Preliminary Research Of Volatile Compounds In Water Dropwort (Oenanthe Stolonifera (Roxb) Wall.)

Water dropwort(Oenanthe stolonifera(Roxb)Wall.)is a perennial aquatic herb with green color,unique flavor,rich nutrition,various pharmacological effects,and the main edible organs are stems and petioles.Water dropwort widely cultivated in the southern region of China,for example,Zhejiang,Jiangsu,and Anhui province etc.Flavor is an important index to evaluate the quality of vegetables,and the volatile compounds are the main source of the flavor of vegetables.In this study,we used stems and petioles of water dropwort as materials to analyzed the volatile compounds of water dropwort with Solid Phase Microextraction(SPME),Gas Chromatography-Mass Spectrometry(GC-MS)and Gas Chromatography-Olfatometry(GC-O)technique with aim to preliminary determine the flavor substances of water dropwort.At the same time,analysis of influence factors(such as variety resources,cultivation mode and cultivation season,temperature etc.)on volatile compounds and flavor substances of water dropwort was also carried out.We obtained the following results:1.The method of SPME and GC-MS for extraction and separation of volatile compounds in water dropwort is constructed:DB-5MS(30 m*0.25 mm*0.25 μm),Helium was the carrier gas with a flow-rate of 0.8 mL/min.The split ratio was 5:1,and injector temperature was 250℃.The temperature program used for the column was as follows:initial temperature 50℃,5℃/min to 75℃ for 3 min,10℃/min to 155℃ for 4 min,and then 5℃/min to 210℃ for 2 min.Ion source temperature was 250℃,and ionization mode EI,transmission line temperature was 250℃,and electronic energy was 70 eV,and detector voltage was 350 V,and the mass range was 33-300 amu.The optimum SPME conditions were SPME fiber coated with 100 μm polydimethylsiloxane(PDMS),40℃ for extraction temperature,and extraction time for 45 min.2.The stems and petioles of water dropwort ’sq035’ cultivated in autumn winter were used as materials to analyze volatile compounds.A total of 21 kinds of volatile compounds were identified including 20 kinds of terpenoid which was the main substance category of water dropwort.The highest content of volatile compounds was y-terpinene(38.39 μg/g),a-pinene(20.58 μg/g),(3-pinene(20.14 μg/g),and caryophyllene(19.4 μg/g).A total of 10 kinds of flavor substances of water dropwort were identified using GC-0 technology,among which,the terpenoids was the main flavor category in water dropwort.Of these 10 kinds of flavor substances of water dropwort,y-terpinene was described as pine,and caryophyllene was described as delicate fragrance and grass,and odor intensity were 4 level,these flavor substances was initially considered as the characteristic flavor compounds of water dropwort.3.A total of 46 kinds of volatile compounds including terpenoids,esters,alkanes and benzene were identified from 10 species of water dropwort.The content of y-terpinene in water dropwort ’sq034,and ’sq035’ was significantly higher than other water dropwort species,and the content of caryophyllene in water dropwort ’sq02’ was the highest among all the test species.The content of caryophyllene was significantly higher than γ-terpinene in water dropwort ’sq02’and ’sq037’,so those two resources had higher delicate fragrance.4.A total of 39 volatile compounds were identified including terpenoids,alcohols,esters,ethers and benzene from ’Fu Qin No.1’ usually cultivated in the spring,summer,autumn and winter seasons.The types(34 types)of volatile compounds in ’Fu Qin No.1’ cultivated in the spring was the highest,and the total content(337.6 μg/g)of volatile compounds in ’Fu Qin No.1’cultivated in summer was the highest among these species.’Fu Qin No.1’ cultivated in the summer contained the highest content of y-terpinene and caryophyllene than cultivated in other seasons.The contents of y-terpinene showed higher amount than caryophyllene in spring and summer and autumn,so higher pine oil flavor was very common in these three seasons,especially in summer.However,the content of y-terpinene was lower than caryophyllene when cultivated in winter,so the product organ had delicate fragrance in this season.5.A total of 24 kinds of volatile compounds were identified in ’Li Yang Bai Qin’ for softening cultivation,and 26 kinds of volatile compounds were identified from control plant,and the content of volatile compounds of ’Li Yang Bai Qin’ were lowed.A total of 23 volatile compounds were identified in ’Yi Xing Bai Qin’ for deep softening cultivation,and while 24 kinds of volatile compounds were identified in control plant,and the content of volatile compounds of ’Yi Xing Bai Qin’ were increased.The content of y-terpinene and caryophyllene,the characteristic flavor compounds of water dropwort content was significantly increased by soil softening and deep softening cultivation,while the amount of increased content of caryophyllene showed significantly higher than γ-terpinene.Soil softening and deep softening cultivation could significantly increase the delicate fragrance of water dropwort.6.The content of volatile compounds of water dropwort was increased with the treated temperature and treated time due under 24℃ and 30℃ conditions,suggesting that the increased temperature could improve the content of volatile compounds of water dropwort.After treatment for 36 h under 24℃ and 30℃ conditions,the content of γ-terpinene and caryophyllene were increased with the temperature increasing,although different trend of these two substances was found for 12 h and 24 h.The content of γ-terpinene and caryophyllene were increased with the temperature increasing,and the content of γ-terpinene and caryophyllene were highest at 24℃for 72 h,and 30℃ for 60 h respectively.