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Scientia Silvae Sinicae ›› 2021, Vol. 57 ›› Issue (8): 33-42.doi: 10.11707/j.1001-7488.20210804

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

Jinmei Yuan1,2,Jing Luo1,2,Linlin Zhu1,2,Wan Xi1,2,Xumei Zeng1,2,Kangshun Xiong1,2,Caiyun Wang1,2,Riru Zheng1,2,*   

  1. 1. Key Laboratory for Horticultural Plant Biology of Ministry of Education Huazhong Agricultural University Wuhan 430070
    2. Key Laboratory of Urban Agriculture in Central China, Ministry of Agriculture and Rural Affairs Wuhan 430070
  • Received:2020-05-11 Online:2021-08-25 Published:2021-09-30
  • Contact: Riru Zheng

Abstract:

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 contained γ-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.

Key words: Osmanthus fragrans, blossoming period, free aroma compounds, glycosylated aroma compounds, GC-MS analysis

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