A refining method for coffee essential oil

Abstract

The present invention provides a method for refining coffee essential oil, belonging to the technical fields of enzyme technology and coffee refining technology. The method comprises the following steps: S1. Extract the coffee raw materials with an extraction solvent. After extraction, centrifuge to obtain the supernatant for standby; S2. Concentrate the supernatant obtained in step S1, remove the extraction solvent and collect the concentrated solution for standby; Decolorize and remove impurities from the concentrated solution with activated carbon and diatomaceous earth, and then perform suction filtration to obtain the crude coffee essential oil; S3. Enzymatically hydrolyze the crude coffee essential oil obtained in step S2 with lipase. After enzymatic hydrolysis, filter to collect the enzymatic hydrolysate for standby; S4. Remove the impurities in the crude coffee essential oil from the enzymatic hydrolysate obtained in step S3 by steam distillation method, so as to separate and obtain the refined coffee essential oil. The present invention refines coffee essential oil by combining enzyme technology and steam distillation technology, further refines coffee essential oil to improve the stability of coffee essential oil, and solves the problems existing in the application of coffee essential oil.

Description

Technical Field

[0001] The present invention relates to the technical fields of enzyme technology and coffee refining technology, and particularly relates to a method for refining coffee essential oil. Background Art

[0002] Coffee essential oil is obtained from coffee and is a natural raw material, which is widely used in the fields of food and cosmetics. At the same time, it is widely loved by consumers because of its various effects. For example, it has a unique coffee fragrance, which can not only improve appetite but also bring pleasure to people. At the same time, it has antioxidant ability, which can help neutralize free radicals and protect cells from oxidative damage. In addition, coffee essential oil has the effect of improving the skin, which can effectively shrink pores, reduce dark circles under the eyes, prevent skin inflammation, etc., and has broad market prospects. However, there are still some problems in the application of coffee essential oil. For example, precipitation will occur after coffee essential oil is placed at room temperature for a long time, and at the same time, its unique coffee fragrance will be decomposed and deteriorated. Therefore, various problems that occur in the application of coffee essential oil urgently require a solution.

[0003] The reason for the above problems is that there are some impurities in the coffee essential oil raw material. Therefore, during the storage process of coffee essential oil, the impurities are likely to precipitate; in addition, coffee essential oil is prone to deterioration after long-term storage, resulting in the disappearance of its unique coffee fragrance substances. Therefore, how to further refine coffee essential oil is the key to solving the problem. The traditional method for oil refining is the distillation method, but the distillation method has disadvantages, such as serious energy consumption, high temperature is likely to cause product deterioration, and it is difficult to explore the specific conditions of distillation. Therefore, it is necessary to find other methods to solve this problem. Summary of the Invention

[0004] In view of the above problems existing in the prior art, the present invention provides a method for refining coffee essential oil. The present invention refines coffee essential oil by combining enzyme technology with steam distillation technology, and further refines coffee essential oil to improve its stability, thereby solving the problems existing in the application of coffee essential oil.

[0005] The technical solution of the present invention is as follows:

[0006] A method for refining coffee essential oil, comprising the following steps:

[0007] S1. Extract the coffee raw material with an extraction solvent. After extraction, centrifuge and take the supernatant for standby;

[0008] S2. Concentrate the supernatant obtained in step S1, remove the extraction solvent and collect the concentrated solution for standby; decolorize and remove impurities from the concentrated solution with activated carbon and diatomaceous earth, and then perform suction filtration to obtain the crude coffee essential oil;

[0009] S3. Subject the crude coffee essential oil obtained in step S2 to enzymatic hydrolysis with lipase, and after the enzymatic hydrolysis is completed, filter to collect the enzymatic hydrolysate for standby.

[0010] S4. Remove the impurities in the crude coffee essential oil from the enzymatic hydrolysate obtained in step S3 by steam distillation, so as to separate and obtain the refined coffee essential oil.

[0011] Preferably, the coffee raw material in step S1 is coffee powder, which is sieved through a 20-60 mesh sieve and has a water content of less than 2%.

[0012] Preferably, the extraction solvent in step S1 is at least one of ethanol, methanol or acetone; the material-liquid ratio of the coffee raw material to the extraction solvent is 1:5-10 (w / v), and the specific unit is 1 g:5-10 mL.

