Palm fruit oil, palm fruit oil with high unsaturated fatty acid content and preparation method of palm fruit oil

Abstract

The invention belongs to the technical field of plant extraction, and particularly relates to palm fruit oil, palm fruit oil with high unsaturated fatty acid content and a preparation method of the palm fruit oil. The preparation method of the palm fruit oil comprises the following steps: removing kernels of palm fruits to obtain palm pulp; and drying and crushing the palm pulp, carrying out supercritical carbon dioxide extraction, and separating to obtain the palm fruit oil. According to the method, high-selectivity, low-temperature, efficient and non-toxic extraction operation is achieved through a supercritical carbon dioxide extraction method, the highest-quality essential fatty acid, carotenoid, VitE and other nutritional ingredients in the palm fruits are preserved, and effective ingredients in the palm fruits can be reserved to the maximum extent; the active substance content and the purity of the palm fruit oil can be favorably improved, and the residues of chemical extracts and the nutrition loss of high-temperature oil preparation are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of plant extraction, and particularly relates to palm fruit oil and high-unsaturated fatty acid palm fruit oil and a preparation method thereof. Background Art

[0002] The palm fruit, also known as the oil palm, consists of a pulpy outer layer and a hard kernel within. The pulp can be used to produce palm oil, which contains essential linoleic acid and is cholesterol-free and trans-unsaturated, making it ideal for human absorption and utilization. Furthermore, palm oil is rich in active ingredients such as carotenoids and vitamin E, which are beneficial to human health. Furthermore, palm oil is highly sought after in the food industry for its digestibility, as well as its antioxidant properties. Currently, global palm oil production reaches 70 million tons, accounting for 62.67% and 61.02% of the world's total imports and exports of major vegetable oils, making it the world's most produced and traded vegetable oil.

[0003] China has yet to establish large-scale oil palm cultivation and production. Currently, China's edible oil self-sufficiency rate is 30.1%, and palm oil is entirely imported, accounting for 20% of China's total edible oil consumption. For both edible oil safety and vegetable oil trade in China, a change in the current situation is necessary. The country's existing oil palm trees need to be rationally developed and fully utilized. Therefore, both from a practical and economic perspective, the development of the palm oil industry holds broad prospects.

[0004] Currently, palm oil extraction methods primarily include mechanical pressing and solvent extraction. Solvent extraction offers high extraction efficiency and produces high crude protein and fiber content. Mechanical pressing, on the other hand, is the most commonly used extraction method in palm oil processing plants due to its low cost and ease of operation. However, it suffers from drawbacks such as high residual oil content and significant loss of functional components.

[0005] Therefore, the current method of extracting palm oil still needs to be improved. Summary of the Invention

[0006] The main purpose of the present invention is to provide a palm fruit oil and high-unsaturated fatty acid palm fruit oil and a preparation method thereof. The present invention uses a supercritical carbon dioxide extraction method to achieve highly selective, low-temperature extraction, high efficiency, and non-toxic extraction operation, thereby preserving the highest quality essential fatty acids, carotenoids, Vitamin E and other nutrients in the palm fruit, so that the effective ingredients therein can be retained to the greatest extent, which helps to improve the active substance content and purity of the palm fruit oil, avoid chemical extract residues and nutrient loss during high-temperature oil production.

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

[0008] A first aspect of the present invention provides a method for preparing palm fruit oil, comprising the following steps: removing the core of a palm fruit to obtain palm pulp; drying and crushing the palm pulp, and then subjecting the palm pulp to supercritical carbon dioxide extraction to separate and obtain palm fruit oil.

[0009] In some embodiments of the present invention, the extraction conditions of the supercritical carbon dioxide extraction include: extraction temperature of 25°C to 65°C, extraction pressure of 15MPa to 45MPa, carbon dioxide flow rate of 20L / h to 60L / h, and extraction time of 2h to 6h.

[0010] In some embodiments of the present invention, the extraction conditions of the supercritical carbon dioxide extraction include: extraction temperature of 30°C to 45°C, extraction pressure of 25MPa to 35MPa, carbon dioxide flow rate of 40L / h to 50L / h, and extraction time of 4h to 6h.

[0011] In some embodiments of the present invention, the separation process includes: carbon dioxide gas carrying palm pulp extract flows out of the extraction kettle and flows into a first separation kettle to obtain palm fruit oil after separation; and carbon dioxide gas carrying water flows into a second separation kettle to precipitate water, and the carbon dioxide gas flows back to the extraction kettle.

[0012] In some embodiments of the present invention, the separation temperature of the first separation kettle is 25° C. to 65° C., and the pressure is 6 MPa to 15 MPa.

