الفهرس 
ACKNOWLEDGEMENT
Ability fungi to produce mycotoxinsOnly 14 pages are availabe for public view
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Abstract
ThepresentThesisaimedtostudythenaturalcontaminationofsomekindsoffruitsandtheirprocessedproductswithfungiandtheirtoxins.Thirtyhundredandfiftysamplesoffreshfruitincludeapples,guava,oranges,mangoes,apricots,figs,grapesandplums,aswellastwohundredandfortysamplesofcannedjuiceforapples,oranges,guavaand mangoes,beside onehundredand fiftysamplesofdriedfruitsofapricots,plumsandfigsandraisinswerecollectedfromdifferentmarketsinAssiutGovernorate,Egypt.Allsampleswereanalyzedforthepresenceoffungiandmycotoxins.Theisolatedfungiwereidentifiedandthemostpredominantgeneraoffungiwereexaminedfortheirability toproducemycotoxins.Theeffectofsulfurdioxidetreatmentontheremovalanddestructionoffungaltoxinswasalsostudied in some samplescontaminated with these toxins.
Themainresultsobtainedduringthisinvestigationcouldbesummarizedas follow:
1- Atotalof2321isolatesbelongingto14generaoffilamentousfungi wereisolatedandidentified.
2- ThemostcommonfungalgenerawereAspergillusandPenicillium.Aspergillusgenusshowedthegreatestspectrumbybeingrepresentedby21specieswhilethegenusPenicilliumrepresented by14 species.
3- Aspergillusspeciesrecordedthehighestpredominance,with
547isolates,followedbythegenusPensillium,whichrepresentedby369isolatesfromfruitsamplesandtheirprocessedproducts.
4- Thepercentageoffungal contaminationin freshfruitwashigher than fruitjuices inEgyptianmarkets.
5- Thepercentageoffungalcontaminationinthedriedfruitwashigherthanthepercentageofitspresenceinthesamefreshfruitlocated in the Egyptian market.
6- Therearenospecificfungalfloraforeachkindoffruitsandtheirprocessedproducts,butthereisasimilaritybetweenthefungiisolated from alltypes of samples in this study.
7- Atotalof123differentisolatesofAspergillus(80isolates)andPenicillum(43isolates)fromfreshfruitsamplesandprocessedproductsinthisstudywerescreenedfordeterminetheirabilityto produce mycotoxins. The resultsshowed that:
- 40isolatesofAspergillus(50%)werefoundtoproduceatleast one type of mycotoxins.
- Eightoutof13isolatesofAspergillusflavushavetheabilityto produce aflatoxins.
- Aspergillusparasiticusshowedhighabilitytoproduceaflatoxin,8outof13isolateshavetheabilitytoproduceaflatoxins.
- 6outof7isolatesofAspergilluscarbonariushavetheabilityto produce ochratoxin.
- Isolatesof Aspergillusochraceus(12isolates)showedalowerabilitytoproduceochratoxin,whereonly5isolatesproduced this toxin.
- ThegenusPenicilliumhadanabilitytoproducepatulinandcitrinin14outof43showedtheirabilitytoproducethesemycotoxins.
8- Atotalofonehundredandnine(109)samples(freshfruit39samples)and(40samplesoffruitjuicesand30driedfruitssamples)wereselectedtoinvestigatethepresenceofmycotoxinsbychromatographytechnique.Theresultsshowed the following:
- Mycotoxinsappearedindriedfruitsweresignificantlyhigher than in freshfruitsandfruitjuices.
- Samplesofdriedgrapesanddriedfigswerethehighestcontaminationbymycotoxinscomparedtotheothertypesofdriedfruits in the Egyptianmarkets.
- AflatoxinsandochratoxinAwerethemostprevalentmycotoxins in driedfruitsamples.
- Patulin,citrinin,aflatoxinandochratoxinAwerethemostcommonmycotoxins in freshfruit.
-Aflatoxinwasfoundtobethemostcommonmycotoxinsinfruitandprocessedproducts.26samplescontaminatedwithaflatoxinwhileochratoxinA(OTA)waspresentinonly6samples,butpatulinappearedin4samplesoffreshapplesand3 samples in apple juice.
9- Aflatoxinswerequantifiedinfruitproducts(fruitjuicesanddriedfruits) usingHPLCtechnique.Theresultsindicatedthat:
- Applejuicesampleswerecontaminatedwiththefourtypesofaflatoxinsatconcentrationsof5.0563,0.0202,3.0999and408887 μg/l foraflatoxinsB1,B2,G1and G2, respectively.
- Driedfigscontaminatedwithaflatoxins,whereaflatoxinB1andB2werepresentin0.0113and2.034μg/kgrespectively,whileaflatoxinsG1andG2showed3.560and2.034μg/kgrespectively.
10- Sulfurdioxidetreatmentwaseffectiveineliminatingaflatoxinsinapplejuicesamplecontainingapproximately5.0563µg,0.0202µg,3.0999µgand4.8887µg,B1,B2,G1
andG2,respectively.Treatingthissamplewith50ppmSo2for1hatroomtemperaturereducedaflatoxinsB1,B2,G1andG2concentrationsbyapproximately36.5,51.5,60.9and68.5%respectively.Aflatoxinsconcentrationwasreducedapproximatelyto3.7,0.0,1.4,and6.4%forB1,B2,G1andG2,respectivelywhentheconcentrationofsulfurdioxidewasincreased to 150 ppm.
11- Sulfurdioxidetreatmentwasalsoeffectiveineliminatingaflatoxinsindriedfigsamplescontainingapproximately2.795397,0.011374,2.034143and3.560501µgofB1,B2,G1
andG2,respectively.Treatingthissamplewith500ppmSo2for8hatroomtemperaturereducedaflatoxinsB1,B2,G1andG2concentrationbyapproximately25.7,64.1,64.8and45.9%,respectively.Aflatoxinswerereducedapproximatelyto 0.242, 4.92, 0.417 and0.033% of B1,B2,G1andG2,
respectivelywhentheconcentrationofsulfurdioxidewasincreased to 1500 ppm.