Method for improving the frost resistance of edible fats

Abstract

The present application aims to provide a method for improving the anti-freezing property of edible oil, which is achieved by screening existing decolorizing agents, selecting decolorizing agents with specific specific surface area and macropore volume of decolorizing agents by means of optimization or compounding, and decolorizing with the overall decolorizing agent surface area / oil weight and the overall decolorizing agent macropore volume / oil weight in a specific ratio, so that the produced edible oil can achieve significant improvement in anti-freezing property.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of edible oil refining processing, and particularly relates to a processing method for improving the frost resistance of edible oil. BACKGROUND

[0002] The frost resistance of edible oil refers to the state of edible oil under low temperature conditions. For example, lard and palm oil are in solid form at room temperature, and peanut oil appears solid precipitate under low temperature conditions, indicating that the frost resistance of these oils is poor, but the frost resistance of oil has no adverse effect on the quality of oil. Different oils have different holding times at 0 degrees. Generally, animal oils can solidify at room temperature, and have poor freezing performance. Some vegetable oils also have poor frost resistance due to a high content of internal saturated fat. However, soybean oil, which is mainly composed of linoleic acid, generally has weaker frost resistance than corn oil and sunflower oil.

[0003] Soybean oil is extracted from soybeans. The soybean oil purchased by consumers in the market or supermarket is generally produced by refining soybean oil to remove impurities and harmful substances in the soybean oil. In actual production, due to various reasons such as soybean raw material varieties, production places and the like, the frost resistance of the produced soybean first-grade oil will have great differences. Individual batches of soybean oil will also appear crystalline substances under low temperature conditions. Due to the consumers' inherent impression of soybean oil, when the soybean oil appears to separate out under low temperature, the consumers will suspect that the oil is adulterated, affecting the product quality and brand image.

[0004] Related scholars have made various guesses about the factors affecting the frost resistance of soybean oil, such as the content of saturated fatty acids, the content of monoglycerides or diglycerides, and the content of sterols in soybean oil, but ultimately failed to confirm the direct correlation between these factors and frost resistance (Production Practice of Frost Resistance First-Grade Soybean Oil, China Oil and Fat, 2014, Vol. 39, No. 1, Zuo Qing et al. Research on Frost Resistance of First-Grade Soybean Oil, Grain and Oil, 2014, Vol. 27, No. 6, Wang Hua-lin et al.).

[0005] Due to the inability to determine the specific factors affecting the frost resistance of soybean oil, researchers have shifted their focus to optimizing existing processes to find the impact of condition optimization on frost resistance improvement, such as improving the operating parameters of individual sections or increasing the dewaxing section to reduce the content of insoluble substances in oil (A Method for Improving the Frost Resistance of Oil, Invention Patent Application No. 201911410350.4, Publication No. CN 113122379 A). However, whether adjusting parameters or adding new processing steps will affect the existing soybean oil processing technology and increase the production cost. SUMMARY

[0006] TECHNICAL PROBLEM

[0007] For unknown reasons, individual batches of vegetable oil (such as soybean oil) have poor frost resistance, and long-term storage at low temperatures can cause the oil to become cloudy or have insoluble substances precipitated; this phenomenon is a normal phenomenon of the oil, but because it occurs less frequently, it does not meet the inherent impression of consumers on vegetable oil, which can lead to a decrease in consumer willingness to purchase or a mistaken belief that the oil has been illegally added, affecting the sale of the oil and the brand image.

[0008] Technical solution

[0009] To solve the above problems, the present inventors screened existing decolorizing agents, and through optimization or compounding, a decolorizing agent with a specific surface area and macropore volume was obtained, and the decolorizing agent was used for decolorization at a specific ratio of decolorizing agent surface area / oil weight and macropore volume / oil weight. The use of a decolorizing agent that can simultaneously satisfy both parameters for decolorization processing can significantly improve the frost resistance of the produced edible oil.

[0010] Thus, in one aspect, the present application provides a processing method for improving the frost resistance of edible oil, which comprises the following steps:

[0011] (1) Optional degumming section: optionally degumming the raw oil of the edible oil;

[0012] (2) Neutralization section: neutralizing the oil obtained in the preceding step by adding phosphoric acid and sodium hydroxide solution in sequence;

[0013] (3) Optional dewaxing section: optionally dewaxing the oil obtained in the preceding step;

[0014] (4) Decolorization section: decolorizing the oil obtained in the preceding step by adding a decolorizing agent, wherein the overall decolorizing agent surface area / oil weight is 150 m 2 / 100 g of oil or more, preferably 170 m 2 / 100 g of oil or more, and the overall decolorizing agent macropore volume / oil weight is higher than 0.024 cm 3 / 100 g of oil; and

[0015] (5) Deodorization section: deodorizing the oil obtained in the preceding step.

