A low-temperature spiral pressing method of xanthoceras sorbifolia bunge with high oil yield

Abstract

The application discloses a high-oil-yield low-temperature spiral pressing method of Xanthoceras sorbifolia bunge, and belongs to the technical field of food processing. The high-oil-yield low-temperature spiral pressing method of Xanthoceras sorbifolia bunge is characterized by adding sesame into Xanthoceras sorbifolia bunge, mixing, and then performing low-temperature spiral pressing, wherein the weight ratio of Xanthoceras sorbifolia bunge to sesame is 3:1-1:3. When co-pressing, a material group with suitable water content and fiber content is formed, the problems of a smooth bore, low oil yield and slagging during single Xanthoceras sorbifolia bunge pressing are solved, the residual oil content of single cold-pressed cake of Xanthoceras sorbifolia bunge and sesame is higher than 10%, and the residual oil content of the cake of the application is lower than 5%. The application not only solves a series of problems in the Xanthoceras sorbifolia bunge pressing process, but also improves the oil yield of Xanthoceras sorbifolia bunge and sesame, obtains mixed oil products with higher nutritional value, and has a good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, specifically relating to a low-temperature spiral pressing method for high oil yield of *Sapindus mukorossi*. Background Technology

[0002] The kernels of *Xanthoceras sorbifolium* contain abundant oil and plant protein, making them highly nutritious. The seeds are edible and can be pressed for oil; the kernels contain over 60% oil, which is of high quality, clear in color, and fragrant. It is rich in polyunsaturated fatty acids (90%), making it highly nutritious and possessing certain medicinal value, with effects in preventing and treating cardiovascular diseases such as hypertension and arteriosclerosis. *Xanthoceras sorbifolium* oil contains 2-4% nervonic acid, which helps prevent and repair nerve damage and promotes brain development. *Xanthoceras sorbifolium* is rich in protein, containing all eight essential amino acids, making it a complete protein source and an excellent protein resource.

[0003] Currently, the production processes for *Xanthoceras sorbifolium* oil include hydraulic pressing and enzymatic pressing. Hydraulic pressing suffers from drawbacks such as discontinuous production, high energy consumption, high residual oil content, and a narrow application range for the oil cake. Enzymatic pressing is characterized by high cost, cumbersome operation, and high energy consumption. Screw pressing is a widely used physical pressing method in industry, offering advantages such as low energy consumption, continuous production, and simple operation. When the raw material enters the pressing chamber, it is subjected to internal pressure applied by one or more pressing screws, which rotate and propel the material forward. As the material is compressed and squeezed, the oil begins to separate from it and flows out through the gaps in the screws, achieving physical separation of the oil from the raw material. However, due to the high oil content and low crude fiber content of *Xanthoceras sorbifolium*, the pressure generated within the pressing chamber during screw pressing is low, making efficient oil separation difficult, leading to slippage and extremely low production efficiency. Therefore, there is an urgent need for a *Xanthoceras sorbifolium* pressing method that achieves high production efficiency, high oil yield, low energy consumption, and low oil content in the oil cake. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a low-temperature spiral pressing method for high oil yield of *Sapindus mukorossi*.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for low-temperature spiral pressing of *Sapindus mukorossi* with high oil yield involves adding sesame seeds to *Sapindus mukorossi*, mixing them, and then performing low-temperature spiral pressing. The weight ratio of *Sapindus mukorossi* to sesame seeds is 3:1 to 1:3.

[0007] In one specific embodiment, the parameters of the low-temperature screw press are: rotation speed of 15-45 rpm, pressing temperature of 60-75°C, inlet temperature of less than 40°C, and outlet cake temperature of less than 70°C.

[0008] In one specific embodiment, the moisture content of the *Sapindus mukorossi* fruit and sesame seeds is 4–9%.

[0009] In one specific embodiment, the *Xanthoceras sorbifolium* is a dehulled *Xanthoceras sorbifolium* seed kernel.

[0010] In one specific embodiment, the method for low-temperature spiral pressing of *Sapindus mukorossi* fruit with high oil yield includes the following steps:

[0011] (1) The shelled kernels of *Sapindus mukorossi* and sesame seeds were heat-treated to reduce their moisture content to 4-9%;

[0012] (2) Heat-treated *Sapindus mukorossi* seeds and sesame seeds are mixed in a weight ratio of 3:1 to 1:3;

[0013] (3) The mixture of *Sapindus mukorossi* seeds and sesame seeds was subjected to low-temperature screw pressing with the following parameters: speed 15-45 rpm, pressing temperature 60-75℃, in-press temperature below 40℃, and out-of-press cake temperature below 70℃.

