A method for preparing coffee diglyceride

Abstract

The present invention provides a method for preparing coffee diglyceride, belonging to the field of biotechnology. The present invention provides a method for preparing coffee diglyceride, comprising the following steps: 1) mixing coffee oil and glycerol, then adding a composite catalyst and choline chloride to fully mix to obtain a mixed solution; 2) subjecting the mixed solution to catalytic reaction, filtration, and molecular distillation in sequence to obtain coffee diglyceride; the catalytic reaction steps include: first vacuum catalysis, first nitrogen bubbling; second vacuum catalysis, second nitrogen bubbling, and adding a composite catalyst; third vacuum catalysis, third nitrogen bubbling; fourth vacuum catalysis, fourth nitrogen bubbling, and adding a composite catalyst; fifth vacuum catalysis, fifth nitrogen bubbling. The above preparation method is simple, low-cost, and the obtained coffee diglyceride has a high yield, high purity, and good flavor.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology, and in particular relates to a method for preparing coffee diglyceride. Background Art

[0002] Coffee oil, also known as coffee fat, is an essence extracted from coffee beans. It contains rich nutrients and unique chemical composition. The main components of coffee oil include triglycerides, monoacylglycerols and free fatty acids, among which free fatty acids have an important influence on the flavor of coffee.

[0003] Vegetable oils are usually mainly composed of saturated or unsaturated fatty acids. Soybean oil contains 80% unsaturated fatty acids, of which linoleic acid accounts for half of the total fatty acids. Coffee oil has both high levels of saturated fatty acids (palmitic acid) and high levels of polyunsaturated fatty acids (linoleic acid).

[0004] The unique molecular structure of diacylglycerols (DAG) gives DAG emulsifying, lubricating, and antistatic properties. It also has the advantages of nutrition and good processability. It can regulate blood lipids, inhibit weight gain, relieve diabetes, prevent arteriosclerosis, and reduce intestinal burden, and is therefore used as a functional oil substitute.

[0005] Diglycerides prepared from different oils may differ in flavor and other aspects. These differences are mainly due to factors such as the source of the oil, fatty acid composition, production process, and post-processing. Therefore, diglycerides prepared from coffee oil can not only provide the characteristic aroma of coffee, but also have certain health benefits. However, there are currently few methods for preparing diglycerides using coffee oil, and the preparation methods of diglycerides can be mainly divided into traditional chemical catalysis and enzyme catalysis. The traditional chemical method has the characteristics of randomness. Since polyunsaturated fatty acids are sensitive to temperature, the equipment investment is large, the cost is high, there are many by-products, and separation and purification are difficult; high temperature will cause damage to unsaturated fatty acids and affect product quality. Therefore, enzymatic catalysis is usually used for preparation, but there are still problems such as low diglyceride yield, difficulty in separation and purification, low lipase utilization and reuse rate, and difficulty in separation. Summary of the invention

[0006] In view of this, the object of the present invention is to provide a method for preparing coffee diglyceride, which has high yield, good flavor, convenient and simple preparation and low cost.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing coffee diglyceride, comprising the following steps:

[0009] 1) mixing coffee oil and glycerin, and then adding a composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0010] 2) subjecting the mixed solution to catalytic reaction, filtration, and molecular distillation in sequence to obtain coffee diglyceride;

[0011] Preferably, the catalytic reaction step comprises:

[0012] The first vacuum catalysis and the first nitrogen bubbling;

[0013] The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst;

[0014] The third vacuum catalysis, the third nitrogen bubbling;

[0015] The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added;

[0016] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0017] More preferably, the vacuum catalysis time is independently 1.5-2h, and the nitrogen bubbling time is independently 0.5-1h;

[0018] Further preferably, the vacuum degree of the vacuum catalysis is 0.3-0.5 kPa;

[0019] By adopting the above technical solution, the direction of generating diglycerol is promoted, because a part of water will be generated when generating diglycerol, and the excess water will affect the reaction in the direction of esterification reaction. Timely removal of the generated water can make the reaction balance in the direction of esterification reaction, thereby increasing the content of diglycerol, and vacuum catalysis can timely remove the generated water. At the same time, nitrogen bubbling can make the catalyst in the system constantly move and fully react with the raw materials, and nitrogen bubbling can diffuse the water inside the system to the outside, and then continue to remove the water through vacuum catalysis.

