One-step dewaxing and degreasing method for improving the separation efficiency and anti-freezing performance of rice bran oil

Abstract

The present invention provides a method for one-step dewaxing of rice oil to improve the separation efficiency and anti-freezing performance. Specifically, the present invention provides a method for improving the separation efficiency of wax esters in the rice oil to be dewaxed and / or increasing the freezing time of the dewaxed rice oil, as well as a method for dewaxing rice oil, the method comprising the steps of mixing a crystallization promoter and the rice oil to be dewaxed and cooling and crystallizing the resulting mixed oil, wherein the crystallization promoter is a rice oil with a wax content lower than that of the rice oil to be dewaxed. The present invention uses an appropriate amount of wax as the crystal seed for removing high-melting-point lipids, achieving one-step and efficient removal of wax and high-melting-point lipids, and obtaining a significant improvement in separation efficiency and freezing performance.

Description

Technical Field

[0001] The present invention relates to a method for one-step dewaxing and degreasing to improve the separation efficiency and anti-freezing performance of rice bran oil. Background Art

[0002] Rice bran is rich in nutrients, contains various bioactive components, has health care functions, and is known as the "natural nutrition treasure house". Rice bran oil belongs to the deep processing products of rice bran. Its fatty acid composition is relatively reasonable, closest to the dietary recommendation standard of humans, and contains rich components such as VE, squalene, sitosterol, and ferulic acid. It is internationally recognized as a natural and green healthy oil. There is information showing that long-term consumption of rice bran oil has obvious effects on preventing cardiovascular diseases, improving human immunity, regulating blood sugar, etc. Therefore, rice bran oil is deeply favored by consumers.

[0003] Crude rice bran oil has a deep color, high acid value, many impurities, and complex components. Therefore, the refining process is relatively complex. The most common one is the freeze dewaxing process. The reasonable cooling crystallization rate, temperature, crystallization stirring speed, and ripening time are the key to this process. Currently, in order to increase the freezing time of rice bran oil, the methods adopted by enterprises are mainly to remove wax and esters in rice bran oil. The wax content in rice bran oil is usually above 3% by mass fraction. If you want to improve the freezing performance, it is necessary to increase the refining process and adopt the method of dewaxing first and then removing high-melting-point fats to improve the anti-freezing performance. Usually, after dewaxing, 2-3 times of degreasing treatment are required, or an additional high-temperature decolorization treatment method is added on the basis of conventional decolorization. This not only requires an increase in equipment and labor input, but also significantly reduces the production efficiency and production capacity. Summary of the Invention

[0004] The first aspect of the present invention provides a method for improving the separation efficiency of wax and fat in rice bran oil to be dewaxed and degreased and / or increasing the freezing time of dewaxed rice bran oil, or a method for dewaxing and degreasing rice bran oil. The method includes the step of mixing a crystallization promoter and rice bran oil to be dewaxed and degreased and cooling and crystallizing the obtained mixed oil. Among them, the crystallization promoter is rice bran oil with a wax content lower than that of the rice bran oil to be dewaxed and degreased.

[0005] In one or more embodiments, the crystallization promoter is dewaxed rice bran oil, dewaxed and degreased rice bran oil, decolorized rice bran oil, deodorized rice bran oil, or rice bran oil that has been degummed and deacidified obtained in the refining section.

[0006] In one or more embodiments, the wax content of the rice bran oil with a wax content lower than that of the rice bran oil to be dewaxed and degreased is ≤3.2%.

[0007] In one or more embodiments, the mass ratio of the rice bran oil to be dewaxed and degreased to the crystallization promoter is 6:4 to 9:1, preferably 7:3 to 8:2.

[0008] In one or more embodiments, the cooling crystallization includes: cooling the mixed oil from the crystal-breaking temperature to 25 ± 1 °C at a cooling rate of 3-4 °C / h and holding for 0-3 h, then cooling to 20 ± 1 °C at a cooling rate of 2-3 °C / h and holding for 0-3 h, then cooling to 7 ± 1 °C at a cooling rate of 0.5-1.5 °C / h and holding for 3-6 h, and then cooling to 0-3 °C at a cooling rate of 0.5-1.5 °C / h; preferably, the crystal-breaking temperature is 60-80 °C.

[0009] In one or more embodiments, the method further includes: after the cooling crystallization is completed, performing solid-liquid separation to obtain a clear liquid, thereby obtaining rice oil with an increased freezing time.

