Method for extracting lycopene from tomatoes

Abstract

The invention discloses a method for extracting lycopene from tomatoes, and belongs to the technical field of lycopene extraction. The method for extracting lycopene from tomatoes comprises the following steps: cutting tomato fruits into blocks, and drying; mixing the dried tomato fruits with an extraction solvent, heating, carrying out heat-preservation and pressure-preservation extraction, and condensing steam to obtain an extracting solution after the extraction is finished; and cooling, crystallizing and purifying the extracting solution to separate out lycopene. According to the method, a green solvent is used, the operation process is simple, the lycopene extraction rate is remarkably increased, and green and efficient extraction of lycopene in tomatoes is achieved; and meanwhile, the purity and bioavailability of the extraction and crystallization integrated lycopene product are higher than those of the lycopene product obtained by the traditional method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lycopene extraction, and particularly relates to a method for extracting lycopene from tomatoes. BACKGROUND

[0002] Lycopene is a kind of straight-chain hydrocarbon compound with 11 conjugated double bonds and 2 non-conjugated double bonds, which is widely present in tomatoes, watermelons, guavas, papayas and grapefruits, and belongs to carotenoids. These conjugated double bonds make it have multiple spatial configurations, but mainly divided into trans and cis configurations. The bioavailability of equal amounts of lycopene is about 10 times that of cis lycopene (Circulation, 2021, 144, 14059.). Natural lycopene is mainly synthesized through the mevalonate pathway in plants, resulting in the presence of lycopene in tomatoes in the trans configuration (J. Agric. Food. Chem., 2023, 71, 35.). Some tomato eating methods in daily life have low bioavailability, for example, the bioavailability of fresh tomatoes is only 10%, while the bioavailability of dried tomatoes and tomato fried eggs is 15% and 20%, respectively, and the bioavailability of these processed tomatoes is still less than 35% after passing through the digestive system. If the isomerization rule of lycopene can be mastered, the natural trans configuration can be converted to cis configuration during extraction and purification, which is expected to significantly improve its bioavailability.

[0003] The common lycopene extraction method is organic reagent extraction method. Due to the unique liposoluble characteristics of lycopene, according to the principle of "like dissolves like", weakly polar reagents such as alkanes, chlorinated hydrocarbons and benzene need to be selected. However, such reagents have low boiling points, strong volatility and toxicity, and large-scale use will cause serious harm to the human body and the environment, and it is difficult to remove the residues in the product, affecting the product quality. Using edible oil as a solvent to recover lycopene from tomato paste processing waste avoids the use of toxic organic reagents, making the extraction process green and safe, but edible oil has high viscosity and poor diffusion effect, which affects the extraction efficiency and yield of lycopene. In recent years, supercritical CO2 technology has been used for lycopene extraction. In the supercritical state, CO2 has high diffusion as a gas and high density as a liquid, which has good extraction effect while ensuring the process to be green and environmentally friendly. However, the pressure required by this technology is too high, the operation process is risky, and it is not conducive to industrial production.

[0004] In addition to the extraction process to be optimized, the purification process of the extract is also problematic. In particular, there are many active ingredients in tomatoes, including carotenoids, fatty acids, sterols, polysaccharides and flavonoids, etc. The purity of lycopene in the extract is too low to meet the needs of subsequent product preparation. The current purification methods of lycopene are mainly divided into crystallization method and column chromatography method. The crystallization method needs to dissolve the lycopene extract with weakly polar organic reagents first, and then the lycopene is precipitated by adding anti-solvent, which usually includes acetone, DMSO, etc. The column chromatography method also needs to be dissolved with weakly polar organic reagents before sampling and elution. The above purification processes need to use a large amount of toxic organic reagents, which is harmful to the human body and the environment. In addition, the current extraction and purification processes of lycopene are isolated from each other, which is not efficient and increases energy consumption.

[0005] Subcritical extraction technology has been widely used in the extraction of plant active ingredients, including polysaccharides, flavonoids and phenolic acids, etc. This technology destroys the hydrogen bonds between solvent molecules by heating, thereby reducing the polarity of the solvent. Under subcritical conditions, the viscosity of the solvent is reduced and the penetration ability is enhanced, so that the active ingredients can be efficiently extracted from the polar to the medium polar. However, lycopene has weak polarity, and green solvents such as ethanol have poor extraction effect at low temperature, which means that subcritical needs to be above 250℃ to better extract, and at such a high temperature, lycopene is severely degraded, making subcritical water extraction difficult.

[0006] Therefore, a method for extracting lycopene from tomatoes is proposed. SUMMARY

[0007] In view of the deficiencies of the prior art, the purpose of the present application is to provide a method for extracting lycopene from tomatoes, which solves the problems in the prior art.