[0020] The amount of the added composite catalyst is 1-2wt% of the coffee oil. By adopting the above technical solution, the activity of the catalyst slightly decreases as the catalytic reaction proceeds due to the reduction of the surface contact area, and the catalytic effect is maintained by supplementing part of the composite catalyst in the middle process.

[0021] Preferably, in step 1), the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride is 20-30:10-15:2-8:5-7. By adopting the above technical solution, choline chloride has a significant effect on the regional selectivity and chemical reaction balance of lipase. Choline chloride can be used as an ionic liquid to control the biocatalytic activity of the enzyme by adjusting the reaction conditions. At a suitable concentration, choline chloride can maintain or enhance the enzymatic activity of lipase.

[0022] Preferably, the preparation method of the composite catalyst is:

[0023] The porous graphene, metal salt and water are uniformly mixed and then sodium hydroxide is added to react for 1-2 hours; then the modified porous graphene is obtained by filtering, washing, drying and calcining;

[0024] The modified porous graphene, lipase, water and surfactant are mixed for 1-2 hours, vacuumed for 10-20 minutes and then filtered and dried to obtain a composite catalyst.

[0025] Preferably, the weight ratio of the porous graphene, metal salt, water and sodium hydroxide is 10:2-4:20:2-6.

[0026] Preferably, the metal salt is ferric nitrate, manganese nitrate, or cobalt nitrate; the weight ratio of the ferric nitrate, manganese nitrate, and cobalt nitrate is 1:1:1.

[0027] Preferably, the calcination temperature is 300-400° C., and the calcination time is 1-2 h.

[0028] Preferably, the mass ratio of the modified porous graphene, lipase, water and surfactant is 10:5-8:20:0.5-1.

[0029] Preferably, the lipase is Novozyme 435, Lipozyme RM IM or Lipozyme 435. By adopting the above technical solution, light porous carbon is modified with transition metal to have a certain catalytic ability, and then the catalytic activity of the lipase is improved by loading the lipase, and the lipase is loaded in the porous carbon so that it is not easy to fall off, which is convenient for filtration and continued use after the catalysis is completed; and the composite catalyst has moderate hydrophilicity, because too high hydrophilicity will limit the lipase from contacting the hydrophobic oil phase, making the reaction difficult to proceed.

[0030] Preferably, the temperature of the catalytic reaction in step 2) is 55-58°C.

[0031] Preferably, the molecular distillation step of step 2) is to centrifuge the filtered catalytic reaction liquid to obtain the supernatant and perform the first distillation under the conditions of vacuum degree 0.1-10Pa, rotation speed 180-200r / min, feed rate 2-2.5ml / min, condensation temperature 25-27°C, and distillation temperature 140-145°C;

[0032] Then the distillate is subjected to a second distillation under the conditions of vacuum degree 0.1-10 Pa, rotation speed 250-255 r / min, feed speed 8-10 ml / min, condensation temperature 25-27° C., and distillation temperature 178-182° C. By adopting the above technical solution, the two distillation temperatures are both below 200° C., which can reduce flavor loss.

[0033] Beneficial technical effects:

[0034] 1. The present invention loads lipase in a carrier, and the carrier is prepared by porous graphene loaded with transition metals. The load is firm and not easy to fall off, it is easy to separate from the solution, the hydrophilicity is moderate, and it has the effect of improving catalytic activity.

[0035] 2. The reaction efficiency is improved by adopting the vacuum catalysis-nitrogen bubbling method. At the same time, the catalytic carrier is porous and easy to float in the system, thereby improving the catalytic effect.

[0036] 3. The present invention improves the regional selectivity of lipase by using choline chloride, synergistic composite catalyst, and vacuum catalysis-nitrogen bubbling catalysis mode, thereby significantly improving the yield of coffee diglyceride.

[0037] 4. The molecular distillation temperature of the present invention is low, the reaction conditions are mild, and the loss of flavor and nutrition in the coffee diglyceride is small. DETAILED DESCRIPTION

[0038] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0039] Example 1

[0040] This embodiment provides a method for preparing coffee diglyceride, comprising the following steps:

[0041] 1) Preparation of composite catalyst:

[0042] The raw materials are weighed according to the weight ratio of porous graphene, metal salt, water and sodium hydroxide of 10:3:20:3, wherein the metal salt is ferric nitrate, manganese nitrate and cobalt nitrate; and the weight ratio of ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1.