[0013] More preferably, the extraction temperature in step S1 is 50-80 °C, and the extraction time is 1-4 h; the rotation speed of the centrifugation is 4000-8000 rpm, and the centrifugation time is 10-30 min.

[0014] Preferably, the relative vacuum degree of the concentration in step S2 is -0.080 to -0.095 MPa, the concentration temperature is 40-60 °C, and the concentration condensation temperature is 0-10 °C.

[0015] More preferably, the addition amount of the activated carbon in step S2 is 0.1-1% of the weight of the concentrated solution, and the addition amount of the diatomite is 0.1-1% of the weight of the concentrated solution; the time for decolorization and impurity removal is 1-4 h, and the temperature for decolorization and impurity removal is 25-60 °C.

[0016] After step S2 is completed, the yield of the crude coffee essential oil is 8-15%.

[0017] Preferably, the lipase in step S3 is solid lipase, and the enzyme activity is 30000-100000 U / g.

[0018] More preferably, the addition amount of the lipase in step S3 is 0.02-0.1% of the weight of the crude coffee essential oil, the enzymatic hydrolysis temperature is 25-45 °C, and the enzymatic hydrolysis time is 2-6 h.

[0019] Preferably, the conditions of the steam distillation method in step S4 are: the distillation temperature is 80-100 °C, the distillation time is 1-4 h, and the condensation temperature is -20-0 °C.

[0020] After step S4 is completed, the impurity yield of the crude coffee essential oil is 0.05-0.2% based on the crude coffee essential oil, and the remaining part is the refined coffee essential oil finished product.

[0021] The beneficial technical effects of the present invention are as follows:

[0022] 1. First, the present invention extracts the volatile oil and non-volatile oil from coffee through solvent extraction. The crude product obtained after concentration and decolorization contains certain impurities. Then, the present invention adds lipase to enzymatically hydrolyze the crude product, so that the impurities can be separated by steam distillation, and then refined coffee essential oil is obtained.

[0023] The present invention first adopts the combined technology of lipase and steam distillation to prepare coffee essential oil, and there is no relevant report at home and abroad. The prepared coffee essential oil product has good stability in part. There will be no precipitation after long-term storage, and its unique coffee flavor will not disappear. In addition, its antioxidant ability is not affected.

[0024] 2. During the preparation process of the present invention, the impurities in the coffee essential oil mainly exist in solid form, and the refined coffee essential oil exists in liquid form. It has an obvious coffee flavor and can further expand the application range of coffee essential oil. The present invention does not need to adopt complex preparation conditions such as high temperature and high pressure, thus significantly reducing the energy consumption cost during the manufacturing process, improving safety, and embodying the concept of green environmental protection, which is suitable for large-scale industrial production. Description of the Drawings

[0025] Figure 1 It is the precipitation situation of the crude coffee essential oil (left figure) and the finished coffee essential oil (right figure) after being placed for 1 month.

[0026] Figure 2 It is the total ion current chromatogram of the impurities in the crude coffee essential oil.

[0027] Figure 3 It is the total ion current chromatogram of the refined coffee essential oil. Detailed Embodiments

[0028] The present invention will be specifically described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0029] The lipase used in the following examples is commercially available.

[0030] Example 1:

[0031] S1. Weigh 100 g of Yunnan coffee powder (which has passed through a 60-mesh sieve and has a water content of 1.34%), then add 500 mL of ethanol, extract at 50 °C for 1 h. After extraction, centrifuge (the centrifugation speed is 5000 rpm and the centrifugation time is 30 min), and collect the supernatant for standby after centrifugation.

[0032] S2. Concentrate the clear liquid (the relative vacuum degree of concentration is -0.080 MPa, the concentration temperature is 60 °C, and the condensation temperature of concentration is 0 °C). After concentration, add activated carbon (0.2% of the weight of the concentrated liquid) and diatomaceous earth (0.2% of the weight of the concentrated liquid), then decolorize and remove impurities at 30 °C for 1 h, and then perform suction filtration to collect the crude coffee essential oil for standby. The yield of the crude coffee essential oil is 8.25%.