[0010] In one or more embodiments, the method includes:

[0011] Heating for crystal-breaking: heating the mixed oil of the mixed crystallization promoter and the rice oil to be dewaxed at 60-80 °C;

[0012] Cooling crystallization: cooling the mixed oil from the crystal-breaking temperature to 25 ± 1 °C at a cooling rate of 3-4 °C / h and holding for 0-3 h, then cooling to 20 ± 1 °C at a cooling rate of 2-3 °C / h and holding for 0-3 h, then cooling to 7 ± 1 °C at a cooling rate of 0.5-1.5 °C / h and holding for 3-6 h, and then cooling to 0-3 °C at a cooling rate of 0.5-1.5 °C / h; and

[0013] Solid-liquid separation: performing solid-liquid separation on the product of the cooling crystallization activity, and the liquid part is the dewaxed rice oil with an increased freezing time.

[0014] The second aspect of the present invention provides a method for preparing rice oil, the preparation method including a dewaxing step and any one or more steps selected from degumming, deacidification, decolorization, and deodorization, wherein the dewaxing step is implemented by using the dewaxing method according to any embodiment of the present invention.

[0015] The third aspect of the present invention provides rice oil prepared by using the method according to any embodiment herein; preferably, the freezing time of the rice oil is ≥ 100 minutes, preferably ≥ 120 minutes, more preferably ≥ 150 minutes, more preferably ≥ 200 minutes, and more preferably ≥ 300 minutes.

[0016] The fourth aspect of the present invention provides the application of rice oil with a wax content ≤ 3.2% as a crystallization promoter in improving the separation efficiency of wax esters in the rice oil to be dewaxed or in the preparation of rice oil with a freezing time ≥ 100 minutes; wherein, the wax content of the rice oil to be dewaxed is higher than that of the rice oil used as the crystallization promoter, and the wax content of the rice oil to be treated used in the preparation is higher than that of the rice oil used as the crystallization promoter.

[0017] In one or more embodiments, the crystallization promoter is as described in any of the embodiments herein.

[0018] In one or more embodiments, the dosage ratio of the crystallization promoter to the rice bran oil to be dewaxed is as described in any of the embodiments herein.

[0019] In one or more embodiments, the improvement or preparation includes the freeze crystallization step as described in any of the embodiments herein.

[0020] The fifth aspect of the present invention provides a method for preparing an oil and fat composition and / or a blended oil, the method comprising: A) a step of preparing rice bran oil by using the method described in any of the embodiments of the present invention, and B) a step of preparing the oil and fat composition and / or the blended oil by using the rice bran oil obtained in step A. Description of the Drawings

[0021] Figure 1 : Crystallization morphology diagrams of comparative examples and examples. Detailed Description

[0022] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as in the examples) can be combined with each other to form preferred technical solutions.

[0023] Traditional rice bran oil is dewaxed and deoiled with high melting point by two dry fractionation processes during preparation. The present invention discovers that by mixing rice bran oil with a wax content lower than that of the rice bran oil to be dewaxed with the rice bran oil to be dewaxed, and then performing a cooling crystallization process, the wax and high melting point fat can be efficiently removed in one step through a one-step dewaxing and deoiling process, while obtaining the maximum separation efficiency and improvement in freezing performance. Moreover, the present invention does not require additional investment and does not need to introduce exogenous substances as crystal seeds, which is extremely suitable for industrial promotion. Thus, the present invention is completed.

[0024] Therefore, the present invention provides a method for improving the separation efficiency of wax fat in rice bran oil to be dewaxed and / or improving the freezing time of dewaxed rice bran oil, and a method for dewaxing and deoiling rice bran oil, the method comprising mixing the rice bran oil to be dewaxed with a crystallization promoter, heating the obtained mixed oil to the crystal-breaking temperature, and then performing cooling crystallization.

