Monascus pigment is a deep purplish red powder with a slight odor and a melting point of 165-192 °C. The fat-soluble pigment in Monascus pigment can be dissolved in a solvent such as diethyl ether, chloroform, ethanol, acetic acid or n-hexane, and the solubility is the highest in acetic acid and the lowest in n-hexane. Commonly used solvents are ethanol and acetic acid, the concentration of ethanol is 75% to 82%, and the solubility of red yeast pigment is best when the concentration of acetic acid is 78%. The solubility of Monascus pigment in water is related to the pH of the aqueous solution. It is highly soluble under neutral or alkaline conditions, and its solubility tends to decrease in the acidic range below pH 4.0 or in salt solutions containing more than 5%. When the content of monascus pigment is low, the solution is bright red, and when the content is high, it is dark brown with fluorescence. It has excellent coloring properties for proteins. Once dyed, it will not fade when washed with water.

1 Stability to pH

The effect of pH on Monascus pigment is more complicated, and the effects on the components of Monascus pigment are also different. Generally, Monascus pigment is relatively stable in the neutral range, and neutrality is preferred even in the case of heating. However, in the case of two kinds of acid and alkali, the partial alkaline ratio is better than the acidity, and the loss rate is small.

2 Thermal stability

It has been proved by research that the Monascus pigment has better thermal stability and is superior to other synthetic pigments, and its heat resistance is also excellent in natural pigments.

3 light stability

The alcohol solution of Monascus pigment is less affected by ultraviolet light, but sunlight can reduce the chroma. Through the light stability analysis of red, orange and yellow pigments in Monascus pigments, it was found that the red, orange and yellow pigments in the Monascus pigments have great photostability, and the yellow pigment has the strongest photostability. Followed by red pigment, orange pigment is the most unstable to light.

4 Stability to other substances

It has been proven that monascus pigments are not affected by common metal ions and oxidants and reducing agents.

5 antibacterial

Antibacterial tests on 54 susceptible microorganisms in food showed that Monascus pigment had strong inhibitory effects on Bacillus cereus, Mycobacterium, Bacillus subtilis, Staphylococcus aureus and Pseudomonas fluorescens.

It has been studied to inhibit the effect of Monascus pigment on Clostridium botulinum, and it is proved that the extract can cause cracks in the vegetative cells of Clostridium botulinum, which is of great significance in meat production.

6 antioxidant

The antioxidant activity of Monascus pigment was verified by three kinds of antioxidant models, namely hydroxyl radical system, superoxide anion radical system and diphenyl picryl base free system. It was proved that red yeast red pigment and orange pigment were very strong. The ability to scavenge free radicals, in which the red pigment component has the best antioxidant properties.