Monoterpenes distribution

Effect of wine ageing on monoterpene composition. Several studies have been made in which alterations in monoterpene distribution in wines over time or with increases in temperature were recorded (84-89). The effect on wine flavor of prolonged ageing or exposure to elevated temperatures is a loss of fruit bouquet. By contrast, brief heating of juices of aromatic grapes can enhance the fruit flavor by increasing the concentration of free volatile monoterpenes through hydrolysis of precursors. 

Mondello et al. (2, 20-23) have used a multidimensional gas chromatographic system based on the use of mechanical valves which were stable at high temperatures developed in their laboratory for the determination of the enantiomeric distribution of monoterpene hydrocarbons (/3-pinene, sabinene and limonene) and monoterpene alcohols (linalol, terpinen-4-ol and a-terpineol) of citrus oils (lemon, mandarin, lime and bergamot). Linalyl acetate was also studied in bergamot oil. The system consisted of two Shimadzu Model 17 gas chromatographs, a six-port two-position valve and a hot transfer line. The system made it possible to carry out fully... 

Figure 10.3 Gas cliromatograms of a cold-pressed lemon oil obtained (a) with an SE-52 column in the stand-by position and (b) with the same column showing the five heart-cuts (c) shows the GC-GC chiral chromatogram of the ti ansfeired components. The asterisks in (b) indicate electric spikes coming from the valve switcliing. The conditions were as follows SE-52 pre-column, 30 m, 0.32 mm i.d., 0.40 - 0.45 p.m film tliickness cairier gas He, 90 KPa (stand-by position) and 170 KPa (cut position) oven temperature, 45 °C (6 min)-240 °C at 2 °C/min diethyl-tert-butyl-/3-cyclodextrin column, 25 m X 0.25 mm i.d., 0.25 p.m film thickness cairier gas He, 110 KPa (stand-by position) and 5 KPa (cut position) oven temperature, 45 °C (6 min), rising to 90 °C (10 min) at 2 °C/min, and then to 230 °C at 2 °C/min. Reprinted from Journal of High Resolution Chromatography, 22, L. Mondello et al, Multidimensional capillary GC-GC for the analysis of real complex samples. Part IV. Enantiomeric distribution of monoterpene hydrocarbons and monoterpene alcohols of lemon oils , pp. 350-356, 1999, with permission from Wiley-VCH.

L. Mondello, M. Catalfamo, A. R. Proteggente, I. Bonaccorsi and G. Dugo, Multidimensional capillar y GC-GC for the analysis of real complex samples. Part III. Enantiomeric distribution of monoterpene hydr ocarbons and monoterpene alcohols of mandarin oils , 7. Agric. Food Chem. 46 54-61 (1998). 

Table 5.3 Distribution of halogenated monoterpenes in Plocamium hamatum from the Great Barrier Reef (from Konig et al., 1999)...

The second example features R cartilagineum, a cold-water species that enjoys a wide distribution (Gabrielson and Scagel, 1989). Patterns of variation for halogenated monoterpenes have been reported for this species collected from several locations that include Atlantic, Pacific, and Antarctic waters. Both cyclic and acyclic... 

The hydrogenation of the monoterpenes (—)- and (-l-)-carvone was studied extensively. Several microorganisms were used in these reductions. They catalyzed the production of all possible stereoisomers, but some of them only in small quantities. The distribution of the products depended on the catalyst applied116. 

ENANTIOMERIC DISTRIBUTION OF ODOROUS OXYGENATED MONOTERPENES IN AROMATIC PLANTS... 

Enantiomeric Distribution of Odorous Oxygenated Monoterpenes in Aromatic Plants... 

Ravid U, Enantiomeric distribution of oxygenated monoterpenes in some Mentha essential oils, Perfum Flavor 23(4) 25-30, 1998. 

Enuntiotneric Distribution of Odorous Oxygonuted Monoterpenes in Aromutic Plunts... 

G., Dugo, G., and McNair, H. 1999. Multidimensional capillary GC-GC for the analysis of real complex samples Part IV. Enantiomeric distribution of monoterpene hydrocarbons and monoterpene alcohols of lemon oils. J. High Resolut. Chromatogr. 22 350-356. 

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