[0025] In this text, the crystallization promoter is rice oil with a wax content lower than that of the rice oil to be dewaxed of fat. The rice oil with a wax content lower than that of the rice oil to be dewaxed of fat can be any rice oil as long as its wax content is lower than that of the rice oil to be dewaxed of fat. Preferably, the crystallization promoter can be commercial rice oil, or dewaxed rice oil, rice oil dewaxed of fat, decolorized rice oil, deodorized rice oil, degummed and decolorized rice oil, etc. obtained in the refining section. In some embodiments, the wax content of some rice oil to be dewaxed of fat (such as degummed and deacidified rice oil) may also be relatively low. Therefore, such rice oil to be dewaxed of fat can also be used as the crystallization promoter for rice oil to be dewaxed of fat with a relatively high wax content. Mix these two types of rice oil to be dewaxed of fat, and adopt the cooling crystallization process described in the present invention to dewax of fat. Preferably, the wax content of the rice oil with a wax content lower than that of the rice oil to be dewaxed of fat is ≤3.2%.

[0026] Generally, the dosage (mass) ratio of the rice oil to be dewaxed of fat to the crystallization promoter is from 9:1 to 6:4. In some embodiments, the dosage ratio of the two is 7:3 to 8:2, or 8:2 to 6:4.

[0027] In some embodiments, the wax content of the crystallization promoter is less than 95% of the wax content of the rice oil to be dewaxed of fat, preferably less than 80%, and preferably simultaneously satisfies the wax content ≤3.2%.

[0028] In this text, the crystal-breaking temperature is usually 60 - 80°C. After heating to the crystal-breaking temperature and the mixed oil is fully mixed and dissolved, the cooling crystallization procedure can be started.

[0029] The cooling crystallization in this text may include: cooling the mixed oil from the crystal-breaking temperature to 25 ± 1°C at a cooling rate of 3 - 4°C / h and keeping it at a constant temperature for 0 - 3 h, then cooling it to 20 ± 1°C at a cooling rate of 2 - 3°C / h and keeping it at a constant temperature for 0 - 3 h, then cooling it to 7 ± 1°C at a cooling rate of 0.5 - 1.5°C / h and keeping it at a constant temperature for 3 - 6 h, and then cooling it to 0 - 3°C at a cooling rate of 0.5 - 1.5°C / h.

[0030] After the cooling crystallization is completed, solid-liquid separation can be carried out at a temperature not higher than 5°C, and the liquid part obtained is the dewaxed rice oil of fat of the present invention.

[0031] Currently, the freezing time of common rice oil is generally about 30 minutes. The freezing time of the dewaxed rice oil of fat obtained by the method of the present invention is significantly prolonged. The freezing time of the rice oil of the present invention can be more than 100 minutes. In some embodiments, the freezing time of the rice oil of the present invention can be more than 120 minutes, or more than 150 minutes, and even higher than 300 minutes. In some embodiments, the freezing time of the dewaxed rice oil of fat of the present invention is more than 8 times that of the control dewaxed rice oil of fat.

[0032] In some embodiments, the present invention provides a method for preparing rice bran oil, which includes a dewaxing step and one or more of the conventional steps such as degumming, neutralization, decolorization, and deodorization. The feature of this method is that the dewaxing is carried out by using the dewaxing method described in any of the embodiments herein.

[0033] The present invention also provides a rice bran oil, whose freezing time is ≥100 minutes, preferably ≥120 minutes, more preferably ≥150 minutes, more preferably ≥200 minutes, and more preferably ≥300 minutes. Preferably, the rice bran oil is prepared by using the method described in any of the embodiments herein.

[0034] In some embodiments, the present invention provides the use of a rice bran oil with a wax content of ≤3.2% as a crystallization promoter in the preparation of rice with a freezing time of ≥100 minutes. In a preferred embodiment, the preparation is carried out by using the method described in any of the embodiments herein.

[0035] In some embodiments, the present invention also provides a method for preparing an oil-based composition and / or a blended oil, which includes: the step of preparing rice bran oil by using the method described in any of the embodiments of the present invention, and the step of using the rice bran oil to prepare the oil-based composition and / or the blended oil.

[0036] In one or more embodiments, the oil-based composition and the blended oil further contain a base oil. Preferably, the base oil is a mixture of one or more of vegetable oils, animal oils, and algal oils. Preferably, the vegetable oil is selected from one or any mixture of palm oil, palm kernel oil, peanut oil, rapeseed oil, soybean oil, linseed oil, cottonseed oil, safflower oil, perilla oil, camellia oil, castor oil, palm fruit oil, peanut oil, coconut oil, olive oil, cocoa butter, Chinese tallow tree seed oil, almond oil, apricot kernel oil, tung oil, rubber seed oil, rice bran oil, corn germ oil, wheat germ oil, sesame oil, evening primrose oil, hazelnut oil, pumpkin seed oil, walnut oil, grape seed oil, sesame oil, borage oil, seabuckthorn oil, tomato seed oil, macadamia oil, and cocoa butter. Preferably, the animal oil is selected from one or more of beef tallow, mutton tallow, lard, and chicken oil.