[0043] Then, the porous graphene, metal salt and water are evenly mixed and sodium hydroxide is added to react for 1.5 hours; then, the modified porous graphene is obtained by filtering, washing, drying and calcining at 350° C. for 1.5 hours;

[0044] The modified porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed in a mass ratio of 10:6:20:0.5 for 1.5 hours, vacuumed for 15 minutes, and then filtered and dried to obtain a composite catalyst.

[0045] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 25:12:6:6, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0046] 3) The mixed solution is maintained at 56° C. and subjected to a first vacuum catalysis and a first nitrogen bubbling;

[0047] The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst;

[0048] The third vacuum catalysis, the third nitrogen bubbling;

[0049] The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added;

[0050] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0051] The vacuum catalysis time is independently 2 hours, the nitrogen bubbling time is independently 1 hour, and the vacuum degree is 0.3 kPa.

[0052] The amount of the added composite catalyst is 2 wt % of the coffee oil.

[0053] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0054] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0055] Example 2

[0056] This embodiment provides a method for preparing coffee diglyceride, comprising the following steps:

[0057] 1) Preparation of composite catalyst:

[0058] The raw materials are weighed according to the weight ratio of porous graphene, metal salt, water and sodium hydroxide of 10:4:20:2, wherein the metal salt is ferric nitrate, manganese nitrate and cobalt nitrate; and the weight ratio of ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1.

[0059] Then, the porous graphene, metal salt and water are evenly mixed and sodium hydroxide is added to react for 1 hour; then, the modified porous graphene is obtained by filtering, washing, drying and calcining at 300° C. for 2 hours;

[0060] The modified porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed in a mass ratio of 10:5:20:1 for 1 hour, vacuumed for 10 minutes, and then filtered and dried to obtain a composite catalyst.

[0061] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 20:10:2:5, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0062] 3) The mixed solution is maintained at 55° C. and subjected to a first vacuum catalysis and a first nitrogen bubbling;

[0063] The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst;

[0064] The third vacuum catalysis, the third nitrogen bubbling;

[0065] The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added;

[0066] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0067] The vacuum catalysis time is independently 1.5 h, the nitrogen bubbling time is independently 0.5 h, and the vacuum degree is 0.4 kPa.

[0068] The amount of the added composite catalyst is 1wt% of the coffee oil.

[0069] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0070] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0071] Example 3

[0072] This embodiment provides a method for preparing coffee diglyceride, comprising the following steps:

[0073] 1) Preparation of composite catalyst:

[0074] The raw materials are weighed according to the weight ratio of porous graphene, metal salt, water and sodium hydroxide of 10:2:20:6, wherein the metal salt is ferric nitrate, manganese nitrate and cobalt nitrate; and the weight ratio of ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1.

[0075] Then, the porous graphene, metal salt and water are evenly mixed and sodium hydroxide is added to react for 2 hours; then, the modified porous graphene is obtained by filtering, washing, drying and calcining at 400° C. for 1.5 hours;

[0076] The modified porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed at a mass ratio of 10:8:20:1 for 2 hours, vacuumed for 20 minutes, and then filtered and dried to obtain a composite catalyst.

[0077] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 30:15:8:7, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0078] 3) The mixed solution is maintained at 58° C. and subjected to a first vacuum catalysis and a first nitrogen bubbling;

[0079] The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst;

[0080] The third vacuum catalysis, the third nitrogen bubbling;

[0081] The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added;

[0082] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0083] The vacuum catalysis time is independently 2 hours, the nitrogen bubbling time is independently 1 hour, and the vacuum degree is 0.5 kPa.

[0084] The amount of the added composite catalyst is 2 wt % of the coffee oil.

[0085] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0086] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0087] Example 4

[0088] The method of this example is the same as that of Example 1, except that the enzyme used is Lipozyme RM IM (enzyme activity 10000 U / mL).

[0089] Example 5

[0090] The method of this example is the same as that of Example 1, except that the enzyme used is Lipozyme 435 (enzyme activity 10000 U / mL).

[0091] Example 6

[0092] The method of this embodiment is the same as that of embodiment 1, except that the step 2) of molecular distillation is to centrifuge the filtered catalytic reaction liquid to obtain the supernatant and perform the first distillation under the conditions of vacuum degree 10Pa, rotation speed 180r / min, feed rate 2.3ml / min, condensation temperature 26°C, and distillation temperature 143°C;

[0093] The distillate was then subjected to a second distillation under the conditions of a vacuum degree of 10 Pa, a rotation speed of 255 r / min, a feed rate of 10 ml / min, a condensation temperature of 27° C., and a distillation temperature of 182° C.