[0014] (4) After pressing, the oil is coarsely filtered through a filter cloth and then finely filtered through a 0.22-50μm microporous membrane to obtain *Sapindus mukorossi* sesame oil.

[0015] In one specific embodiment, the heat treatment temperature of step (1) is 65-70°C, and the treatment method is low-temperature hot air or heat transfer oil heating.

[0016] In one specific embodiment, the moisture content of the *Sapindus mukorossi* fruit and sesame seeds is 8%.

[0017] In one specific embodiment, the weight ratio of the *Sapindus mukorossi* fruit to sesame seeds is 3:1.

[0018] In one specific embodiment, the rotation speed of the low-temperature spiral press in step (3) is 35 rpm.

[0019] In a specific embodiment, the pressing temperature of the low-temperature spiral pressing in step (3) is 70°C.

[0020] Advantages of the technical solution of this invention

[0021] Hydraulic pressing methods suffer from drawbacks such as discontinuous production, high energy consumption, residual oil content exceeding 10% in the oil cake, and limited application range of the oil cake. Enzymatic pressing methods are characterized by complex pretreatment processes, high costs due to the need for protease addition, and numerous equipment steps leading to high energy consumption. This invention presents a spiral low-temperature pressing method for *Xanthoceras sorbifolium* seeds, resulting in low energy consumption and residual oil content below 5%. The oil cake contains over 55% protein, making it suitable for food, pharmaceutical, and health product production. This invention incorporates a certain amount of sesame seeds into *Xanthoceras sorbifolium* seeds for co-pressing, forming a material mass with suitable moisture and fiber content. This solves the problems of slippage, low oil yield, and slag buildup associated with pressing *Xanthoceras sorbifolium* alone. Furthermore, while cold-pressing *Xanthoceras sorbifolium* and sesame alone results in residual oil content exceeding 10%, this invention achieves less than 5%. The *Xanthoceras sorbifolium* oil prepared using this invention via a purely physical method and microporous membrane filtration is clear and transparent, with low acid value and peroxide value, and high content of active ingredients such as sterols, vitamin E, nervonic acid, and sesamol.

[0022] Cold pressing of *Sapindus mukorossi* fruit alone has the following disadvantages:

[0023] (1) Slag: During cold pressing, slag is produced due to the low crude fiber content of the *Xanthoceras sorbifolium* kernel. This slag not only causes slag overflow and slippage, but also reduces the oil yield. (2) High residual oil rate: Because the *Xanthoceras sorbifolium* kernel is soft, it is difficult to generate a sufficiently high extrusion pressure in the pressing chamber. Therefore, it is difficult to extract the oil from the *Xanthoceras sorbifolium* during the pressing process, resulting in a high residual oil rate in the cake. (3) Slow speed: The *Xanthoceras sorbifolium* raw material has low hardness and a long residence time in the pressing chamber. At the same time, in order to solve the problems of slag overflow and low oil yield, it is necessary to frequently stop the machine for cleaning and adjust the pressing process parameters, which will increase production costs and time costs. (4) The oil is cloudy and has low transparency after conventional plate and frame filtration.

[0024] The combined spiral pressing process for *Sapindus mukorossi* and sesame can solve the following technical problems:

[0025] (1) Slippery chamber problem: The addition of sesame increases the friction between materials, increases the overall fiber content and hardness of the materials, thereby improving the slippery chamber phenomenon of *Xanthoceras sorbifolium* during the pressing process. (2) Low oil yield: The physical properties of *Xanthoceras sorbifolium* and sesame are complementary, which can easily form high pressure in the pressing chamber, which helps to improve the overall oil yield. (3) Slag overflow problem: Since the addition of sesame helps to form a more stable pressing material layer, mixed pressing can reduce the slag overflow phenomenon that may occur when *Xanthoceras sorbifolium* is pressed alone. (4) Solving the problem of high residual oil in sesame cake when cold-pressed alone: ​​When sesame is cold-pressed alone, the pressing speed is fast and the material stays in the pressing chamber for a short time, resulting in high residual oil in the cake under the same pressure conditions; when pressed together, the material properties of the two are complementary and the pressing speed is moderate, which helps to reduce the residual oil rate in the cake, thereby improving the utilization rate of sesame cake. (5) Microporous membrane filtration can remove micron-sized particles, making the oil clearer and more transparent. The filter membrane below 0.45μm also has a sterilization effect, which can extend the shelf life of *Xanthoceras sorbifolium* oil and increase the content of nervonic acid. (6) Low-temperature heating below 70℃ is used to adjust the moisture content of the raw materials while ensuring that the nervonic acid in the kernel of *Sapindus mukorossi* is not lost.

