What Is Natural Food Coloring Paprika Oleoresin?

Since the middle of the last century, scientists have been studying how to obtain Paprika Oleoresin and its applications in the field of food and other fields [1]. Paprika Oleoresin is a natural food-grade pigment that is extracted, isolated and refined from chili peppers using scientific methods. Paprika Oleoresin is rich in nutrients that are beneficial to human health, such as L-ascorbic acid, β-carotene, stearic acid and linoleic acid. In addition to its nutritional and health benefits, Paprika Oleoresin also has anti-cancer and anti-radiation effects, and eating Paprika Oleoresin also has a certain effect on human health.

1 The origin of Paprika Oleoresin

Chili peppers originated in the jungles of Chile in Central and South America, and were later successfully cultivated in Mexico. It is an annual herb of the Solanaceae family. The earliest record of chili peppers in China is probably in the “Eight Notes of Compliance with Life” compiled by Gao Lian in 1591 during the Ming Dynasty. In China, chili peppers have gradually become a common vegetable and seasoning, especially in Sichuan and other places, where they are famous for their spicy and numbing taste. Paprika red pigment is a yellow to red natural pigment obtained from the ripe fruit of the Solanaceae family. It is a conjugated polyene oxygen derivative and is divided into two categories: ① zeaxanthin and β-carotene both have vitamin A activity, both are yellow in color and have low polarity; ② the highly polar and dark red paprika red pigment and paprika carmine account for about 50% to 60% of the total carotenoids[2].

2 Paprika Oleoresin composition and properties

2.1 Paprika Oleoresin composition

Paprika Oleoresin is the main coloring pigment in chili peppers, accounting for 0.2 %-0.5 % of the peel. Suzuki et al. [3] studied the carotenoids in chili peppers and found that more than 50 types of carotenoids have been isolated from chili peppers, and more than 30 types have been classified and identified. The results showed that Paprika Oleoresin with a color value of 104 units had the following indicators: the mass fraction of fatty acids was 80-85%, which contained the main components such as stearic acid, myristic acid, linoleic acid, octadecanoic acid, palmitic acid, etc. as the main components; vitamin C content is 0.2%~1.1%; vitamin E content varies from 0.6%~1.0%; each 100 g of sample contains about 140 to 170 mg of protein (total nitrogen); carotenoids such as R-carotene, zeaxanthin, capsanthin, capsanthin, and β-carotene, with the proportion of capsanthin and capsanthin accounting for about half to two-thirds of the total. In addition to paprika xanthophyll, butterfly xanthophyll, paprika red di-stearate, paprika red acetate, paprika pigment fatty acid ester, etc., which can be used as edible red pigments, it also contains about 14% zeaxanthin, about 13.9% β-carotene, and about 5.5% picrocrocin.

2.2 Physical and chemical properties of Paprika Oleoresin

2.2.1 Physical properties

Paprika Oleoresin has no pungent taste, is brightly colored and shiny, has a good visual appearance, is stable and not affected by changes in pH. In appearance, Paprika Oleoresin is reddish-brown needle-like crystals or a thick, blood-red oily liquid. It is highly soluble in highly polar organic solvents and insoluble in water and glycerin.

2.2.2 Chemical properties

Paprika oleoresin stored in the cells of the intact tissue of the chili fruit is relatively stable to heat and visible light. This is due to the formation of a lipid protective film by certain substances in the cells and the cell membrane. Once the paprika oleoresin is extracted, it lacks protection and is prone to oxidation. In addition, factors such as co-oxidants, light and high temperatures can all promote the oxidative decomposition of paprika oleoresin, resulting in discoloration. Paprika oleoresin has a melting point of about 175°C and is prone to discoloration under ultraviolet light.

Paprika Oleoresin is resistant to acids and alkalis, is neutral or slightly alkaline, and is basically unaffected by reducing agents. Metal ions such as K+, Na+, Al3+, Zn2+, and Ca2+ have no effect on it. It reacts with inorganic acids to turn blue, and CO2+, Cu2+, Fe3+ can cause it to fade, and it can form a precipitate with Pb3+ [4,5].

