Assessment of Volatile Chemical Composition of the Essential Oil of Jatropha ribifolia (Pohl) Baill by HS-SPME-GC-MS Using Different Fibers

Effect of irrigation on the production and volatile compounds of sweet basil cultivars (Ocimum basilicum L.)

Introduction: Irrigation plays an important role in the cultivation of medicinal plants. There is a lack of information on intraspecific variability of reactions to the effect of drought.

Objective: The aim of the current study was to test the effect of irrigation on four sweet basil (Ocimum basilicum L.) cultivars (‘Genovese’, ‘Kasia’, ‘Keskenylevelű’, ‘Wala’).

Methods: In an open field experiment irrigated and non-irrigated treatments were set. Plants were harvested in full flowering stage. Before the harvest, the stomatal conductance and chlorophyll content were measured. The production-related parameters were recorded. In the plant material the glandular hair density, essential oil content and composition (GC-MS) and volatile composition (SPME-GC-MS) were identified.

Results: Stomatal conductance of the irrigated plants was 2.5–4.5 times higher than in the non-irrigated ones. The chlorophyll content showed only slight changes. The irrigation had a positive effect on the production. The leaf to stem ratio was not modified by the watering. Irrigation negatively influenced the glandular hair density and the EO content, however it increased the EO yield by 40–129%, depending on the cultivar. Significant compositional changes were registered only in the EO of cultivar ‘Kasia’ for linalool, 1,8-cineole and tau-cadinole ratios.

Conclusion: Irrigation increases the biomass and EO yield of basil while the composition of the EO is mostly unchanged. Only slight differences were observed among the cultivars.

Characterization of the Key Aroma Compounds in Proso Millet Wine Using Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

The volatile compounds in proso millet wine were extracted by headspace solid-phase microextraction (85 μm polyacrylate (PA), 100 μm polydimethylsiloxane (PDMS), 75 μm Carboxen (CAR)/PDMS, and 50/30 μm divinylbenzene (DVB)/CAR/PDMS fibers), and analyzed using gas chromatography-mass spectrometry; the odor characteristics and intensities were analyzed by the odor activity value (OAV). Different sample preparation factors were used to optimize this method: sample amount, extraction time, extraction temperature, and content of NaCl. A total of 64 volatile compounds were identified from the wine sample, including 14 esters, seven alcohols, five aldehydes, five ketones, 12 benzene derivatives, 12 hydrocarbons, two terpenes, three phenols, two acids, and two heterocycles. Ethyl benzeneacetate, phenylethyl alcohol, and benzaldehyde were the main volatile compounds found in the samples. According to their OAVs, 14 volatile compounds were determined to be odor-active compounds (OAV > 1), and benzaldehyde, benzeneacetaldehyde, 1-methyl-naphthalene, 2-methyl-naphthalene, and biphenyl were the prominent odor-active compounds (OAV > 50), having a high OAV. Principal component analysis (PCA) showed the difference of distribution of the 64 volatile compounds and 14 odor-active compounds with four solid-phase microextraction (SPME) fibers.

Determination of Volatile Compounds in Foxtail Millet Sake Using Headspace Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

The volatile compounds in foxtail millet sake were extracted by headspace solid-phase microextraction (HS-SPME) and analyzed using gas chromatography-mass spectroscopy (GC-MS). Different methods of sample preparation were used to optimize this method (SPME fiber types, sample amount, extraction time, extraction temperature, content of NaCl, and rotor speed). For final method of sample preparation, 8 mL of sake was placed in a 15 mL headspace vial with addition of 1.5 g of NaCl; a 50/30 μm DVB/CAR/PDMS SPME fiber was used for extraction at 50°C for 30 min with 10 rpm continuous stirring. A total of 41 volatile compounds were identified from the sake sample, including 9 esters, 6 alcohols, 4 acids, 4 aldehydes, 9 hydrocarbons, 7 benzene derivatives, and 2 others. The main volatile compounds were ethyl acetate, phenylethyl alcohol, butanedioic acid diethyl ester, and hexadecane. According to their odors active values (OAVs), 10 volatile compounds were established to be odor active compounds and to contribute to the typical foxtail millet sake aroma. Hexanoic acid ethyl ester was the most prominent odor active compound.