[0013] In some embodiments of the present invention, the separation temperature of the first separation kettle is 45° C. to 55° C., and the pressure is 8 MPa to 10 MPa.

[0014] In some embodiments of the present invention, the separation temperature of the second separation kettle is 15° C. to 45° C., and the pressure is 4 MPa to 7 MPa.

[0015] In some embodiments of the present invention, the separation temperature of the second separation kettle is 20° C. to 30° C., and the pressure is 4 MPa to 6 MPa.

[0016] In some embodiments of the present invention, the palm pulp is dried to a moisture content of 2% to 10%.

[0017] In some embodiments of the present invention, the palm pulp is dried at a temperature of 40° C. to 60° C., and the drying time is 16 hours to 24 hours.

[0018] In some embodiments of the present invention, the palm pulp is crushed to a particle size of 10 mesh to 60 mesh.

[0019] In some embodiments of the present invention, the palm pulp is crushed to a particle size of 20 mesh to 40 mesh.

[0020] A second aspect of the present invention provides palm fruit oil, which is prepared using the preparation method described in the first aspect.

[0021] A third aspect of the present invention provides a method for preparing high-unsaturated fatty acid palm oil, the method comprising the following steps:

[0022] heating and melting the palm fruit oil prepared by the preparation method of the first aspect or the palm fruit oil of the second aspect until it becomes a uniform liquid to obtain molten palm fruit oil;

[0023] The molten palm fruit oil is subjected to gradient cooling separation to obtain the high-unsaturated fatty acid palm fruit oil.

[0024] The present invention combines the above-mentioned extraction method with the gradient cooling separation method to effectively separate highly unsaturated fatty acids, reduce the residues of saturated fatty acids and low-unsaturated fatty acids, and increase the content and purity of highly unsaturated fatty acids in palm fruit oil, thereby improving the nutritional value and application prospects of palm fruit oil.

[0025] In some embodiments of the present invention, the temperature of the molten palm oil is 70°C to 80°C.

[0026] In some embodiments of the present invention, the gradient cooling separation process includes: a first stage, rapidly cooling the molten palm fruit oil to 45°C to 55°C, preferably 45°C to 50°C, and keeping it warm for 1h to 3h, preferably 1h to 2h, to promote the crystallization of high-melting-point saturated fatty acids; a second stage, cooling the palm fruit oil obtained after the first stage cooling to 25°C to 35°C, preferably 25°C to 30°C, and keeping it warm for 3h to 6h, preferably 4h to 6h, so that medium and low-melting-point saturated fatty acids are gradually precipitated; a third stage: cooling the palm fruit oil obtained after the second stage cooling to 10°C to 20°C, preferably 15°C to 20°C, and keeping it warm for 0.5h to 1h, preferably 0.8h to 1h, to complete the crystallization process; separation: separating the liquid palm oil and the solid crystallized part of the palm fruit oil obtained after the third stage cooling at a preset temperature, collecting the liquid palm fruit oil, and obtaining the high-unsaturated fatty acid palm fruit oil.

[0027] In some embodiments of the present invention, the cooling rate of the first stage is 2°C / min to 3°C / min; and / or, the cooling rate of the second stage is 0.5°C / min to 1°C / min; and / or, the cooling rate of the third stage is 0.2°C / min to 0.5°C / min.

[0028] In some embodiments of the present invention, separation is performed using a vacuum heat-insulated filter press system or a low-temperature centrifuge.

[0029] In some embodiments of the present invention, the preset temperature is 20°C to 25°C.

[0030] The fourth aspect of the present invention provides a high-unsaturated fatty acid palm fruit oil, which is prepared using the preparation method described in the third aspect.

[0031] Compared with the prior art, the present invention achieves the following technical effects:

[0032] (1) The present invention uses supercritical carbon dioxide extraction technology to achieve high selectivity, low-temperature extraction, high efficiency, and non-toxic operation, preserving the highest quality essential fatty acids, carotenoids, and vitamin E in palm fruit, so that the effective ingredients can be retained to the greatest extent, which helps to improve the active substance content and purity of palm fruit oil, avoid chemical extract residues and nutrient loss during high-temperature oil production.

[0033] (2) The supercritical carbon dioxide extraction method of palm oil in the present invention not only has the advantages of simple process, short extraction time, accurate process parameter range, and easy industrialization, but also can obtain high-quality products with zero emissions, practice environmental friendliness, and save time and cost for subsequent refining. It is a method with very significant economic and social value.

[0034] (3) Compared with the solvent extraction process, the method of extracting palm oil by supercritical carbon dioxide of the present invention has the advantages of high selectivity and non-toxicity. It can avoid the disadvantages of high crude protein and crude fiber content in the product caused by direct solvent extraction and difficulty in subsequent separation. At the same time, it can avoid the use of large amounts of organic solvents, is non-toxic and has no environmental pollution, and is suitable for industrial production.