[0016] In another aspect, the present application provides the use of a decolorizing agent to improve the frost resistance of oil, wherein the overall decolorizing agent surface area of the decolorizing agent is between 50 m 2 / g-1000 m 2 / g, preferably 150 m 2 / g-500 m 2 / g; and the overall decolorizing agent macropore volume of the decolorizing agent is 0.015 cm3 / g - 0.035 cm 3 / g, preferably 0.020 cm 3 / g - 0.030 cm 3 / g; when the decoloring agent is added in bulk to the oil, the bulk decoloring agent surface area per oil weight is 150 m 2 / 100 g oil or more, preferably 170 m 2 / 100 g oil or more, while the bulk decoloring agent macropore volume per oil weight of the decoloring agent is higher than 0.024 cm 3 / 100 g oil.

[0017] Beneficial effects

[0018] There is no clear conclusion on the influencing factors affecting the freezing performance of soybean oil at present. Under this condition, some studies adjust the oil processing parameters by a large margin, and then add a dewaxing process to existing processing links to improve the frost resistance of soybean oil. Although these operations can improve the frost resistance of soybean oil, they also greatly increase the processing cost of oil and fat. The present technology selects existing decoloring agents, optimizes or compounding, selects decoloring agents with specific specific surface area and macropore volume of decoloring agents, and decolors with specific bulk decoloring agent surface area per oil weight and bulk decoloring agent macropore volume per oil weight. The decoloring agent that meets two parameters at the same time is used for decoloring processing. The soybean oil produced can significantly improve the frost resistance. Compared with the limit value required by the national standard, the oil and fat processed by the method has a 0℃ freezing test time of at least two to three times. DETAILED DESCRIPTION

[0019] The refining process of edible oil and fat generally has neutralization, decoloring, deodorization sections, and optional degumming and dewaxing sections. In the decoloring section, a decoloring agent is added to the oil and fat to reduce the color of the oil and fat. However, the process of removing pigments or other substances by the decoloring agent is basically physical adsorption without selectivity, that is, in the process of removing pigments, substances that affect the frost resistance of oil and fat (the specific substances are not clear at present) are also removed at the same time.

[0020] The present application provides a processing method for improving the frost resistance of edible oil and fat, which comprises the following steps:

[0021] (1) Optional degumming section: optionally degumming the raw oil of edible oil and fat;

[0022] (2) Neutralization section: neutralizing the oil obtained in the preceding step by adding phosphoric acid and sodium hydroxide solution in sequence;

[0023] (3) Optional dewaxing section: optionally dewaxing the oil obtained in the preceding step;

[0024] (4) bleaching section: the oil obtained from the preceding step is bleached by adding bleaching agent, wherein the total bleaching agent surface area per oil weight is 150 m 2 / 100 g oil or higher, preferably 170 m 2 / 100 g oil or higher, and the total bleaching agent macropore volume per oil weight is higher than 0.024 cm 3 / 100 g oil; and

[0025] (5) deodorization section: the oil obtained from the preceding step is deodorized.

[0026] In the present application, the edible oil can include vegetable oil and animal oil, preferably vegetable oil. The vegetable oil can include soybean oil, sunflower oil, corn oil, rapeseed oil, rice oil, peanut oil, flaxseed oil, cottonseed oil, palm oil, olive oil, camellia oil, safflower seed oil, perilla seed oil, tea seed oil, castor seed oil, coconut oil, wheat germ oil, walnut oil, grape seed oil, hempseed oil, etc. Preferably, the oil is soybean oil, corn oil, rapeseed oil, sunflower oil, rice oil, more preferably soybean oil.

[0027] The process included in the processing method of the present application can be different according to the difference of oil species, and can be determined by those skilled in the art according to the characteristics of specific oil species. In a specific embodiment, the oil is soybean oil or rapeseed oil, and the processing method includes degumming section, neutralization section, bleaching section and deodorization section; in another embodiment, the oil is corn oil, and the processing method includes degumming section, neutralization section, dewaxing section, bleaching section and deodorization section; in yet another embodiment, the oil is sunflower oil, and the processing method includes neutralization section, dewaxing section, bleaching section and deodorization section.

