Fleeting Beauty-The World of Plant Fragrances and Their Application

Abstract

This article is devoted to some aspects of the fragrant substances of plant origin applied in the food industry and perfumery as well. Since antiquity many extractive techniques have been developed to obtain essential oils. Some of them are still applied, but new ones, like microwave or ultrasound-assisted extractions, are more and more popular and they save time and cost. Independently of the procedure, the resulting essential oils are the source of many so-called isolates. These can be applied as food additives, medicines, or can be used as starting materials for organic synthesis. Some substances exist in very small amounts in plant material so the extraction is not economically profitable but, after their chemical structures were established and synthetic procedures were developed, in some cases they are prepared on an industrial scale. The substances described below are only a small fraction of the 2000-3000 fragrant molecules used to make our life more enjoyable, either in food or perfumes. Additionally, a few examples of allelopathic fragrant compounds, present in their natural state, will be denoted and some of their biocidal features will be mentioned as an arising "green" knowledge in agriculture.

Keywords: biopesticides; essential oils; extraction techniques; food additives; fragrant allelochemicals; fragrant molecules.

Figure 1

Potential applications of plant fragrances.

Figure 2

Some food occurring compounds with strong aroma: (1) Vanillin, (2) ethylvanillin, (3) indole, (4) 2-ethylpyrazine-6-methylpyrazine, (5) (E)-3,5-dimethyl-1,2,4-trithiolane, (6) 1-(ethylsulphanyl)ethane-1-thiol, (7) R=Me, ethanethiol, (8) methional, (9) guaiacol, (10) halophenols, (11) furfural and (12) 2-hydroxymethylfuran.

Figure 3

Supercritical fluid extraction (SFE) of essential oils (according Yousefi et al., 2019 [28]; modified).

Figure 4

An ancient distillation apparatus—alembic (lat. alembicus); scheme of an alembic from a medieval manuscript [35] (modified).

Figure 5

Some of natural isolates applied as food additives or perfume ingredients: (13) trans-anethole, (14) eugenol, (15) cinnamaldehyde, (16) safrole, (17) benzaldehyde, (18) thymol, (19) limonene, (20) menthol, (21) terpineol, (22) R-carvone, (23) S-carvone, (24) eucalyptol, (25) citronellal, (26) rhodinol, (27) linalool, (28) linalyl acetate.

Figure 6

Natural isolates applied as food additives or perfume ingredients: (29) 4-methylguaiacol, (30) α-pinene, (31) β-pinene, (32) α-bisabolene, (33) methyl anthranilate, (34) methyl N-methylanthranilate, (35) benzyl acetate, (36) γ-octalactone, (37) γ-decalactone, (38) γ-undecalactone, (39) 2-phenylethanol, (40) geraniol, (41) cedrol, (42) α-santanol, (43) β-santanol.

Figure 7

Structures of some allelopathic compounds: (44) methyl nicotinate, (45) β-cariophyllene, (46) methyl benzoate, (47) phenylacetonitrile, (48) 2-methoxy-4-vinylphenol, (49) 1,4-dimethoxybenzene, (50) dihydrocarveol acetate, (51) geranyl acetate.