[0035] (4) Compared with the most commonly used mechanical pressing process, the method of extracting palm oil with supercritical carbon dioxide of the present invention has the advantages of high extraction rate and low-temperature extraction. It can avoid the disadvantages of large amount of residual oil in the by-products after mechanical pressing and serious loss of functional components during the extraction process, so that nutrients such as essential fatty acids, carotenoids and Vitamin E can be retained to the greatest extent, and the obtained palm oil has higher oil quality.

[0036] (5) The present invention uses a unique gradient cooling design to accurately precipitate saturated fatty acids with different melting points in stages, which can effectively reduce the co-crystallization phenomenon. Compared with the traditional dry method of single-stage cooling, the separation efficiency of saturated fatty acids and unsaturated fatty acids is greatly improved, and the separation of fatty acids with different melting points can be achieved more accurately.

[0037] (6) The method of the present invention can be used to obtain palm oil products with high unsaturated fatty acid content, which are widely applicable to the fields of food, cosmetics, and medicine, and have broad application prospects. In the food field, it can help reduce the risk of cardiovascular disease. In the cosmetic field, it can make products more moisturizing and have skin-care effects. In the pharmaceutical field, it may also have unique medicinal value or serve as a high-quality pharmaceutical excipient, greatly improving the quality and application value of palm oil products.

[0038] (7) The entire fractionation process of the present invention is simple to operate, involving only heating, gradient cooling, and conventional separation operations after crystallization (vacuum insulation filter press or low-temperature centrifugation). It does not require complex equipment and processes and is easy to promote and apply in industrial production.

[0039] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Various other advantages and benefits will become apparent to those skilled in the art by reading the detailed description of the preferred embodiment below. The accompanying drawings are only for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present invention. In the accompanying drawings:

[0041] Figure 1 The present invention is a flow chart of the preparation process of high unsaturated fatty acid palm oil according to one or more embodiments of the present invention. DETAILED DESCRIPTION

[0042] The exemplary embodiments of the present invention will be described in more detail below with reference to specific examples. It should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions.

[0044] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0045] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0046] In the description of the embodiments of the present invention, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0047] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0048] Compared to traditional mechanical pressing and solvent extraction methods, supercritical CO2 extraction technology is increasingly being used for extracting natural active ingredients due to its advantages such as high selectivity, low-temperature extraction, high efficiency, and non-toxicity. However, there are no reports of this method being used to extract palm fruit in China. Breaking with traditional extraction methods and applying supercritical CO2 extraction technology to palm fruit extraction would not only produce a high-quality product with zero emissions and be environmentally friendly, but would also save time and costs in subsequent refining, thus possessing significant economic and social value.

[0049] Furthermore, due to its complex fatty acid composition (including both saturated and unsaturated fatty acids), fractionation technology is key to enhancing its application value. Traditional dry fractionation methods, which often use a single-stage cooling process, suffer from poor crystallization selectivity, low separation efficiency, and high energy consumption.

[0050] For this reason, the present invention effectively combines the extraction of palm fruit oil and the fractionation of high-unsaturated fatty acid palm fruit oil, achieving highly selective, low-temperature extraction, efficient, and non-toxic operation through supercritical carbon dioxide extraction technology. This allows the active ingredients in the palm fruit oil to be retained to the greatest extent, helping to improve the active substance content and purity of the palm fruit oil. On this basis, a palm fruit oil fractionation method based on gradient cooling achieves efficient separation of saturated fatty acids and unsaturated fatty acids through precise temperature control, without the need for chemical reagents, and is simple to operate with low energy consumption. This method can produce palm oil products with high unsaturated fatty acid content, is widely applicable to fields such as food, cosmetics, and medicine, and has a relatively broad application prospect.

[0051] The method for preparing palm oil provided in the first aspect of the present invention is specifically carried out according to the following steps.

[0052] Enucleation

[0053] In an embodiment of the present invention, the palm fruit is separated into the palm kernel and the palm pulp using a de-kerning machine.

[0054] drying

[0055] In an embodiment of the present invention, the palm pulp is oven dried.

[0056] In some embodiments of the present invention, the palm pulp is dried at a temperature of 40°C to 60°C, thereby controlling the moisture content of the palm pulp. For example, the palm pulp can be dried at a temperature of 40°C, 45°C, 50°C, 55°C, 60°C, or any other temperature within the aforementioned range.

[0057] In some embodiments of the present invention, the palm pulp is dried for 16 to 24 hours, thereby achieving moisture control in the palm pulp. For example, the palm pulp can be dried for 16, 17, 18, 19, 20, 21, 22, 23, or 24 hours, or any value within the aforementioned range.