[0026] In addition, the blended oil obtained by jointly pressing *Sapindus mukorossi* and sesame has the following nutritional advantages:

[0027] (1) More Balanced Fatty Acid Composition: The fatty acid compositions of *Xanthoceras sorbifolium* and sesame differ. *Xanthoceras sorbifolium* seed oil mainly contains oleic acid, linoleic acid, and eicosapentaenoic acid (EPA). Among these, unsaturated fatty acids such as oleic acid and linoleic acid account for a large proportion of the total composition. Sesame oil, on the other hand, is mainly composed of linoleic acid, but also contains oleic acid, palmitic acid, arachidic acid, etc., with unsaturated fatty acids making up a large proportion. When *Xanthoceras sorbifolium* and sesame are cold-pressed together, their fatty acids can complement each other. On the one hand, the linoleic acid in sesame oil makes the jointly pressed oil more effective in preventing cardiovascular disease, anti-aging, and disease prevention and anti-cancer effects. On the other hand, other fatty acids in *Xanthoceras sorbifolium* seed oil, such as nervonic acid, can form a more balanced combination with the fatty acids in sesame oil, improving the overall nutritional value of the oil. Therefore, the joint cold pressing of *Xanthoceras sorbifolium* and sesame can make the fatty acid composition more balanced, preserving their respective advantages while improving the overall nutritional value through mutual complementarity. Such oil products may have broader application prospects in the food and health product fields.

[0028] (2) Rich in various nutrients:

[0029] The main nutritional components of *Xanthoceras sorbifolium* include: *Xanthoceras sorbifolium* oil contains sterols, vitamin E, and abundant unsaturated fatty acids. Phytosterols are a class of beneficial bioactive components found in vegetable oils, nuts, and seeds. Studies have shown that the total sterol content in *Xanthoceras sorbifolium* oil is 0.498% using GC-MS, and five phytosterol monomers have been isolated from the oil, exhibiting various pharmacological activities, with its lipid-lowering function being particularly significant. Vitamin E (VE) contains tocopherols and tocotrienols, and has antioxidant, antitumor, cholesterol-inhibiting, and cardiovascular disease-preventing effects. The average vitamin E content of *Sapindus mukorossi* oil is 757.86 mg / kg, which is generally higher than that of peanut oil (413.5 mg / kg), rapeseed oil (595.9 mg / kg), sesame oil (320.0 mg / kg), and camellia seed oil (65.7 mg / kg). Among them, the average tocopherol content is 399.60 mg / kg, which is higher than that of rice bran oil (338.2 mg / kg), olive oil (240.7 mg / kg), grapeseed oil (168.7 mg / kg), and palm oil (215.6 mg / kg). The average tocotrienol content is 358.74 mg / kg, which is second only to palm oil (530.04 mg / kg). Unsaturated fatty acids such as linoleic acid and linolenic acid help regulate blood lipids, clear blood clots, regulate immunity, and maintain retinal health.

[0030] Sesame oil is rich in natural vitamin E and sesamin, possessing excellent antioxidant and free radical scavenging effects. It can improve symptoms of psoriasis, eczema, rheumatism, and arthritis. It can form a "lipid film" on the skin's surface, similar to the skin's natural sebum, providing excellent moisturizing effects, promoting skin regeneration, and aiding in blood circulation and sun protection. Furthermore, cold-pressed sesame oil is one of the "three major detoxifying oils," rich in various unsaturated fatty acids and containing valuable fat byproducts (such as sesamol and sesaminol). These two components can bind with heavy metal waste hidden in fats and remove toxins from the body, thus exerting an excellent detoxifying effect. It is ideal for facial, internal, and oral cleansing.

[0031] The blended oil not only contains the nutrients of both *Sapindus mukorossi* and sesame, but may also produce better functional activity due to the synergistic effect of the two ingredients.

