Views: 0 Author: Site Editor Publish Time: 2021-08-19 Origin: Site
Essential oils are liquid products of steam or water distillation of plant parts (leaves, stems, bark, seeds, fruits, roots and plant exudates). Expression is used exclusively for the extraction of citrus oil from the fruit peel, because the chemical components of the oil are easily damaged by heat. Citrus oil production is now a major by-product process of the juice industry. An essential oil may contain up to several hundred chemical compounds and this complex mixture of compounds gives the oil its characteristic fragrance and flavour. An essential oil may also be fractioned and sold as individual natural components. Other processing options can also produce further products that can be sold alongside essential oils. The plant parts can be extracted with organic solvents to produce oleoresins, concretes and absolutes or extracted with a near or supercritical solvent such as carbon dioxide to produce very high quality extracts. These oleoresins and extracts contain not only the volatile essential oil but also the concentrated non-volatile flavour components and these have wide application in the food and pharmaceutical industries. The solvent extraction processes are more difficult and complex than steam distillation and will normally be beyond the financial resources of most small scale processors, but supplying the raw materials to these extraction plants can be a market option.
The most important spices traditionally traded throughout the world are products of tropical environments. The major exceptions to this group are the capsicums (chilli peppers, paprika), and coriander which are grown over a much wider range of tropical and non- tropical environments. Production of spices and essential oils in these wet and humid environments brings special difficulties for crop and product management. Drying the crop to ensure a stable stored product is of particular importance, and in wet humid environments this creates the need for efficient and effective drying systems.