**2.2.3 Frankincense**

204 Distillation – Advances from Modeling to Applications

H NMR spectrum of group B obtained from hexane extract by bulb-to-bulb

The obtained fractions were analyzed, and santalol derivatives with a formyl group (Group B) were found to play an important role in the odor of sandalwood chips. The diagram (Fig. 4) indicates the scent profile of sandalwood obtained by this method. - Santaol has been reported to be the principal constituent of sandalwood odor. In contrast, -santalol has been reported to be only a supporting component of sandalwood odor because -santalol has a weaker odor than does -santalol. However, we found that both -santalol and -santalol derivatives with a formyl group were important constituents of

This result demonstrates that bulb-to-bulb distillation is useful for collecting very small

The unique woody aroma of patchouli is one of the four major woody notes derived from essential oils, and serves as an indispensable scent in modern fragrance. Although many studies have been performed, the key components that constitute this odor have not been successfully identified (Nabeta et al., 1993; Singh et al., 2002). Suitably appraising patchouli

Despite being a topic of investigation for many years, the complete odor profile of patchouli remains elusive for three reasons: first, the scents of individual compounds are weak; second, the compounds are structurally diverse and complex; and third, the aroma changes over time. To overcome these obstacles, we performed bulb-to-bulb distillation of the

The composition of the hexane extract of patchouli leaves was analyzed by 1H and 13C NMR spectroscopy. One constituent of the extract was found to be patchoulol, but its content was low and the other constituents were unidentified. We presumed that the

fragrance is crucial in order to produce potentially useful synthetic compounds.

patchouli hexane extract, which had a similar odor as the base material.

Fig. 6. <sup>1</sup>

distillation (200 MHz, CDCl3).

sandalwood odor.

**2.2.2 Patchouli** 

fractions from a mixture.

The resin of frankincense is obtained from many species of trees in the genus Boswellia. Frankincense has been used as a valuable fragrance source since ancient times, and has been reported to possess a wide range of bioactivity. Many compounds have been identified in frankincense (Hamm et al., 2005; Mertens et al., 2009). To our knowledge, however, the effects of particular odor components have not been clarified in detail. There are two representative species of frankincense. The main components of frankincense are markedly different between these two species. One has many monoterpenes (e.g., -pinene) as key compounds that contribute to frankincense odor. The other contains diterpenes as the main constituents, along with octyl acetate and octanol. This latter species is used in traditional Japanese incense.

The hexane extract of frankincense is a highly viscous oil, suggesting that it contains a large amount of compounds that contribute relatively little to the characteristic odor of frankincense. The NMR spectrum of the extract (Fig. 8) supports this assessment. We did a bulb-to-bulb distillation to evaluate the key compounds of frankincense odor. First, fraction 1 was obtained from distillation below 124 °C at 0.09 Torr. The constituents were octanol and octyl acetate (Fig. 9). Then, the temperature and pressure were maintained at 124 °C (0.09 Torr), and highly similar constituents were collected in the three different bulbs according to the slightly different boiling point of each constituent (Fig. 9).

Separation of Odor Constituents by Microscale Fractional Bulb-To-Bulb Distillation 207

**0 9 8 7 6 5 4 3 2 1 ppm**

**0 9 8 7 6 5 4 3 2 1 ppm**

**9 8 7 6 5 4 3 2 1 ppm**

**9 8 7 6 5 4 3 2 1 ppm**

Fig. 10. 1H NMR spectra of fractions 1, 2, 3, and 4 from top to bottom (200 MHz, CDCl3)

Fig. 8. 1H NMR spectrum of hexane extract from frankincense resin (200 MHz, CDCl3)

Fig. 9. Separation of scent components from the hexane extract of frankincense resin.

We evaluated the odor of this species by focusing on the difference in odor between the hexane extract and the steam-distilled oil and separation of odor components by bulb-tobulb distillation.