[0094] Example 7

[0095] The method of this embodiment is the same as that of embodiment 1, except that the step 2) of molecular distillation is to centrifuge the filtered catalytic reaction liquid to obtain the supernatant and perform the first distillation under the conditions of vacuum degree 5Pa, rotation speed 190r / min, feed rate 2.5ml / min, condensation temperature 27°C, and distillation temperature 145°C;

[0096] Then the distillate was subjected to a second distillation under the conditions of vacuum degree 7 Pa, rotation speed 255 r / min, feed rate 10 ml / min, condensation temperature 27° C., and distillation temperature 178° C.

[0097] Comparative Example 1

[0098] The method of this comparative example is the same as that of Example 1, except that lipase is used directly without loading, as follows:

[0099] 1) weighing raw materials according to the mass ratio of coffee oil, glycerol, Novozyme 435 enzyme (enzyme activity 10000 U / mL), and choline chloride of 25:12:1:6, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0100] 3) The mixed solution is maintained at 56° C. and subjected to a first vacuum catalysis and a first nitrogen bubbling;

[0101] The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst;

[0102] The third vacuum catalysis, the third nitrogen bubbling;

[0103] The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added;

[0104] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0105] The vacuum catalysis time is independently 2 hours, the nitrogen bubbling time is independently 1 hour, and the vacuum degree is 0.3 kPa.

[0106] The amount of the added composite catalyst is 2 wt % of the coffee oil.

[0107] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0108] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0109] Comparative Example 2

[0110] The method of this comparative example is the same as that of Example 1, except that choline chloride is not added.

[0111] Comparative Example 3

[0112] The method of this comparative example is the same as that of Example 1, except that the lipase is directly loaded on porous carbon as follows:

[0113] 1) Preparation of composite catalyst:

[0114] Porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed at a mass ratio of 10:6:20:0.5 for 1.5 hours, vacuumed for 15 minutes, and then filtered and dried to obtain a composite catalyst.

[0115] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 25:12:6:6, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0116] 3) The mixed solution is maintained at 56° C. and subjected to a first vacuum catalysis and a first nitrogen bubbling;

[0117] The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst;

[0118] The third vacuum catalysis, the third nitrogen bubbling;

[0119] The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added;

[0120] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0121] The vacuum catalysis time is independently 2 hours, the nitrogen bubbling time is independently 1 hour, and the vacuum degree is 0.3 kPa.

[0122] The amount of the added composite catalyst is 2 wt % of the coffee oil.

[0123] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0124] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0125] Comparative Example 4

[0126] The method of this comparative example is the same as that of Example 1, except that vacuum catalysis is not used, as follows:

[0127] 1) Preparation of composite catalyst:

[0128] The raw materials are weighed according to the weight ratio of porous graphene, metal salt, water and sodium hydroxide of 10:3:20:3, wherein the metal salt is ferric nitrate, manganese nitrate and cobalt nitrate; and the weight ratio of ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1.

[0129] Then, the porous graphene, metal salt and water are evenly mixed and sodium hydroxide is added to react for 1.5 hours; then, the modified porous graphene is obtained by filtering, washing, drying and calcining at 350° C. for 1.5 hours;

[0130] The modified porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed in a mass ratio of 10:6:20:0.5 for 1.5 hours, vacuumed for 15 minutes, and then filtered and dried to obtain a composite catalyst.

[0131] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 25:12:6:6, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0132] 3) maintaining the mixed solution at 56° C. and passing through a first catalyst and a first nitrogen bubbling;

[0133] second catalysis, second nitrogen bubbling, and adding composite catalyst;

[0134] third catalysis, third nitrogen bubbling;

[0135] The fourth catalysis, the fourth nitrogen bubbling, and the addition of the composite catalyst;

[0136] fifth catalysis, fifth nitrogen bubbling;

[0137] The catalysis time is independently 2 hours, and the nitrogen bubbling time is independently 1 hour;

[0138] The amount of the added composite catalyst is 2 wt % of the coffee oil.