[0032] (3) High nutritional value: Since blended oil combines the nutritional components of two raw materials, its nutritional value is higher than that of oil made from a single oilseed, and it can meet the human body's needs for a variety of nutrients.

[0033] In conclusion, the combined spiral pressing process of *Sapindus mukorossi* and sesame can not only solve a series of problems in the pressing process of *Sapindus mukorossi*, but also improve the utilization rate of sesame cake and obtain a blended oil with higher nutritional value by optimizing the raw material ratio and making full use of the nutritional components of the two raw materials. Detailed Implementation

[0034] Unless otherwise stated, the terms used in this invention generally have the meanings commonly understood by those skilled in the art.

[0035] The present invention will now be described in further detail with reference to specific embodiments and data. These embodiments are merely illustrative and are not intended to limit the scope of the invention in any way.

[0036] Unless otherwise specified, the experimental materials, reagents, and chemicals used in the following examples can be purchased through general channels.

[0037] Example 1

[0038] A method for low-temperature spiral pressing of *Sapindus mukorossi* fruit with high oil yield, comprising the following steps:

[0039] (1) Select the kernels of *Sapindus mukorossi* that are free from mold and insect infestation, remove the shells, and after color sorting, treat them by low-temperature hot air or heat transfer oil heating, with a heating temperature of 65-70℃, so that the moisture content of the shelled kernels is 4-9%.

[0040] (2) After washing the sesame seeds, they are treated by low-temperature hot air or heat transfer oil heating at a temperature of 65-70℃ to achieve a moisture content of 4-9%.

[0041] (3) After the treatment in step (1), the kernels of *Sapindus mukorossi* are mixed with the sesame seeds in step (2) at a weight ratio of 3:1 to 1:3. After mixing, the mixture is put into a single screw press. During the pressing process, the screw speed is set to 15 to 45 rpm, the press head temperature is 60 to 75°C, the pressing temperature is controlled to be below 40°C, and the cake temperature is below 70°C.

[0042] (4) After pressing, the oil is coarsely filtered through a filter cloth and then finely filtered through a 0.22-50μm microporous membrane to obtain high-quality Sapindus mukorossi sesame oil.

[0043] The cake obtained after the above pressing can be ultra-finely pulverized to obtain 200-400 mesh protein powder, which can be used to prepare Xanthoceras sorbifolium protein powder.

[0044] The optimal pressing process is as follows: *Xanthoceras sorbifolium* is dehulled; the moisture content of *Xanthoceras sorbifolium* and sesame seeds is 8%; the weight ratio of dehulled *Xanthoceras sorbifolium* and sesame seeds is 3:1; the pressing parameters are: 35 rpm and 70℃. Under these optimal conditions, the oil yield is 56.47%, and the residual oil rate is 4.31%. Under these optimal conditions, the best results can be achieved by combining *Xanthoceras sorbifolium* and sesame seeds in a spiral pressing process. This not only increases oil yield and reduces production costs but also improves oil quality and enhances the product's market competitiveness.

[0045] The effect of the ratio of *Sapindus mukorossi* fruit to sesame seeds on the pressing effect

[0046] The amount of sesame seeds added not only affects the final flavor and nutritional components of the oil, but also directly impacts the oil yield and residual oil content. Appropriate amounts of sesame seeds can improve the quality and taste of the oil, while also helping to increase oil yield and reduce residue and slippery texture.

[0047] Pure *Xanthoceras sorbifolium*, pure sesame, and mixtures of *Xanthoceras sorbifolium* and sesame in different weight ratios (3:1, 2:1, 1:1, 1:2, 1:3) were pressed, and the oil yield, residual oil yield, nervonic acid content, unsaturated fatty acid content, sesamin, sesamol, and vitamin E content were measured to compare the effect of the ratio of *Xanthoceras sorbifolium* and sesame on the pressing effect.

[0048] The pressing methods for pure *Sapindus mukorossi* fruit, pure sesame seeds, and mixtures of *Sapindus mukorossi* fruit and sesame seeds in different weight ratios (3:1, 2:1, 1:1, 1:2, 1:3) are as follows:

[0049] After the kernels of *Xanthoceras sorbifolium* were shelled and the sesame seeds were washed, they were subjected to heat treatment at 65–70°C to reduce their moisture content to 8%.

