HOLY BASIL Ocimum sanctum
Leaves; frequently, the entire herb (all aerial parts) is harvested. Best harvesting season is 
before flowering. Basil leaves should always be used fresh, as they lose most of their flavour within a few weeks after drying. However, in the Georgian spice mixture khmeli-suneli, dried basil is employed
| Botanical Name | Ocimum sanctum |
| Source | Entirely
natural oil originally steam distilled from the plant of Ocimum
Sanctum / sacred basil / holy basil grown in India. |
| Color | Yellow to pale color |
| Specific Gravity | 0.92551 |
| Referactive Index | 1.242 |
| Solubility | Soluble in all proportion of 90% alcohol |
| Description | In flavoring liquor, chewing tooth pastes, cold rub oil, etc. |
Fresh basil leaves have a strong and characteristic aroma, not comparable to any other spice, although there is a hint of cloves traceable. 
In addition to the “Mediterranean type” most common in the West, there is a plethora of other varieties or cultivars with different flavour, many of which are hybrids. India has its “Sacred Basil” (O. sanctum = O. tenuiflorum) with intensive, somewhat pungent smell; in Thailand, there is another sweet basil with a great licorice aroma (see also cicely). Varieties sold to gardeners in the West include cinnamon basil, camphor basil, anise basil and Mexican spice basil; the latter has a very pleasant, complex and warm flavour, with a wonderful sweet note more reminiscent to cinnamon than to anise.
A last group of cultivars is characterized by citrus odour: Thai lemon basil (O. citriodorum) has a distinct balm-like flavour, and then there are lime basil and another lemon basil (O. americanum) which has an extraordinarily pure and fresh lemon aroma (see also lemon myrtle on lemon fragrance in general).
Perennial basil species from Africa (Ocimum kilimandscharicum) and Asia (Ocimum canum) have recently been introduced to the European herb and gardening market. These species has a strong, but less pleasant flavour; hybrids between them and Mediterranean basil are a recent innovation, with novel appearance and flavour, and enjoy growing popularity.
All basil varieties have in common that their dried leaves are much less aromatic than fresh ones; deep-freezing the herb is the best method of preservation. 
In English language, the common basil grown in Italy and other Mediterranean countries is often termed “sweet basil”; this is, though, misleading, because Thai basil has much more of a sweet quality. Thus, I will avoid this term and speak of “Mediterranean type” and “Thai type” instead.
The essential oil (less than 1%) is of complex and variable composition. Within the species, several different chemical races exist, and furthermore climate, soil and time of harvest influence not only the amount but also the composition of the essential oil. The most important aroma 
components are 1,8 cineol, linalool, citral, methyl chavicol (estragole), eugenol and methyl cinnamate, although not necessarily in this order; in fact, hardly any basil contains all of these compounds in significant amounts. African species often contain camphor.
Further monoterpenes (ocimene, geraniol, camphor), sesquiterpenes (bisabolene, caryophyllene) and phenylpropanoids (methyl eugenol) can be present in varying amounts and strongly influence the flavour. There is considerable infraspecific variation, opening favourable perspectives for future plant breeding by selection.
The quality traded in Europe, Western Asia and North America (Mediterranean type, also known as French or European Basil) is characterized by 1,8 cineol and linalool, plus smaller amounts of estragole and eugenoles. This description holds also for both green-leaved and red-leaved (anthocyanin containing) strains. Eastern European cultivars contain slightly more eugenol.