[0037] The present invention will be illustrated below by means of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The wax content test, freezing experiment, and crystal morphology described in the comparative examples and examples are carried out as follows.

[0038] Wax content test:

[0039] Heat the oil sample until it becomes clear and transparent. Weigh 4 g of the oil sample into a pre-weighed centrifuge tube, add 20 g of acetone refrigerated at 4 °C for 4 h, shake and centrifuge, then pour out the supernatant. Repeat this process three times. Place the centrifuge tube and the solid phase inside in an oven at 105 °C to constant weight, and calculate the content of acetone-insoluble matter, which is generally defined as the wax content.

[0040] Freezing experiment:

[0041] Adopt the standard of GB / T 17756. The specific operation method is as follows: Heat the well-mixed refined oil sample (200 - 300 mL) to 130 °C, then immediately stop heating and filter while it is still hot. Pour the filtered oil into an oil sample bottle, tightly stopper it with a cork, cool it to 25 °C, and seal it with paraffin. Then immerse the oil sample bottle in an ice-water bath at 0 °C and start timing. Cover it with ice water to keep the ice-water bath at 0 °C.

[0042] Crystal morphology:

[0043] Observe the crystal morphology at the end of crystal cultivation using a microscope.

[0044] The sources of the rice bran oil used in the examples and comparative examples are as follows:

[0045] The rice bran oil to be dewaxed with a wax content of 4.5% is the rice bran oil that has been degummed and deacidified, purchased from Qinhuangdao Jinhai Food Industry Co., Ltd.;

[0046] The dewaxed rice bran oil with a wax content of 0% is the rice bran oil that has been degummed, deacidified, and dewaxed, purchased from Qinhuangdao Jinhai Food Industry Co., Ltd.;

[0047] The rice bran wax paste, which is a mixture of rice bran wax and high-melting-point fat removed in the dewaxing section of rice bran oil, with a rice bran wax content of 50%, is purchased from Qinhuangdao Jinhai Food Industry Co., Ltd.;

[0048] The dewaxed rice bran oil with other wax contents is prepared using the above two rice bran oil raw materials and / or rice bran wax paste.

[0049] Comparative Example 1

[0050] The raw material, the rice bran oil to be dewaxed, is the rice bran oil that has been degummed and deacidified. Test the wax content according to the method described above, and the measured wax content is 4.5%. Heat the rice bran oil to be dewaxed to about 65 °C to break the crystals. Then cool it at a cooling rate of 3 °C / h to 25 °C, then at a cooling rate of 2 °C / h to 20 °C, then at a cooling rate of 0.5 °C / h to 7 °C and keep it at a constant temperature for 3 h, and then at a cooling rate of 0.5 °C / h to 3 °C. After the cooling program is completed, perform solid-liquid separation using a centrifuge under the condition of not higher than 5 °C. The clear liquid is the dewaxed rice bran oil product. Conduct a freezing experiment and observe the crystal morphology at the end of crystal cultivation according to the method described above. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown inFigure 1 。

[0051] Comparative Example 2

[0052] The raw material of the rice oil to be dewaxed is the rice oil that has been degummed and deacidified. The wax content is measured according to the method described above, and the measured wax content is 4.5%. The dewaxed rice oil (wax content 3.5%) is back-mixed into the rice oil to be dewaxed. The mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 8:2. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 65 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 3 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0053] Example 1

[0054] The raw material of the rice oil to be dewaxed is the rice oil that has been degummed and deacidified. The wax content is measured according to the method described above, and the measured wax content is 4.5%. The dewaxed rice oil (wax content 0) is back-mixed into the rice oil to be dewaxed. The mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 7:3. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 65 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 3 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0055] Example 2

[0056] The raw material of the rice oil to be dewaxed is degummed and deacidified rice oil. The wax content is measured according to the method described above, and the measured wax content is 4.5%. Dewaxed rice oil (with a wax content of 0) is back-mixed into the rice oil to be dewaxed, and the mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 7:3. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 65 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 0 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0057] Example 3

