Vegetable extracts as natural sources of dyes

Among cosmetic and food additives, dyes are receiving, in the past two decades, the largest number of adverse criticism. As a matter of fact, more than a real technological tool (as for example antimicrobics and emulsifiers) they simply represent an answer of industry to market needs. The choice of natural colorants instead of synthetic ones is certainly due to healthy concerns, though real safety and healthiness of natural substances is not scientifically stated yet. Toxicological investigations about food colours, for example, are already performed all over the world, and every year they result in revisions, and often reductions, of their authorised maximum content. This kind of impulses, together with the modification of the requests from consumers, has caused a general lowering of industrial interest toward synthetic dyes. Therefore, the finding out and exploitation of naturally occurring dyes find strong motivations, that range from the field of food additivation to many other sectors, from cosmetics to clothes. The interest in all plants able to give pigments to be used by industry, is therefore increasing. Some of these plants are already known (Isatis, Rubia, Safflower), and before the worldwide spreading of synthetic dyes they were largely used with this purpose; the literature about this subject, however, also quotes many other species as potentially interesting, both coming from spontaneous Mediterranean flora and native of other areas. This work summarizes uses and prospects of several herbaceous species that could be useful natural dyes resources, which are already used by industry or that could be used in future.