[0008] The purpose of the present application can be achieved by the following technical solutions:

[0009] A method for extracting lycopene from tomatoes, comprising the following steps:

[0010] S1, cutting and drying the tomato fruits;

[0011] S2, mixing the dried tomato fruits with an extraction solvent, heating and extracting under pressure, and then obtaining an extract after condensation of the steam;

[0012] S3, cooling and crystallizing the extract to precipitate lycopene.

[0013] Further, the extraction solvent is at least one of ethanol and limonene.

[0014] Further, the ratio of the extraction solvent to the dried tomato fruit is (20-50):1 mL / g.

[0015] Further, in S2, the extraction temperature is 120-180 DEG C, and the extraction time is 30-120 min.

[0016] Further, in S2, the extraction pressure is 0.5-2 Mpa.

[0017] Further, in S2, the extraction temperature is 140 DEG C, and the extraction time is 90 min.

[0018] Further, the concentration of lycopene in the extraction solution is 22-110 mu g / mL.

[0019] Further, the concentration of lycopene in the extraction solution is 44 mu g / mL.

[0020] Further, the crystallization temperature is 0-20 DEG C.

[0021] Further, the crystallization time is greater than 6 h.

[0022] The beneficial effects of the present application are:

[0023] 1. The extraction and crystallization method avoids using non-green organic solvents, and the operation process is simple. The results show that the lycopene content is increased from 0.511 mg / g in traditional organic extraction (ethyl acetate extraction) to 0.985 mg / g, realizing the green and efficient extraction of lycopene in tomatoes. At the same time, the lycopene product purity is up to 9.01% in the integrated extraction and crystallization, and the cis ratio is 52.07%, which is higher than the national food standard (≥5%), and the bioavailability (cis ratio) is much higher than that of the conventional method.

[0024] 2. The present application fully explores the change rule of lycopene cis-trans structure with time at different temperatures, and uses the influence rule of temperature on the polarity of green solvents such as ethanol to realize the integrated process of subcritical green solvent extraction and crystallization purification of high-cis lycopene, and high-purity and cis-structure lycopene can be obtained from tomatoes only by using green and environmentally friendly solvents such as ethanol. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0026] Figure 1 is the high performance liquid chromatogram of lycopene standard;

[0027] Figure 2 is the high performance liquid chromatogram of the tomato extract of the present application;

[0028] Figure 3 is the standard curve graph of lycopene;

[0029] Figure 4 is the process and principle diagram of lycopene extraction and crystallization of the present application;

[0030] Figure 5 is the comparison graph of reflux extraction rate and cis ratio of subcritical ethanol and ethyl acetate. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] A method for extracting lycopene from tomatoes, comprising the following steps:

[0033] S1, pretreatment of tomatoes: taking fresh tomato fruit parts, cutting and drying to constant weight;

[0034] S2, subcritical extraction: loading the dried tomato fruits into an extraction tank, adding an extraction solvent, sealing the extraction tank, turning on the heating switch to heat, extracting under constant temperature and pressure, opening the extraction tank valve when the extraction is completed to make the internal steam cool into liquid through condensate water, and then cooling the liquid through a cooling tank to finally obtain the extraction liquid and store it in a collection container;

[0035] S3, low-temperature cooling crystallization: after the extraction is completed, the extraction liquid is placed in a low-temperature environment for crystallization, the green solvent polarity is restored, and finally the lycopene is completely precipitated.

[0036] In S1, the drying temperature is 50-60℃, and the time is 40-60h.

[0037] In S2, the extraction solvent is at least one of ethanol and limonene.

[0038] In S2, the ratio of the extraction solvent to the tomato fruits is (20-50): 1 mL / g.

[0039] In S2, the extraction temperature is 120-180℃, the extraction time is 30-120min, and the extraction pressure is 0.5-2Mpa.

[0040] In S3, the concentration of lycopene in the extraction solution is 22-110 μg / mL.

[0041] In S3, the crystallization temperature is 0-20 ℃, and the crystallization time is greater than 6 h.

[0042] The lycopene extraction and crystallization process and principle involved in the above embodiments are shown in Figure 4 .

[0043] The technical solutions of the present application are illustrated below by the following examples.

[0044] In Examples 1-8, the method for calculating the lycopene content in the extraction solution is as follows:

[0045] As shown in Figure 3 , the standard curve is drawn using the peak area of the chromatogram (as shown in Figure 1 ) of lycopene standard with different concentrations, by taking the standard concentration as the horizontal coordinate and the lycopene absorption peak area as the vertical coordinate, and by calculating the relationship between the peak area and the concentration: Y =

[0046] 1.32662X + 0.80506 (R2 = 0.9995), which is used to calculate the content of the extracted lycopene (as shown in Figure 2 ).