[0033] S3. Weigh 8 g of the crude coffee essential oil, then add 4 mg of lipase (solid lipase, enzyme activity is 30000 U / g, 0.05% of the weight of the crude coffee essential oil), and carry out enzymatic hydrolysis at 25 °C for 5 h. After enzymatic hydrolysis, filter to collect the enzymatic hydrolysate for standby.

[0034] S4. Put the enzymatic hydrolysate into an essential oil hydrosol machine, and use steam distillation technology to remove impurities in the crude coffee essential oil. The temperature of the essential oil hydrosol machine is set at 85 °C, the distillation time is 4 h, and the condensation temperature is -15 °C, obtaining 4.8 mg of impurities (the yield of impurities is 0.06%), and the remaining part is the refined coffee essential oil product.

[0035] Example 2:

[0036] S1. Weigh 500 g of Yunnan coffee powder (passed through a 20-mesh sieve, water content is 1.82%), then add 4000 mL of methanol, and extract at 70 °C for 2 h. After extraction, centrifuge (the centrifugation speed is 6000 rpm, and the centrifugation time is 20 min), and collect the clear liquid for standby after centrifugation.

[0037] S2. Concentrate the clear liquid (the relative vacuum degree of concentration is -0.090 MPa, the concentration temperature is 50 °C, and the condensation temperature of concentration is 4 °C). After concentration, add activated carbon (0.5% of the weight of the concentrated liquid) and diatomaceous earth (0.5% of the weight of the concentrated liquid), then decolorize and remove impurities at 40 °C for 2 h, and then perform suction filtration to collect the crude coffee essential oil for standby. The yield of the crude coffee essential oil is 9.83%.

[0038] S3. Weigh 40 g of the crude coffee essential oil, then add 32 mg of lipase (solid lipase, enzyme activity is 50000 U / g, 0.08% of the weight of the crude coffee essential oil), and carry out enzymatic hydrolysis at 35 °C for 3 h. After enzymatic hydrolysis, filter to collect the enzymatic hydrolysate for standby.

[0039] S4. Put the enzymatic hydrolysate into an essential oil hydrosol machine, and use steam distillation technology to remove impurities in the crude coffee essential oil. The temperature of the essential oil hydrosol machine is set at 90 °C, the distillation time is 2.5 h, and the condensation temperature is -10 °C, obtaining 44 mg of impurities (the yield of impurities is 0.11%), and the remaining part is the refined coffee essential oil product.

[0040] Example 3:

[0041] S1. Weigh 1 kg of Yunnan coffee powder (which has passed through a 40-mesh sieve and has a water content of 1.19%), then add 10 L of methanol, extract at 80 °C for 4 h. After extraction, centrifuge (centrifugation speed: 8000 rpm, centrifugation time: 10 min), and collect the supernatant for later use after centrifugation.

[0042] S2. Concentrate the supernatant (concentration relative vacuum degree: -0.095 MPa, concentration temperature: 40 °C, concentration condensation temperature: 10 °C). After concentration, add activated carbon (1% of the weight of the concentrated solution) and diatomaceous earth (1% of the weight of the concentrated solution), then decolorize and remove impurities at 60 °C for 4 h, and then perform suction filtration to collect the crude coffee essential oil for later use. The yield of the crude coffee essential oil is 13.68%.

[0043] S3. Weigh 130 g of the crude coffee essential oil, then add 130 mg of lipase (solid lipase, enzyme activity: 80000 U / g, 0.1% of the weight of the crude coffee essential oil), and carry out enzymatic hydrolysis at 45 °C for 2 h. After enzymatic hydrolysis, filter to collect the enzymatic hydrolysate for later use.

[0044] S4. Put the enzymatic hydrolysate into an essential oil hydrosol machine, and use steam distillation technology to remove impurities in the crude coffee essential oil. The temperature of the essential oil hydrosol machine is set at 100 °C, the distillation time is 4 h, and the condensation temperature is -5 °C, obtaining 234 mg of impurities (impurity yield: 0.18%), and the remaining part is the refined coffee essential oil finished product.

