gram reaction and colony features were also investigated. The 12 samples showed high microbial load which ranged from 1.8×106cfu/ml to 2.8×106cfu/ml. A total of 43 lactic acid bacteria were isolated which comprised of Lactobacillus spp (12), Streptococcus spp (9), Lactococcus spp (7), Pediococcus spp (8) and Leuconostoc spp (7). Lactobacillus spp had 100% occurrence in the 12 samples. Lactic acid bacteria are essential bacteria responsible for the fermentation of maize to akamu.

TABLE OF CONTENTS

Title page                                                                                                                                i

Certification                                                                                                                           ii

Dedication                                                                                                                              iii

Acknowledgements                                                                                                                iv

Table of contents                                                                                                                    vi

List of tables                                                                                                                           vii

Abstract                                                                                                                                  viii

CHAPTER ONE

1.0        Introduction                                                                                                          1

1.1       Food fermentation                                                                                                      1

1.2       Akamu                                                                                                                        2

1.3       Aim                                                                                                                             3

1.4       Objectives                                                                                                                   3

CHAPTER TWO

2.0       Literature review                                                                                                        4

2.1       Lactic acid bacteria                                                                                                    4

2.2       Physiology and morphology                                                                                       6

2.3       General description of lactic acid bacteria                                                                 8

2.4       Applications of lactic acid bacteria                                                                            9

2.5       Cereal                                                                                                                          12

2.6       Maize                                                                                                                          13

2.6.1    Distribution                                                                                                                 14

2.6.2    Nutritional Value and Health Benefits                                                                       14

2.6.3    Medicinal Value                                                                                                         15

2.6.4    Economic Importance                                                                                                15

CHAPTER THREE

3.0       Materials and methods                                                                                                16

3.1       Sources of material                                                                                                     16

3.2       Sample preparation                                                                                                     16

3.3       Preparation of media for bacteria isolation                                                                16

3.4       Enumeration of bacteria from locally fermented maize                                             16

3.5       Isolation of microorganism                                                                                        17

3.6       Characterization of bacteria isolates                                                                           17

3.6.1    Colony features of bacteria isolates                                                                            17

3.6.2    Microscopic Feature                                                                                                   17

3.6.3    Biochemical Tests for Identification of Bacteria                                                       18

3.7       Identification of isolates                                                                                             19

CHAPTER FOUR

4.0       Results                                                                                                                        20

CHAPTER FIVE

5.0       Discussion                                                                                                                   25

5.1       Conclusion                                                                                                                  25

REFERENCES                                                                                                                      

LIST OF TABLES

Table          Title of table                                                     page

 1         Total viable bacterial count of the samples                                                    23

 2         Occurrence of lactic acid bacterial in fermented maize                                 22

 3         bacteriological identification of the lactic acid bacteria isolate                         23

CHAPTER ONE

1.0        INTRODUCTION

1.1       FOOD FERMENTATION

Food is any substance or mixture of substances both solid and liquid, which are intended for human consumption or ingestion for their nutritional support for the body or pleasurable benefits. It usually consists of plant or animal origin, which contains essential nutrients such as carbohydrates, fats, proteins, vitamins or minerals and is ingested and assimilated by an organism to produce energy, stimulate growth and maintain life (Abdulmumeen et al., 2012, Francis, 2000).

Many African foods are fermented before consumption. Food fermentation has over the years become a part of the cultural and traditional norm among indigenous communities in Africa. Different parts of West Africa are removed with their own favorite food that has evolved over centuries depending on the customs, tradition and religion (Chelule et al., 2010).

Food fermentation involves the use of microorganisms and enzymes for the production of foods with distinct quality attributes that are quite different from the original agricultural raw materials.

Fermentation is one of the oldest and most important traditional food processing and preservation techniques (Aworh, 2008).

Fermentation has been used as a means of improving the quality of food (Lei and Jakobsen, 2004). It inhibits spoilage and pathogenic microorganism by a combination of factors which include production of organic acid, hydrogen peroxide, antibiotic-like substances and the lowering of oxidation reduction potentials (Pan and Zhang, 2008).

Fermentation process serves as a means of providing a source of nourishment for large rural populations. Fermentation enhances the nutrient content of food through synthesis of proteins, vitamins and essential amino acids (Zhang et al., 2010).

Fermentation in food processing is the conversion of carbohydrate to alcohol using yeast and/or bacteria. Under anaerobic conditions (Frazies and Westhoff, 2008).

Microbiological processing is an age long tradition in food production, but there are few documented works on these African foods (Raheem, 2006). Fermentation process for many African food products constitute a vital body of indigenous knowledge used for food preservation acquired by observation and experience and passed from generation to generation (Aworh, 2008). Cereal foods are the most important substrates for fermented foods in sub-Saharan Africa and that fermentation will lead to production of numerous food types – alcoholic and non-alcoholic. The types, flavors and peculiarities of the fermented food are cultural attributes in West Africa (Muller, 1980). Interaction between microorganisms, plants and animal are natural and constant (Frazies and Westhoff, 2008).

1.2       AKAMU

Akamu is traditionally made from maize. Several reports had identified steeping and souring as the two fermentation stages involved in the traditional process of akamu. It is prepared by steeping clean grain of maize in water at room temperature for 48-72hours. The steep water is decanted and the fermented maize grain is washed with clean water and then wet-milled. The bran is removed by wet sieving and sievate is allowed to settle for another 24-48hours, a process referred to as souring during which time fermentation also proceeds to solid starchy matter and akamu sediments (Akingbala et al., 1980). The wet akamu usually has smooth texture, a sour flavor resembling that of yoghurt and characteristic aroma that differentiate it from starch and flour. The color of the akamu depends on the color of the maize grains: yellow maize for yellow akamu and white maize for white akamu.

The wet akamu can be boiled at 8-10% total solids into a porridge or pap which serves as a weaning food for infants, breakfast for children and convenient meal for the convalescence (Onyekwere et al., 1989).

In general, a wide spectrum of microorganism is usually during fermentation process. But a few types usually determine the quality of the end products (Abegaz, 2007).

1.3       AIM   

To determine the lactic acid bacterial species associated with the fermentation of maize to akamu

1.4       OBJECTIVES

To isolate lactic acid bacterial species associated with locally fermented maize (akamu).

To characterize and identify them using morphological, physiological and biochemical techniques.  

Buyers has the right to create dispute within seven (7) days of purchase for 100% refund request when you experience issue with the file received. 

Dispute can only be created when you receive a corrupt file, a wrong file or irregularities in the table of contents and content of the file you received. 

ProjectShelve.com shall either provide the appropriate file within 48hrs or send refund excluding your bank transaction charges. Term and Conditions are applied.

Buyers are expected to confirm that the material you are paying for is available on our website ProjectShelve.com and you have selected the right material, you have also gone through the preliminary pages and it interests you before payment. DO NOT MAKE BANK PAYMENT IF YOUR TOPIC IS NOT ON THE WEBSITE.

In case of payment for a material not available on ProjectShelve.com, the management of ProjectShelve.com has the right to keep your money until you send a topic that is available on our website within 48 hours.

You cannot change topic after receiving material of the topic you ordered and paid for.