[0047] Example 1

[0048] Accurately weigh 60 g of dried tomato fruit, put it into the extraction tank, add 2400 mL of ethanol, seal the extraction tank, turn on the stirring, adjust to 200 r / min, turn on the heater, heat to 140 ℃, at this time the pressure in the tank is 1.2 Mpa, extract for 30 min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through a low-temperature cooling tank, and finally the extraction solution enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 801.51 mg / g, and the cis-occupancy is 63.66%.

[0049] Example 2

[0050] Accurately weigh 60 g of dried tomato fruit, put it into the extraction tank, add 2400 mL of ethanol, seal the extraction tank, turn on the stirring, adjust to 200 r / min, turn on the heater, heat to 140 ℃, at this time the pressure in the tank is 1.2 Mpa, extract for 60 min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through a low-temperature cooling tank, and finally the extraction solution enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 895.22 mg / g, and the cis-occupancy is 63.97%.

[0051] Example 3

[0052] Accurately weigh 60g of dried tomato fruit, put it into the extraction tank, add 2400ml of ethanol, seal the extraction tank, turn on the stirring, adjust to 200r / min, turn on the heater, heat to 140℃, at this time the pressure in the tank is 1.2Mpa, keep the temperature and pressure for 90min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through the low-temperature cooling tank, and finally the extraction liquid enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 985.05mg / g, and the cis-occupies 68.02%.

[0053] Example 4

[0054] Accurately weigh 60g of dried tomato fruit, put it into the extraction tank, add 2400ml of ethanol, seal the extraction tank, turn on the stirring, adjust to 200r / min, turn on the heater, heat to 140℃, at this time the pressure in the tank is 1.2Mpa, keep the temperature and pressure for 120min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through the low-temperature cooling tank, and finally the extraction liquid enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 853.54mg / g, and the cis-occupies 69.40%.

[0055] The lycopene extraction rate data of examples 1-4 is shown in table 1.

[0056] Table 1: Lycopene extraction data statistics table of examples 1-4

[0057]

[0058] According to table 1, the lycopene extraction rate increases first and then decreases with the extension of time. When the time is short (30-90min), lycopene is gradually extracted from the tomato matrix, and the extraction rate gradually increases. However, when the heating extraction time is further extended to 120min, lycopene will be degraded under high temperature for a long time, and the extraction rate will decrease. Therefore, 90min is the optimal time for lycopene extraction at 140℃.

[0059] Example 5

[0060] Accurately weigh 60 g of dried tomato fruit, put it into the extraction tank, add 2400 mL of ethanol, seal the extraction tank, turn on the stirring, adjust to 200 r / min, turn on the heater, heat to 120℃, at this time the pressure in the tank is 1.2 Mpa, heat and keep pressure for 90 min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through the low-temperature cooling tank, and finally the extraction liquid enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 923.16 mg / g, and the cis ratio is 52.41%.

[0061] Example 6

[0062] Accurately weigh 60 g of dried tomato fruit, put it into the extraction tank, add 2400 mL of ethanol, seal the extraction tank, turn on the stirring, adjust to 200 r / min, turn on the heater, heat to 140℃, at this time the pressure in the tank is 1.2 Mpa, heat and keep pressure for 90 min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through the low-temperature cooling tank, and finally the extraction liquid enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 985.05 mg / g, and the cis ratio is 68.02%.

[0063] Example 7

[0064] Accurately weigh 60 g of dried tomato fruit, put it into the extraction tank, add 2400 mL of ethanol, seal the extraction tank, turn on the stirring, adjust to 200 r / min, turn on the heater, heat to 160℃, at this time the pressure in the tank is 1.2 Mpa, heat and keep pressure for 90 min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through the low-temperature cooling tank, and finally the extraction liquid enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 689.58 mg / g, and the cis ratio is 72.11%.

[0065] Example 8

[0066] Accurately weigh 60 g of dried tomato fruit, put it into the extraction tank, add 2400 mL of ethanol, seal the extraction tank, turn on the stirring, adjust to 200 r / min, turn on the heater, heat to 180℃, at this time the pressure in the tank is 0.5-2 Mpa, heat and keep pressure for 90 min. After the extraction is completed, open the condensation circulating pump, cool the steam discharged from the extraction tank with cooling water, further cool it through the low-temperature cooling tank, and finally the extraction liquid enters the receiving tank. The extraction rate measured by high performance liquid chromatography is 83.79 mg / g, and the cis ratio is 75.51%.

[0067] The lycopene extraction rate data of Examples 5-8 are shown in Table 2:

[0068] Table 2: Lycopene extraction data statistics of Examples 5-8

[0069]

[0070] According to the data in Table 2, with the increase of temperature, the extraction rate of lycopene first increases, then decreases after reaching a critical temperature. When the temperature reaches 140°C, the extraction rate of lycopene reaches the highest. This is because, in the subcritical state, the properties of ethanol change with temperature, when the temperature increases, the polarity of subcritical ethanol decreases, according to the principle of similar dissolves similar, when it decreases to similar with lycopene, the extraction rate is larger. Of course, with the increase of temperature, the molecular diffusion rate also increases, and the extraction efficiency of the solvent to lycopene also increases. When the temperature continues to increase, the polarity similarity decreases, and the temperature is too high, part of lycopene decomposes, resulting in a decrease in extraction rate. Therefore, 140°C is selected as the best extraction temperature, at which the extraction rate of lycopene is the largest.

