Flavor compound in star anise

Star anise (Illicium verum) is an aromatic evergreen tree bearing purple-red flowers and anise-scented star-shaped fruit. Star anise belongs to the Magnoliaceae family and its fruit is a very important element as a spice in the Oriental cuisine.

Star anise has a sweet anise-like odor and is produced as a source of fragrance and flavor in several industries.

Additionally, the essential oils from star anise are composed of prenylated C6–C3 compounds, lignans, sesquiterpenes, and flavonoids, each with different types of compounds which are also important with respect to its vast medicinal properties.

The major components of star anise essential oil are trans-anethole (82.7%), carryophyllene (4.8%) and limonene (2.3%).

Among all of them, the anethole compounds are responsible for its characteristic taste. Anethole, formally 1-methoxy-4-[(1E)-prop-1-en-1-yl]benzene, is an anisole derivative that is the major constituent of the oils of star anise. Although the main component of star anise is (E)-anethole, which accounts for over 85% of the constituents, the odor of (E)-anethole is different from that of the material itself. Anethole is a sweet, anise, and balsam tasting compound.

Beside trans-anethole there were 24 constituents which in total make less than 15.00% of the essential oil. This includes limone, α-pinene, safrol, β-phellandrene, α-terpineol, and farnesol
Flavor compound in star anise

Discovery of aromatic compound terpenes

Terpenes are aromatic compounds found in many plants. The common plant sources of terpenes are tea, thyme, cannabis, Spanish sage, and citrus fruits (e.g., lemon, orange, mandarin). The term 'Terpene' is derived from the term 'turpentine'. They are responsible for the odor of pine trees and for the colors of carrots and tomatoes. β-Carotene, found in carrots, and vitamin A are both terpenes.

The essential oils were used in the ancient Egypt for various ceremonies. Camphor was introduced by Arabs around 11th century.

The method of getting plant essential oils via fatty extraction was identified by the early Middle Ages. The process of distillation of oils from rosemary and sage was described by Arnaud de Villanosa (1th century).

Analyses of oils obtained from plants started by French botanist Jacques-Julien Houtou de Labillardière in 1818. Dumas proposed the name ‘Terpene” derived from turpentine. In 1887, Otto Wallach proposed that isoprenoid unit (5C) is present always in terpenes.

When Otto Wallach began his systematic studies of the terpenes, he observed that individual terpene structures contained multiples of a 5-carbon unit that allowed them to be classified according to the number of such units they contained. The canonical C5 unit proved to be isoprene, which Wallach recognized as the core terpenoid structure.

The structure of camphor was discovered by Bredt in the year 1893, that of pinene via Wagner in year 1894 and that of citral by Tiemann in the year 1895.

The structure of beta carotene from carrot was isolated by Wackenrodder and its correct molecular formula was determined by Will Statter.
Discovery of aromatic compound terpenes

Aromatic compounds of coffee

Aroma science is highly complex. Researchers typically analyze the fragrances evolved during coffee bean roasting by gas chromatography coupled with olfactometry, in which skilled testers sniff and define the smell of each recognizable element.

In Italy and France the aroma and taste of coffee are importance. Consumption of coffee is part of the culture and in France the name “café” stands for the drink as well as the place where it can be served. Espresso is a preferred beverage in Italy and France because of the strong aroma of the coffee.

Aroma substances are volatile compounds which are perceived by the odor receptor sites of the smell organ, i. e. the olfactory tissue of the nasal cavity. Coffee aroma is composed of a great variety of functional chemical groups, where the composition depends on factors such as species and variety, growth conditions and crop, storage, roasting degree, let alone all other process conditions.

Coffee contains several hundred different chemical compounds, but only minorities of these contribute to the aroma. A compound’s contribution to aroma is dependent on both its concentration and the threshold at which its smell can be perceived by humans.

The basic taste sensations in coffee are formed by volatile compounds present in coffee beans. They are the main factors responsible for the aroma. They belong to various chemical groups: aliphatic hydrocarbons, sulfur compounds, pyrazines, pyridines, oxazoles, pyrroles, furans, aldehydes, ketones and phenols but only a relatively small group of them (called the key components) is responsible for the aroma of coffee, such as dimethyl disulfide, which is an essential element for improving the fragrance of coffee aroma.
Aromatic compounds of coffee