[0058] In an embodiment of the present invention, the palm pulp is dried to a moisture content of 2% to 10%. For example, the moisture content of the palm pulp after drying can be controlled to be one of 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any other value within the above range.

[0059] crush

[0060] In an embodiment of the present invention, the dried palm pulp is pulverized by a pulverizer.

[0061] In some embodiments of the present invention, the dried palm pulp is crushed to a mesh size of 10 to 60 mesh using a grinder, for example, the palm pulp is crushed to a mesh size of 20 to 40 mesh using a grinder, thereby obtaining palm fruit powder with a particle size of 10 to 60 mesh.

[0062] For example, the particle size of the palm fruit powder can be one of 10 mesh, 20 mesh, 30 mesh, 40 mesh, 50 mesh, 60 mesh, or any value that meets the above range.

[0063] extraction

[0064] In an embodiment of the present invention, the crushed palm fruit powder is placed in an extraction kettle, supercritical carbon dioxide gas is introduced, and extraction is performed under specific extraction conditions.

[0065] In some embodiments of the present invention, the extraction conditions of supercritical carbon dioxide extraction include: extraction temperature of 25°C to 65°C, extraction pressure of 15MPa to 45MPa, carbon dioxide flow rate of 20L / h to 60L / h, and extraction time of 2h to 6h.

[0066] In some embodiments of the present invention, the extraction conditions of supercritical carbon dioxide extraction include: extraction temperature of 30°C to 45°C, extraction pressure of 25MPa to 35MPa, carbon dioxide flow rate of 40L / h to 50L / h, and extraction time of 4h to 6h.

[0067] The extraction temperature provided by the present invention can be one of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or any value within the above range. The extraction pressure provided by the present invention can be one of 15MPa, 20MPa, 25MPa, 30MPa, 35MPa, 40MPa, 45MPa, or any value within the above range. The carbon dioxide flow rate provided by the present invention can be one of 20L / h, 30L / h, 40L / h, 50L / h, 60L / h, or any value within the above range. The extraction time provided by the present invention can be one of 2h, 3h, 4h, 5h, 6h, or any value within the above range.

[0068] Separation

[0069] Carbon dioxide gas carrying palm fruit oil flows out of the extraction kettle and flows into the separation kettle 1. After the pressure is adjusted, palm fruit oil that is basically free of water can be obtained from the separation kettle 1. Palm fruit oil is obtained at the outlet of the separation kettle 1, thereby realizing the extraction of palm fruit oil.

[0070] In some embodiments of the present invention, the separation temperature of the separation kettle 1 is 25° C. to 65° C., and the pressure is 6 MPa to 15 MPa.

[0071] In some embodiments of the present invention, the separation temperature of the separation kettle 1 is 45° C. to 55° C., and the pressure is 8 MPa to 10 MPa.

[0072] For example, the separation temperature of the separation tank 1 can be one of 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or any value within the above range. The pressure of the separation tank 1 can be one of 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, or any value within the above range.

[0073] At the same time, most of the water brought out by the carbon dioxide gas from the extraction kettle is precipitated through the separation kettle 2. It can be understood that the carbon dioxide gas carrying water flows into the separation kettle 2, precipitates water, and the carbon dioxide gas is converted into gas through two low-pressure separation kettles and flows back to the extraction kettle through the purification device.

[0074] In some embodiments of the present invention, the separation temperature of the separation kettle 2 is 15° C. to 45° C., and the pressure is 4 MPa to 7 MPa.

[0075] In some embodiments of the present invention, the separation temperature of the separation kettle 2 is 20° C. to 30° C., and the pressure is 4 MPa to 6 MPa.

[0076] For example, the separation temperature of the separation tank 2 can be one of 15° C., 20° C., 25° C., 30° C., 35° C., 40° C., 45° C., or any value within the above range. The pressure of the separation tank 2 can be one of 4 MPa, 5 MPa, 6 MPa, 7 MPa, or any value within the above range.

[0077] A second aspect of the present invention provides palm fruit oil, which is prepared by the extraction method of the first aspect.

[0078] The third aspect of the present invention provides a method for preparing high-unsaturated fatty acid palm oil, which is specifically carried out according to the following steps.

[0079] Preparation of palm fruit oil

[0080] In an embodiment of the present invention, the palm fruit oil prepared by the preparation method described in the first aspect is used as raw oil to obtain high-unsaturated fatty acid palm fruit oil.

[0081] Preprocessing

[0082] In an embodiment of the present invention, the palm oil is heated and melted to a uniform liquid state to obtain molten palm oil.