[0028] In some embodiments, in step (1), degumming is performed by using hydration degumming to remove hydrated phospholipids and insoluble impurities. In some embodiments, in step (1), the degumming conditions are temperature 65-80°C, preferably 70-75°C; water addition amount is 0.5wt%-2wt% of the amount of oil processed, preferably 0.5wt%-1wt%.

[0029] In some embodiments, in step (2), the non-hydrated phospholipids, free fatty acids and other impurities in the oil are removed by adding phosphoric acid and then neutralizing with sodium hydroxide solution. In some embodiments, the oil processing in step (2) is carried out at a temperature of 65-80°C, preferably 70-75°C. In some embodiments, the concentration of the phosphoric acid is 75wt%-85wt%, and the concentration of the sodium hydroxide solution is 6wt%-16wt%. In preferred embodiments, in step (2), 0.01wt%-0.07wt% of the phosphoric acid, based on the amount of the processed oil, is added to the oil and reacted for 30-50min, and then 0.5wt%-2wt% of the sodium hydroxide solution, based on the amount of the processed oil, is added and reacted for 10-25min.

[0030] In some embodiments, after the acid-base reaction, the oil is warmed to 85-90°C, centrifuged, and then washed with water. In some embodiments, the water washing is carried out by adding water and phosphoric acid / citric acid, wherein the amount of water added is 4wt%±2wt% of the amount of the processed oil, and the amount of phosphoric acid / citric acid added is 0.2wt%±0.1wt% of the amount of the processed oil. In some embodiments, after the water washing, the oil is centrifuged again, and the oil after the second centrifugation is vacuum dehydrated. In this application, the phosphoric acid / citric acid is 75wt%-85wt% of phosphoric acid, citric acid monohydrate, or a combination thereof.

[0031] In some embodiments, in step (3), the oil is dewaxed by low-temperature crystallization filtration to remove waxes in the oil. In some embodiments, the dewaxing section includes adding 0.1wt%-2wt%, preferably 0.1wt%-0.5wt%, of a crystallization promoter, based on the amount of the oil to be dewaxed, to the oil to be dewaxed, cooling to 0-10°C, preferably 4-8°C, and dewaxing for 5-20h, preferably 15-20h. The crystallization promoter is diatomaceous earth and / or perlite.

[0032] In some embodiments, in step (4), the oil is decolorized by adding a decolorizing agent to remove pigments and factors affecting the freeze resistance of the oil. The total specific surface area of the decolorizing agent is 50m 2 / g-1000m 2 / g, preferably 150m 2 / g-500m 2 / g, preferably 150m 3 / g-0.035cm 3 / g, preferably 150m 3 / g-0.030cm 3 / g, preferably 150m

[0033] The decoloring agent can be selected from one or more of activated clay, activated carbon, palygorskite, bentonite. In preferred embodiments, the decoloring agent comprises at least two (e.g., two, three or four) of activated clay, activated carbon, palygorskite, bentonite. In specific embodiments, the decoloring agent is selected from activated clay+bentonite; activated clay+palygorskite; activated clay+activated carbon+palygorskite+bentonite; activated carbon+palygorskite+bentonite; or activated clay+palygorskite+bentonite.

[0034] In some embodiments, the amount of the decoloring agent added is 0.5wt%-2.5wt% of the amount of the oil processed, preferably 0.8wt%-2wt%. When the decoloring agent comprises activated clay and palygorskite, the mass ratio of activated clay to palygorskite is (1-5):1; when the decoloring agent comprises activated clay and bentonite, the mass ratio of activated clay to bentonite is (3-15):1; when the decoloring agent comprises activated clay, activated carbon, palygorskite, bentonite, the mass ratio of activated clay, activated carbon, palygorskite, bentonite is (3-10):1:(2-5):1; when the decoloring agent comprises activated carbon, palygorskite, bentonite, the mass ratio of activated carbon, palygorskite, bentonite is (1-2):5:1; when the decoloring agent comprises activated clay, palygorskite, bentonite, the mass ratio of activated clay, palygorskite, bentonite is (3-10):(1-3):1.