[0058] The raw material of the rice oil to be dewaxed is degummed and deacidified rice oil. The wax content is measured according to the method described above, and the measured wax content is 4.5%. Dewaxed rice oil (with a wax content of 0) is back-mixed into the rice oil to be dewaxed, and the mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 9:1. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 70 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3.5 °C / h and held at a constant temperature for 1 h, then cooled to 20 °C at a cooling rate of 2.5 °C / h and held at a constant temperature for 1 h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 2 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0059] Example 4

[0060] The raw material, the rice oil to be dewaxed, is the rice oil that has been degummed and deacidified. The wax content is measured according to the method described above, and the measured wax content is 4.5%. The dewaxed rice oil (with a wax content of 0) is back-mixed into the rice oil to be dewaxed, and the mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 8:2. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 80 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 1 °C / h and held at a constant temperature for 4 h, and then cooled to 1 °C at a cooling rate of 1 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0061] Example 5

[0062] The raw material, the rice oil to be dewaxed, is the rice oil that has been degummed and deacidified. The wax content is measured according to the method described above, and the measured wax content is 4.5%. The dewaxed rice oil (with a wax content of 0) is back-mixed into the rice oil to be dewaxed, and the mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 6:4. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 70 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 4 °C / h and held at a constant temperature for 3 h, then cooled to 20 °C at a cooling rate of 3 °C / h and held at a constant temperature for 3 h, then cooled to 7 °C at a cooling rate of 1.5 °C / h and held at a constant temperature for 6 h, and then cooled to 3 °C at a cooling rate of 1.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0063] Example 6

[0064] The wax content of the raw material, the rice oil to be dewaxed, is 4.1%. The dewaxed rice oil (with a wax content of 0) is back-mixed into the rice oil to be dewaxed, and the mass ratio of the rice oil to be dewaxed to the dewaxed rice oil is 7:3. The temperature of the mixed oil of the rice oil to be dewaxed and the dewaxed rice oil is raised to about 65 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 3 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown inFigure 1 。

[0065] Example 7

[0066] The wax content of the raw material degumming rice bran oil to be dewaxed is 3.6%. Degummed rice bran oil (wax content is 0) is back-mixed into the degumming rice bran oil to be dewaxed. The mass ratio of the degumming rice bran oil to be dewaxed to the degummed rice bran oil is 8:2. The temperature of the mixed oil of the degumming rice bran oil to be dewaxed and the degummed rice bran oil is raised to about 70 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 0 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the degumming rice bran oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0067] Example 8

[0068] The wax content of the raw material degumming rice bran oil to be dewaxed is 4.5%. Degummed rice bran oil (wax content is 3%) is back-mixed into the degumming rice bran oil to be dewaxed. The mass ratio of the degumming rice bran oil to be dewaxed to the degummed rice bran oil is 6:4. The temperature of the mixed oil of the degumming rice bran oil to be dewaxed and the degummed rice bran oil is raised to about 70 °C to break the crystals. Then it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 3 °C at a cooling rate of 0.5 °C / h. After the cooling procedure is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the degumming rice bran oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0069] Example 9

[0070] The wax content of the raw material, the rice bran oil to be dewaxed, is 3.5%. The dewaxed rice bran oil (with a wax content of 2%) is recycled and mixed into the rice bran oil to be dewaxed. The mass ratio of the rice bran oil to be dewaxed to the dewaxed rice bran oil is 8:2. The temperature of the mixed oil of the rice bran oil to be dewaxed and the dewaxed rice bran oil is raised to about 70 °C to break the crystals. Then, it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 3 °C at a cooling rate of 0.5 °C / h. After the cooling process is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice bran oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0071] Example 10

[0072] The wax content of the raw material, the rice bran oil to be dewaxed, is 3%. The dewaxed rice bran oil (with a wax content of 1%) is recycled and mixed into the rice bran oil to be dewaxed. The mass ratio of the rice bran oil to be dewaxed to the dewaxed rice bran oil is 9:1. The temperature of the mixed oil of the rice bran oil to be dewaxed and the dewaxed rice bran oil is raised to about 70 °C to break the crystals. Then, it is cooled to 25 °C at a cooling rate of 3 °C / h, then cooled to 20 °C at a cooling rate of 2 °C / h, then cooled to 7 °C at a cooling rate of 0.5 °C / h and held at a constant temperature for 3 h, and then cooled to 3 °C at a cooling rate of 0.5 °C / h. After the cooling process is completed, solid-liquid separation is carried out using a centrifuge under the condition of not higher than 5 °C, and the clear liquid is the dewaxed rice bran oil product. The freezing experiment is carried out according to the method described above, and the crystal morphology at the end of crystal cultivation is observed. The freezing results are shown in Table 1, and the crystal morphology at the end of crystal cultivation is shown in Figure 1 。

