Extractives

Extractives are chemical substances present in various materials that can be removed by solvent extraction. They are typically non-structural, low-molecular-weight compounds that do not form part of the material's backbone. The exact composition of extractives varies by material and species and can influence properties such as color, odor, taste, and reactivity. Commonly studied types include resins, waxes, fats, oils, tannins, essential oils, and pigments. Extraction is usually performed with organic solvents or water, and yields are reported as a mass percentage.

In coal science, extractives denote the soluble organic constituents that can be removed by solvent extraction, separate from fixed carbon and mineral matter. They include waxes, resins, oils, tannins, and other organics. Their amount varies with coal type and maturity and can influence processing properties such as coking behavior, odor, and color. The measurement is performed by solvent extraction (for example, Soxhlet extraction) and reported as a percentage of the coal mass.

In wood and plants, extractives are non-structural compounds leached by solvents and include essential oils, terpenes, fats, waxes, tannins, pigments, and phenolics. They affect color, odor, decay resistance, and drying, and are often the target of natural product isolation, flavor and fragrance production, and pharmacognosy. Extraction methods include solvent extraction, steam distillation, hydrodistillation, and supercritical CO2.