[0045] Test Example 1: Comparison of precipitation

[0046] The crude coffee essential oil prepared in Example 3 is as Figure 1 shown in the left figure. After being placed for 1 month, precipitation will occur and the coffee flavor will deteriorate. The refined coffee essential oil finished product in Example 3 is as Figure 1 shown in the right figure. After being placed for 1 month, it is still clear and transparent without precipitation, and has an obvious coffee flavor.

[0047] Test Example 2: Gas chromatographic-mass spectrometric analysis of impurities and finished products

[0048] After removing water from the crude coffee essential oil and the refined coffee finished product prepared in Example 3 with anhydrous magnesium sulfate, dilute with acetone, and separate and identify using a GC-QTOF / MS gas chromatograph-mass spectrometer. Qualify according to its retention time and quantify by the internal standard method. The total ion chromatograms of the crude product impurities and the refined coffee essential oil are as Figure 2 、 3 shown, and the component analysis tables of impurities and the refined coffee essential oil as shown in Tables 1 and 2 are obtained.

[0049] Table 1 Component analysis of impurities in crude coffee essential oil

[0050] Serial number Component RT Chinese name Relative concentration (mg / kg) 1 8.725 2,3-Dimethylfuran 0.047 2 8.731 3,4-Dimethylfuran 0.047 3 9.638 1-Cyclopropylacetone 0.236 4 9.815 Norbornane 0.866 5 10.245 Spiro[2,4]hepta-4,6-diene 20.876 6 10.492 2,2,4-Trimethylhexane 0.372 7 11.037 4-Methyl-3-penten-2-one 1.520 8 11.520 2,3,5-Trimethylhexane 0.298 9 11.730 2,4-Dimethylheptane 0.333 10 11.972 2,6-Dimethylheptane 0.109 11 12.182 2,5-Dimethylheptane 0.360 12 12.421 4-Hydroxy-4-methyl-2-pentanone 6.154 13 21.145 Undecane 0.169 14 32.862 2,4-Di-tert-butylphenol 0.031 15 51.110 2,2'-Methylenebis-(4-methyl-6-tert-butylphenol) 0.119

[0051] As can be seen from Table 1 above, a total of 15 compounds were detected in the crude coffee essential oil impurities: 2,3-dimethylfuran, 3,4-dimethylfuran, 1-cyclopropylacetone, norbornane, spiro[2,4]hepta-4,6-diene, 2,2,4-trimethylhexane, 4-methyl-3-penten-2-one, 2,3,5-trimethylhexane, 2,4-dimethylheptane, 2,6-dimethylheptane, 2,5-dimethylheptane, 4-hydroxy-4-methyl-2-pentanone, undecane, 2,4-di-tert-butylphenol, 2,2'-methylenebis-(4-methyl-6-tert-butylphenol). The specific component among them is 1-cyclopropylacetone.

[0052] Component analysis of the refined coffee essential oil in Table 2

[0053]

[0054] As can be seen from Table 2 above, a total of 15 volatile compounds were detected in the refined coffee essential oil: 2,2-dimethyltetrahydrofuran, 3,4-dimethylfuran, 2,3-dimethylfuran, norbornane, spiro[2,4]hepta-4,6-diene, 2,2,4-trimethylhexane, 4-methyl-3-penten-2-one, 2,3,5-trimethylhexane, 2,4-dimethylheptane, 2,6-dimethylheptane, 2,5-dimethylheptane, 4-hydroxy-4-methyl-2-pentanone, undecane, 2,5-di-tert-butylphenol, 2,2'-methylenebis-(4-methyl-6-tert-butylphenol). The specific component among them is 2,2-dimethyltetrahydrofuran.

[0055] It should be noted that not all the components included in Table 1 are impurities that cause the poor performance of the crude product. Those substances that only exist in Table 1 but not in Table 2 are the impurities that cause the poor performance of the crude product. These impurities will cause the precipitation and deterioration of the crude coffee essential oil during storage. Therefore, what needs to be removed in the present invention refers to these impurities. In addition, since the proportion of impurities is very small, there will be some essential oil adhering to them.

[0056] Test Example 3: Thermal stability evaluation of the crude coffee essential oil and the refined coffee essential oil finished product

[0057] Sample 1: The crude coffee essential oil prepared by steps S1-S2 of Example 3.

[0058] Sample 2: The finished coffee essential oil prepared by steps S1-S4 of Example 3.