[0083] In some embodiments of the present invention, the temperature of the molten palm fruit oil is 70° C. to 80° C. For example, the temperature of the molten palm fruit oil may be one of 70° C., 71° C., 72° C., 73° C., 74° C., 75° C., 76° C., 77° C., 78° C., 79° C., 80° C., or any value within the above range.

[0084] In some embodiments of the present invention, the heating and melting temperature of the palm oil is 70° C. to 80° C. For example, the heating and melting temperature can be one of 70° C., 71° C., 72° C., 73° C., 74° C., 75° C., 76° C., 77° C., 78° C., 79° C., 80° C., or any value within the above range.

[0085] Gradient cooling separation

[0086] In an embodiment of the present invention, the molten palm fruit oil is subjected to gradient cooling separation to obtain high unsaturated fatty acid palm fruit oil.

[0087] In some embodiments of the present invention, the gradient cooling separation process includes three cooling stages and separation steps, and the specific operations are as follows:

[0088] In the first stage, the molten palm oil is rapidly cooled to 45°C to 55°C and kept warm for 1 to 3 hours to promote the crystallization of high-melting-point saturated fatty acids.

[0089] The cooling temperature of the first-stage molten palm fruit oil provided by the present invention can be a range consisting of any two values within the above range, for example, 45°C to 50°C, or 50°C to 55°C, and so on. For example, the cooling temperature of the first-stage molten palm fruit oil can be one of 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, or any value within the above range.

[0090] The holding time of the first stage molten palm oil after cooling to the preset temperature provided by the present invention can be a value within the range formed by any two values within the above range, for example, it can be 1 hour to 2 hours, or 2 hours to 3 hours, and so on. Exemplarily, the holding time of the first stage can be one of 1 hour, 1.2 hours, 2.4 hours, 1.5 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.8 hours, 3 hours, or any value that meets the above range.

[0091] In some embodiments of the present invention, the cooling rate in the first stage is 2°C / min to 3°C / min. For example, the cooling rate in the first stage can be one of 2°C / min, 2.1°C / min, 2.2°C / min, 2.3°C / min, 2.4°C / min, 2.5°C / min, 2.6°C / min, 2.7°C / min, 2.8°C / min, 2.9°C / min, 3°C / min, or any value within the above range.

[0092] In the second stage, the palm oil obtained after the first stage of cooling is cooled to 25°C to 35°C and kept warm for 3h to 6h to gradually precipitate the medium and low melting point saturated fatty acids.

[0093] The cooling temperature of the palm fruit oil in the second stage provided by the present invention can be a range consisting of any two values within the above range, for example, 25°C to 30°C, or 30°C to 35°C, and so on. For example, the cooling temperature of the palm fruit oil in the second stage can be one of 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, or any value within the above range.

[0094] The holding time of the palm oil in the second stage after cooling to the preset temperature provided by the present invention can be a value within the interval formed by any two values within the above range, for example, it can be 3h to 4h, or it can be 4h to 6h, and so on. Exemplarily, the holding time of the second stage can be one of 3h, 3.2h, 3.4h, 3.5h, 3.6h, 3.8h, 4h, 4.2h, 4.4h, 4.5h, 4.6h, 4.8h, 5h, 5.2h, 5.4h, 5.5h, 5.6h, 5.8h, 6h, or any value that meets the above range.

[0095] In some embodiments of the present invention, the cooling rate in the second stage is 0.5°C / min to 1°C / min. For example, the cooling rate in the second stage can be one of 0.5°C / min, 0.6°C / min, 0.7°C / min, 0.8°C / min, 0.9°C / min, 1°C / min, or any value within the above range.

[0096] The third stage) cools the palm oil obtained after the second stage cooling to 10°C to 20°C and keeps it warm for 0.5h to 1h to complete the crystallization process.

[0097] The cooling temperature of the palm fruit oil in the third stage provided by the present invention can be a range consisting of any two values within the above range, for example, 10°C to 15°C, or 15°C to 20°C, and so on. For example, the cooling temperature of the palm fruit oil in the third stage can be one of 10°C, 11°C, 12°C, 13°C, 14°C, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, or any value within the above range.

[0098] The holding time of the palm oil in the third stage after cooling to the preset temperature provided by the present invention can be a range consisting of any two values within the above range, for example, 0.5h to 0.8h, or 0.8h to 1h, and so on. For example, the holding time in the third stage can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, or any value within the above range.

[0099] In some embodiments of the present invention, the cooling rate in the third stage is 0.2°C / min to 0.5°C / min. For example, the cooling rate in the third stage can be one of 0.2°C / min, 0.3°C / min, 0.4°C / min, 0.5°C / min, or any value within the above range.

[0100] Separation) The palm fruit oil obtained after the third stage of cooling is separated at a preset temperature from the liquid palm oil and the solid crystallized part, and the liquid palm fruit oil is collected to obtain high unsaturated fatty acid palm fruit oil.

