Anthocyanin, also known as flower pigment, is a water-soluble natural pigment commonly found in nature. There are more than 20 types of anthocyanins known to man, and 6 types in food, such as geranium pigment, cornflower pigment, peony pigment and petunia pigment.
Anthocyanins are mainly used in the food industry for coloring foods, but also in fuels, pharmaceuticals and cosmetics.
Anthocyanins are chemical treasures of science, with their antioxidant, vision-protective, anti-cancer, and radiation-protective properties, and therefore require continuous research on their extraction methods and their application in the food industry.
01 Anthocyanins in food applications
Anthocyanins have been widely used in various fields, especially in food coloring technology, due to their good coloring properties. However, with the advancement of science and technology, anthocyanins have been found to be effective not only in coloring foods, but also in preventing cardiovascular diseases, neurological diseases, cancer, diabetes and other diseases.
However, during processing and storage, anthocyanins have high requirements on external environmental conditions, such as temperature, pH, light, moisture and even oxygen, which can affect the stability of anthocyanins. The addition of metal ions, whey protein or pH adjustment to the anthocyanin solution can help to improve the stability of anthocyanins, as well as the microencapsulation of anthocyanins or the addition of co-colorants.
Moreover, microencapsulation of anthocyanins has a strong ability to scavenge free radicals in the organism, thus enhancing the activity of antioxidant enzymes such as superoxide dismutase and glutathione peroxidase, which can all contribute to the overall total antioxidant properties of cells to a certain extent, thus greatly improving the cell survival rate.
The technological innovation based on this biological property of anthocyanins can largely solve the problem of application in food production. In the microcapsules of anthocyanins, the inner wall of microcapsules can play a certain protective role and effectively improve the chemical stability of anthocyanins in different external environments.
02 Main extraction techniques of anthocyanins
2.1 Ultrasonic extraction technology
Ultrasonic extraction method uses ultrasonic waves to accelerate the dissolution of active ingredients, thus improving the extraction efficiency of anthocyanins. The highest extraction rate of anthocyanins from purple potatoes was achieved when the temperature was kept at 60°C, the ethanol concentration was 90% and the overall processing time was about 1h.
Moreover, after conducting many extraction experiments, scientists found that the ultrasonic technique was more efficient and less destructive to anthocyanins.
2.2 Microwave Extraction Technology
Microwave has a strong penetrating ability, and microwave can also promote intermolecular motion, to play a certain role in warming, so microwave-assisted extraction technology to improve the extraction rate of anthocyanins in purple corn kernels and purple-skinned grapes, the use of microwave extraction technology, anthocyanin extraction efficiency is significantly higher than the traditional solvent extraction methods.
2.3 Organic solvent extraction technology
Among the general extraction solvents, hydrochloric acid and methanol are the most used solvents, and the effect of using acidified methanol to extract radish anthocyanins is also very good, so the extraction technology of organic solvents has been applied to the extraction of most anthocyanin-rich substances such as grape seeds, blueberries and pomegranate peels.
2.4 Supercritical fluid extraction technology
Supercritical fluid extraction is an extraction method that uses the effect of temperature and pressure on the solubility of supercritical fluids.
In the supercritical state, after the chemical substances to be separated come into contact with the supercritical fluid, the chemical substances are extracted in turn according to their polar size, molecular weight and boiling point. This extraction technique has the advantages of high extraction rate, no solvent residue and low energy consumption for extraction.
However, due to the polar characteristics of anthocyanins themselves, attention should be paid to the pressure and organic solvent deployment during extraction, and the purity of anthocyanins extracted by supercritical fluid extraction was 97.82%.
In general, among the above extraction techniques, solvent extraction is easy to operate, but in practice, there are problems of long extraction time, large solvent consumption and certain pollution to the external environment. In contrast, ultrasonic and microwave techniques are more efficient, although they require higher experimental equipment.
03 Practical applications in the food industry
In the food industry, manufacturers often add color to optimize the color and sensory properties of food. Within the scope of food safety regulations, the mass production and use of natural anthocyanin food coloring is permitted: purple sweet potato coloring, mulberry coloring, purple corn coloring, kale coloring, eggplant skin coloring, grape skin coloring, and berry coloring, among others.
In the actual production process, anthocyanins are natural pigments with high safety, which are commonly used in wine, food and beverage, jam, candy and all kinds of food, giving food a variety of beautiful coat, and in addition to giving food brilliant colors, anthocyanins can also provide higher-order nutritional value.
For example, in the United States and Europe, mixed health drinks made from lingonberries and other fruits are very popular among middle-aged and elderly consumers, and the direct economic benefit of anthocyanin health drinks consumed in Europe and the United States is several billion dollars per year. The direct economic benefits of anthocyanin health drinks consumed in Europe and the United States are 1 billion US dollars per year, and the sales of anthocyanin health drinks are expected to grow rapidly worldwide with the continuous in-depth research on the health functions of anthocyanins. In recent years, with our national health care awareness and living water to achieve green teaching; the introduction of corporate culture, talent training into the connotation of the practical training base construction.
