Study on the Development of Natural Color

With the development of China's economy and the improvement of people's living standards, people are increasingly demanding food safety. Natural colors are pigments obtained from the cell tissues of animals and plants in nature through certain technical means. Compared with synthetic pigments, they are non-toxic and have natural colors. In addition, most natural colors also have certain health, nutritional and pharmacological effects. Therefore, in recent years, scientific and technological workers have conducted a lot of research on the development and application of natural color resources.

1 Physiological functions of Natural Color

A large number of studies have shown that Natural Color is not only non-toxic and safe, but also has very important health, nutritional and pharmacological effects.

Lycopene is one of the most effective antioxidants. Eating a certain amount of lycopene-rich foods such as tomatoes every day will help reduce the risk of chronic diseases such as cancer and cardiovascular disease. The level of lycopene in human serum and tissues is negatively correlated with many types of cancer such as breast cancer and prostate cancer [1]. Lycopene has been recognized as a Group A nutrient by the Food and Agriculture Organization of the United Nations (FAO), the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA A) and the World Health Organization (WHO), and is used as a food additive with both nutritional and coloring functions in more than 50 countries and regions, and is widely used in the fields of food, medicine and cosmetics.

Curcumin has various physiological functions, such as anti-mutagenic, anti-tumor, anti-oxidant, lowering blood lipids and anti-atherosclerosis, as well as anti-inflammatory, anticoagulant, anti-infective, and preventing the formation of age spots [2].

Lutein belongs to the carotenoid family of lutein and can be used to prevent vision loss and blindness caused by age-related macular degeneration of the retina and delay the onset of degenerative eye diseases [3].

Capsanthin is not only bright in color, but also can be used to treat cerebrovascular disease [3].

Astaxanthin has the effect of preventing liver cancer, oral cancer, colorectal cancer, bladder cancer and breast cancer. Drugs for the treatment and prevention of tumors can be developed using astaxanthin [3].

Bioflavonoids, also known as vitamin P, are often found in combination with vitamin C. They are widely distributed in nature and are secondary metabolites of plants. They are a group of natural colors found in vegetables, fruits, flowers and grains. They are called bioflavonoids because they are mostly yellow in color. They have the following properties: (1) they can resist free radicals, directly inhibit the growth of cancer cells and resist the action of carcinogenic factors; (2) they can be used to treat arrhythmia, angina pectoris, myocardial infarction, etc.; ③ they can dilate blood vessels, improve the contraction and relaxation of cardiovascular smooth muscle, and can be used to prevent and treat cardiovascular disease, migraine, atherosclerosis, etc.; ④ they have a certain effect on acute and chronic hepatitis, cirrhosis, fatty liver, and toxic liver damage caused by galactosamine and CCl4; ⑤ they can promote the recovery of pancreatic β cells, lower blood sugar and serum cholesterol, improve glucose tolerance, and can treat diabetes and its complications. It can also inhibit aldose reductase, and therefore can treat diabetes and its complications. It has anti-inflammatory and anti-allergic effects, and is commonly used in clinical practice to treat abscesses, ulcers and allergies[4].

2 Research on the development of natural color resources

There are many types of natural food coloring. The main raw material resources can be divided into: plant Natural Color resources, animal Natural Color resources and microbial Natural Color resources. At present, the most researched and applied Natural Color resources in China are plant-based resources. Reported plants that have been researched and developed as pigment resources include red beets (purple cabbage), red radish, purple cabbage, red pepper, red amaranth, carrot, spinach, perilla, hawthorn, sour dates, sea buckthorn, mulberry, gooseberry, firethorn, black beans, black rice, sesame, comfrey, okra, safflower, chrysanthemum, bilberry, gardenia, rose balsam, Chinese lantern plant, blue indigo, peach (cactus fruit), red and blue, celosia, redwood, Chinese evergreen, Yunnan stone, Wuzhishan orchid, spirulina, multi-spike cactus, bamboo, camphor tree, etc., most of which are forest plants. There are also agricultural and sideline products that are used as raw materials: sorghum hulls, peanut endosperm, yellow slurry for producing corn starch, and wine lees [5].

Wu Chunhua et al. [6] extracted a brown pigment from chestnut shells. Qualitative and stability experiments on the pigment showed that it was a flavonoid pigment with good stability to light, temperature, reducing agents, oxidants, and pH.

Guo Yuankai [7] extracted natural color from grapefruit peel. The method of microwave heating was used for extraction of orange-yellow pigment, which is fast, efficient, simple and easy to carry out, and the orange-yellow pigment extracted by microwave has excellent performance.

