Views:1 Author:Site Editor Publish Time: 2021-08-11 Origin:Site
Curcumin is a kind of yellow and slightly acidic diphenyl heptane substances, is the nature of the very rare diketone colored substances, It mainly includes Curcumin, demethoxycurcumin, bisdemethoxycurcumin and tetrahydrocurcumin, demethoxycurcumin and bisdemethoxycurcumin.
Curcumin is a natural yellow pigment, with strong coloration, bright color, strong thermal stability, safety, non-toxic and other characteristics, can be widely used as a colorant in cakes, candies, drinks, ice cream, colored wine and other food, is considered as one of the most valuable development of natural food pigments. Also is the United Nations Food and Agriculture Organization (FAO) and the World Health Organization (WHO) stipulated the use of high safety of natural pigments. In addition, curcumin also has anti-corrosion and health care functions, is widely used in medicine, spinning and dyeing, feed and other industries.
Curcumin is a kind of natural pigment, which can be obtained by washing, drying and grinding the underground rhizome of curcuma, turmeric and Zedoary, and then extracting, filtering, concentrating and refining with ethanol and other organic solvents.
Curcumin mainly consists of three active components: curcumin (C21H20O6, molecular weight 368, about 70%), demethoxy-curcumin (C20H18O5, molecular weight 338, about 15%) and dimethoxy-curcumin (C19H16O4, molecular weight 308, about 10%) .
Studies have shown that curcumin is almost non-toxic to humans and animals, and its colouring power is stronger than all synthetic pigments and natural pigments, which is 3 ~ 4 times that of lemon yellow and sunset yellow.
The crystallization of curcumin is orange yellow powder, with a special aroma, melting point of 179~182℃, with lipophilic, easily soluble in glacial acetic acid,
Ethyl acetate and alkaline solution, and soluble in 95% ethanol, propylene glycol, but insoluble in water.
The maximum absorption peak of curcumin in 95% ethanol solution was around 425nm. High purity (>90%) curcumin is pure yellow in acidic environment, brown or reddish brown in alkaline environment, and rose red in pH=7.0~8.0, so it can be used as a chemical reaction indicator (determination of boron ion).
Curcumin contains a number of double bonds, phenolic hydroxyl group, carbonyl group and so on, so the chemical reactivity is strong.
The stability of curcumin is easily affected by light, temperature, acidity, metal ions and other factors. Light and heat can promote its oxidation decomposition, lose the ability to color. The pigment loss rate was about 33% after 5h direct sunlight. Under acidic or neutral conditions, the solubility of curcumin is low and precipitate easily.