[0035] In the present application, the specific surface area of the whole decoloring agent refers to S=∑decoloring agenti(wt%)*specific surface areai; the macropore volume of the whole decoloring agent refers to V=∑decoloring agenti(wt%)*macropore volumei; in the above formula, decoloring agenti(wt%) refers to the mass ratio of decoloring agenti to the compounded decoloring agent, and specific surface areai and macropore volumei refer to the specific surface area and macropore volume of decoloring agenti, respectively. Those skilled in the art can easily calculate the whole decoloring agent surface area per oil weight or the whole decoloring agent macropore volume per oil weight after the decoloring agent is added to the oil in a specific amount.

[0036] In the present application, macropore refers to a pore with a pore width greater than 50nm.

[0037] In some embodiments, the decoloring temperature is 100-120℃, preferably 105-115℃; the decoloring time is 30-60min; and the decoloring vacuum degree is 10-200mbar.

[0038] In some embodiments, in step (5), vacuum high temperature condition is used for deodorization to remove the small amount of free fatty acid and odor substances remained in the oil; the vacuum degree of the deodorization tank is 0-500 pa (0-5 mbar); the deodorization time is 30-120 min, preferably 50-90 min; the deodorization temperature is 220-250 °C, preferably 235-245 °C, and the steam amount is 0.3 wt%-2 wt%.

[0039] In another aspect, the present application provides use of a decoloring agent to improve the freezing resistance of oil, wherein the total specific surface area of the decoloring agent is between 50 m 2 / g and 1000 m 2 / g, preferably between 150 m 2 / g and 500 m 2 / g; the total macropore volume of the decoloring agent is between 0.015 cm 3 / g and 0.035 cm 3 / g, preferably between 0.020 cm 3 / g and 0.030 cm 3 / g; when the decoloring agent is added to oil, the total specific surface area of the decoloring agent per unit weight of oil is above 150 m 2 / 100 g oil, preferably above 170 m 2 / 100 g oil, while the total macropore volume of the decoloring agent per unit weight of oil is above 0.024 cm 3 / 100 g oil.

[0040] In some embodiments, the decoloring agent can be selected from one or more of activated clay, activated carbon, attapulgite, and bentonite. In preferred embodiments, the decoloring agent comprises at least two (e.g., two, three, or four) of activated clay, activated carbon, attapulgite, and bentonite. In specific embodiments, the decoloring agent is selected from activated clay + bentonite; activated clay + attapulgite; activated clay + activated carbon + attapulgite + bentonite; activated carbon + attapulgite + bentonite; or activated clay + attapulgite + bentonite.

[0041] In some embodiments, the amount of the decoloring agent added is 0.5wt%-2.5wt% of the amount of the oil processed. When the decoloring agent comprises activated white clay and attapulgite, the mass ratio of activated white clay and attapulgite is (1-5):1; when the decoloring agent comprises activated white clay and bentonite, the mass ratio of activated white clay and bentonite is (3-15):1; when the decoloring agent comprises activated white clay, activated carbon, attapulgite and bentonite, the mass ratio of activated white clay, activated carbon, attapulgite and bentonite is (3-10):1:(2-5):1; when the decoloring agent comprises activated carbon, attapulgite and bentonite, the mass ratio of activated carbon, attapulgite and bentonite is (1-2):5:1; when the decoloring agent comprises activated white clay, attapulgite and bentonite, the mass ratio of activated white clay, attapulgite and bentonite is (3-10):(1-3):1.

[0042] Embodiment

[0043] Next, the application will be further described in detail by way of examples, but the application is not limited to these examples only.

[0044] Embodiment 1

[0045] Degumming: water was added to soybean crude oil 500g (provided by COFCO) for hydration degumming, the amount of water added was 1% (w / w) of the amount of the oil processed, and the reaction was carried out at 75°C for 30min, and after centrifugation, degummed oil was obtained.

[0046] Neutralization: 0.4wt% of phosphoric acid (85%, w / w) of the amount of the oil processed was added to the degummed oil, and the reaction was carried out at 75°C for 45min, then 1.5wt% of sodium hydroxide aqueous solution (liquid alkali concentration was 8wt%) of the amount of the oil processed was added, and the reaction was carried out at 75°C for 20min, and after warming to 85°C, centrifugation was carried out, and the oil after centrifugation was washed with 4wt%±2wt% of water and 0.2wt%±0.1wt% of phosphoric acid / citric acid, and then centrifugation was carried out again, and the oil after the second centrifugation was heated to 95°C in a container with a pressure less than 200mbar, and dried for 20min to obtain neutralized oil.