[0050] The heat-treated *Xanthoceras sorbifolium* and sesame seeds were mixed in different weight ratios to prepare *Xanthoceras sorbifolium*: sesame mixtures (3:1, 2:1, 1:1, 1:2, 1:3). The heat-treated pure *Xanthoceras sorbifolium*, pure sesame seeds, and *Xanthoceras sorbifolium*: sesame mixtures in different ratios were subjected to low-temperature screw pressing. The pressing parameters were: screw speed 30 rpm, press head temperature 65℃, feed temperature controlled below 40℃, and cake temperature below 70℃.

[0051] The specific measurement indicators and methods are as follows:

[0052] Determination of oil yield and residual oil content: GB / T 14488.1-2008 "Determination of oil content in vegetable oilseeds";

[0053] Nervonic acid content determination: GC-MS analysis method was used.

[0054] (1) Methyl esterification method: Weigh about 100 mg of oil sample and place it in a stoppered test tube. Add 1-2 mL of a mixture of petroleum ether (30-60℃) and benzene (1:1). Shake to dissolve the oil. Add 1-2 mL of 0.4 mol / L KOH-methanol solution. Mix well and let stand at room temperature for 5-10 min. Add 12 mL of water, shake and let stand. Take the upper layer solution for chromatographic analysis.

[0055] (2) GC-MS analysis conditions: Carrier gas He, column inlet pressure 109.8 kPa, split ratio 20:1, injection temperature 250℃, injection volume 1 μL, interface temperature 270℃, temperature program 1500℃ 10℃ / min 220℃, 220℃ 5℃ / min 280℃, 280℃ hold for 3 min. Mass spectrometry ionization mode EI, ion source temperature 200℃, ionization mode 70 eV, accelerating voltage 6 kV, resolution 800, scan range m / z: 50~450.

[0056] Determination of unsaturated fatty acid content: GB / T 22223-2008 "Determination of total fat, saturated fat (acid) and unsaturated fat (acid) in food - hydrolysis extraction-gas chromatography";

[0057] Vitamin E content determination: determined by reversed-phase high-performance liquid chromatography according to GB 5009.82—2016;

[0058] The content of sesamin and sesamol was determined according to GB / T 31579—2015 "Grain and Oil Inspection: Determination of Sesamin and Sesamin in Sesame Oil by High Performance Liquid Chromatography".

[0059] The fatty acid composition was determined according to GB 5009.168—2016, "National Food Safety Standard - Determination of Fatty Acids in Food".

[0060] The results are shown in Table 1.

[0061] Table 1. Effect of the ratio of *Sapindus mukorossi* fruit to sesame on pressing efficiency.

[0062]

[0063] As shown in Table 1, with the pressing oil yield, residual oil rate of cake and nervonic acid content as the main evaluation indicators, and taking into account the content of vitamin E, sesamol and sesamin, the pressing effect is best when the ratio of *Sapindus mukorossi* fruit to sesame is 3:1.

[0064] The effect of raw material moisture content on pressing effect

[0065] The moisture content of *Sapindus mukorossi* and sesame directly affects their physical properties and oil extraction efficiency during pressing. Appropriate moisture content helps the raw materials form a uniform cake structure during pressing, improving pressing efficiency. Excessive moisture content may lead to poor material flowability during pressing, reducing oil yield; while excessively low moisture content may make the raw materials too dry, increasing the difficulty of pressing.

[0066] After the kernels of *Xanthoceras sorbifolium* were shelled and the sesame seeds were washed, they were subjected to heat treatment at 65–70°C to reduce their moisture content to 5%, 8%, and 12%, respectively.

[0067] The heat-treated *Xanthoceras sorbifolium* and sesame seeds were mixed in a weight ratio of 3:1 to form a *Xanthoceras sorbifolium*: sesame mixture. This *Xanthoceras sorbifolium*: sesame mixture was subjected to low-temperature screw pressing with the following pressing parameters: screw speed 30 rpm, press head temperature 65℃, feed temperature controlled below 40℃, and cake temperature below 70℃.

[0068] The oil yield and residual oil content were determined according to GB / T 14488.1-2008 "Determination of Oil Content in Vegetable Oilseeds". The results are shown in Table 2.

[0069] Table 2. Effect of raw material moisture content on pressing effect

[0070] Moisture content (%) Oil yield (%) Residual oil content (%) 5 52.54 6.12 8 54.06 4.65 12 51.81 6.81

[0071] A suitable moisture content helps to increase oil yield and reduce residual oil content. Table 2 shows that the raw material with a moisture content of 8% (Sapindus mukorossi: sesame = 3:1) exhibits better pressing performance. Too low a moisture content may lead to overly dry raw material, increasing the difficulty of pressing; while too high a moisture content may result in poor flowability of the raw material during pressing, reducing oil yield.

