The BACIS Archives

[ BNB - 98061 ]

• Olfactive Properties and Chemical Structures

INTRODUCTION

In the forthcoming issues the chemical identities of odourant molecules with various odour types will be discussed. Some general odour types as, for instance, green, fruity and floral will be treated. Subsequently, the chemical identities of specific odour descriptors as, for example, for rose, jasmine and lily-of-the valley will be discussed.

DISCUSSION

The various odour aspects are, for example, green, citrusy, watery, metallic, floral, fatty, aldehydic, vegetative, coniferous, minty, medicinal, fruity, honey, buttery, animal, erogenic, aromatic, spicy, powdery, dusty, earthy, smoky, woody, balsamic, musky, amber.

Specific odour descriptors within one odour aspect are, for instance:

• fruity: e.g. apple, pear, banana, strawberry, raspberry, peach, pine apple
• green: grass, citrus leaf, floral, vegetative
• floral: e.g. lily-of-the-valley, rose, jasmine, lilac, ylang ylang, tuberose
• aromatic: e.g. bitter almond, anise, vanilla, honey
• spicy: e.g. clove, nutmeg, cinnamon
• woody: e.g. cedarwood, sandalwood, vetiver, patchouli
• balsamic: styrax, tolu- and peru-balsam, olibanum
• musky: floral, vegetative, animal

• Chemical Identities of Aroma Chemicals with a Green Odour

INTRODUCTION

In these series olfactive properties of chemical compounds will be discussed. This issue will be devoted to the chemical identities of compounds with a green odour characteristic.

DISCUSSION

Specific odour descriptors within the green odour-aspects are, for instance: grass, fruity (apple), citrus leaf, floral (hyacinth), vegetative (green bellpepper).

(Z)-3-Hexenol and (E)-2-hexenal are olfactively character-impact compounds for freshly mown green grass. In other words: these compounds represent the odour of green grass; the aromatic chemicals are also called leaf alcohol and leaf aldehyde respectively.

Amongst the volatile compounds, which represent the organoleptic quality of green apples, one finds the lower alkyl esters of (Z)-3-hexenol as, for instance, the acetate, isobutyrate and isovalerate.

Lower 3-alkyl-2-methoxypyrazine as, for instance, 3-propyl, 3-sec-butyl and 3-isobutyl-, are as trace constituents (ppm concentrations) olfactively important constituents for green citrus leaves.
These compounds have been found in petitgrain bigarade oil (oil from bitter orange leaves).

The hyacinth flower contains as an olfactively green character-impact compound 2-phenylacetaldehyde.

3-Isobutyl-2-methoxypyrazine is an organoleptic important constituent of green bellpepper. This compound gives a green character to many green vegetables; it is olfactively very strong and intensive and it has an extremely low threshold value.