[0101] In some embodiments of the present invention, separation is performed using a vacuum heat-insulated filter press system or a low-temperature centrifuge.

[0102] In some embodiments of the present invention, the preset temperature is 20° C. to 25° C. For example, the preset temperature may be one of 20° C., 21° C., 22° C., 23° C., 24° C., 25° C., or any value within the above range.

[0103] The fourth aspect of the present invention provides a high-unsaturated fatty acid palm fruit oil, which is prepared using the preparation method described in the third aspect.

[0104] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which this invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments, and equipment used in the following examples are all commercially available or can be obtained through existing methods; the amounts of the experimental reagents used, unless otherwise specified, are the amounts used in conventional experimental procedures; and the experimental methods, unless otherwise specified, are all conventional methods.

[0105] Example 1

[0106] A palm oil preparation method comprises the following steps:

[0107] De-nucleating: The palm fruit is separated into palm kernel and palm pulp by a de-nucleating machine;

[0108] Drying: Dry the palm pulp in an oven at 50°C with the moisture content controlled at 3%.

[0109] Crushing: crush the dried palm pulp into 40 mesh using a crusher.

[0110] Extraction: The crushed palm fruit powder is placed in an extraction kettle and supercritical carbon dioxide gas is introduced for extraction. The extraction conditions are: extraction temperature 40°C, pressure 30 MPa, carbon dioxide flow rate 40 L / h, and extraction time 4 hours.

[0111] Separation: Carbon dioxide gas carrying palm oil flows from the extraction kettle into the separation kettle. The separation conditions are: temperature of separation kettle 1 is 50°C and pressure is 10 MPa; temperature of separation kettle 2 is 25°C and pressure is 4 MPa. Palm oil is collected from the outlet of separation kettle 1.

[0112] Example 2

[0113] A high-unsaturated fatty acid palm fruit oil, the preparation method of which comprises the following steps:

[0114] De-nucleating: Palm fruit is separated into palm kernel and palm pulp using a de-nucleating machine.

[0115] Drying: Dry the palm pulp in an oven at 50°C with the moisture content controlled at 3%.

[0116] Crushing: crush the dried palm pulp into 40 mesh using a crusher.

[0117] Extraction: The crushed palm fruit powder is placed in an extraction kettle and supercritical carbon dioxide gas is introduced for extraction. The extraction conditions are: extraction temperature 40°C, pressure 30 MPa, carbon dioxide flow rate 40 L / h, and extraction time 4 hours.

[0118] Separation: Carbon dioxide gas carrying palm oil flows from the extraction kettle into the separation kettle. The separation conditions are: temperature of separation kettle 1 is 50°C and pressure is 10 MPa; temperature of separation kettle 2 is 25°C and pressure is 4 MPa. Palm oil is collected from the outlet of separation kettle 1.

[0119] Gradient cooling separation: High unsaturated fatty acid palm oil is obtained by gradient cooling separation. The specific operation process is as follows:

[0120] 1) Pretreatment: Heat the palm oil to 80°C to completely melt it into a uniform liquid to obtain molten palm oil.

[0121] 2) First stage: The molten palm oil was rapidly cooled to 50°C at a rate of 3°C / min and maintained at this temperature for 2 hours to promote the crystallization of high-melting-point saturated fatty acids.

[0122] 3) The second stage: cooling to 30°C at a rate of 1°C / min and maintaining for 5 hours to allow the medium and low melting point saturated fatty acids to gradually precipitate.

[0123] 4) The third stage: further cooling to 20°C and maintaining for 1 hour to complete the crystallization process.

[0124] 5) Separation: The liquid palm oil and the solid crystalline portion are separated by vacuum filtration at 20°C to obtain high unsaturated fatty acid palm fruit oil.

[0125] Comparative Example 1

[0126] In the prior art, palm oil is prepared by squeezing, and the preparation steps are as follows:

[0127] (1) Palm fruit is steamed for 2 h and then passed through a thresher to separate the pulp from the shell.

[0128] (2) The separated pulp enters the press for mechanical pressing, and the mixed pulp coming out of the press enters the centrifuge for preliminary oil-water separation.

[0129] (3) After preliminary precipitation, the product is filtered through a filtering device to obtain palm oil.

[0130] Comparative Example 2

[0131] In the prior art, palm oil is prepared by pressing combined with dry fractionation, and the preparation steps are as follows:

[0132] (1) Palm fruit is steamed for 2 h and then passed through a thresher to separate the pulp from the shell.

[0133] (2) The separated pulp enters the press for mechanical pressing, and the mixed pulp coming out of the press enters the centrifuge for preliminary oil-water separation.