3 Paprika Oleoresin's health benefits

3.1 It can be used as an antioxidant to effectively prevent cancer and atherosclerosis. Paprika oleoresin is a carotenoid that is good for eyesight and has an anti-mutagenic effect on cells. It is currently a popular antioxidant. Antioxidants have a certain degree of preventive effect on cancer. Studies have shown that people with low levels of carotenoids and vitamin A in the body are twice as likely to develop cancer as people with normal levels of carotenoids and vitamin A in the body. For example, many spicy-food-loving ethnic groups in regions such as India and Southeast Asia have a lower cancer incidence rate than Western countries. Therefore, eating more fruits and vegetables rich in carotenoids and vitamin A, such as oranges, carrots, and peppers, can effectively prevent low-density lipoprotein from oxidizing to form harmful lipids and avoid the accumulation of fat in blood vessels, which can cause atherosclerosis.

3.2 Boosts the immune system and combats aging

Paprika Oleoresin contains carotenoids with vitamin A activity, including cryptoxanthin and zeaxanthin. Paprika Oleoresin also contains β-carotene, which not only eliminates the harm caused by free radicals in the body, but also converts into vitamin A, which supplements the body's nutrients. It has the effect of preventing cataracts, boosting the immune system, and delaying aging.

3.3 Prevents the harmful effects of radiation

Gao Lan et al. [6] studied different types of spices such as red pepper, curcumin, curry, and black pepper to compare their radiation protection effects. The study showed that Paprika Oleoresin had the most prominent protective effect.

4 Extraction method of Paprika Oleoresin

4.1 Oil solvent method

This method involves fully immersing dry paprika powder or paprika fruit skins in liquid edible oils such as rapeseed oil, cottonseed oil, or soybean oil at room temperature, allowing the paprika red pigment to dissolve fully in the oils, and finally processing the mixture to obtain paprika red pigment. The technical difficulty with this process is that it is difficult to separate the pigment from the oil, so it is difficult to obtain a product with a high color value.

4.2 Organic solvent method

This method is the conventional extraction method for paprika oleoresin. It uses an organic solvent with lipophilicity to extract crude paprika oleoresin from dried red pepper powder. The specific steps are as follows: the red pepper is washed, then crushed and dried. The crude paprika oleoresin is then extracted using a constant temperature organic solvent, and the extract is concentrated and recovered by vacuum distillation. This method is simple to operate, but the recovery rate of the extracted product is low, the purity is poor, and it is prone to cause foreign odors and solvent residues. Therefore, it needs to be improved in many ways to eliminate foreign odors and impurities. The following methods can be used to improve the purity and quality of the product: (1) Eliminate the strange resinous smell of crude paprika oil by steam distillation, and then extract Paprika Oleoresin after separate operations such as alkali treatment, organic solvent extraction, and distillation. (2) Treat the paprika oleoresin separately with alkali, extract it with an organic solvent, concentrate it, and then extract it again with an oil solvent, and finally eliminate the strange smell by steam distillation. ③First, the fat in the oleoresin is saponified with a 16% to 43% KOH (or NaOH) lye, then extracted with dimethyl ketone. The extract is treated with an inert gas under reduced pressure and concentrated with an organic solvent to obtain a pure product.

4.3 Silica gel column chromatography separation method

This method uses the differences in molecular structure and properties of capsaicin and the pigment, whose solubility and binding forces in the eluent and stationary phase are different, and therefore the distribution coefficients in the eluent and stationary phase are also different, to achieve the separation of capsaicin and the pigment. The separation of paprika red pigment using silica gel column chromatography requires low-cost equipment and a simple operating process, and can achieve good separation results as well as the removal of the pungent taste [7]. Chen Yongmei [8] found that different eluents had different effects on the separation of paprika oleoresin. For example, acetone and petroleum ether (1:10) had a better separation effect than ethanol and petroleum ether (3:6). In terms of particle size, the extraction rate of powder from small chili peppers is significantly higher than that of powder from large particles; in terms of the choice of extraction solution, the pigment yield of the acetone extract is higher than that of the petroleum ether and ethanol.