[0047] Decolorization: the neutralized oil was heated to 105°C in an environment with a pressure less than 200mbar, 1% (w / w) of the compounded decoloring agent (activated white clay: attapulgite = 5:1) was added, and adsorption was carried out for 30min to obtain decolorized oil.

[0048] Deodorization: the decolorized oil was vacuumed to a pressure of 500pa (5mbar), 0.5wt% of water vapor was introduced during processing, and heating was carried out to 245°C for deodorization for 60min to obtain refined first grade soybean oil.

[0049] Embodiment 2

[0050] Degumming: Water was added to the crude soybean oil 500g (provided by COFCO) for hydration degumming, the amount of water added was 1% (w / w) of the amount of oil processed, reacted at 70°C for 30min, after centrifugation, degummed oil was obtained.

[0051] Neutralization: 0.4wt% of phosphoric acid (85%, w / w) of the amount of oil processed was added to the degummed oil, reacted at 75°C for 45min, then 1wt% of sodium hydroxide aqueous solution (liquid alkali concentration was 12wt%) of the amount of oil processed was added, reacted at 75°C for 20min, after centrifugation, the oil was washed with 4wt%±2wt% water and 0.2wt%±0.1wt% phosphoric acid / citric acid of the amount of oil processed, then centrifuged again, the oil after the second centrifugation was heated to 95°C in a container with a pressure less than 200mbar, dried for 20min, and neutralized oil was obtained.

[0052] Decolorization: The neutralized oil was heated to 105°C in an environment less than 200mbar, 1.1% (w / w) of the compound decolorizing agent (active white clay: bentonite = 10:1) was added and adsorbed for 30min, and decolorized oil was obtained.

[0053] Deodorization: The decolorized oil was vacuumed to a pressure of 500pa (5mbar), 1wt% water vapor was introduced during processing, heated to 240°C for deodorization for 60min, and refined first grade soybean oil was obtained.

[0054] Example 3

[0055] Degumming: Water was added to the crude soybean oil 500g (provided by COFCO) for hydration degumming, the amount of water added was 1.2% (w / w) of the amount of oil processed, reacted at 75°C for 30min, after centrifugation, degummed oil was obtained.

[0056] Neutralization: 0.5wt% of phosphoric acid (85%, w / w) of the amount of oil processed was added to the degummed oil, reacted at 70°C for 45min, then 2wt% of sodium hydroxide aqueous solution (liquid alkali concentration was 8wt%) of the amount of oil processed was added, reacted at 75°C for 20min, after centrifugation, the oil was washed with 4wt%±2wt% water and 0.2wt%±0.1wt% phosphoric acid / citric acid of the amount of oil processed, then centrifuged again, the oil after the second centrifugation was heated to 95°C in a container with a pressure less than 200mbar, dried for 20min, and neutralized oil was obtained.

[0057] Decolorization: The neutralized oil was heated to 115°C in an environment less than 200mbar, 1.2% (w / w) of the compound decolorizing agent (active white clay: attapulgite = 1:1) was added and adsorbed for 30min, and decolorized oil was obtained.

[0058] Deodorization: The bleached oil was vacuumed to a pressure of 500 Pa (5 mbar) and 1.5 wt% steam was introduced during the process. The oil was heated to 235 °C for 90 min to obtain refined soybean oil.

[0059] Example 4

[0060] Degumming: The degumming was carried out by adding water to the crude soybean oil 500 g (provided by COFCO) at a ratio of 0.8% (w / w) of the processed oil. The mixture was reacted at 75 °C for 30 min. The degummed oil was obtained after centrifugation.

[0061] Neutralization: 0.5 wt% of phosphoric acid (85%, w / w) was added to the degummed oil, and the mixture was reacted at 75 °C for 45 min. Then, 1.5 wt% of sodium hydroxide solution (liquid caustic concentration of 8 wt%) was added, and the mixture was reacted at 75 °C for 20 min. The temperature was increased to 85 °C, and the oil was centrifuged. The centrifuged oil was washed with 4 wt% ± 2 wt% of water and 0.2 wt% ± 0.1 wt% of phosphoric acid / citric acid, and then centrifuged again. The oil was heated to 95 °C in a container with a pressure less than 200 mbar, and dried for 20 min to obtain the neutralized oil.

