3个桂花品种花瓣游离态和糖苷态香气成分

Free and Glycosylated Aroma Components in Petals of Three Osmanthus fragrans Cultivars

【目的】明确不同桂花品种的主要游离态和糖苷态香气物质,为桂花的产业应用提供理论依据。【方法】选取3个栽培广泛且香味典型的桂花品种‘晚银桂’、‘潢川金桂’和‘橙红丹桂’的未展期、半展开期、完全展开期和枯萎期花瓣为材料,采用有机溶剂萃取、Amberlite XAD-2树脂吸附洗脱分离结合糖苷酶水解法分别提取游离态和糖苷态香气物质,再通过气相色谱质谱技术(GC-MS)对香气物质进行成分鉴定和定量分析。【结果】1)3个品种共检测出25种游离态香气物质、28种糖苷态香气物质,包括单萜、单萜醇、单萜酮、单萜氧化物、芳香族类化合物、酯类、烷烃类和其他物质。糖苷态香气物质的含量显著高于游离态香气物质。大量单萜类香气物质经过氧化、羟化后易连接糖基,形成无色无香的糖苷态香气物质。2)桂花的游离态和糖苷态香气物质会随着花期变化不断积累,游离态物质在花瓣完全展开期含量达到最大值,而糖苷态香气物质在开花末期含量达到最大值。3)3个品种的香气物质成分相似但是含量差异显著。‘晚银桂’和‘潢川金桂’的游离态香气物质主要为反式-β-紫罗酮、γ-癸内酯、8-羟基芳樟醇,糖苷态香气物质主要是4-羟基-苯乙醇、4-羟基-β-紫罗酮和3-氧代-α-紫罗醇。‘橙红丹桂’的游离态香气物质主要为γ-癸内酯、芳樟醇氧化物和4-羟基苯乙醇,糖苷态香气物质主要为4-羟基苯乙醇、3-氧代-α-紫罗醇和8-羟基芳樟醇。综合分析,‘晚银桂’和‘潢川金桂’中富含类胡萝卜素裂解产物紫罗酮及其衍生物,而‘橙红丹桂’则富含芳樟醇及其衍生物,类胡萝卜素是否裂解是造成品种间香气差异的重要因素。4)3个品种的游离态和糖苷态香气物质中的芳樟醇及其衍生物、紫罗酮及其衍生物和γ-癸内酯和香叶基丙酮均为重要的香气活性物质,具有花香、果香等香味特质,对花卉产品的香味浓郁度和香型起到重要作用。【结论】桂花的非挥发态香气物质即游离态和糖苷态种类和含量丰富,品种间存在较大差异,其中富含的单萜及其衍生物、酯类物质和芳香族化合物可以通过添加水解酶和溶剂萃取的方法加以提取和释放,从而提升花卉产品的香味品质。

【Objective】This study was conducted to reveal the main free and glycosylated aroma compounds of different Osmanthus fragrans cultivars.The results could provide theoretical foundation for industrial application of O.fragrans.【Method】The petals of three widely cultivated O.fragrans cultivars,‘Wan Yingui’,‘Huangchuan Jingui’and‘Chenghong Dangui’,were selected as materials.The petals at the unexpanded period,initial blossoming period,full blossoming period and late blossoming period were collected and extracted with organic solvent,Amberlite XAD-2 resin adsorption and elution separation combined with glucosidase hydrolysis were conducted for extracting free and glycosylated aroma compounds.The aroma compounds were then identified and quantitatively analyzed by gas chromatography-mass spectrometry(GC-MS).【Result】1)A total of 25 free and 28 glycosylated aroma compounds were determined in the three cultivars,mainly including monoterpenes,monoterpene alcohols,monoterpene ketones,monoterpene oxides,aromatic compounds,esters,alkanes and others.Massive monoterpenes tended to connect with sugars after oxidation and hydroxylation,forming colorless and odorless glycosides.Thus,the content of glycosylated aroma compounds was significantly higher than that of the free aroma compounds.2)The free and glycosylated aroma compounds continued to accumulate during the blossoming period progress.The content of free aroma compounds reached the maximum at the full blossoming stage,while the content of glycosides reached the maximum at the end of flowering.3)The aroma components of the three cultivars were similar,but the content was significantly different.The free aroma compounds of‘Wan Yingui’and‘Huangchuan Jingui’were mainly trans-β-ionone,γ-decalactone and 8-hydroxylinalool,while the glycosides were mainly 4-hydroxy-phenyl alcohol,4-hydroxy-β-ionone,3-oxo-α-ionol.The free aroma compounds of‘Chenghong Dangui’dominantly containedγ-decalactone,linalool oxides,4-hydroxy-phenyl alcohol,while the glycosides were mainly 4-hydroxyphenyl alcohol,3-oxo-α-ionol and 8-hydroxylinalool.Based on the total contents of aroma compounds,linalool and its derivatives dominated the aroma compounds in‘Chenghong Dangui’,while ionone and its derivatives took major proportion in‘Wan Yingui’and‘Huangchuan Jingui’.The cleavage of carotenoids was the key factor for causing the differences among cultivars.4)Among all the free and glycosylated aroma compounds,γ-decalactone,linalool,ionone and their derivatives were important aromatic compounds with floral and fruitly characteristics.【Conclusion】Our results demonstrate that a large amount of free and glycosylated monoterpenes and their derivatives,esters,aromatic compounds are widely distributed in Osmanthus fragrans flowers with significant differences among cultivars.Those compounds can be extracted by organic solvent and hydrolase to promote the aroma quality of industrial products.