[0139] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0140] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0141] Comparative Example 5

[0142] The method of this comparative example is the same as that of Example 1, except that nitrogen bubbling is not performed, as follows:

[0143] 1) Preparation of composite catalyst:

[0144] The raw materials are weighed according to the weight ratio of porous graphene, metal salt, water and sodium hydroxide of 10:3:20:3, wherein the metal salt is ferric nitrate, manganese nitrate and cobalt nitrate; and the weight ratio of ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1.

[0145] Then, the porous graphene, metal salt and water are evenly mixed and sodium hydroxide is added to react for 1.5 hours; then, the modified porous graphene is obtained by filtering, washing, drying and calcining at 350° C. for 1.5 hours;

[0146] The modified porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed in a mass ratio of 10:6:20:0.5 for 1.5 hours, vacuumed for 15 minutes, and then filtered and dried to obtain a composite catalyst.

[0147] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 25:12:6:6, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0148] 3) The mixed solution is maintained at 56° C. and subjected to a first vacuum catalysis;

[0149] The second vacuum catalysis, adding composite catalyst;

[0150] Third vacuum catalysis;

[0151] Fourth, vacuum catalysis and adding composite catalyst;

[0152] Fifth vacuum catalysis;

[0153] The vacuum catalysis time is independently 3 hours, and the vacuum degree is 0.3 kPa.

[0154] The amount of the added composite catalyst is 2 wt % of the coffee oil.

[0155] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0156] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0157] Comparative Example 6

[0158] The method of this comparative example is the same as that of Example 1, except that no composite catalyst is added, as follows:

[0159] This embodiment provides a method for preparing coffee diglyceride, comprising the following steps:

[0160] 1) Preparation of composite catalyst:

[0161] The raw materials are weighed according to the weight ratio of porous graphene, metal salt, water and sodium hydroxide of 10:3:20:3, wherein the metal salt is ferric nitrate, manganese nitrate and cobalt nitrate; and the weight ratio of ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1.

[0162] Then, the porous graphene, metal salt and water are evenly mixed and sodium hydroxide is added to react for 1.5 hours; then, the modified porous graphene is obtained by filtering, washing, drying and calcining at 350° C. for 1.5 hours;

[0163] The modified porous graphene, Novozyme 435 enzyme (enzyme activity 10000 U / mL), water, and surfactant were weighed and mixed in a mass ratio of 10:6:20:0.5 for 1.5 hours, vacuumed for 15 minutes, and then filtered and dried to obtain a composite catalyst.

[0164] 2) weighing raw materials according to the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride of 25:12:6:6, then mixing the coffee oil and glycerol evenly, and then adding the composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution;

[0165] 3) The mixed solution is maintained at 56° C. and subjected to a first vacuum catalysis and a first nitrogen bubbling;

[0166] The second vacuum catalysis, the second nitrogen bubbling;

[0167] The third vacuum catalysis, the third nitrogen bubbling;

[0168] The fourth vacuum catalysis, the fourth nitrogen bubbling;

[0169] The fifth vacuum catalysis, the fifth nitrogen bubbling;

[0170] The vacuum catalysis time is independently 2 hours, the nitrogen bubbling time is independently 1 hour, and the vacuum degree is 0.3 kPa.

[0171] 4) After the catalysis is completed, the composite catalyst is filtered out and the filtered catalytic reaction liquid is centrifuged to obtain the supernatant for the first distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 200 r / min, feed rate 2 ml / min, condensation temperature 25° C., and distillation temperature 140° C.;

[0172] The distillate was then subjected to a second distillation molecular distillation under the conditions of vacuum degree 0.1 Pa, rotation speed 250 r / min, feed rate 8 ml / min, condensation temperature 25° C., and distillation temperature 180° C. to obtain coffee diglyceride.

[0173] Experimental Example 1

[0174] Sampling and testing were performed on each embodiment and comparative example before and after catalytic distillation. The test results are shown in Tables 1 and 2.

[0175] Table 1 Percentage content of each component before distillation

[0176]

[0177] Table 2 Percentage content of each component after distillation

[0178]

[0179]

[0180] As shown in Table 1, the content of diglyceride generated by catalysis in the coffee oil of the present invention is higher than 85%; as shown in Table 2, the purity of diglyceride can be further improved after molecular distillation, and the final content of diglyceride is higher than 98%.

[0181] Experimental Example 2

[0182] The composite catalyst in Example 1 was filtered and reused, and diglyceride was prepared by the method of Comparative Example 1. The catalytic activity percentage of the composite catalyst was tested, as shown in Table 3.