[0134] (3) After preliminary precipitation, the product is filtered through a filtering device to obtain palm oil.

[0135] (4) obtaining target palm oil by dry fractionation, specifically comprising:

[0136] Stage 1: Palm oil is heated to about 60°C to turn the oil into pure liquid.

[0137] Stage 2: The heated palm oil is cooled to supercooled and supersaturated, at which point the temperature is 20°C. The palm oil is filtered, and the filtrate is the target palm oil.

[0138] Performance Testing

[0139] The present invention conducted performance tests on the palm oil prepared in Examples 1 and 2 and Comparative Examples 1 and 2 in terms of physical and chemical indicators and nutritional components.

[0140] Physical and chemical indicators:

[0141] The palm oil obtained in Examples 1-2 and Comparative Examples 1-2 was tested for physical and chemical indices such as acid value, peroxide value, red value and odor.

[0142] The acid value is determined in accordance with GB5009.229-2016.

[0143] The peroxide value is determined in accordance with GB5009.227-2016.

[0144] The red value is determined according to GB / T 22460-2008.

[0145] Odor is measured according to GB / T 5525-2008.

[0146] The test results are shown in Table 1.

[0147] Table 1 Summary of the physical and chemical indicators of palm oil in the embodiments and comparative examples

[0148]

[0149]

[0150] Nutritional Information:

[0151] The palm oil obtained in Examples 1-2 and Comparative Examples 1-2 was tested for nutritional components such as vitamin E, carotenoids, and sterols.

[0152] Vitamin E was determined by high performance liquid chromatography with reference to GB / T26635-2011.

[0153] Carotenoids were determined by high performance liquid chromatography with reference to GB 5009.248-2016.

[0154] Sterols were determined by gas chromatography-mass spectrometry with reference to NY / T 3111-2017.

[0155] The test results are shown in Table 2.

[0156] Table 2 Summary of the operating components of palm oil in the examples and comparative examples

[0157] project Example 1 Example 2 Comparative Example 1 Comparative Example 2 Vitamin E (ppm) 725 607 612 556 Carotenoids (ppm) 647 278 538 132 Total sterols (ppm) 618 425 354 273

[0158] Palm oil fatty acid composition analysis:

[0159] The palm oil obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was subjected to fatty acid detection using a gas chromatography-mass spectrometer. The detection method was as follows:

[0160] (1) Sample preparation.

[0161] Take 20 μl of the sample and add 500 μl of isopropanol, mix well, centrifuge at 13,000 rpm for 10 minutes, and take the supernatant for detection.

[0162] (2) GC-MS conditions.

[0163] The instrument model was an Agilent 7890B-5977, with an HP-5MS gas chromatograph column (30 m x 0.25 mm x 0.25 μm). He carrier gas flow rate was 1 mL / min in constant flow mode, the column temperature was programmed, and the injection port temperature was 280°C. The injection volume was 1 μL, with a split ratio of 10:1. Mass spectrometry was performed using an electron impact ionization source with an electron energy of 70 eV, an ion source temperature of 220°C, a transfer line temperature of 280°C, a solvent delay of 2.5 min, and full scan acquisition over a range of 10 to 650 amu.

[0164] (3) Test results

[0165] The contents of various fatty acid components in the palm oil obtained in Examples 1-2 and Comparative Examples 1-2 are shown in Table 3.

[0166] Table 3 Summary of fatty acid components of palm oil in Examples and Comparative Examples

[0167]

[0168] Combining Tables 1, 2, and 3, it can be seen that compared to the pressing method in Comparative Example 1, the acid value and peroxide value of Example 1 using the supercritical extraction method are significantly lower than those of Comparative Example 1, and the color and odor are also significantly better than those of Comparative Example 1, indicating that the oil product quality of Example 1 is superior to that of Comparative Example 1. This demonstrates that supercritical carbon dioxide extraction can help improve the quality of palm oil.

[0169] Compared to the supercritical carbon dioxide extraction method in Example 1 and the pressing method in Comparative Example 1, the vitamin E, carotenoid, and total sterol contents in Example 1 were all higher than those in Comparative Example 1, indicating that the nutritional content of Example 1 was higher than that of Comparative Example 1. This indicates that supercritical carbon dioxide extraction helps retain nutrients, resulting in a higher oil quality of the resulting palm oil.

[0170] By comparing the fatty acid compositions of the palm oil in Examples 1 to 2 and Comparative Examples 1 to 2, it can be seen that the unsaturated fatty acid content in Example 2 and Comparative Example 2 is higher, indicating that both the gradient cooling separation method and the dry fractionation method can help increase the content of unsaturated fatty acids, and the increase in Example 2 is higher, which indicates that the gradient cooling separation method has better separation efficiency in separating saturated fatty acids and can more effectively increase the content of unsaturated fatty acids in palm oil.

