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Title of Thesis

Abdul Hamid
Institute/University/Department Details
University of the Punjab
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
mycotoxins, fungal contamination, aspergillus flavus, aflatoxins, decontamination

Mycotoxins are produced by fungal contamination of foods and feeds. The toxicity syndrome resulting from the intake of such contaminated material by animal and man, usually by ingestion, has been termed mycotoxicoses. The appearance of mold on foods made them taste bad and caused some loss or spoilage. The damage caused by molds to foods and feeds centered primarily on economic loss. It was recognized in early 1960, that some mold metabolites could be very poisonous to higher forma of life.

Now it is well known that the most potent substances known to induce cancer are naturally occurring, are found in foods in certain areas of the world, and are not added by the manufacturers. These products are known as aflatux1na. They are metabolites of the mold Aspergillus flavus (hence the name Aspergillus flavus toxin), produced during mold growth on a wide variety of foods and feeds.

Aflatoxins are highly carcinogenic for some animal species. As little as 100ug of aflatoxin 81 produces liver cancer when fed to rats. The rainbow trout appears to be the most sensitive in this respect, and hepatomas develop at dietary levels of about ppb of aflatoxin 81, or even less. Aflatoxins. have other genetic effects also. Aflatoxin 81 is mutagenic and teratogenic as well as carcinogenic. Aflatoxin affects the viability of seeds (viability of the contaminated corn was one-third to one quarter the control, proably due to degradation by the mold).

Aflatoxins have been found in a wide variety of human and animal food, including rice, wheat, groundnuts, black pepper, maize, oil seed and even wine. Recently a report has been published showing a strong association in man between primary liver cancer in Kenya and the eating food contaminated with aflatoxin. The incidence of this type of cancer is particularly high in parts of Africa compared to Western Europe, as is the aflatoxin level in human food consumed.

The mold responsible grows best in areas of high temperature and humidity. It likes substrate with high water content. For this reason foods contaminated with aflatoxin are found in Africa, Indo-Pakistan subcontinent, South East Asia, South America, and the southern united state.

There are two main parameters, moisture and temperature, essential for the growth of fungi responsible for the production of aflatoxins on any commodity. Fifty samples of each commodity namely wheat, sorghum, maize, cotton seed cake, mustard seed cake, raw ground nuts and broken rice were procured from different locations in Punjab and screened for the presence of aflatoxin (natural contamination). 1t was concluded that higher the moisture level in the food or feedstuff more are the chances for fungal growth and hence the production of aflatoxin.

All the above seeds and all oil seed cakes were experimentally contaminated to find whether there was any variety of grains resistant to aflatoxin elaboration. No variety of seed was observed to be resistant either to the fungal growth or the production of aflatoxin. It was concluded that under the favorable environmental conditions (moisture and temperature) there were chances of fungal growth and presence of aflatoxins.

Naturally contaminated samples of sorghum, maize, cotton seed cake and raw ground nuts when quantitatively analyzed were found to be contaminated with large quantities of aflatoxin B1 i.e. From 50 ug/kg to 1500 ug/kg of aflatoxin 81 indicating that if ingested by human beings or animals they cause cancerous growth in the liver or excretion of aflatoxin M1 a hydroxylated metabolite of aflatoxin 81 1n the lactating cows or mothers milk.

Mycoflors of all the samples was investigated Wheat had 20.5% isolated of Aspergillu flavus sorghum 19.2% maize 40.7%, cotton seed cake 45.3%, mustard seed cake 5.9%, raw groundnuts 42.1% and there were no isolates in case or broken rice.

The ability of above isolate to produce aflatoxin was noted. Forty per cent isolates of Aspergillus flavus 1n case of wheat, 25% from sorghum, 73.3% from maize, 47.3% from cotton seed cake, 23.5% from mustard seed cake and 37.5% from raw ground nuts were capable of producing aflatoxin B1 it was possible to achieve physical separation of contaminated maize samples only. From 87% to 100% to aflatoxin 81 reduction was achieved but it was impractical to perform such an operation when the bulk quantity was affected which aflatoxin. Thus it was concluded that physical separation (hand sorting of cateye fluorescent kernels) was neither economical nor practicable when the grain size was small.

All the 350 samples of wheat, sorghum, maize. Cotton seed cake, mustard seed cake, raw groundnuts and broken rice were experimentally contaminated with a toxigenic strain of Aspergillus flavus to record the varietals resistance offered by any sample. None of the samples proved resistant to Asperillus flavus growth or production of aflatxin.

After considering a host of probabilities, chemical methods were found to be most suitable to detoxify the grain. Grain were ammoniated in plastic bogs at various concentration of immune with varying concentration degree of moisturel and temperature. In case of wheat non-detectable levels were achieved in 7 days at 30 °c and 18% moisture with 2% ammonis added. Initial level of aflatoxin was 500 ug/ kg. The same result was achieved (non-detectable level of aflatoxin) 1n 3 days at 40 oC and 18% moislure with 2% ammonia added.

In case of sorghum non-detectable levels were achieved in 14 days at 20°c and 18% moisture with 2.0% ammonia added and again non-detectable levels were obtained in 7 days at 40oc the non detectable levels of aflatoxin contamination were achieved with 18% moisture and 1% ammonia.

In case of maize non-detectable levels were abtained in 7 days at 30oc and 18% moisture with 1.5% ammonia added. At 40oc and 18% moisture with 105% ammonia added. The non-detectable levels were reached in 3 days.

Similarly with 1000 up/kg initial aflatoxin contamination level experiments were conduct for detoxification. It was concluded from the experiments that ammonistion brought the level of contamination much below the limits under national laws and regulation of certain countries as well as European Economic Community directive. The grains after treatment with hot air to eliminate **cessive ammonia could be used for animal feeding (ruminants and poultry) safely. The process would results in saving large quantities of grain other wise would have been lost.

Detoxification experiments were also performed by passing the ammoniated grains through an oil expeller (acrew press). Percentage reduction in the amount of aflatoxin 81 varied from 92% to 98% in case of wheat 95% to 100% in case of sorghum and 95% to 100 in case of maize.

The second method expeller detoxification was most suitable in the detoxification of contaminated grain. This method was quick and less time consuming. In this case due to excessive heat of the expeller chamber ammonia was automatically expelled from meal and the detoxified materials in flakes were obtained.

The process of ammoniation was found to be the most economical and practical for decontamination of the food grain crops contaminated with aflatoxin in varying amounts. In the view of the above studies it is suggested that all the grain crops obtained as agricultural products should be preliminarily screened for aflatoxin contamination and the affected materials should be detoxified before utilization as animal feed. This imperative step in this direction will help to control the spread of various diseases.

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S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
230.48 KB
2 1 Introduction 1
145.85 KB
3 2 Review Of Literature 10
23882.9 KB
4 3 Experimental 50
418.35 KB
  3.1 Materials And Methods 50
  3.2 Analytical 68
  3.3 Decontamination 76
5 4 Results 78
1080.65 KB
6 5 Discussion 158
501.5 KB
  5.1 General 158
  5.2 Detoxification 167
  5.3 Aflatoxin Inactivation And Affect Of Temperature 169
  5.4 Aflatoxin/ Inactivation And Effect Of Ammonia And Moisture Level 172
  5.4 Physical Changes In The Ammoniated Grains 175
  5.5 Detoxification In The Expeller 177
7 6 Summary 181
68.83 KB
8 7 Appendices 185
201.44 KB
9 8 Bibliography 199
250.31 KB
10 9 Plates 215
219.95 KB