不同成熟期鲜枣香气物质变化及相关合成酶活性研究

Changes in Aroma Components and Related Enzyme Activities in Fresh Jujube Fruit at Different Ripening Stages

为探究鲜枣香气物质的形成机理,本试验分析了不同成熟期壶瓶枣、板枣、赞皇大枣3个品种鲜枣中香气成分的变化及其与脂氧合酶(LOX)途径关键酶活性之间的关系。采用顶空固相微萃取-气相色谱-质谱联用(HS-SPME-GC-MS)分析技术对挥发性化合物进行定性定量分析,利用香气活性值(OAV)分析挥发性化合物对鲜枣香味的贡献,同时利用紫外分光光度法检测鲜枣中脂氧合酶途径关键酶活性的变化。结果表明,共鉴定出46种香气成分,己醛、(E)-2-己烯醛、(Z)-2-庚烯醛、(E)-2-壬烯醛、(E)-2-辛烯醛、1-戊烯-3-酮和月桂酸对鲜枣香气有较大贡献。其中(E)-2-己烯醛含量在壶瓶枣(0.18~2.20 mg·kg^(-1))、板枣(2.09~4.67 mg·kg^(-1))和赞皇大枣(2.07~4.20 mg·kg^(-1))中最高,且在赞皇大枣中随成熟度增加而逐渐升高。同时,LOX、ADH及醇酰基转移酶(AAT)活性在不同的成熟期达到最大值,并对醛类、酯类和酮类香气成分有重要影响。综上所述,鲜枣成熟过程中LOX途径中关键酶活性的变化与香气成分的变化密切相关,不同成熟阶段鲜枣香气成分的含量存在明显差异。本研究结果不仅有助于揭示果实成熟和品质形成的机制,还可为鲜枣的品质控制和调控提供重要的科学依据。

To explore the formation mechanism of aroma substances in fresh jujube and provide scientific proof for the changes in aroma quality during storage and processing,this paper investigated the changes of aroma components in fresh jujube of Hupingzao(HPZ),Banzao(BZ),and Zanhuangdazao(ZHDZ)at various stages of maturity and their relationship with the functions of key enzymes of LOX pathway.Headspace solid phase micro-extraction-gas chromatography-mass spectrometry(HS-SPME-GC-MS)analysis technology was used to qualify and quantify the volatile compounds.The contribution of volatile compounds to the fresh jujube aroma was evaluated by the aroma activity value(OAV).Simultaneously,ultraviolet spectrophotometry was used to detect changes in the key enzyme activities of the lipoxygenase pathway in fresh jujube.A total of 46 aroma components was identified;and among them,hexanal,(E)-2-hexenal,(Z)-2-heptenal,(E)-2-nonenal,(E)-2-octenal,1-penten-3-one,and lauric acid had significant contributions to the aroma of fresh jujube.In addition,the content of(E)-2-hexenal was the highest aroma in HPZ(0.18-2.20 mg·kg^(-1)),BZ(2.09-4.67 mg·kg^(-1))and ZHDZ(2.07-4.20 mg·kg^(-1)).Moreover,it was increased along with the maturity stage in ZHDZ.Aldehydes,esters,and ketones were significantly impacted by the simultaneous maximum activities of lipoxygenases(LOX),alcoholdehydrogenase(ADH),and alcohol acyl transferase(AAT)at various ripening stages.In conclusion,there are notable differences in the contents of aroma components at different maturity stages of fresh jujube and that changes in key enzyme activities of LOX pathway during the ripening process of fresh jujube were closely related to changes in aroma compounds.This study elucidates the mechanism of quality formation during fruit ripening,which offered a crucial scientific foundation for the regulation and quality control of fresh jujube.