Zhang Ruiyu et al. [8] extracted natural color from nasturtium and studied the stability of the pigment. At room temperature, the pigment is stable in a sucrose medium with a pH of 3.0 to 7.0. The amount of salt used in food processing, low concentrations of calcium and magnesium ions have little effect on the pigment. Iron ions, natural strong light and H2 O2 will degrade the pigment.

Gong Hui et al. [9] studied the process of extracting red pigment from the leaves of the creeper, and found that the red pigment it contains has certain value for use.

Hou et al. [10] conducted a process study on the extraction of red pigments from red maple trees. The experiment showed that the optimal conditions for extracting red pigments from red maple trees were: extraction temperature 80 °C, extraction time 0.5 h, material to liquid ratio 1:100, 75% ethanol extractant and extraction pH 1.

Jiang Linbin et al. [11] studied the process conditions for the extraction of the food red pigment H from red pitaya. The experimental results showed that the optimal process conditions were: 70% aqueous ethanol as the extraction agent; extraction time 5 h, with two extractions, the red pigment H has been basically completely leached out; the liquid-to-material ratio is 1:2 (fruit weight w: volume of extraction agent); the extraction is carried out under neutral pH conditions; the temperature is better for extraction at room temperature. When administered to mice by gavage (ig), the maximum tolerated dose (MTD) was 60 g of ointment/kg, indicating that the red dragon fruit pigment H is low in toxicity.

Xie Fengni et al. [12] studied the extraction and properties of purple sweet potato red pigment. The results showed that the extraction efficiency was better when 1:1 0.1 mol/L HCl was used to extract purple sweet potato red pigment at a temperature of 50°C for 4 h with an ethanol volume fraction of 95%. Purple sweet potato red pigment is a kind of anthocyanin pigment. The pH value has a significant effect on the color of the pigment. The color is stable under acidic conditions and has good thermal stability. Light accelerates the degradation of the pigment. Metal ions Na+, Mg+2, Ca+2, A1+3, Cu+2, pb+2, Zn+2 have no effect on the color of the pigment, while Fe+3 and Sn+4 have a negative effect. Purple sweet potato pigment also has a certain degree of antioxidant capacity. Additives such as sucrose, glucose and salt have no effect on the color of the pigment.

Henna is an annual herb belonging to the family Bignoniaceae. Its flowers come in pink, red, and purple-red, and are rich in red and yellow pigments. The pigment components are henna quinone and henna ether. Henna quinone is an acidic pigment with excellent skin rejuvenation, moisturizing, and emollient properties. The whole herb is used in medicine and has extremely high development and utilization value. Su Huina et al. [13] used henna as a raw material to study the extraction process of its pigments. The optimal process conditions for the extraction of henna pigments are as follows: a 75% ethanol solution (pH=1) is used as the extracting agent, the liquid-to-material ratio is 1:100, and the extraction is carried out at 80°C for 30 minutes.

Jujube is widely distributed in China. Jujube skin pigment is a water-soluble pigment. The raw material is readily available, the extraction is simple, and it has certain nutritional value and medicinal functions. Chen Lianwen et al. [14] studied the extraction and performance determination of jujube skin pigment. They studied the extraction conditions of jujube skin pigment, the effects of heat, light, acidity, oxidants, reducing agents, and several commonly used food additives and common metal ions on its stability. This research will provide a good theoretical basis for the development and utilization of wild jujube skin pigments.

It can be seen that the development of Natural Color resources has great potential, and there are still many natural resources to be developed. These studies are of great significance for meeting society's demand for Natural Color.

3 Application research of Natural Color

Most Natural Colors are non-toxic and have no side effects, and are highly safe. Natural plant pigments are mostly anthocyanins, flavonoids, and carotenoid compounds, which not only have a coloring effect, but also enhance the body's physiological functions. Natural Colors have a more natural coloring tone, closer to the color of natural substances. Natural Colors are very sensitive to changes in pH, and the hue will change greatly accordingly. Anthocyanins, for example, are red in acidic conditions, purple in neutral conditions and blue in alkaline conditions. Therefore, with the progress of society and technology, the use of natural colors in the food, pharmaceutical, cosmetic and health product industries has gradually become more widespread, and the technology for their use has gradually improved, gradually becoming an indispensable part of beautifying social life. Research and development of natural colors is valued by countries around the world, and there are currently more than 100 edible natural colors that have been developed internationally [15].

Paprika red is a natural color extracted from dried red peppers, and is mainly used as a red food coloring. Paprika red has no spicy taste, is bright in color, and can be adjusted to different shades from red to orange. It is widely used in biscuits, pastries, cosmetics, instant noodles, pickles, etc., and has the dual function of coloring and nutrition.