[0183] Table 3 Enzyme activity detection

[0184] frequency Enzyme activity percentage 10 98.5 20 94.2 30 91.7 40 88.1 50 85.9

[0185] According to Table 3, the loaded lipase can be recycled and can also maintain high enzyme activity after multiple uses, and can be reused to reduce costs.

[0186] Experimental Example 3

[0187] 50 volunteers were selected to conduct sensory evaluation on the coffee diester oil of each embodiment and comparative example, including:

[0188] 1. Coffee aroma: 0-3 points, take the average score.

[0189] 2. Add 1wt% to regular coffee and evaluate the taste and flavor with a score of 0-3, taking the average score.

[0190] Table 4 Evaluation report

[0191] Coffee aroma Taste Flavor Example 1 2.92 2.87 2.79 Example 2 2.87 2.68 2.86 Example 3 2.94 2.86 2.74 Example 4 2.88 2.79 2.77 Example 5 2.86 2.73 2.70 Example 6 2.76 2.66 2.69 Example 7 2.81 2.68 2.77 Comparative Example 1 1.36 0.75 0.86 Comparative Example 2 1.27 0.65 0.72 Comparative Example 3 0.98 0.96 1.03 Comparative Example 4 1.03 0.76 0.88 Comparative Example 5 1.84 0.88 1.03 Comparative Example 6 2.67 2.57 2.26

[0192] As shown in Table 4, the addition of the coffee diester oil of Examples 1-4 can significantly improve the taste and flavor of coffee, and the unique aroma of coffee is significantly improved.

[0193] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing coffee diglyceride, characterized in that: The following steps are involved: 1) mixing coffee oil and glycerin, and then adding a composite catalyst and choline chloride and mixing thoroughly to obtain a mixed solution; 2) subjecting the mixed solution to catalytic reaction, filtration, and molecular distillation in sequence to obtain coffee diglyceride; The preparation method of the composite catalyst is: The porous graphene, metal salt and water are uniformly mixed and then sodium hydroxide is added to react for 1-2 hours; then the modified porous graphene is obtained by filtering, washing, drying and calcining; The modified porous graphene, lipase, water and surfactant are mixed for 1-2 hours, vacuumed for 10-20 minutes and then filtered and dried to obtain a composite catalyst; The weight ratio of the porous graphene, metal salt, water and sodium hydroxide is 10:2-4:20:2-6; The metal salts are ferric nitrate, manganese nitrate and cobalt nitrate; the weight ratio of the ferric nitrate, manganese nitrate and cobalt nitrate is 1:1:1; The calcination temperature is 300-400°C and the calcination time is 1-2h; The mass ratio of the modified porous graphene, lipase, water and surfactant is 10:5-8:20:0.5-1; The lipase is Novozyme 435 enzyme, Lipozyme RMIM or Lipozyme 435; The catalytic reaction step comprises: The first vacuum catalysis and the first nitrogen bubbling; The second vacuum catalysis, the second nitrogen bubbling, and the addition of the composite catalyst; The third vacuum catalysis, the third nitrogen bubbling; The fourth step is vacuum catalysis, the fourth step is nitrogen bubbling, and the composite catalyst is added; The fifth vacuum catalysis, the fifth nitrogen bubbling; The vacuum catalysis time is independently 1.5-2h, and the nitrogen bubbling time is independently 0.5-1h; The amount of the added composite catalyst is 1wt%-2wt% of the coffee oil.

2. The method according to claim 1, characterized in that: In the step 1), the mass ratio of coffee oil, glycerol, composite catalyst and choline chloride is 20-30:10-15:2-8:5-7.

3. The method according to claim 1, characterized in that The temperature of the catalytic reaction in step 2) is 55-58°C.

4. The method according to claim 1, characterized in that: The molecular distillation step of step 2) is to centrifuge the filtered catalytic reaction liquid to obtain the supernatant and perform the first distillation under the conditions of vacuum degree 0.1-10Pa, rotation speed 180-200r / min, feed rate 2-2.5ml / min, condensation temperature 25-27°C, and distillation temperature 140-145°C; Then the distillate is subjected to a second distillation under the conditions of vacuum degree 0.1-10Pa, rotation speed 250-255r / min, feed rate 8-10ml / min, condensation temperature 25-27°C, and distillation temperature 178-182°C.

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