Anthocyanins, also known as floral pigments, are water-soluble natural pigments commonly found in nature. There are about 20 anthocyanins known to mankind, and six of them are found in food, such as geranium pigment, cornflower pigment, peony pigment, and petunia pigment.

Anthocyanins are mainly used in the food industry to color food, and are also found in fuels, pharmaceuticals, and cosmetics.

Anthocyanins have antioxidant, vision-protecting, anti-cancer, and radiation-protecting effects, and are the chemical treasures of the scientific community. Therefore, there is a need for continuous research on the extraction methods of anthocyanins and their applications in the food field.

Application of anthocyanins in food

Anthocyanins are widely used in various fields with their good coloring properties, especially in food coloring technology. However, with the continuous improvement of science and technology, it is found that anthocyanins can not only help coloring of food, but also have significant effect on the prevention and treatment of cardiovascular disease, neurological disease, as well as cancer, diabetes and other diseases.

However, anthocyanins in the processing and storage process, the external environmental conditions have high requirements, temperature, pH, light, water and even oxygen will affect the stability of anthocyanins. If the anthocyanin solution to add metal ions, whey protein or adjust the pH value can help to improve the stability of anthocyanins, in addition, anthocyanin microencapsulation or the addition of co-colorants can also help to improve the stability of anthocyanins.

Moreover, microencapsulation of anthocyanins has a strong scavenging ability for free radicals in the organism, thus enhancing the activity of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase and other antioxidant enzymes, which can play a certain degree of enhancement of the overall cellular antioxidant properties, thus greatly improving the survival rate of cells.

And based on this biological characteristics of anthocyanins for technological innovation, can to a large extent to solve the problem of application in food production, in the microcapsules of anthocyanins, the inner wall of the microcapsule can play a certain role in the protection of anthocyanins in different external environments to effectively improve the chemical stability of anthocyanins.

The main extraction technology of anthocyanins

2.1 Ultrasonic extraction technology

Ultrasonic extraction method is to use ultrasonic waves to accelerate the dissolution of active ingredients, thus improving the extraction efficiency of anthocyanins, when the temperature is maintained at 60 ℃, the ethanol concentration of 90% and the overall processing time of about 1h, the extraction rate of anthocyanins in purple potatoes reaches the highest value.

Moreover, after conducting many extraction experiments, scientists have found that ultrasonic technology has a higher extraction efficiency and is less destructive to anthocyanins.

2.2 Microwave extraction technology

Microwave has a strong penetrating ability, and microwave can also promote the intermolecular movement, play a certain role in heating, so the microwave-assisted extraction technology can be used to improve the extraction rate of anthocyanins in purple corn kernel and purple grapes, the use of microwave extraction technology of anthocyanins extraction efficiency is significantly higher than the traditional solvent extraction method.

2.3 Organic solvent extraction technology

General extraction solvents, hydrochloric acid and methanol are more widely used solvents, the use of acidified methanol to extract radish anthocyanins is also very good, so the extraction of organic solvents has been applied to the extraction of grape seeds, blueberries and pomegranate skins and other anthocyanin-rich substances in most of the extraction work.

2.4 Supercritical fluid extraction technology

Supercritical fluid extraction is an extraction method that utilizes the effects of temperature and pressure on the solubility of supercritical fluids.

Under the supercritical state, after the chemical substances to be separated are in contact with the supercritical fluid, the chemical substances will be extracted out sequentially according to their polar size, molecular weight and boiling point, and this extraction technology has the advantages of high extraction rate, no solvent residue and low energy consumption for extraction.

However, due to the polar characteristics of anthocyanin itself, attention should be paid to the pressure and the deployment of organic solvents during the extraction, and the purity of anthocyanin extracted by supercritical fluid extraction method was as high as 97.82%.

Generally speaking, among the above extraction techniques, solvent extraction is easy to operate, but in practice, there are problems of longer extraction time, larger solvent consumption and certain pollution to the external environment. While ultrasonic and microwave technology, although the requirements of the experimental equipment is higher, but the efficiency is higher.

Practical application in the field of food

In the food field, manufacturers often add color to optimize the color and sensory properties of food. Within the scope of food safety regulations, the following natural anthocyanin food colorings are permitted for large-scale production and use: purple sweet potato pigment, blackberry pigment, purple corn pigment, kale pigment, eggplant skin pigment, grape skin pigment, and berry pigment, etc. In the actual production process, the use of natural anthocyanin food colorings is not only limited to the production of food, but also to the production of food products.

In the actual production process, anthocyanin belongs to the higher safety of natural pigments, commonly used in wine, food and beverage, jam, candy and various types of food, so that the food has a variety of beautiful coat, and in addition to give the food color, anthocyanin can also provide a higher order of nutritional value, for example, added anthocyanin yogurt not only has a unique flavor, but also has a certain health function. For example, yogurt with added anthocyanins not only has a unique flavor, but also has a certain health function, mulberry anthocyanins, blueberry anthocyanins, etc. have been applied to yogurt products, so that the fermented yogurt has a fragrant and fruity flavor.

Anthocyanins can not only be used in the field of common ingredients, based on the unique health effects of anthocyanins on the human body, the use of anthocyanins developed by the relevant health care products have also begun to gradually increase, for example, the United States, Europe and other regions, the use of lingonberries and other fruits produced by the health care of the mixed drinks are very popular with middle-aged and old-aged consumers, the annual consumption of anthocyanins in Europe and the United States of the health care of beverages of the direct economic benefits of a number of 1 billion dollars. The direct economic benefits of anthocyanin health drinks consumed in Europe and America amount to 1 billion US dollars annually, and with the continuous and in-depth research on the health functions of anthocyanins, the sales volume of anthocyanin health drinks worldwide will grow rapidly, and the economic benefits brought by anthocyanins can be said to be very objective. In recent years, with the national health consciousness and living water to realize green teaching; the introduction of corporate culture, talent training into the connotation of practical training base construction.