دراسات على اسباب تــدهــــور بـعض الحبـــوب أثـــناء التخــــزين ومقاومتها

Abstract: SUMMARY
The present investigation was planned to study the yellow corn grains-associated fungi, aflatoxin production ability of the isolated fungi, effect of yellow corn grains infestation with Aspergillusflavus under different grain grades, temperatures, moisture content percentages and storage periods on percentage of infection, total protein percentage, amino acid content, total charbohydrate percentage and production of aflatoxins. Efficiency of some fungicides and preservatives against the infection of stored grains with A.flavus and some histopathological and haematological examinations of rats fed on yellow corn grains contaminated with aflatoxins of A. flavus were also studied.
The obtained results could be summarized as follows:-
1. The most dominant fungi which were found to be associated with yellow corn grains could be arranged descendingly, according to the occurrence percentage, as follows:Aspergillusflavus, Penicilliumfuniculosum, Aspergillusterreus, Fusariummoniliforme, F. oxysporum, F.graminearum, Aspergillusniger, Alternaria sp., Rhizopus sp., MacrophominaphaseolinaandFusarium sp.
2. Fractionation of aflatoxins by thin layer chromatography method showed the absence of aflatoxins in the filtrates obtained from the all isolated fungi, except the filterate of yellow corn grains infected with Aspergillusflavus. The production of aflatoxins by A. flavus was effected by the grade of grains as well as its moisture content so, the production was increased from grade one to grade five and from 17 % to 23 % moisture content within each grade. Also, the concentration of aflatoxin B1 is higher than that of aflatoxin B2. Grade one exhibited the least concentrations of both B1 and B2 ,while grade five showed the highest concentrations of both and B2.

3. The percentage of infection of yellow corn grains caused by A. flavus was significantly increased by increasing the storage temperature degree, grain moisture content percentage, time of storage and percentage of broken kernels ( grade of grains ).
4. The protein content, of A. flavus-infected yellow corn grains with moisture content percentage either low ( 17 % ) or high ( 23 % ), was decreased when stored under low temperature ( 10 C or 18 C ) for a storage period as long as 90 days in all tested grade compared with the control. While that of grains with 17 % moisture content was decreased and that of grains with 23 % moisture content was increased to the max. (100%) when stored under high temperature ( 28 C or the room temperature, 25 - 30.2 C ) for a storage period of 30 days only in all tested grades.
5. Storage of grains infected with A. flavus and with moisture content either low
(17 %) or high ( 23 % ) under high temperature ( 28 C. or 25-30.2 C. ) caused reduction in concentration of proline ( in all tested grads ), reduction in concentration of both lysine and arginine ( in grade one only ), while others remain unchanged such as threonine and leucin ( in grade five only ), but concentrations of the other examined amino acids were increased. In the same time, storage of A. flavus infected grains with 17 % moisture content under temperature of 25 - 30.2C. reduced the total amino acids content of grains by about 0.6 and 6.7 % in grades one and five, respectively, while storage of those with 23 % moisture content under temperature of 28 C. increased the total amino acids content by about 19.04 % as shown in grade three.
Publication year 1996
Organization Name
Country Egypt
Author(s) from ARC
Publication Type Master Thesis
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