| In this experiment,corn gluten meal(CGM)was used as the research object.The quality variation and the accumulation dynamic condition of deoxynivalenol(DON,15AC-DON)of CGM with different Fusarium graminearum inoculated dose and moisture were studied by hypoxia and oxygen.It provides a theoretical basis for the effective anti-mildew measures of corn by-products during storage,and the reduction of DON and 15AC-DON pollution and the use of mildewed feed.The main research contents and results are as follows:Test 1 The quality variation and the accumulation dynamic condition of DON and 15AC-DON of CGM inoculated with Fusarium graminearum under anoxic conditionsTwo factors test design was used in this trial.Under anaerobic conditions,inoculated dose of Fusarium graminearum were 1×10~3,1×10~4and 1×10~5conidia/g,moisture contents of CGM were 13%,16%,20%,22%.Ziplock culture,temperature25±2℃,humidity 75%±5%,time 60d.Samples were collected to detect different nutrional composition and DON 15AC-DON on 0,5,10,15,20,30,60 d of trial.Every sample was detected 3 times.The results are as follows:(1)The nutrients that provide nitrogen sources for Fusarium graminearum:protein nitrogen(amino acids)and non-protein nitrogen.Initial moisture and Fusarium graminearum inoculated dose all played a role in the change of CP,but had no effect on amino acid changes,and there was no significant change in CP in low moisture content(13%and 16%)(P>0.05),the CP with high moisture content(20%and 22%)increased linearly with the prolongation of culture time(P<0.01),and the amino acid changed quadratic curve with the prolongation of culture time(P<0.01),the initial moisture and Fusarium graminearum inoculated dose had an interaction effect on CP changes,and had no interaction effect on amino acid changes.(2)The nutrients that provide carbon sources for Fusarium graminearum:EE,starch,CF and NFE.The initial moisture played a major role in the changes of EE,starch,CF and NFE while the inoculated dose of Fusarium graminearum was not the main influencing factor.The EE,starch,CF and NFE of different moisture content groups decreased linearly with the prolongation of culture time(P<0.01),the initial moisture and Fusarium graminearum inoculated dose had no interaction effect on EE,starch,CF and NFE.(3)Other nutrients:moisture,energy,Ash.The initial moisture played a major role in the change of moisture and energy,while the inoculated dose of Fusarium graminearum was not the main influencing factor.The initial moisture and Fusarium graminearum inoculated dose had no effect on the change of Ash,and energy in different moisture content groups decreased linearly with the prolongation of culture time(P<0.01),and the moisture showed a quadratic curve(P<0.01).The initial moisture and Fusarium graminearum inoculated dose had no interaction effect on energy and moisture change.(4)Acid value,protein solubility.Initial moisture plays a major role in acid value,protein solubility change,while Fusarium graminearum inoculated dose was not the main influencing factor.Protein solubility in different moisture content groups decreased linearly with the prolongation of culture time(P<0.01),the acid value increased linearly(P<0.01).There was no interaction effect on protein solubility and acid value.(5)The total number of molds.Initial moisture and Fusarium graminearum inoculated dose play a role in the total number of molds.There was no significant change in the total number of molds in low moisture content(13%and 16%)and inoculated Fusarium graminearum 1×10~3-1×10~5conidia/g groups(P>0.05),the total number of molds with high moisture content(20%and 22%)showed a quadratic curve with the prolongation of culture time(P<0.01),and both had an interaction effect on the total number of molds.(6)Accumulation dynamic condition of DON and 15AC-DON:DON in CGM was detected on the 5th,15th,20th,and 60th day of the test.On the 15th day of the test,when the moisture content was 20%,and the inoculated dose of Fusarium graminearum was 1×10~5conidia/g,the maximum DON content was 9.88 mg/kg.15AC-DON was detected on the 5th,30th,and 60th day after the test.On the 5th day of the experiment,the moisture content was 22%,and the inoculated dose of Fusarium graminearum was 1×10~3conidia/g,the highest 15AC-DON content was16.53 mg/kg.Test 2 The quality variation and the accumulation dynamic condition of DON and 15AC-DON of CGM inoculated Fusarium graminearum under oxygen conditionsSingle factor test design was used in this trial.Under oxygen conditions,inoculated dose of Fusarium graminearum were 1×10~5,1×10~6and 1×10~7,moisture contents of CGM were 22%.Erlenmeyer flask culture,temperature 25±2℃,humidity75%±5%,time 60 d.Samples were collected to detect different nutritional composition and DON 15AC-DON on 0,5,10,15,20,30,60 d of trial.Every sample was detected 3 times.The results are as follows:(1)The nutrients that provide nitrogen sources for Fusarium graminearum:protein nitrogen(amino acids)and non-protein nitrogen.The inoculated dose of Fusarium graminearum had no effect on the changes of CP and amino acid,but the amino acid showed a quadratic curve with the prolongation of culture time(P<0.01).(2)The nutrient that provided carbon source for Fusarium graminearum:EE,starch,CF and NFE.The inoculated dose of Fusarium graminearum had no effect on the changes of EE,starch,CF and NFE.The EE,starch,CF and NFE decreased linearly with the prolongation of culture time(P<0.01).(3)Other nutrients:moisture,energy,Ash.The inoculated dose of Fusarium graminearum had no effect on the changes of moisture,energy and Ash,while the energy,decreased linearly with the prolongation of culture time(P<0.01),and the moisture showed a quadratic curve(P<0.01).(4)Acid value,protein solubility.The inoculated dose of Fusarium graminearum had no effect on acid value,protein solubility change(P>0.05),while protein solubility decreased linearly with the prolongation of culture time(P<0.01).The acid value increased linearly(P<0.01).(5)The total number of molds.The inoculated dose of Fusarium graminearum had an effect on the change of mold.The total number of molds showed a quadratic curve change with the prolongation of culture time(P<0.01).(6)Accumulation dynamic conditon of DON and 15AC-DON:The DON production of Fusarium graminearum was that between 0～10 d,and the content of DON reached 3.20,8.67,15.63 mg/kg;DON mid-production:between 11 d～15 d,the content of DON reached 5.64,38.36,63.72 mg/kg;the late stage of DON production:between 16 d～60 d,the content of DON reached 6.17,18.27,23.51 mg/kg.The accumulation dynamic condition of 15AC-DON was follws:between 0～10 d,and the content of 15AC-DON reached 11.51,18.61,53.76 mg/kg;between 11 d～15 d,15AC-DON content reached 11.39,80.11,69.05 mg/kg;between 16 d～60 d,the contents of 15AC-DON reached 13.71,18.82 and 21.42 mg/kg.In summary:under anoxic conditions,the initial moisture was the main influencing factor for the quality change of CGM.The higher the moisture was,the longer the culture time was and the worse the quality of CGM was.The inoculated dose of Fusarium graminearum was not a major factor affecting quality.DON and15AC-DON could be detected on some time of trial.Under the condition of oxygen conditon,the inoculated dose of Fusarium graminearum had no effect on nutrient changes,and had an effect on mold and toxin accumulation.The longer the culture time was,the higher the inoculated dose of Fusarium graminearum was and the worse the quality of CGM was.There are a dose-depended reladtionship between inoculated dose of Fusarium graminearum and DON,15AC-DON contents.DON and15AC-DON showed ealier stage,middle stage and later stage accumulation dynamic condition regularity within 60 d. |
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