Corn yellow pigment and alcohol-soluble protein can be widely used in the pharmaceutical, food, packaging and other industries. Corn yellow pigment is a carotenoid pigment extracted from the waste material (corn zein) in the production of corn starch, as well as natural colors such as cryptoxanthin, which can be used to color food and cosmetics. Cryptoxanthin can be broken down to produce vitamin A, which is essential for the human body. When extracting zeaxanthin, an alcohol-soluble protein is also obtained. This is an edible protein with excellent film-forming, adhesive and moisture-proof properties, and can be used in the pharmaceutical industry as a moisture-proof outer film for drugs and in the food industry as a fresh-keeping coating [16].

Rubiachin pigment is a promising biological pigment. It is bright and vivid, and can be used as a cosmetic additive to significantly improve the antibacterial, anti-inflammatory, emollient and freckle-removing effects of cosmetics. It can also be used as a food additive in fruit wine, beverages, snacks and other foods to increase their heat-clearing and disinfecting, anti-inflammatory and antibacterial, disease-preventing and anti-cancer effects.

In addition to being used in food to enhance the flavor and to have antibacterial, bacteriostatic and shelf-life-extending effects, red yeast rice pigment also has antibacterial properties. In addition, red yeast rice pigment, as a traditional Chinese medicine, also has the functions of lowering blood lipids, blood pressure, and blood sugar, inhibiting tumor cells, and treating dysentery and stomach diseases.

Sodium zinc chlorophyllin can be used in medicine to treat chronic osteomyelitis, chronic ulcers, skin wounds, leukopenia and other conditions, and is a good coloring agent and nutritional supplement in the food industry. In addition to being a green pigment and deodorant, sodium copper chlorophyllin also has many physiological functions in medicine. For example, sodium copper chlorophyllin or its derivatives can promote the metabolism of body cells, heal gastrointestinal ulcers and restore liver function. It can be used to treat infectious hepatitis, hemorrhoids, leukemia, uterine disorders, and gastric and duodenal ulcers. It can also enhance hematopoietic function and promote recovery of the body from radiation damage.

Turmeric pigment is widely used in food and medicine because of its strong coloring power and its anti-inflammatory, free radical scavenging, toxin-inhibiting, and anticancer properties. It is a rare medicinal herb that can be used for both food and medicine, and it is also a spice. Its main physiological function is to scavenge free radicals[17].

In summary, Natural Color has its own unique coloring ability and physiological functions, and is widely used. In recent years, it has aroused the interest of many scientific and technological workers, and a large amount of research has been carried out on the extraction process and resource development of Natural Color. China is a vast country with a special geographical location, with cold, warm, subtropical and tropical regions. It is rich in plant resources and has many varieties. The production areas of many varieties are relatively concentrated, and there are many raw materials for the production of Natural Color in the northern and southern regions, which can be developed and utilized. In particular, some edible and medicinal plants have special development value. We believe that in the near future, through the unremitting efforts of scientific and technological workers, Natural Color will eventually completely replace synthetic pigments in the application of food, medicine, health products and other aspects. ◇

References

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[7] Guo Yuankai. Extraction of natural color from pomelo peel under microwave conditions. Hebei Chemical Industry, 2007, 30 (12): 52-53.

[8] Zhang Ruiyu, Wang Wenjuan. Extraction method and stability study of natural color from nasturtium. Food Research and Development, 2007, 28(3): 60-65.

[9] Gong Hui, Diao Haipeng, Zhao Yan, et al. Study on the ultrasonic extraction process of red pigment from ivy leaves. Journal of Shanxi Medical University, 2009, 40(5): 455-457.

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[11] Jiang Linbin, Lin Cuiwu, Zhao Shukai, et al. Extraction process conditions for the edible red pigment H of red pitaya. Chemical Research and Application, 2003, 15(2): 272-273.

[12] Xie Fengni, Wang Hui, Ma Yan, et al. Extraction and properties of purple sweet potato pigment. Journal of South China Normal University, 2008, 1: 98-102.

[13] Su Huina, Cao Zhixing, Li Junchong, et al. Study on the optimal extraction process of impatiens pigment. Zhejiang Chemical Industry, 2006, 37(9): 11-13.

[14] Chen Lianwen, Zeng Ni. Study on the extraction and performance determination of the pigment from the skin of wild jujube by ultraviolet spectrophotometry. Journal of Beijing Institute of Education (Natural Science Edition), 2009, 4(1): 4-9.

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