Method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction

Abstract

The present invention belongs to the technical field of plant oil extraction, and specifically relates to a method for extracting peony seed oil by two steps of water enzyme-supercritical extraction. The present invention uses a water enzyme method and a supercritical extraction technology in combination, and optimizes the processes of the water enzyme method and the supercritical extraction technology respectively, obtains an enzyme preparation combination with the best effect of the water enzyme method, greatly improves the extraction efficiency, obtains a higher peony seed oil yield, reduces the production cost, and is expected to be widely used in industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of plant oil extraction, and particularly relates to a method for extracting peony seed oil in two steps of water enzyme-supercritical extraction. Background Art

[0002] Peony (Paeonia suffruticosa Andr.) is a deciduous shrub belonging to the genus Paeonia in the family Ranunculaceae. It is widely planted in China, especially in Heze and Luoyang. Peony seeds are abundant in sources, with an annual output of 60,000 tons. They are a promising substitute for imported oil crops. Peony seed oil has a protein content of 18%-22%, a lipid content of 29%-34%, and a higher content of unsaturated fatty acids than other vegetable oils such as peanut oil and soybean oil. The unsaturated fatty acids in peony seed oil are mainly oleic acid, linoleic acid and linolenic acid, which have a series of health benefits such as delaying aging and preventing obesity. In 2011, the Ministry of Health of China listed peony seed oil as a new resource food with great development potential.

[0003] Pressing, leaching and the combination of the two are the three common processing technologies for producing edible oil. The pressing method has the disadvantages of high power consumption, easy wear of equipment parts, and high residual oil rate in the oil cake; although the leaching method has a high oil yield, the oil produced by the leaching method cannot avoid solvent residues, which inhibits consumers' purchasing desire; the pre-pressing leaching method also has the problem of solvent residues. In order to reduce the impact of residual flux on vegetable oil, the use of green solvents has become an effective way to solve the above problems. Among them, water, ethanol, carbon dioxide, etc. are increasingly valued as green solvents. The water-enzyme method using water as a solvent is simple to operate and has mild conditions. It is a safe and pollution-free oil extraction method because the cell wall can undergo enzymatic hydrolysis under mild conditions, which can better guarantee the quality of the oil. However, the extraction efficiency of peony seed oil extracted by the water-enzyme method is low, and there is still a large amount of oil in the residue that cannot be extracted, resulting in a waste of resources; the extraction efficiency of supercritical carbon dioxide extraction technology using carbon dioxide as a solvent is relatively high, but the price of supercritical extraction equipment is high and the volume of the extraction kettle is limited, so the extraction cost is high. At present, there is an urgent need for a peony seed oil extraction method that takes into account both extraction efficiency and cost to further promote the production and wide application of peony seed oil. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for extracting peony seed oil in two steps of aqueous enzyme-supercritical extraction. The efficient extraction of peony seed oil is achieved by combining aqueous enzyme method and supercritical extraction technology. The process is reasonable, operability is strong, and cost is low.

[0005] The method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction of the present invention comprises the following steps:

[0006] (1) crushing peony seeds and soaking them in water, adding an enzyme preparation, performing an enzymolysis reaction, and obtaining an enzymolysis solution;

[0007] (2) heating the enzymatic hydrolyzate to inactivate the enzyme, collecting the upper layer of fat after centrifugation, and collecting the peony seed residue for later use;

[0008] (3) After the peony seed residue is dried to constant weight, it is placed in a supercritical CO2 extraction kettle for extraction, and the oil is collected regularly using a semi-continuous extraction method.

[0009] The peony seeds are ground into a particle size of 20-60 mesh, preferably 40 mesh.

[0010] The mass volume ratio of the peony seeds to water is 1 g: (4-6) mL, preferably 1 g: 5 mL.

