DETECTION OF ASPERGILLUS FLAVUS AND ASPERGILLUS PARASITICUS AND ESTIMATION OF AFLATOXINS IN SORGHUM PURCHASED IN UMUAHIA MAIN MARKET.

ABSTRACT

Sorghum is the fifth most important cereal after rice, wheat, maize and barley. Like every other plant, sorghum is attacked by microorganisms. Fungal species such as Aspergillus parasiticus and Aspergillus flavus grow on sorghum and consequently produce a mycotoxin known as aflatoxin. Aflatoxin is a toxic metabolite which causes acute illnesses such as liver damage ad cancer, even death when consumed in large quantity. Aspergillus parasiticus and Aspergillus flavus were isolated from sorghum seeds by culturing on Potato Dextrose Agar and the level of aflatoxin content of the seeds determined using ELISA method. Sorghum treated with only water, water and salt and water, salt and heat dried had a total viable count of 1.8x101cfu/ml, 7x101cfu/ml and 8x101cfu/ml respectively. The total aflatoxin content of the samples were 2.80ppb, 2.70ppb and 2.35ppb respectively. In addition, the aflatoxin content of the untreated sample was 4.00ppb. The germinative energy of all treated samples were 100%, 80% and 30% respectively.  Hence, producers should adopt treatment of raw sorghum with salt and heat-drying it in the HACCP steps to ensuring production of food safe for consumption. However, for production processes that require germination of the grains, the grains should first be germinated before heat-drying since it reduces the seeds germinative energy. 

TABLE OF CONTENTS

Title Page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgement ﾿ iv

Table of Contents ﾿ v

Abstract  ﾿ x

Chapter one: ﾿ Introduction ﾿ 1

1.1. ﾿ ﾿ Overview ﾿ 1

1.2. ﾿ Sorghum and Fungi ﾿ 2

1.3. ﾿ Contamination conditions ﾿ 3

1.4. ﾿ Aims and Objectives ﾿ 4

Chapter two: ﾿ Literature Review ﾿ 5

2.1. ﾿ Aflatoxins ﾿ 5

2.2. ﾿ Toxicology ﾿ 10

2.3. ﾿ Pathology ﾿ 12

2.3.1. ﾿ Aflatoxicosis ﾿ 12

2.3.2. ﾿ Aflatoxicosis and child health in Nigeria ﾿ 12

2.3.3. ﾿ Aflatoxicosis and hepatic deaseas ﾿ 13

2.3.4. ﾿ Other effects of aflatoxicosis ﾿ 14

2.4. ﾿ Diagnosis ﾿ 15

2.5. ﾿ Prevention and control of exposure to aflatoxins ﾿ 15

2.5.1. ﾿ Education ﾿ 15

2.5.2. ﾿ Processing ﾿ 16

2.5.3. ﾿ Use of Antioxidants and Minerals ﾿ 16

2.5.4. ﾿ Aflatoxins Monitoring ﾿ 16

Chapter Three: Materials and Methods ﾿ 18

3.1. ﾿ Isolation of Aspergillus flavus and Aspergillus parasiticus ﾿ 18

3.1.1. ﾿ Materials and instruments used ﾿ 18

3.1.2. ﾿ Sample preparation ﾿ 19

3.1.3. ﾿ Medium preparation ﾿ 20

3.1.4. ﾿ Plating the seeds ﾿ 20

3.1.5. ﾿ Total viable count on assay. ﾿ 20

3.1.6. ﾿ Counting of the colonies ﾿ 21

3.1.7. ﾿ Germinative energy ﾿ 21

3.2. ﾿ Estimation of aflatoxins ﾿ 22

3.2.1. ﾿ Materials and instruments used ﾿ 22

3.2.2. ﾿ Sample preparation ﾿ 23

3.2.3. ﾿ Aflatoxn detection ﾿ 24

Chapter four: ﾿ Result ﾿ 25

4.1. ﾿ Total viable count (TVC) from the assay of all treated sample. ﾿ 26

4.2. ﾿ Germinative energy of treated samples. ﾿ 27

4.3. ﾿ Microorganisms isolated from all the samples ﾿ 28

4.4. ﾿ The Aflatoxin content of all samples ﾿ 29

Chapter five: ﾿ Discussion, Recommendations and Conclusion ﾿ 30

5.1. ﾿ Discussion ﾿ 30

5.2. ﾿ Recommendations ﾿ 31

5.3. ﾿ Conclusion ﾿ 31

References ﾿

LIST OF TABLES

Table ﾿ Title ﾿ Page

2.1 ﾿ Some Aflatoxins and Sources. ﾿ 7 ﾿

2.2 ﾿ Chemical and physical properties of some 

aflatoxins ﾿ 8

 4.1 ﾿ Total viable count (TVC) from the assay 

 of all treated sample. ﾿ 26

  4.2 ﾿ Germinative energy of treated samples. ﾿ 27

  4.3  ﾿ Microorganisms isolated from all the samples ﾿ 28

  4.4 ﾿ The Aflatoxin content of all the samples ﾿ 29

LIST OF FIGURES

Figure ﾿ Title ﾿ Page

 2.1. ﾿ Structure of aflatoxins B1, B2, G1, and G2 ﾿ 9

 2.2. ﾿ Pathways and consequences for Aflatoxin in 

animal metabolism ﾿ 11 ﾿