Timely detection of Mediterranean fruit fly (Medfly) is very important so that eradication action can be taken on time. The larvae stage of this insect is the most dangerous stage as it is within the pulp of the fruit...Timely detection of Mediterranean fruit fly (Medfly) is very important so that eradication action can be taken on time. The larvae stage of this insect is the most dangerous stage as it is within the pulp of the fruit, making it hard to detect by visual inspection. In most countries at ports of entry the inspector check a small sample of fruit by visual inspection or by cutting the produce and searching for fungus and pests. This paper will investigate a quick, reliable and sensitive method to determine the presence of fruit flies. Our research focuses on developing the technology for detecting hidden infestations by using the Head Space-Soild Phase Micro Extraction (HS-SPME) method coupled with Gas Chromatography-Mass Spectrocopy (GC-MS) technique. Five different types of fruit were infested with an early stage of Medfly Ceratitis capitata Wiedemann (Diptera: Tephidae). We investigated to detect the differences in volatile organic compounds (VOC’s) between infested and non- infested fruits by using HS-SPME with (GC-MS). The results indicated that for few chemicals no significant differences between infested and non-infested fruit can be seen, especially in the fruits with first instar. However, in case of third instar larvae infested fruits significant differences in the chemicals can be seen as compare to non infested fruits and other instar infestations. These chemicals include ethyl (Z)-2 butenoate, 2-heptanone, anisole, β-cis-ocimene, 1,3,7-nonatriene,4,8-dimethy-,ethyl octyate, isoamyl caproate and 1β,4βh,10βh- guaia-5,11-diene, in apple. Ethyl (Z)-2-butenoate, (+)-2-bornanone, (-)-trans- isopiperitenol, methyl caprate, caryophyllene and farnesene in orange. Butanoic acid, 3-methyl-,2-methylbutul acetate, sabinene, β-myrcene, octanoic acid, methyl ester, dihydrocarvone, (-)-trans-isopiperitenol and ethyl laurate in mandarin. Butyl 2-methylbutanoate, terpinen-4-ol, P-menth-8-en-2-one, E-,(3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene and dodecanoic acid, ethyl ester in lemon. Decane, 3-methyl-, p-menth-1,4(8)-diene, 1-undecene and α-cubebene in avocado. Thus, the VOC’s method could provide a possible tool for detecting tephritid larvae and this method could be adopted by industries importing and exporting fruit.展开更多
为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一...为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一级和双井绿茶二级四个不同等级的双井绿茶的香气物质进行了检测分析。结果表明,从四个不同等级的双井绿茶中共鉴定出70种香气物质,主要包括醇类、烯烃类、烷烃类、酯类等化合物。不同等级的双井绿茶中香气物质组成及相对含量均有差异,通过主成分分析(Principal component analysis,PCA)和偏最小二乘法-判别分析(Partial least squares-discriminant analysis,PLS-DA),可以有效区分不同等级的双井绿茶。不同等级双井绿茶香气差异主要由反式-β-金合欢烯、香叶醇、水杨酸甲酯、茉莉酮、苯乙醇等14种关键化合物差异引起。在不同等级双井绿茶中关键香气物质表现出不同的分布规律,随着芽叶开展,α-椰油烯、石竹烯及己酸乙酯含量降低,而顺式-3-己烯醇、香叶醇及水杨酸甲酯含量呈增加趋势,芳樟醇、茉莉酮、反式-橙花叔醇含量从低到高,随后含量又迅速下降。本文研究了不同等级双井绿茶中香气物质的组成特征及关键香气物质的分布规律,为今后双井绿茶生产提供了理论依据。展开更多
文摘Timely detection of Mediterranean fruit fly (Medfly) is very important so that eradication action can be taken on time. The larvae stage of this insect is the most dangerous stage as it is within the pulp of the fruit, making it hard to detect by visual inspection. In most countries at ports of entry the inspector check a small sample of fruit by visual inspection or by cutting the produce and searching for fungus and pests. This paper will investigate a quick, reliable and sensitive method to determine the presence of fruit flies. Our research focuses on developing the technology for detecting hidden infestations by using the Head Space-Soild Phase Micro Extraction (HS-SPME) method coupled with Gas Chromatography-Mass Spectrocopy (GC-MS) technique. Five different types of fruit were infested with an early stage of Medfly Ceratitis capitata Wiedemann (Diptera: Tephidae). We investigated to detect the differences in volatile organic compounds (VOC’s) between infested and non- infested fruits by using HS-SPME with (GC-MS). The results indicated that for few chemicals no significant differences between infested and non-infested fruit can be seen, especially in the fruits with first instar. However, in case of third instar larvae infested fruits significant differences in the chemicals can be seen as compare to non infested fruits and other instar infestations. These chemicals include ethyl (Z)-2 butenoate, 2-heptanone, anisole, β-cis-ocimene, 1,3,7-nonatriene,4,8-dimethy-,ethyl octyate, isoamyl caproate and 1β,4βh,10βh- guaia-5,11-diene, in apple. Ethyl (Z)-2-butenoate, (+)-2-bornanone, (-)-trans- isopiperitenol, methyl caprate, caryophyllene and farnesene in orange. Butanoic acid, 3-methyl-,2-methylbutul acetate, sabinene, β-myrcene, octanoic acid, methyl ester, dihydrocarvone, (-)-trans-isopiperitenol and ethyl laurate in mandarin. Butyl 2-methylbutanoate, terpinen-4-ol, P-menth-8-en-2-one, E-,(3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene and dodecanoic acid, ethyl ester in lemon. Decane, 3-methyl-, p-menth-1,4(8)-diene, 1-undecene and α-cubebene in avocado. Thus, the VOC’s method could provide a possible tool for detecting tephritid larvae and this method could be adopted by industries importing and exporting fruit.
文摘为探究不同等级双井绿茶香气物质组成特征,利用顶空固相微萃取-气相色谱-质谱联用技术(Headspace solid-phase micro extraction and gas chromatography mass spectrometry,HS-SPME-GC/MS)对修水县双井银毫、双井绿茶特级、双井绿茶一级和双井绿茶二级四个不同等级的双井绿茶的香气物质进行了检测分析。结果表明,从四个不同等级的双井绿茶中共鉴定出70种香气物质,主要包括醇类、烯烃类、烷烃类、酯类等化合物。不同等级的双井绿茶中香气物质组成及相对含量均有差异,通过主成分分析(Principal component analysis,PCA)和偏最小二乘法-判别分析(Partial least squares-discriminant analysis,PLS-DA),可以有效区分不同等级的双井绿茶。不同等级双井绿茶香气差异主要由反式-β-金合欢烯、香叶醇、水杨酸甲酯、茉莉酮、苯乙醇等14种关键化合物差异引起。在不同等级双井绿茶中关键香气物质表现出不同的分布规律,随着芽叶开展,α-椰油烯、石竹烯及己酸乙酯含量降低,而顺式-3-己烯醇、香叶醇及水杨酸甲酯含量呈增加趋势,芳樟醇、茉莉酮、反式-橙花叔醇含量从低到高,随后含量又迅速下降。本文研究了不同等级双井绿茶中香气物质的组成特征及关键香气物质的分布规律,为今后双井绿茶生产提供了理论依据。