[0011] The dosage of the enzyme preparation is 5-15 mg of enzyme protein per gram of peony seeds, preferably 10 mg of enzyme protein per gram of peony seeds. It should be noted in this step that if the aqueous enzyme reaction system is small, too small an amount of the enzyme preparation used may easily lead to poor enzymatic reaction effect due to inaccurate weighing. The enzyme preparation can be added with water to be configured as a solution to reduce the error in weighing the enzyme preparation dosage. However, the additional amount of water added to the solution cannot exceed the range of the mass volume ratio of the peony seeds to the water dosage, and the amount of the enzyme preparation solution is still based on the weight of the enzyme protein.

[0012] The enzyme preparation is one or more of papain, cellulase, pectinase, β-glucosidase, α-amylase, saccharifying enzyme and xylanase. The preferred enzyme preparation is composed of papain, cellulase and pectinase, and their mass percentages are 16.15%, 31.33% and 52.52% respectively based on the weight of enzyme protein.

[0013] The enzymatic hydrolysis reaction temperature is 40-60°C, preferably 50°C; the reaction time is 2-5h, preferably 3h.

[0014] The heating temperature for inactivating the enzyme is 80-100°C, preferably 90°C.

[0015] The centrifugal speed is 10000-12000 rpm, and the centrifugal time is 15-20 min.

[0016] The ratio of the mass of the dried peony seed residue to the volume of the extraction kettle is 1 g: (3-5) mL, preferably 1 g: 4 mL.

[0017] The extraction pressure is 55-65MPa, preferably 59.8MPa; the extraction temperature is 45-55°C, preferably 49.4°C; the extraction time is 60-120min, preferably 95min; a semi-continuous extraction method is adopted, and the oil is collected every 15-30min, preferably 20min.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The method of the present invention has high extraction efficiency for extracting peony seed oil. On the one hand, by the combination of water-enzyme method and supercritical extraction technology, since the enzyme in the process of water-enzyme oil extraction destroys the cell wall structure to a certain extent, the supercritical carbon dioxide extraction technology makes it easier to extract peony seed oil in the residue, and the two are combined to improve the extraction efficiency of peony seed oil; on the other hand, the present invention optimizes the process of water-enzyme method and supercritical extraction technology respectively, further improves the extraction efficiency, and obtains a higher yield of peony seed oil.

[0020] 2. The method of the present invention has reasonable process, strong operability and low cost. The present invention solves the defects of incomplete oil extraction by aqueous enzyme method and high price of large-volume supercritical carbon dioxide equipment. Most of the oil is extracted from peony seeds by aqueous enzyme method, which greatly reduces the volume of oil extraction residue, and then supercritical carbon dioxide extraction is used to thoroughly extract the oil in the residue, which reduces the production cost and is expected to be widely used in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 , the result diagram of optimizing enzyme preparation ratio by mixing design;

[0022] Figure 2 , comparison of the physical and chemical properties of peony seed oil extracted by different methods;

[0023] Figure 3 , bar chart of fatty acid content of peony seed oil. DETAILED DESCRIPTION

[0024] To further illustrate the method and effect of the present invention, the present invention is further described below in conjunction with examples. The embodiments described herein are only used to explain the present invention, not to limit the present invention. If specific conditions are not indicated in the examples, conventional conditions are usually followed, or conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples are commercially available unless otherwise specified.

[0025] Example 1

[0026] The method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction of the present invention comprises the following steps:

[0027] (1) 500 g of peony seeds were crushed into 40 meshes and then soaked in 2500 mL of water, an enzyme preparation having an enzyme protein content of 5 g was added, and enzymolysis was performed in a 55° C. water bath for 3 h to obtain an enzymatic solution, wherein the enzyme preparation consisted of papain and cellulase, and the mass percentage of the enzyme protein was 50%;

[0028] (2) heating the enzymatic hydrolyzate to 90° C. to inactivate the enzyme, centrifuging at 10,000 rpm for 20 min, collecting the upper layer after the solution was separated to obtain 62.4 g of peony seed oil, with a peony seed oil extraction rate of 12.48%, and collecting the peony seed residue for later use;

[0029] (3) Drain and air-dry the peony seed residue, dry it at 65°C to constant weight, weigh 25 g of the dried peony seed residue and place it in a 100 mL supercritical CO2 extraction kettle for extraction. A semi-continuous extraction method was adopted with an extraction pressure of 55 MPa, an extraction temperature of 45°C, and an extraction time of 60 min. The oil was collected every 20 min, and a total of 1.365 g of peony seed oil was obtained, with a calculated extraction rate of 5.46%.

