Extraction method of lycopene
At present, lycopene products on the market are mainly divided into: (1) synthetic products synthesized by chemical methods; (2) Biosynthesis produced by microorganism (Blakeslea trispora) fermentation; (3) Natural lycopene products prepared from natural biological resources. Among them, according to the manufacturing process, it can be divided into: (1) products prepared with organic solvents as extraction media; (2) Products prepared with supercritical fluid (carbon dioxide, etc.). ) as the extraction medium. The products are mainly used as food colorants and food nutritional supplements in the form of lycopene crystals, tomato oleoresin and lycopene capsules. There are 100 kinds of lycopene products in the international market. At present, domestic industrialized production methods mainly include solvent method and extraction method. Generally speaking, although the production and research of lycopene in China have developed rapidly in recent years, it is still in its infancy and there is a lot of room for development.
At present, the extraction methods of lycopene mainly include the following:
3. 1 direct crushing method
Because the content of lycopene in tomato subcutaneous epidermal cells is high, generally between10 ~15 mg/100g, lycopene can be extracted from tomato skin. The dried tomato skin can be directly eaten as a colorant after being crushed. This is the simplest and most practical method to extract and use.
3.2 Organic solvent extraction method
Lycopene is a fat-soluble carotenoid, insoluble in water, methanol and ethanol, soluble in ether, petroleum ether, hexane and acetone, soluble in chloroform, carbon disulfide, benzene and other organic solvents. Using this characteristic, lipophilic organic solvents can be selected to extract this pigment from tomato waste or tomato products. The general steps are as follows: pretreating, drying and crushing fresh tomatoes or tomato skins, selecting organic solvents or mixed solvents as extraction solutions for solid-liquid extraction, and finally vacuum concentrating the extraction solutions to obtain crude lycopene. This method is simple and easy to operate, but the product obtained by this method has low purity and low yield. The lycopene content is about 5% ~ 15%, and lycopene crystals are usually not produced, but an oily substance, namely lycopene oleoresin. In addition, there are still some problems such as residual organic solvents, which affect its popularization and use. A patent in Europe used 95% ethanol as solvent, extracted at 78℃ for 5 hours by countercurrent method to obtain pigment solution, and then concentrated in vacuum to remove the solvent to obtain powdered pigment product. Recently, it was reported that Hu Wenzhong et al. studied the leaching effect under different leaching temperatures, ratio of material to liquid, leaching time and leaching times. It was found that using ethyl acetate as the extraction solvent of lycopene, the ratio of material to liquid was 1 g: 3 ml, the temperature was 55℃, the time was 55 minutes, and the extraction was carried out by dehydration and stirring for three times. It is also found that using cellulase (0.3-0.5%) can decompose cellulose in tomato pulp, destroy cell wall, accelerate the dissolution of lycopene from cells, reduce the number of extraction times and the amount of extractant, and improve the extraction effect.
3.3 Supercritical fluid extraction method
Supercritical fluid extraction technology is a new extraction, separation and purification technology in food industry. Compared with the traditional organic solvent extraction method, it has the advantages of simple process, low cost, non-toxicity, easy recovery, no chemical solvent consumption and residue, no cracking of the extract at high temperature, no pollution and so on. Especially because the extraction process is low temperature treatment, it is especially suitable for the extraction of high heat-sensitive substances such as lycopene. Cang Jiuna et al. used supercritical CO2 extraction technology to extract lycopene from tomato skin. The effects of extraction pressure, extraction temperature, CO2 flow rate and extraction time on the extraction rate were studied by single factor experiment and orthogonal experiment. The optimum extraction conditions were as follows: extraction pressure 26MPa, extraction time 3.0 h, extraction temperature 40℃ and CO2 flow rate 30 kg/h. Under these conditions, the extraction rate of lycopene was 26.34 mg/ 10. Japanese researchers studied the extraction of lycopene from tomato skin by supercritical carbon dioxide. After the raw materials were crushed or treated with pectinase and cellulase, the extraction rate could reach 95% under the conditions of extraction pressure of 270kg/cm2 and extraction temperature of 40℃.
3.4 Microwave Radiation Extraction Method
Microwave radiation extraction refers to the technology and method of extracting various chemical components from various substances by using microwaves and suitable solvents in a microwave reactor. Because lycopene is a fat-soluble pigment, organic solvents are not easy to penetrate the cell wall and cell membrane of such substances, so the extraction time is long. In recent years, microwave radiation technology has been applied. Li Fang et al. studied the effect of microwave radiation on the extraction of lycopene from tomato sauce. The results show that microwave radiation can significantly improve the extraction rate of lycopene. The optimum extraction conditions were as follows: ethyl acetate as extraction solvent, extraction power of 360 W, extraction time 15 s, material-liquid ratio 1 g: 2 ml, extraction for three times, and the extraction rate was over 90%. Compared with supercritical CO2, microwave radiation extraction has the advantages of low cost, low investment and high extraction rate, and has broad application prospects in the extraction of natural pigments.