NMR revealed that each fraction contained different components (Fig. 10). The odor of fraction 4 was similar to that of the hexane extract. The main components of fraction 4 were found to be diterpenes—in particular, incensole derivatives. This result shows that these incensoles make a key contribution to the odor of frankincense (Hasegawa et al., 2011).

#### **2.2.4 Vetiver**

Vetiver essential oil is a spice that provides base notes, similarly to materials such as sandalwood and patchouli. Vetiver is used as an essential material for providing fragrance, for instance in perfume, that emerges comparatively late and lasts a long time. Vetiver is said to provide the heart of the perfume. Although vetiver is important in terms of fragrance, there is still much research to do into its odor properties.

Conventionally GC-MS has been used to analyze scent components (Anonis, 2004; Weyerstahl et al., 2000), but we thought that this method would be insufficient for

Fig. 8. 1H NMR spectrum of hexane extract from frankincense resin (200 MHz, CDCl3)

Fig. 9. Separation of scent components from the hexane extract of frankincense resin.

bulb distillation.

**2.2.4 Vetiver** 

We evaluated the odor of this species by focusing on the difference in odor between the hexane extract and the steam-distilled oil and separation of odor components by bulb-to-

NMR revealed that each fraction contained different components (Fig. 10). The odor of fraction 4 was similar to that of the hexane extract. The main components of fraction 4 were found to be diterpenes—in particular, incensole derivatives. This result shows that these incensoles make a key contribution to the odor of frankincense (Hasegawa et al., 2011).

Vetiver essential oil is a spice that provides base notes, similarly to materials such as sandalwood and patchouli. Vetiver is used as an essential material for providing fragrance, for instance in perfume, that emerges comparatively late and lasts a long time. Vetiver is said to provide the heart of the perfume. Although vetiver is important in terms of

Conventionally GC-MS has been used to analyze scent components (Anonis, 2004; Weyerstahl et al., 2000), but we thought that this method would be insufficient for

fragrance, there is still much research to do into its odor properties.

Fig. 10. 1H NMR spectra of fractions 1, 2, 3, and 4 from top to bottom (200 MHz, CDCl3)

Separation of Odor Constituents by Microscale Fractional Bulb-To-Bulb Distillation 209

Fig. 13. 1H NMR spectrum of Group A, B, and C from top to bottom (200 MHz, CDCl3)

In the field of fragrance chemistry, the determination of scent profiles is a fundamental and vital endeavor. However, almost all essential oils that are used as fragrances are composed of many types of odorants, and the fragrances of the scent materials are not formed by mere superposition of individual odorants. This problem has hindered the precise evaluation of the base constituents of fragrance. We have demonstrated that the complex scent profiles of

**3. Conclusion** 

identifying the complex combinations of odorants that form the overall vetiver scent. Then, we used bulb-to-bulb diffraction to divide the hexane extract into groups with different characteristic odors; each group contained structurally similar compounds (Fig. 11).

Fig. 11. Separation of scent components from commercial vetiver essential oil.

The 1H NMR spectrum of a commercial vetiver essential oil (Quinessence Aromatherapy Ltd.) indicates that this oil was constituted by many compounds (Fig. 12). The separation of groups with different odors and different structures could not be accomplished by the aforementioned distillation procedure. In this case, the lower boiling group, group A, was first separated from the oil; then the distillation was stopped and bulbs B and C were replaced with fresh ones. We succeeded in the separation of the oil (Fig. 13). If this change was not done, the separation was poor.

Fig. 12. 1H NMR spectrum of commercial vetiver essential oil (200 MHz, CDCl3).

Fig. 13. 1H NMR spectrum of Group A, B, and C from top to bottom (200 MHz, CDCl3)

#### **3. Conclusion**

208 Distillation – Advances from Modeling to Applications

identifying the complex combinations of odorants that form the overall vetiver scent. Then, we used bulb-to-bulb diffraction to divide the hexane extract into groups with different

characteristic odors; each group contained structurally similar compounds (Fig. 11).