[0030] Example 2

[0031] The method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction of the present invention comprises the following steps:

[0032] (1) 500 g of peony seeds were crushed to 40 mesh and then soaked in 2500 mL of water. An enzyme preparation with an enzyme protein content of 2.5 g was added and enzymolyzed in a 55°C water bath for 3 h to obtain an enzymatic solution. The enzyme preparation consisted of papain, cellulase and pectinase, and their mass percentages were 16.15%, 31.33% and 52.52% respectively based on the weight of enzyme protein. The enzyme preparation was screened in the Plackett-Burman experiment to promote oil extraction. The optimal ratio of papain, cellulase and pectinase was obtained by mixing design optimization. The optimization results are shown in FIG. Figure 1 ;

[0033] (2) heating the enzymatic hydrolyzate to 90° C. to inactivate the enzyme, centrifuging at 10,000 rpm for 20 min, collecting the upper layer after the solution was separated to obtain 53.35 g of peony seed oil, with a peony seed oil extraction rate of 10.71%, and collecting the peony seed residue for later use;

[0034] (3) Drain and air-dry the peony seed residue, dry it at 65°C to constant weight, weigh 25 g of the dried peony seed residue and place it in a 100 mL supercritical CO2 extraction kettle for extraction. A semi-continuous extraction method was adopted with an extraction pressure of 55 MPa, an extraction temperature of 45°C, and an extraction time of 60 min. The oil was collected every 20 min, and a total of 1.39 g of peony seed oil was obtained, with a calculated extraction rate of 5.57%.

[0035] Example 3

[0036] The method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction of the present invention comprises the following steps:

[0037] (1) 500 g of peony seeds were crushed into 40 meshes and then soaked in 2500 mL of water, an enzyme preparation having an enzyme protein content of 5 g was added, and enzymolysis was performed in a water bath at 55° C. for 3 h to obtain an enzymatic solution, wherein the enzyme preparation consisted of papain, cellulase and pectinase, and the mass percentages thereof were 16.15%, 31.33% and 52.52% respectively based on the weight of enzyme protein;

[0038] (2) heating the enzymatic hydrolyzate to 90° C. to inactivate the enzyme, centrifuging at 10,000 rpm for 20 min, collecting the upper layer after the solution was separated to obtain 81.6 g of peony seed oil, with a peony seed oil extraction rate of 16.32%, and collecting the peony seed residue for later use;

[0039] (3) Drain and air-dry the peony seed residue, dry it at 65°C to constant weight, weigh 25 g of the dried peony seed residue and place it in a 100 mL supercritical CO2 extraction kettle for extraction. A semi-continuous extraction method was adopted with an extraction pressure of 65 MPa, an extraction temperature of 45°C, and an extraction time of 120 min. The oil was collected every 20 min, and a total of 1.31 g of peony seed oil was obtained, with a calculated extraction rate of 5.24%.

[0040] Example 4

[0041] The method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction of the present invention comprises the following steps:

[0042] (1) 1000 g of peony seeds were crushed into 40 meshes and then soaked in 5000 mL of water, an enzyme preparation having an enzyme protein content of 10 g was added, and enzymolysis was performed in a water bath at 55° C. for 3 h to obtain an enzymatic solution, wherein the enzyme preparation consisted of papain, cellulase and pectinase, and the mass percentages thereof were 16.15%, 31.33% and 52.52% respectively based on the weight of enzyme protein;

[0043] (2) heating the enzymatic hydrolyzate to 90° C. to inactivate the enzyme, centrifuging at 10,000 rpm for 20 min, collecting the upper layer after the solution was separated to obtain 165.22 g of peony seed oil, with a peony seed oil extraction rate of 16.42%, and collecting the peony seed residue for later use;

[0044] (3) Drain and air-dry the peony seed residue, dry it at 65°C to constant weight, weigh 25 g of the dried peony seed residue and place it in a 100 mL supercritical CO2 extraction kettle for extraction. A semi-continuous extraction method was adopted with an extraction pressure of 55 MPa, an extraction temperature of 55°C, and an extraction time of 120 min. The oil was collected every 20 min, and a total of 1.283 g of peony seed oil was obtained, with a calculated extraction rate of 5.13%.

