Importance of Biochemistry

Extraction of plants and raw natural extracts

Extraction of plants?


How do you extract chemicals from plants?

Extraction of plants :

Extraction of plants,Raw natural extracts are generally produced in places where aromatic plants are grown, but food industries increasingly prefer to use extracts and elaborate preparations, rather than spices and herbs as they are. 

This choice is dictated by organoleptic and microbiological considerations , by greater ease of automation of production chains and by better homogenization within the food product.

Extraction of plants.Essential oils.

According to the origin of the plants ( species , variety), the ecology of the environment and the care taken by the producing countries (methods of harvest, collection, preparation, drying, storage, packaging), spices and aromatics exhibit significant variations in the composition of raw natural extracts.

In France, the region of Grasse has the largest number of firms dealing with natural materials and raw extracts intended for the creation of perfumes and for the formulation of complex aromatic preparations used in food.

Several types of extracts are available on the market

  • Essential oils

These are products extracted from plants either by steam entrainment or by hydrodistillation , or by expression. In general, the whole plant is not extracted, but only certain parts: roots, rhizomes , wood , bark, leaves, flowers, flower buds, fruits, seeds, fruit juice, or excretions of the plant (gums or exudates ).

Sampling of natural extracts.

In order for it to be interesting to extract the essential oil from a plant by steam entrainment, this oil must represent a significant quantity of the fresh or dried plant; such is the case of spices and aromatics: cloves (15 to 20%), mace (10 to 13%), nutmeg (8 to 9%), cardamom (4 to 10%), cumin (2 to 5%) , pepper (1 to 2.5%).

The other technique for obtaining essential oils , the expression is only used for the manufacture of citrus or citrus essences. These fruits contain in their bark large quantities of essences which are found inside oil bags. The principle of the extraction of these essential oils consists in breaking these gasoline pockets by mechanical means, pressure , incision or cold abrasion . The essential oil entrained by a stream of water will be separated by decantation or centrifugation.

  • Oleoresins: concrete and resinoids

The extracts obtained with solvents volatile organic – ether of petroleum , hexane, diethyl, ether alcohol ethyl, acetone , carbon dioxide , methylene chloride, benzene , toluene , etc. – are more complete than essential oils because they contain not only volatile compounds but also other constituents which were not entrainable by water vapor ( triglycerides, waxes, lipid colorants and flavoring compounds). Note that the solvent must be removed with the greatest care so as not to remove the most volatile constituents. In addition, most of the solvents used are subject to strict regulations dictated by health considerations. In particular, their residual content in food must be less than ppb (1 mg / kg); moreover, only solvents without risk of toxicity are authorized.

By this method of extraction, two types of products are made: concrete from fresh plant substances, and resinoids from dry plant substances. The term “oleoresin” indifferently denotes one or the other of these two extracts.

The yields obtained by this technique vary depending on the raw material and the type of solvent used: vanilla pod with ethanol (30 to 47% relative to the fresh weight), pepper with methylene chloride (5 to 15%), ginger with acetone (3.9 to 10.3%) and with ethanol (3.1 to 6.9%).

  • Other types of extracts

To lesser degrees, other techniques are also used for the preparation of extracts: cold maceration, hot digestion , decoction by boiling, leaching or percolation cold or under pressure, hot then cold infusion , and alcoholic tincture. . In the case of fruits, we also make juice concentrates, concentrated infusions and alcoholates.

  • Aromas from thermal reactions

In this category, we find all the aromatic preparations obtained by heat treatment of a mixture of precursors. They result either from Maillard reactions or from caramelization reactions, or from pyrolysis reactions (smoke aroma). Depending on the precursors and the operating conditions, there is an infinite number of more or less well defined aromatic compositions. Note that these reactions are causing aromas of coffee or cocoa products during the roasting coffee beans or beans of cocoa .

  • Natural refined extracts

From the raw extracts, it is possible to carry out splits. Depending on the techniques used (cryoconcentration, distillation under reduced pressure, ultrafiltration , reverse osmosis , etc.), various products will be obtained: absolute by washing with alcohol followed by elimination of the alcohol; soluble essences; Fractionated essences (terpeneless and sesquideterpenic essences), etc.

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