[0072] The effect of processing methods on pressing efficiency of Xanthoceras sorbifolium

[0073] The kernels of *Xanthoceras sorbifolium* seeds were processed separately, with some kernels being dehulled and others not. They were then subjected to heat treatment at 65–70°C to reduce their moisture content to 8%.

[0074] Low-temperature screw pressing was performed on both dehulled and undehulled *Sapindus mukorossi* fruits. The pressing parameters were: screw speed 30 rpm, press head temperature 65℃, feed temperature controlled below 40℃, and cake temperature controlled below 70℃.

[0075] The oil yield and residual oil content were determined according to GB / T 14488.1-2008 "Determination of Oil Content in Vegetable Oilseeds". The results are shown in Table 3.

[0076] Table 3. Effects of processing methods on pressing efficiency of *Sapindus mukorossi* fruit.

[0077] Handling method Oil yield (%) Residual oil content (%) Pressing after dehulling 54.34 4.84 direct pressing 30.21 6.57

[0078] As shown in Table 3, the oil yield of *Sapindus mukorossi* after shelling is significantly increased and the residual oil rate is reduced.

[0079] The effect of pressing temperature on pressing effect

[0080] The feed temperature is a key factor affecting oil extraction efficiency and quality. In low-temperature screw pressing, an appropriate feed temperature helps preserve the oil's nutrients and flavor while preventing oxidation and nutrient loss caused by high temperatures. Too low a feed temperature may result in incomplete pressing, while too high a discharge temperature may trigger oil oxidation and reduce oil quality.

[0081] The temperature of the cake residue reflects the degree of heating of the raw material during the pressing process and has a certain impact on the residual oil content and nutritional components. A suitable cake residue temperature helps ensure the stability and efficiency of the pressing process and reduces the residual oil content. Excessively high temperatures may cause further oxidation of the oil in the cake residue, affecting oil quality; while excessively low temperatures may affect the pressing effect, resulting in a higher residual oil content.

[0082] After the kernels of *Xanthoceras sorbifolium* are shelled and the sesame seeds are washed, they are subjected to heat treatment at a temperature of 65–70°C to reduce their moisture content to 6%.

[0083] The heat-treated *Xanthoceras sorbifolium* and sesame seeds were mixed in a weight ratio of 3:1 to form a *Xanthoceras sorbifolium*: sesame mixture. This *Xanthoceras sorbifolium*: sesame mixture was subjected to low-temperature screw pressing with the following pressing parameters: screw speed 30 rpm, press head temperature 60-75℃, press in temperature below 40℃, and cake temperature below 70℃.

[0084] The oil yield and residual oil content were determined according to GB / T 14488.1-2008 "Determination of Oil Content in Vegetable Oilseeds".

[0085] The results are shown in Table 4.

[0086] Table 4. Effect of pressing temperature on pressing effect

[0087] Pressing temperature (°C) Oil yield (%) Oilseed cake residual oil content (%) 60 48.21 6.83 65 50.53 6.25 70 52.67 4.91 75 49.06 6.67

[0088] The effect of pressing speed on pressing effect

[0089] After the kernels of *Xanthoceras sorbifolium* are shelled and the sesame seeds are washed, they are separately heat-treated at 65–70°C to reduce their moisture content to 6%. The heat-treated *Xanthoceras sorbifolium* and sesame seeds are then mixed at a weight ratio of 3:1 to form a *Xanthoceras sorbifolium*:sesame mixture. This mixture is then subjected to low-temperature screw pressing with the following parameters: screw speeds set to 15, 25, 35, and 45 rpm; press head temperature set to 65°C; feed temperature controlled below 40°C; and cake temperature controlled below 70°C.

[0090] The oil yield and residual oil content were determined according to GB / T 14488.1-2008 "Determination of Oil Content in Vegetable Oilseeds". The results are shown in Table 5.

[0091] Table 5. Effect of pressing speed on pressing effect

[0092] Pressing speed (rpm) Oil yield (%) Oilseed cake residual oil content (%) 15 47.67 6.60 25 49.54 6.01 35 50.66 5.86 45 48.48 6.22

[0093] Comparative Example

[0094] After the kernels of *Xanthoceras sorbifolium* are shelled and the sesame seeds are washed, they are subjected to heat treatment at a temperature of 65–70°C to reduce their moisture content to 8%.