[0045] Example 5

[0046] The method for extracting peony seed oil by two steps of aqueous enzyme-supercritical extraction of the present invention comprises the following steps:

[0047] (1) 2000 g of peony seeds were crushed into 40 meshes and then soaked in 10000 mL of water, an enzyme preparation having an enzyme protein content of 20 g was added, and enzymolysis was performed in a water bath at 55° C. for 3 h to obtain an enzymatic solution, wherein the enzyme preparation consisted of papain, cellulase and pectinase, and the mass percentages thereof were 16.15%, 31.33% and 52.52% respectively based on the weight of enzyme protein;

[0048] (2) heating the enzymatic hydrolyzate to 90° C. to inactivate the enzyme, centrifuging at 10,000 rpm for 20 min, collecting the upper layer after the solution was separated to obtain 329.2 g of peony seed oil, with a peony seed oil extraction rate of 16.46%, and collecting the peony seed residue for later use;

[0049] (3) Drain and air-dry the peony seed residue, dry it at 65°C to constant weight, weigh 25 g of the dried peony seed residue and place it in a 100 mL supercritical CO2 extraction kettle for extraction. A semi-continuous extraction method was adopted with an extraction pressure of 59.8 MPa, an extraction temperature of 49.4°C, and an extraction time of 95 min (the optimal conditions for supercritical CO2 extraction obtained after optimization by Central Composite Design). The oil was collected every 20 min, and a total of 1.575 g of peony seed oil was obtained, with a calculated extraction rate of 6.3%.

[0050] The peony seed oil extracted by the embodiment of the present invention and the peony seed oil extracted by the organic solvent leaching method were tested for physical and chemical properties, and the comparison results are as follows: Figure 2 As can be seen from the figure, the peony seed oil extracted by the two-step aqueous enzyme-supercritical extraction has significant advantages in terms of relative density and iodine value; at the same time, the types and contents of fatty acids in the peony seed oil extracted by the embodiment of the present invention were tested, and the results are as follows Figure 3 It can be seen that the peony seed oil extracted by the method of the present invention has a high content of unsaturated fatty acids and good oil quality.

Claims

1. A method for extracting peony seed oil in two steps of aqueous enzyme-supercritical extraction, characterized in that: The following steps are involved: (1) crushing peony seeds, soaking them in water, adding an enzyme preparation, performing an enzymatic hydrolysis reaction, and obtaining an enzymatic hydrolyzate; (2) heating the enzymatic hydrolysate to inactivate the enzyme, collecting the upper layer of fat after centrifugation, and collecting the peony seed residue for later use; (3) After the peony seed residue is dried to a constant weight, it is placed in a supercritical CO2 extraction kettle for extraction, and the oil is collected regularly using a semi-continuous extraction method; The peony seed crushing particle size is 20-60 mesh; The mass volume ratio of peony seeds to water is 1g: (4-6)mL; The dosage of the enzyme preparation is 5-15 mg of enzyme protein per gram of peony seeds; The enzyme preparation is composed of papain, cellulase and pectinase, and the mass percentages thereof are 16.15%, 31.33% and 52.52% respectively based on the weight of enzyme protein; The enzymatic reaction temperature is 40-60°C and the reaction time is 2-5h; The heating temperature for enzyme inactivation is 80-100℃; The ratio of the mass of the dried peony seed residue to the volume of the extraction kettle is 1 g: (3-5) mL; The extraction pressure is 55-65MPa, the extraction temperature is 45-55°C, and the extraction time is 60-120min.

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