[0059] The above samples were heated in an oil bath at 180 °C for 2 h, and the acid value was used as the evaluation index of thermal stability to compare the thermal stability of the above samples. The results are shown in Table 3.

[0060] Table 3 Thermal stability evaluation

[0061] Sample Acid value before heating (mgKOH / oil) Acid value after heating (mgKOH / oil) Sample 1 2.34 3.52 Sample 2 2.8 3.03

[0062] The thermal stability of the crude coffee essential oil and the refined coffee essential oil product was evaluated by the acid value before and after heating. The results in Table 2 showed that after enzymatic hydrolysis with lipase, the acid value of the refined coffee essential oil before heating was slightly higher than that of the crude coffee essential oil, but after heating, the acid value of the refined coffee essential oil was lower than that of the crude coffee essential oil, indicating that the thermal stability of the refined coffee essential oil was stronger than that of the crude coffee essential oil.

[0063] Test Example 4: Evaluation of the antioxidant capacity of the crude coffee essential oil and the refined coffee essential oil product

[0064] Sample 1: The crude coffee essential oil prepared in Steps S1 - S2 of Example 3.

[0065] Sample 2: The coffee essential oil product prepared in Steps S1 - S4 of Example 3.

[0066] Weighed the same weight of Sample 1 and Sample 2, and evaluated their antioxidant capacity by their scavenging ability for DPPH free radicals. The results showed that under the same weight, the scavenging abilities of Sample 1 and Sample 2 for the DPPH solution with the same concentration were different. The scavenging ability of Sample 1 was 61.92%, and the scavenging ability of Sample 2 was 87.66%, indicating that the antioxidant capacity of the refined coffee essential oil was stronger than that of the crude coffee essential oil.

[0067] Although the embodiments of the present invention have been disclosed as above, it is not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, for those of ordinary skill in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirits of the present invention. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A method for refining coffee essential oil, characterized in that: The following steps are involved: S1, extracting the coffee raw material with an extraction solvent, and after the extraction is completed, centrifuging and taking the clear liquid for later use; S2, concentrating the clear liquid obtained in step S1, removing the extraction solvent and collecting the concentrated liquid for later use; decolorizing and removing impurities from the concentrated liquid with activated carbon and diatomaceous earth, and then filtering to obtain a crude coffee essential oil; S3, hydrolyzing the crude coffee essential oil obtained in step S2 with lipase, and filtering and collecting the hydrolyzate after the hydrolysis is completed for later use; S4, removing impurities in the crude coffee essential oil by steam distillation of the enzymatic hydrolyzate obtained in step S3, thereby separating and obtaining refined coffee essential oil; In step S2, the amount of activated carbon added is 0.1-1% of the weight of the concentrated solution, and the amount of diatomaceous earth added is 0.1-1% of the weight of the concentrated solution; the decolorization and impurity removal time is 1-4h, and the decolorization and impurity removal temperature is 25-60°C; The lipase in step S3 is solid lipase with an enzyme activity of 30000-100000 U / g; In step S3, the amount of lipase added is 0.02-0.1% of the weight of the crude coffee essential oil, the enzymolysis temperature is 25-45° C., and the enzymolysis time is 2-6 hours.

2. The refining method according to claim 1, characterized in that The coffee raw material in step S1 is coffee powder, which is sieved through a 20-60 mesh sieve and has a water content of less than 2%.

3. The purification method according to claim 1, characterized in that: In step S1, the extraction solvent is at least one of ethanol, methanol or acetone; the solid-liquid ratio of the coffee raw material to the extraction solvent is 1:5-10 w / v.

4. The refining method according to claim 1, characterized in that: In step S1, the extraction temperature is 50-80°C, and the extraction time is 1-4h; the centrifugal speed is 4000-8000rpm, and the centrifugal time is 10-30min.

5. The purification method according to claim 1, characterized in that: The relative vacuum degree of the concentration in step S2 is -0.080 to -0.095 MPa, the concentration temperature is 40-60°C, and the concentration condensation temperature is 0-10°C.

6. The purification method according to claim 1, characterized in that: The conditions of the steam distillation method in step S4 are: distillation temperature 80-100°C, distillation time 1-4h, and condensation temperature -20-0°C.

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