[0171] At the same time, by comparing the fatty acid compositions of the palm fruit oil in Examples 1-2 and Comparative Examples 1-2, it can be seen that supercritical carbon dioxide extraction combined with gradient cooling separation can effectively obtain high-unsaturated fatty acid palm fruit oil.

[0172] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing palm oil, characterized in that: The preparation method comprises the following steps: removing the core of the palm fruit to obtain the palm pulp; The palm pulp is dried and crushed, and then subjected to supercritical carbon dioxide extraction to separate and obtain palm oil.

2. The method for preparing palm oil according to claim 1, wherein The extraction conditions of the supercritical carbon dioxide extraction include: extraction temperature of 25° C. to 65° C., extraction pressure of 15 MPa to 45 MPa, carbon dioxide flow rate of 20 L / h to 60 L / h, and extraction time of 2 h to 6 h.

3. The method for preparing palm oil according to claim 2, wherein The extraction conditions of the supercritical carbon dioxide extraction include: extraction temperature of 30° C. to 45° C., extraction pressure of 25 MPa to 35 MPa, carbon dioxide flow rate of 40 L / h to 50 L / h, and extraction time of 4 h to 6 h.

4. The method for preparing palm oil according to claim 1, wherein The separation process includes: The carbon dioxide gas carrying the palm pulp extract flows out of the extraction kettle and flows into the first separation kettle to obtain palm fruit oil through separation; and The carbon dioxide gas carrying water flows into the second separation kettle to separate the water, and the carbon dioxide gas flows back to the extraction kettle.

5. The method for preparing palm oil according to claim 4, wherein The separation temperature of the first separation kettle is 25°C to 65°C, and the pressure is 6MPa to 15MPa; and / or, The separation temperature of the second separation kettle is 15°C to 45°C, and the pressure is 4Mpa to 7Mpa; Preferably, the separation temperature of the first separation kettle is 45°C to 55°C, and the pressure is 8MPa to 10MPa; Preferably, the separation temperature of the second separation kettle is 20° C. to 30° C., and the pressure is 4 MPa to 6 MPa.

6. The method for preparing palm oil according to claim 1, wherein The palm pulp is dried until its moisture content is 2% to 10%; Preferably, the palm pulp is dried at a temperature of 40°C to 60°C and for a time of 16h to 24h; Preferably, the palm pulp is crushed to a particle size of 10 to 60 meshes, preferably 20 to 40 meshes.

7. A palm oil, characterized in that The palm oil is prepared by the preparation method according to any one of claims 1 to 6.

8. A method for preparing high unsaturated fatty acid palm oil, characterized in that: The preparation method comprises the following steps: heating and melting the palm fruit oil prepared by the preparation method according to any one of claims 1 to 6 or the palm fruit oil according to claim 7 until it becomes a uniform liquid to obtain molten palm fruit oil; The molten palm fruit oil is subjected to gradient cooling separation to obtain the high unsaturated fatty acid palm fruit oil; Preferably, the temperature of the molten palm oil is 70°C to 80°C.

9. The preparation method according to claim 8, characterized in that The gradient cooling separation process comprises: In the first stage, the molten palm oil is rapidly cooled to 45°C to 55°C, preferably 45°C to 50°C, and kept warm for 1 hour to 3 hours, preferably 1 hour to 2 hours, to promote the crystallization of high-melting-point saturated fatty acids; In the second stage, the palm oil obtained after the first stage of cooling is cooled to 25°C to 35°C, preferably 25°C to 30°C, and kept warm for 3h to 6h, preferably 4h to 6h, so that the medium and low melting point saturated fatty acids are gradually precipitated; The third stage: cooling the palm oil obtained after the second stage cooling to 10°C to 20°C, preferably 15°C to 20°C, and keeping the temperature for 0.5h to 1h, preferably 0.8h to 1h, to complete the crystallization process; Separation: separating the liquid palm oil and the solid crystal portion of the palm fruit oil obtained after the third stage of cooling at a preset temperature, collecting the liquid palm fruit oil, and obtaining the high unsaturated fatty acid palm fruit oil; Preferably, the cooling rate of the first stage is 2°C / min to 3°C / min; and / or, the cooling rate of the second stage is 0.5°C / min to 1°C / min; and / or, the cooling rate of the third stage is 0.2°C / min to 0.5°C / min; Preferably, a vacuum heat-insulated filter press system or a low-temperature centrifuge is used for separation, and the preset temperature is preferably 20°C to 25°C.

10. A high unsaturated fatty acid palm oil, characterized in that: The high-unsaturated fatty acid palm oil is prepared by the preparation method according to any one of claims 8 to 9.

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