[0073] Table 1: Freezing experiment results

[0074]

[0075]

Claims

1. A method for improving the separation efficiency of wax esters in a to-be dewaxed rice bran oil and / or improving the freezing time of the dewaxed rice bran oil, or a method for dewaxing rice bran oil, characterized in that The method includes the steps of mixing a crystallization promoter and the rice bran oil to be dewaxed and cooling and crystallizing the resulting mixed oil, wherein the crystallization promoter is a rice bran oil with a wax content lower than that of the rice bran oil to be dewaxed; The wax content of the rice bran oil with a wax content lower than that of the rice bran oil to be dewaxed is ≤ 3.2%; The cooling and crystallization includes: cooling the mixed oil from the crystal-breaking temperature to 25 ± 1°C at a temperature reduction rate of 3-4°C / h and holding for 0-3 h, then cooling to 20 ± 1°C at a temperature reduction rate of 2-3°C / h and holding for 0-3 h, then cooling to 7 ± 1°C at a temperature reduction rate of 0.5-1.5°C / h and holding for 3-6 h, and then cooling to 0-3°C at a temperature reduction rate of 0.5-1.5°C / h.

2. The method according to claim 1, wherein The crystallization promoter is dewaxed rice bran oil, dewaxed rice bran oil with wax, decolorized rice bran oil, deodorized rice bran oil, or rice bran oil that has been degummed and deacidified obtained in the refining section.

3. The method according to claim 1, characterized in that, The mass ratio of the rice bran oil to be dewaxed to the crystallization promoter is 6:4 to 9:

1.

4. The method according to claim 3, characterized in that, The mass ratio of the rice bran oil to be dewaxed to the crystallization promoter is 7:3 to 8:

2.

5. The method according to claim 1, characterized in that, The crystal-breaking temperature is 60-80°C.

6. The method according to any one of claims 1-5, characterized in that, The method further includes: after the cooling and crystallization is completed, performing solid-liquid separation, obtaining the supernatant, and obtaining the rice bran oil with an increased freezing time.

7. The method according to claim 1, characterized in that, The method includes: Heating for crystal-breaking: heating the mixed oil of the crystallization promoter and the rice bran oil to be dewaxed at 60-80°C and Solid-liquid separation: performing solid-liquid separation on the product of the cooling and crystallization activity, and the liquid part is the dewaxed rice bran oil with an increased freezing time.

8. A method for preparing rice bran oil, the preparation method comprising a dewaxing step and any one or more steps selected from degumming, deacidification, decolorization, and deodorization, characterized in that, Implementing the dewaxing step by using the dewaxing method described in any one of claims 1-7.

9. Use of rice bran oil with a wax content of ≤ 3.2% as a crystallization promoter to improve the separation efficiency of wax esters in rice bran oil to be dewaxed or in the preparation of rice bran oil with a freezing time of ≥ 100 minutes; wherein, The wax content of the rice bran oil to be dewaxed is higher than that of the rice bran oil used as the crystallization promoter, and the wax content of the rice bran oil to be treated used in the preparation is higher than that of the rice bran oil used as the crystallization promoter.

10. The application according to claim 9, characterized in that, The crystallization promoter is as described in claim 2, and the dosage ratio of the crystallization promoter to the rice bran oil to be dewaxed is as described in claim 3 or 4; and / or the improvement or preparation includes the cooling and crystallization step described in claim 1 or 5.

11. A method for preparing an oil and fat composition, characterized in that, The method includes: A) The step of preparing rice bran oil by using the method described in any one of claims 1-8, and B) The step of preparing the oil composition by using the rice bran oil obtained in step A.

12. A method for preparing blended oil, characterized in that, The method includes: A) The step of preparing rice bran oil by using the method described in any one of claims 1-8, and B) The step of preparing the blended oil by using the rice bran oil obtained in step A.

Images