[0071] Based on the results of the above examples, to obtain the maximum extraction rate of lycopene, 140°C can be selected as the best extraction temperature, and the best extraction time is 90 min at this temperature. The following crystallization experiment will be based on the extraction liquid obtained under the optimal conditions.

[0072] Examples 9-13 introduce the purification and crystallization process of lycopene. In Examples 9-13, the steps for testing the purity of lycopene are as follows: a certain mass of crystals is weighed, a certain volume of acetone is added for dissolution, and high performance liquid chromatography is used for determination, and the concentration and cis ratio can be obtained according to the peak area.

[0073] Example 9

[0074] The lycopene extraction liquid with a concentration of 22 μg / mL was placed in a 4°C refrigerator, and after 24 h, the lycopene crystals were precipitated and the crystals were grown. After centrifugation, the precipitate was collected. The experiment measured that the purity was 7.01%, and the cis ratio was 42.29%.

[0075] Example 10

[0076] The lycopene extraction liquid with a concentration of 44 μg / mL was placed in a 4°C refrigerator, and after 24 h, the lycopene crystals were precipitated and the crystals were grown. After centrifugation, the precipitate was collected. The experiment measured that the purity was 9.01%, and the cis ratio was 52.07%.

[0077] Example 11

[0078] The extraction solution with lycopene concentration of 66 μg / mL was placed in a refrigerator at 4°C, and lycopene was allowed to crystallize and grow for 24 h. The precipitate was collected by centrifugation. The purity of the lycopene was measured to be 6.30%, and the cis-lycopene accounted for 52.09%.

[0079] Example 12

[0080] The extraction solution with lycopene concentration of 88 μg / mL was placed in a refrigerator at 4°C, and lycopene was allowed to crystallize and grow for 24 h. The precipitate was collected by centrifugation. The purity of the lycopene was measured to be 6.13%, and the cis-lycopene accounted for 52.05%.

[0081] Example 13

[0082] The extraction solution with lycopene concentration of 110 μg / mL was placed in a refrigerator at 4°C, and lycopene was allowed to crystallize and grow for 24 h. The precipitate was collected by centrifugation. The purity of the lycopene was measured to be 3.87%, and the cis-lycopene accounted for 52.32%.

[0083] The lycopene crystallization data of Examples 9 to 13 are shown in Table 3.

[0084] Table 3 Lycopene crystallization data of Examples 9 to 13

[0085]

[0086] As shown in Table 3, when the lycopene concentration is low, the purity and cis-lycopene ratio of the lycopene crystals increase with the increase of the concentration. This is because the solubility of the cis-lycopene isomer is significantly better than that of the all-trans isomer. When the concentration is low, the lycopene is less than the saturation point, and especially the cis-lycopene isomer is difficult to precipitate, so the purity and cis-lycopene ratio of the precipitate are low. When the concentration increases, the lycopene precipitates and the purity increases. However, when the concentration further increases, the concentration of other active ingredients also increases and reaches the saturation point, so the purity of the lycopene crystals decreases, but the cis-lycopene ratio remains almost unchanged. The extraction solution with a concentration of 44 μg / mL is selected as the optimal concentration, at which the purity of the lycopene is the highest and the cis-lycopene ratio is the best.

[0087] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example", and the like means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0088] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A method for extracting lycopene from tomatoes, characterized in that, Includes the following steps: S1. Cut the tomato fruit into pieces and dry them; S2, the dried tomato fruit is mixed with the extraction solvent, heated and kept at a constant temperature and pressure for extraction, and the steam is condensed to obtain the extract after extraction; S3, the extract is cooled and crystallized to purify it, and lycopene is precipitated.

2. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, The extraction solvent is at least one of ethanol and limonene.

3. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, The ratio of the extraction solvent to the dried tomato fruit is (20-50): 1 mL / g.

4. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, In S2, the extraction temperature is 120-180℃ and the extraction time is 30-120 min.

5. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, In S2, the extraction pressure is 0.5-2 MPa.

6. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, In S2, the extraction temperature was 140℃ and the extraction time was 90 min.

7. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, The concentration of lycopene in the extract is 22-110 μg / mL.

8. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, The concentration of lycopene in the extract was 44 μg / mL.

9. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, The crystallization temperature is 0-20℃.

10. The method for extracting lycopene from tomatoes according to claim 1, characterized in that, The crystallization time is greater than 6 hours.

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