Colourings: natural

Aloe is an example of a yellow-coloured natural plant juice that was used as yellow pigment or glaze. The GALDI mass spectrum of Aloe hepatica, a historic sample from the... 

Holton, T.A. et al., Cloning and expression of cytochrome P450 genes controlling flower colour. Nature, 366, 276, 1993. 

Water-soluble colours natural indicators red in acidic solutions (most stable) and bluer as pH increases... 

Sometimes, especially with intensely coloured natural wines, the second or third woollen thread assumes a brownish-yellow coloration, which should be neglected. 

You can sec now that it is no coincidence that this compound and the two other highly conjugated compounds we met earlier, chlorophyll and p-carotene, are all highly coloured natural pigments. In fact, all dyes and pigments are highly conjugated compounds. 

Earthcycle has developed a line of packaging specific for fresh vegetable and fruit. The packaging trays are water resistant and are available in two colours, natural fibre and vanilla. Other colours are available upon request, using vegetable dyes, so the biodegradability and compostability of the product is not jeopardised. 

Due to the (often) highly coloured nature of fungi, it is advisable to pre-extract the drugs which might be present, in order that colour reaction tests are not... 

In this series the achievement of the now well-established industrial syntheses of carotenoids notably that of fl-carotene has been of practical interest because of the permitted colourant nature of the compound and for the legally stipulated vitaminisation... 

The highly coloured nature of the tetracycline complexes such as the uranyl ion-tetracycline complex may be utilised in analytical procedures. 

In food science, HPLC has been applied to several categories of substances carbohydrates, lipids, vitamins, additives, synthetic colourings, natural pigments, contaminants (degradation products, pesticides, or natiu-ally occurring substances), as well as amino acids and others [1]. Due to space limitations in this text, all of these classes wdl not be covered, but a limited number of specific examples will be presented. Other applications can be found in recently published books and journals. 

Another application of madder extract is its use as food colourant. Natural food colourants are used rather than synthetic ones, because of a consumer preference for natural products. It is widely believed that natural... 

In general, properties such as colour, natural durability and dimensional stability of thermal treated wood differ from those of untreated wood. Depending on the duration and the power of the process, thermally treated wood shows improved rot-resistance properties and also demonstrates increased resistance to both fungi and climatic influences.To warrant the natural durability it must be ensured, however, that the TMT products have no contact to the ground. Furthermore, its dimensional stability can be improved as well as its adhesion property against hydrophobic materials. 

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