Study On The Effect Of The Occurrence Of Tribolium Castaneum On The Volatile Substances In Stored Grain

Tibolium castaneum is one of the most important stored grain pests in the world.It has a strong reproduction ability and causes serious damage to stored wheat and wheat flour.In this article,the volatile substances of wheat and wheat flour infected by T.astaneum were extracted and identified by headspace solid-phase microextraction(HP-SPME)and gas-mass spectrometry(GC-MS).The types,quantity,and content of volatile substances in the stored grain environment were analyzed after different time of infection of T.astaneum,meanwhile,the characteristics of volatile substances in the stored grain environment were discussed when T.astaneum occurred.The main research results were as follows:The extraction and detection conditions of the volatile substances in the stored grain select 65?m PDMS/DVB fiber extraction head,and the equilibration time and extraction time of the headspace solid-phase microextraction is 1.0 h.Use DB-5MS UI column to detect volatile substances.The inlet temperature is set at 260? for 3 min,which first maintains at60? for 3 min,then increase to 110? at 15?/min for 4 min,next increase to 170? at3?/min for 5 min,and finally increase to 240? at 25?/min for 5 min.At the initial stage of infection with T.castaneum adults with initial different density,the main volatile substances of wheat flour were hydrocarbons,alcohols,aldehydes and other substances,esters appeared after 20 d storage,and ketones appeared at 30 d.With the increase of infection time,the total content of volatile substances in wheat flour increased,the content of hydrocarbon decreased,and the contents of aldehydes,acids and esters increased significantly.At the initial stage of infection with T.castaneum adults,the main volatile substances in wheat were hydrocarbons,alcohols,aldehydes,acids,esters and other substances.With the increase of infection time,the total content of wheat increased,the content of hydrocarbons first decreased and then increased,the acids first increased and then decreased,the alcohols and ester decreased.The ketones increased slightly,but the change was not obvious.The volatile substances of wheat flour infected by T.castaneum with different initial states mainly were hydrocarbons,esters aldehydes and alcohols,acids and aldehydes appeared after infection a while,and ketones appeared in wheat flour infected with adult stage.The contents of hydrocarbons,alcohols and other substances in wheat flour increased with the growth and development of T.castaneum,while the changes of esters decreased significantly.The volatiles substances of wheat infected by T.castaneum with different initial states were mainly hydrocarbons,alcohols,aldehydes,acids and other substances,ketones were only found in the wheat infected with T.castaneum at larval and adult stages.With the T.castaneum of growth and infection time,the contents of hydrocarbons,aldehydes and esters in wheat flour at the initial T.castaneum egg stage of infection were significantly decreased,while the contents of alcohols and ketones were increased.At the T.castaneum larval stage of infection,the contents of alcohols increased significantly,while the other substances had no significant changes.The contents of hydrocarbons and other substances in the wheat flour at the initial T.castaneum pupae stage of infection were significantly decreased,while the alcohol substances were significantly increased.The contents of hydrocarbons and aldehydes in wheat flour of T.castaneum adults at the initial stage of infection were significantly decreased,while the alcohols,lipids and other substances were significantly increased.The changes in the substance contents were the most significant after the infection of T.castaneum larvae and adults.The volatiles substances of wheat infected by T.castaneum with different initial states were hydrocarbons,alcohols,aldehydes,acids,aldehydes and other substances,and ketones only appeared in the wheat infected with T.castaneum larval and adults.With the T.castaneum of growth and infection time increasingly,the content of hydrocarbons in the infected wheat decreased significantly.The contents of esters and ketones decreased,while the contents of alcohols and other substances increased significantly in wheat flour at the initial T.castaneum egg stage of infection.The contents of alcohols,esters,ketones and other substances in wheat were significantly increased at the T.castaneum larval of initial infection.The contents of alcohols and esters in the T.castaneum pupal of the initial infection were significantly increased,while the other substances had no obvious changes.Alcohol content increased significantly in wheat at the initial stage of T.castaneum adult infection.The characteristic volatile substances of wheat flour with T.castaneum adults with initial different density were(E)-2-octenal,2-butyl-cyclohexanone,phytol,(E)-2-octenal,pentanal,17-octadecynoic acid,1-undecene,2-isopropyl-5-methyl-1-heptanol and 1,1'-oxybis-decane.The characteristic volatile substances of wheat were isopropyl palmitate,2-pentyl-furan,longifolene,phenylacetaldehyde,3-methyl-1,3,5-pentanetriol,dihydro-5-pentyl-2(3H)-furanone,2-methyl-1,2-dimethylpropyl ester butanoic acid,2,5,5-trimethyl-heptane and hexanal.The characteristic volatile substances of wheat flour with T.castaneum adults with different initial states were 1-(ethenyloxy)-octadecane,2,2,4-trimethyl-hexane,2,3,4-trimethyl-decane,3,7-dimethyl-decane,4,5-dimethyl-nonane,(E)-5-Octadecene,1-hexanol,2-butyl-1-octanol,n-tridecan-1-ol,4-hydroxy-butanoic acid,tridec-2-ynyl ester butanoic acid,1-cyclopentyl-2-propanone,6,10,14-trimethyl-2-pentadecanone and hexadecane.The characteristic volatile substances of wheat with T.castaneum adults with different initial states were 1-cyclopentyl-2-propanone,2-hexanone,4-methyl-dodecane,4-methyl-pentadecane,5-butyl-nonane,2-hexyl-1-decanol.