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Title of Thesis

Determination And Reduction Of Aflatoxin By Gamma Irradiations In Wheat Maize And Rice

Author(s)

Sabahat

Institute/University/Department Details
Department Of Chemistry, Faculty Of Sciences / University Of Agriculture, Faisalabad
Session
2010
Subject
Chemistry
Number of Pages
209
Keywords (Extracted from title, table of contents and abstract of thesis)
Composition, Sensitivity, Humidity, Determination, Linolenic, Rice, Biomass, Maize, Gamma, Irradiations, Methods, Aflatoxin, Reduction

Abstract
Cereals grown world-wide are used as staple food. Due to high temperature, humidity and non-scientific storage prevail the growth of certain species belong to family Aspergillus. Mycotoxins are small (MW ~700), toxic chemical products formed as secondary metabolites by fungal species that readily settle on crops and infect them with toxins in the field or after harvest, during transport and storage. These compounds cause a potential threat to human and animal health through the intake of food products prepared from these commodities. Generally, crops that are stored for more than a few days become a potential target for mould growth and mycotoxin formation. Mycotoxins can occur both in temperate and tropical regions of the world, depending on the species of fungi.The extraction, clean up and analysis methodology for aflatoxins in cereals (maize, rice and wheat) were validated and found it efficient and good in respect of recovery, reproducibility, repeatability, resolution and cost-effective. The extraction solvent (acetonitrile and water) gave ≥ 85% recovery in spiked cereal samples using MycoSep-226 column.The sensitivity (LOD) of HPLCFLD was higher as compared to HPLC-UV-Vis after derivatization of sample extract with trifluoroacetic acid (TFA). The collected cereals samples from Faisalabad Division, Pakistan exhibited high level of aflatoxins but after treatment with γ-irradiation, more than 95% reduction in AFB1 and ≥ 97% in Total (ΣAFB1, AFB2, AFG1 and AFG2) were observed at a dose of 6 kGy. Significant affect of radiation was found in wheat samples because substantial reduction (≥ 95%) was found in AFB1 and total aflatoxins at high dose of radiation.The level of aflatoxin contamination was far behind that the recommended limits of EU and FDA, USA. From the results it is evident that γ- irradiation is a good technology to remove contaminants like aflatoxins from cereal commodities.
The food quality of irradiated cereals was evaluated to study any chemical change in protein (amino acids), fatty acid composition and fungal biomass using different methods.The total biomass (CFU/g) showed linearity behaviour as increasing the dose level of gamma irradiation. In some samples of cereals, no microflora (fungi) was observed after 72 hrs. of incubation.composition revealed that linolenic acid and oleic acid showed decrease whereas no significant change was found in other fatty acids. The unsaturated and poly unsaturated fatty acids remained same after γ-irradiation exposure. The amino acids profile showed that leucine, lysine, tryptophane and valine increased while methionine, phenylalanine and threonine decreased in composition as increased the dose level of exposure of gamma irradiation.Overall no major difference was observed in any essential amino acids.The permanent use of contaminated cereals in the area may pose certain diseases like hepatitis, cancer of liver or effect of other major organs of the human body.The fatty acid

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 CONTENTS

 

 
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2

1

INTRODUCTION

 

1
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3 2 REVIEW OF LITERATURE

2.1 Aflatoxins in cereals
2.2 Legislations about aflatoxins
2.3 Hepatitis and Cancer
2.4 Aflatoxins and Reproduction
2.5 Aflatoxins and Children
2.6 Aflatoxins and Ruminants
2.7 Physio-Chemical Methods for the Diminution of Aflatoxins
2.8 Extraction of Aflatoxins
2.9 Food Irradiation
2.10 Biological Methods
2.11 Nontoxigenic A. flavus AND A. parasiticus
2.12 Trichoderma SPP.
2.13 Other Biological Methods

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4 3 MATERIAL AND METHODS

3.1 Cereal Sampling
3.2 Methodologies Employed for Aflatoxins Analysis
3.3 Quality Control Parameters
3.4 Irradiation of Cereals
3.4.1 Determination of fatty acids methyl ester (FAME)
3.5 Statistical Analysis

71
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5 4 RESULTS AND DISCUSSION

4.1 Validation of extraction and chromatographic techniques
4.2 General Survey of Aflatoxins in Cereal
4.3 Food irradiation and aflatoxins
4.4 Food quality of irradiated cereals

80
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6 5 SUMMARY

 

129
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7 6 LITERATURE CITED

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