3.5 chemical synthesis method
Carotene was isolated from carrot for the first time from 183 1, and β -carotene was synthesized for the first time from 1950. It took 100 years. Up to now, many carotenoids can be synthesized by chemical methods. At present, companies such as Roche in Switzerland and BASF Chemical Company in Germany have produced corresponding lycopene products. Their production is similar to that of VA, and they are generally synthesized from β-ionone. It is also reported that the metabolite of lycopene, 2,6-cyclolycopene-1, 5- diol and 5,6-dihydroxy-5,6-dihydrolycopene, is synthesized from terpinyl acetate through a series of chemical reactions. Recent studies show that they are the main carotenoids in human blood and have good anti-cancer effects.
3.6 Enzyme reaction method
At present, there are two main treatment methods of enzymatic reaction: one is to extract lycopene by the action of tomato's own enzyme, and adjust the pH value of tomato peel residue to 7.5 ~ 9.0 by adding alkali, so that pectinase in tomato peel reacts with cellulase to decompose pectin and cellulose, and the protein complex of lycopene is dissolved out of cells, and the obtained pigment is water-dispersible pigment. The other is to extract lycopene by adding enzymes. The process is as follows: tomato raw materials (tomato sauce, tomato sauce, etc. ) Treating with pectinase and cellulase (0.2% ~ 0.5%) at 50℃ for 3h, removing 90% of non-pigment substances such as pectin and cellulose, centrifugally precipitating, washing with 96% ethanol, filtering, extracting with ethanol and vegetable oil, and separating the oil phase.
3.7 Microbial Fermentation Method
In addition to extracting or chemically synthesizing lycopene from substances containing lycopene, lycopene can also be produced by fermentation of algae, fungi and yeast. This is a new method to obtain carotenoids from Aspergillus Niger. The yield of lycopene can be improved mainly on the basis of adding trisporic acid. The method is carried out from wild-type strains or mutants thereof in separate or mixed cultures. The addition of trisporic acid can be carried out at the beginning of fermentation or during fermentation, and its starter can be a partially purified preparation or its unpurified source. In addition, Blakeslea trispora has a unique metabolic process. Adding vegetable oil, surfactant, antioxidant and various structural analogues can improve the yield of β-carotene, but adding other fermentation promoters can help the yield of other carotenoids. For example, by changing the growth conditions of Blakeslea trispora, which is dominated by β-carotene, additives (Na2CO3, piperidine, etc.) are added. ) can block the last two steps of cyclization in the β -carotene biosynthesis pathway of this strain.
Xiu Yu and others found that adding 3.6mmol/L of 2-(4- methylphenoxy)-triethylamine (MPTA) to Blakeslea trispora for 48 hours could effectively inhibit the synthesis of 96%β- carotene. Adding 15g/L tobacco can promote the production of total carotenoids (170mg/L), but its inhibition on β -carotene synthesis is lower than MPTA. L27(3 13) orthogonal experiment was used to investigate the effect of adding MPTA and tobacco simultaneously on lycopene yield from the aspects of adding time, adding amount and interaction between the two inhibitors. When tobacco 10g/L and MP-TA2.2mmol/L were added simultaneously after 48h of fermentation, the lycopene yield could reach 205mg/L (accounting for 94% of the total carotenoid yield).
From the analysis of product quality, production technology, resource cost and other factors, the production of natural carotenoids such as lycopene by microbial technology will be the future development direction.
3.8 Other methods
With the continuous efforts of scholars from all over the world, many high-tech production technologies have been developed. At present, the breeding research aimed at improving lycopene content, whether conventional breeding or genetic engineering breeding, has achieved remarkable results. Scientists at ARS, the Agricultural Research Service of USDA, have developed a new method to produce lycopene from corn fiber. They have transgenic Fusarium, which can extract lycopene directly from corn fiber. The method greatly reduces the production cost of extracting lycopene from tomato.
Because of its superior physiological function, lycopene, as a natural pigment, has been widely accepted all over the world, and it is also a hot spot in the research of functional food ingredients in the world. This product is contained in the food coloring allowed in Europe and Britain. At present, the World Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have officially listed lycopene in the list of food additives. It is expected to become the best-selling health food additive in the world market in the future. China is rich in tomato resources. How to extract high value-added lycopene from waste tomatoes or tomato products by economic and reasonable extraction methods, and further explore the domestic and foreign markets, is a problem worthy of active research and exploration by scholars.