Abstract:

Objective: This study aims to explore the influence of different preparation and analysis methods on the determination of volatile oil composition and the contents, and reveal the dynamic changes of the contents in the Torreya grandis 'Merrillii' aril during the seed growth and development, as so to provide the rationale for the utilization of the aril. Method: Steam distillation (SD) and headspace solid phase microextraction (HS-SPME) techniques were used and optimized for the sample preparation The gas chromatography-mass spectrometry (GC-MS) was used to determine the volatile components and the contents in the aril during the growth and development of T. grandis seeds. Result: 1) Based on GC-MS analysis, SD was more suitable for the sample preparation of volatile oil from T. grandis seeds in terms of the component and content. 2) The SD-GC-MS analysis showed that there were 47 volatile oil components in the aril, including 21 terpenes (limonene, α-pinene, δ-juniene, etc.), 15 terpene alcohols (linalool, borneol, elemol, etc.), three terpene esters (bornyl acetate, pine oil acetate, and geranyl acetate), and eight other compounds (piperone, antioxidant 264, palmitic acid, etc.). 3) The volatile components in the aril during seed growth and development showed certain regular changes. Among them the content of camphene, β-pinene, and terpinolene increased from May to September; the content of such ingredients as α-pinene, cypressene, and myrcene gradually rose to the peak value from May to August and then declined. The monoterpenoids and sesquiterpenoids showed an obvious negative correlation during May to June and from August to September, while the monoterpenoids and sesquiterpenoids showed an increasing trend from June to July because the aril was growing. PCA suggested that the volatile oil components of aril in May were similar to those in June Conclusion: The extraction condition for T. grandis 'Merrillii' aril is the ratio of material to liquid set as 1:10, and soak time as 1 hour, extraction time as 4 hours. Through the SD-GC-MS detection, 47 compounds were identified, with a total of 13 483.14 μg·g^-1. The main ingredients include limonene and α-pinene compounds. The volatile components in the aril of T. grandis 'Merrillii' are significantly different at different seed growth and development stages. The number of compounds increased from 35 in May to 47 in September. Sesquiterpenoids and oxygenic derivatives increased, and the total content of essential oil increased first and then decreased from May to September. The composition and content of essential oil in the aril were similar from May to June and July to August, but they were significantly different from those in September.

Key words: Torreya grandis, aril, SD, HS-SPME, volatile components, GC-MS