4.4 Supercritical CO2 fluid extraction

This method is an environmentally friendly and efficient new type of extraction and separation technology. Compared with traditional solvent extraction, its outstanding features are: no consumption or residue of the extraction solvent, no pollution, and the ability to prevent thermal degradation of the extract at high temperatures, ensuring that the physiological activity and natural flavour of the extract remain unchanged. This method has a simple process flow, low energy consumption, a non-toxic extraction solvent that is easy to recycle, and a high purity of the product obtained. This technology can be used to extract paprika red pigment from the peel of the chili pepper, and it can also be used to purify, separate, and refine paprika red pigment obtained by solvent extraction, remove solvent residues and peculiar odors, and extract the remaining pungent flavor in the pigment. This process can be used to obtain a product with low impurities, low solvent residues, high purity, no peculiar smell, and a brighter and more vibrant color.

Zhang Xuebin et al. [9] showed that the optimal conditions for extracting paprika oleoresin with supercritical CO2 were an extraction temperature of 32°C, an extraction pressure of 20 MPa, an extraction time of 3.5 h, and a particle size of 50 mesh. The extraction yield of capsanthin under the optimal conditions was 6.68%. By using advanced extraction techniques such as supercritical CO2 fluid extraction, while obtaining the high value-added capsaicin, the Paprika Oleoresin also has the advantages of stable quality, high chroma, and no solvent residue. The whole process is non-polluting and makes full use of high-tech products.

5 Applications of Paprika Oleoresin

5.1 Applications in food

Zhang Zhiqiang et al. [10] used paprika red in the production of pudding ice cream and yogurt. As time passed, there were no significant changes in the properties or color, indicating that the pigment worked well in these two food products. Tao Wendian et al. [11] showed in their experiments that soy sauce made with Paprika Oleoresin as a coloring agent rarely showed floating and delamination on the surface after being stored for 3 months. Using it to make fish soup can make the juice color bright. Both Japan and China have developed additive-free paprika pigment preparations with good stability and coloring effects for making beverages.

5.2 Application in pharmaceuticals

Natural food coloring is now widely used in medicine, for example, to color liquid oral solutions, powders, and tablets, and to color the outer layer of red, yellow, and green pills and tablets. The amount of coloring used in this field is large and the range is wide. It is closely related to human health. The use of synthetic coloring in medicine is strictly controlled, and the use of natural coloring will not harm human health. Wang Mingxuan et al. [12] found that Paprika Oleoresin can be evenly dispersed in syrup under the action of the solubilizer Tween 80 and ethanol. Its advantages as a coloring agent for drug coated tablets are as follows: it is brightly colored and easy to accept, especially for children's medication, and it also has a moisture-proof effect.

5.4 Application in animal feed

Paprika oleoresin is used in animal feed for two reasons: firstly, natural paprika oleoresin is stable and safe as a coloring agent; secondly, some animals cannot produce pigments on their own and can only retain certain pigments in their bodies by eating plants containing the corresponding pigments. Paprika oleoresin not only increases the coloring in fish, shrimp, pigs, cows and goats, but also helps to improve the appearance. The egg yolks of poultry are also colored in a natural way. Poultry cannot synthesize carotenoids themselves, so they absorb carotenoids from the feed and deposit them in the egg yolk [13]. Adding Paprika Oleoresin to the feed can color the skin and egg yolk of chickens and add a bright color.

