Anthocyanin is a water-soluble pigment, which can change color with the pH of cell fluid. Cell sap is red when it is acidic and blue when it is alkaline. Anthocyanin is one of the main pigments that constitute the color of petals and fruits. It is produced by phenylpropanoid pathway and flavonoid biosynthesis pathway. The factors that affect the coloration of anthocyanins include the structure, pH and coloration of anthocyanins. The color of pericarp is influenced by internal and external factors and cultivation techniques. Light can increase anthocyanin content; High temperature will degrade anthocyanins. Anthocyanin is a secondary metabolite of plants and plays an important role in physiology. The color of petals and fruits can attract animals to pollinate and spread seeds (Stintzinand and Carle, 2004). It is commonly found in the tissues of flowers and fruits, as well as in epidermal cells and lower epidermis of stems and leaves. The market price of some fruits is determined by the depth of color. Anthocyanin belongs to flavonoids in phenolic compounds. The basic structure consists of two benzene rings connected by a three-carbon unit (C6-C3-C6). Anthocyanins are produced through phenylpropionic acid pathway and flavonoid biosynthesis pathway, and are catalyzed by many enzymes. There are six aglycones, namely geraniol, cyanidin, delphinidin, paeoniflorin, petunia and mallow. Anthocyanins show different colors due to different hydroxyl groups (-OH), methylation, glycosylation, sugar types and connection positions (Fan, 1998). The expression of color is influenced by the changes of biochemical environmental conditions, such as anthocyanin concentration, color effect and pH value in fluid cells (Clifford, 2000). The aim is to understand the factors affecting anthocyanin biosynthesis and provide reference for field cultivation management.
Orange and yellow are the functions of carotene. 19 10 found β -carotene in carrots, and then found two other isomers of carotene in * * * *, namely α, β and γ. β -carotene has been patented by 1958 (US2849495,1958 on August 26th, patentee: Hoffman Roche), which is mainly extracted from the ocean and can also be artificially synthesized.
There are more than 300 different anthocyanins in nature. They come from different kinds of fruits and vegetables, such as purple sweet potato, blueberry, cranberry, blueberry, grape, elderberry red, blackcurrant, purple carrot and red cabbage, and their colors range from red to blue. These anthocyanins mainly include Delchindin, cyanidin, petunia and paeoniflorin.
The color of anthocyanins changes with the change of PH value, from raspberry red at PH 3 to dark blueberry red at PH 5. In most applications, these pigments have good light, heat and PH stability, and can withstand pasteurization and UHT heat treatment. Anthocyanins are widely used in beverages, sweets, jellies and jams. The color changes of purple sweet potato anthocyanins at different PH values are shown at the bottom right: the color changes of purple sweet potato anthocyanins at different PH values.
In recent years, more and more people began to pay attention to the possible health benefits of anthocyanins as polyphenols. In the future, this characteristic of anthocyanins may be more and more used in functional food and health food. At present, there are mature anthocyanin products in the market, mainly including blueberry anthocyanin, blueberry anthocyanin, cranberry anthocyanin, elderberry anthocyanin, blackberry anthocyanin and black bean skin anthocyanin, with the content of 25% or 40%. Mr. Xue Xifeng of Xi 'an Tianyi Biotechnology Co., Ltd. made a detailed study on the extraction process, and started mass production of 25% anthocyanins at 200 1.