[0095] The heat-treated *Xanthoceras sorbifolium* and sesame seeds were mixed in a weight ratio of 7:3 to form a *Xanthoceras sorbifolium*: sesame mixture. The *Xanthoceras sorbifolium*: sesame mixture, as well as pure *Xanthoceras sorbifolium* and pure sesame seeds, were subjected to low-temperature screw pressing. The pressing parameters were: screw speed 30 rpm, press head temperature 65℃, press in temperature controlled below 40℃, and cake temperature below 70℃.

[0096] The oil yield was determined according to the method specified in GB / T 14488.1-2008 "Determination of Oil Content in Vegetable Oilseeds".

[0097] The results are shown in Table 6.

[0098] Table 6. Pressing effect of a mixture of *Sapindus mukorossi* and sesame seeds in a 7:3 ratio.

[0099] raw material Oil yield (cold pressing only) Overall oil yield after mixing Sapindus mukorossi 53.7％ —— Sesame 40.2％ —— Mixed Cold Press —— 47.8％

[0100] Table 6 shows that the oil yield of cold-pressed *Sapindus mukorossi* alone is 53.7%, and the oil yield of cold-pressed sesame alone is 40.2%. When the two are mixed in a 7:3 ratio for cold pressing, the estimated oil yield is approximately 49.65%, with a residual oil rate of 8.76%. Due to the poor ratio, the actual oil yield is only 47.8%, and the residual oil rate is 9.67%. This demonstrates that a poor ratio leads to a lower oil yield. A poor ratio may also require multiple adjustments to equipment and process parameters, increasing setup costs. Multiple purification and processing steps may also increase operating time and labor costs. Furthermore, a poor ratio may necessitate more frequent monitoring and adjustments to the cold-pressing process. Operators require higher technical skills and more experience to ensure oil quality, increasing operational complexity.

[0101] Effect of baking temperature on nervonic acid content

[0102] After the kernels of *Xanthoceras sorbifolium* were shelled and the sesame seeds were washed, they were subjected to heat treatment at temperatures of 65℃, 100℃, and 135℃, respectively, to reduce their moisture content to 8%.

[0103] The heat-treated *Xanthoceras sorbifolium* and sesame seeds were mixed in a weight ratio of 3:1 to form a *Xanthoceras sorbifolium*: sesame mixture. This *Xanthoceras sorbifolium*: sesame mixture was subjected to low-temperature screw pressing with the following pressing parameters: screw speed set to 35 rpm, press head temperature set to 65°C, feed temperature controlled below 40°C, and cake temperature controlled below 70°C.

[0104] The content of nervonic acid was determined by GB / T 22223-2008 "Determination of total fat, saturated fat (acid) and unsaturated fat (acid) in food - hydrolysis extraction-gas chromatography"; the results are shown in Table 7.

[0105] Table 7. Effect of baking temperature on nervonic acid content

[0106] Raw material baking temperature Oil yield Nervonic acid content 65℃ 54.7％ 2.89％ 100℃ 54.2％ 1.42％ 135℃ 54.1％ 0.36％

[0107] As shown in Table 7, using low-temperature heating below 70℃ and adjusting the moisture content of the raw materials can ensure that the nervonic acid in the kernels of *Sapindus mukorossi* is not lost.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A low-temperature screw pressing method of Xanthoceras sorbifolia Bunge with high oil yield, characterized in that, The steps are as follows: (1) The shelled Xanthoceras sorbifolia Bunge kernel and sesame are respectively subjected to heat treatment, so that the water content is 8%; (2) The heat-treated Xanthoceras sorbifolia Bunge kernel and sesame are mixed according to a weight ratio of 3:1; (3) The mixture of Xanthoceras sorbifolia Bunge kernel and sesame is subjected to low-temperature spiral pressing, and the parameters are as follows: rotation speed 35 rpm, pressing temperature 70 DEG C, inlet temperature lower than 40 DEG C, and outlet cake temperature lower than 70 DEG C; (4) After the pressing is completed, the mixture is coarsely filtered through filter cloth and then finely filtered through a 0.22-50 mu m microporous filter membrane, so as to obtain Xanthoceras sorbifolia Bunge sesame oil; The heat treatment temperature in step (1) is 65-70 DEG C, and the treatment mode is low-temperature hot air or heat conduction oil heating.

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