Some studies have confirmed that paprika can be used to color salmon. Liu Jinni et al. [14] used β-cyclodextrin to encapsulate paprika oleoresin, which not only helped to disperse paprika oleoresin more evenly in the feed, but also promoted the full utilization of paprika red pigment in the feed. In order to study the effect of red pepper powder-added feed on the growth and body color of koi, Sun Jinhui et al. [15] selected koi with an average weight of 7.517±0.58g for a 30-day feeding trial. The results showed that as the amount of red pepper powder added increased, the feed coefficient showed a downward trend, and the protein efficiency, specific growth rate, and relative weight gain rate of the fish in each test group all showed an upward trend. The results of the comprehensive analysis show that adding 5% paprika powder to the feed can achieve the best results in coloring the growth of koi.

6 Conclusion

As food additives develop towards multifunctionality, research on multifunctional natural pigments is also becoming increasingly active. Paprika oleoresin is both safe and nutritious. It has now been valued and researched and developed by the food additive industry and food industry at home and abroad, and has broad market prospects and huge economic benefits. Therefore, the deep processing and development of paprika is imperative.

References

[1] Xia Bangqi. Research and development progress of domestic and foreign paprika pigments [J]. Western Cereals, Oils and Food Science and Technology, 1999 (6): 36-39.

[2] Lei Jianjun, Zhu Zhangsheng, Chen Changming et al. Research progress on the molecular mechanism of paprika oleoresin and its biosynthesis [J]. Acta Horticulturae Sinica, 2023, 50(03): 669-684.

[3] Suzuki, M., and M. Carotenoid cornposition of new cultivar of Capsicum annulTl during maturation and its high capsaicin content. Journal of the Japanese Society for Food Science & Technology--Nippon Shokuhin Kagaku'Kogaku Kaishi, 2003, 50(7): 324-326.

[4] Liu Hong, Wei Xiaoyu, Ma Hui et al. Analysis of the composition of petal anthocyanins in several terrestrial species of orchids [J]. Journal of Jiangsu Agricultural Sciences, 2022, 38(06): 1657-1677.

[5] Chemical Research; Findings on Chemical Research Reported by Investigators at University of Cordoba (A Simple and Rapid Electrochemical Determination of Pungency: Application To Aqueous and Ethanolic Extracts Ofcapsicum Annuumcubana Red) [J]. Chemicals & Chemistry, 2020 .

[6] Gao Lan, Li Haoming. A brief introduction to the health, medicinal and functional properties of the capsaicin in chili peppers [J]. China Food Additives [J], 1997 (3): 45-47.

[7] Zhang Chao, Ma Jingjing, Liu Qing et al. Preparation and application of natural food coloring agent paprika oleoresin [J]. China Food Additives, 2022, 33(07): 225-231. [8] Extraction of paprika oleoresin [J]. Science and Technology Information, 2007(25).

[9] Zhang Xuebin, Tian Zhicong, Liu Lu, et al. Research on the optimization of supercritical CO2 extraction of Paprika Oleoresin by uniform design [J]. Chinese condiments, 2021, 46(01): 153-156.

[10] Zhang Zhiqiang, Jiang Ying, Tian Liping. Stability of Paprika Oleoresin and its application in food [J]. Modern Food Science and Technology, 2006, 22(2): 83-85 .

[11] Tao Wendian, Wu Jianlin. A brief discussion on the extraction and application of natural pigments and the extraction method of paprika red pigment [J]. China Chemical Industry Trade, 2012(5): 246-247 .

[12] Wang Mingxuan, Zhao Shulin. Application of Paprika Oleoresin in the Pharmaceutical and Food Industries [J] . Journal of Northwest University (Natural Science Edition), 1995(6):645-647 .

[13] Yue Yingxiao, Qi Lijun, Huang Liyong et al. Research progress on the stability and application of Paprika Oleoresin [J] . China Food Additives, 2022,33(10):279-283 .

[14] Liu Jinni, Liu Jicheng, Ruan Chongmei et al. Research on the Encapsulation Technology of Paprika Oleoresin Oil with β-Cyclodextrin [J]. China Feed, 2019(21):93-96.

[15] Sun Jinhui, Fan Ze, Qu Mu, et al. Effect of adding red pepper powder to feed on the growth and body color of koi [J]. Aquatic Science and Technology Information, 2016, 43(5):6.