Fig. 11. Separation of scent components from commercial vetiver essential oil.

was not done, the separation was poor.

The 1H NMR spectrum of a commercial vetiver essential oil (Quinessence Aromatherapy Ltd.) indicates that this oil was constituted by many compounds (Fig. 12). The separation of groups with different odors and different structures could not be accomplished by the aforementioned distillation procedure. In this case, the lower boiling group, group A, was first separated from the oil; then the distillation was stopped and bulbs B and C were replaced with fresh ones. We succeeded in the separation of the oil (Fig. 13). If this change

**10 9 8 7 6 5 4 3 2 1 ppm**

Fig. 12. 1H NMR spectrum of commercial vetiver essential oil (200 MHz, CDCl3).

In the field of fragrance chemistry, the determination of scent profiles is a fundamental and vital endeavor. However, almost all essential oils that are used as fragrances are composed of many types of odorants, and the fragrances of the scent materials are not formed by mere superposition of individual odorants. This problem has hindered the precise evaluation of the base constituents of fragrance. We have demonstrated that the complex scent profiles of

**10** 

*Germany* 

**Mass Transport Improvement** 

**Area of Extraction and Distillation** 

Mass transport processes in the food industry are mostly based on the diffusion of soluble products out of food tissue. The main barrier for the diffusion is the biological membrane separating the inner cellular material from the outside. A rupture of the membrane results in an enhanced diffusion rate resulting in a higher yield of the product located in the cell. Most methods used for disintegration of cellular material are mechanical, chemical or thermal based treatments. A new promising technique for cell rupture is the application of pulsed electric fields (PEF). The product is treated with pulses of microseconds at a high electric field strength. The electric field affects the cell membrane of the biological tissue in order to increase the permeability resulting in pore formation. Pore formation facilitates the diffusion process. Moderate PEF settings are used to achieve a disintegration of the cellular material. Some researchers define a moderate PEF treatment by applying a field strength of 0,5 to 1,0 kV/cm and treatment times in a range of 100 and 10.000 µs. The same effects were obtained by other researchers using electric field strengths of 1 to 10 kV/cm and shorter treatment times in the

range of 5 to 100 µs (Schilling et al., 2007; Corrales et al., 2008; López et al., 2009).

the distillation processes by PEF, for example distillation of rose oil was also reported.

**2. Principle of action of cell disintegration using PEF technology** 

resulting in a permeabilisation of the biological membranes.

It has been reported that PEF induces an increase of the mass transfer process resulting in a higher extraction of different intracellular materials, such as sucrose from sugar beet, betalains from red beetroot or polyphenols from grapes during the wine production. An increase in the extraction yield of juices from different fruits and vegetables has also been noted. The drying process can also be improved by PEF application. The reduction in the drying time yields a better end product quality. For example an accelerated osmotic dehydration and drying was reported for different fruits and vegetables, such as potatoes and pepper. An improvement of

The following chapter describes in detail the effect of PEF on the mass transfer and the

The application of PEF using short pulses of a high voltage affects the membrane of a cell

**1. Introduction** 

related application fields.

Claudia Siemer, Stefan Toepfl and Volker Heinz

**by PEF – Applications in the** 

*German Institute of Food Technologies* 

materials can be clarified by microscale fractional bulb-to-bulb distillation. To determine important components in natural materials with complex compositions, the method presented in this chapter is useful not only for perfumery chemicals but for many substances in natural products chemistry.

#### **4. Acknowledgments**

I would like to thank Hideo Yamada at Yamada-matsu Co., Ltd., for providing plant specimens and contributing to sensory evaluations and fruitful discussions. I also would like to thank Shohei Tamada for work in early experiments on vetiver.

#### **5. References**

Anonis, D. P. (2004) *Perfumer & Flavorist*, Vol. *29*, pp. 30-36, ISSN 0272-2666.