[0062] Bleaching: The neutralized oil was heated to 110 °C in an environment with a pressure less than 200 mbar. 1.5% (w / w) of the compounded bleaching agent (activated clay: attapulgite: bentonite = 4:2:1) was added, and the mixture was adsorbed for 30 min to obtain the bleached oil.

[0063] Deodorization: The bleached oil was vacuumed to a pressure of 500 Pa (5 mbar) and 0.5 wt% steam was introduced during the process. The oil was heated to 240 °C for 90 min to obtain refined soybean oil.

[0064] Example 5

[0065] Degumming: The degumming was carried out by adding water to the crude soybean oil 500 g (provided by COFCO) at a ratio of 1% (w / w) of the processed oil. The mixture was reacted at 75 °C for 30 min. The degummed oil was obtained after centrifugation.

[0066] Neutralization: 0.35 wt% of phosphoric acid (85%, w / w) was added to the degummed oil, and the mixture was reacted at 80 °C for 45 min. Then, 1.2 wt% of sodium hydroxide solution (liquid caustic concentration of 12 wt%) was added, and the mixture was reacted at 75 °C for 20 min. The temperature was increased to 85 °C, and the oil was centrifuged. The centrifuged oil was washed with 4 wt% ± 2 wt% of water and 0.2 wt% ± 0.1 wt% of phosphoric acid / citric acid, and then centrifuged again. The oil was heated to 95 °C in a container with a pressure less than 200 mbar, and dried for 20 min to obtain the neutralized oil.

[0067] Decolorization: The neutralized oil was heated to 110°C under less than 200 mbar, 1% (w / w) of the compound decolorizing agent (activated clay: activated carbon: attapulgite: bentonite = 5:1:2:1) was added and adsorbed for 30 min to obtain the decolorized oil.

[0068] Deodorization: The decolorized oil was vacuumized, the pressure was 500 pa (5 mbar), 0.5 wt% water vapor was introduced during the process, heated to 245°C for deodorization for 60 min to obtain the refined first-grade soybean oil.

[0069] Example 6

[0070] Degumming: Water was added to the soybean crude oil 500 g (provided by COFCO Group) for hydration degumming, the amount of water added was 1% (w / w) of the amount of oil processed, reacted at 75°C for 30 min, and after centrifugation, the degummed oil was obtained.

[0071] Neutralization: 0.4 wt% of phosphoric acid (85%, w / w) was added to the degummed oil, which was 0.4 wt% of the amount of oil processed, reacted at 75°C for 45 min, then 2 wt% of sodium hydroxide aqueous solution (liquid alkali concentration was 8 wt%) was added, which was 2 wt% of the amount of oil processed, reacted at 75°C for 20 min, after heating to 85°C, centrifugation was carried out, and the oil after centrifugation was washed with 4 wt% ± 2 wt% water and 0.2 wt% ± 0.1 wt% phosphoric acid / citric acid, which was 4 wt% ± 2 wt% of the amount of oil processed, and then centrifugation was carried out again. The oil after the second centrifugation was heated to 95°C in a container with a pressure of less than 200 mbar, and dried for 20 min to obtain the neutralized oil.

[0072] Decolorization: The neutralized oil was heated to 110°C under less than 200 mbar, 0.8% (w / w) of the compound decolorizing agent (activated carbon: attapulgite: bentonite = 2:5:1) was added and adsorbed for 30 min to obtain the decolorized oil.

[0073] Deodorization: The decolorized oil was vacuumized, the pressure was 500 pa (5 mbar), 0.5 wt% water vapor was introduced during the process, heated to 245°C for deodorization for 60 min to obtain the refined first-grade soybean oil.

[0074] Example 7

[0075] Degumming: Water was added to the corn crude oil 500 g (provided by COFCO Group) for hydration degumming, the amount of water added was 1.5% (w / w) of the amount of oil processed, reacted at 75°C for 30 min, and after centrifugation, the degummed oil was obtained.

[0076] Neutralization: 0.3wt% of phosphoric acid (85%, w / w) was added into the degummed oil, reacted at 80°C for 45min, then 1.5wt% of sodium hydroxide aqueous solution (liquid caustic concentration was 15wt%) was added, reacted at 75°C for 20min, then centrifuged after heating to 85°C, the centrifuged oil was washed with 4wt%±2wt% of water and 0.2wt%±0.1wt% of phosphoric acid / citric acid, then centrifuged again, the twice centrifuged oil was heated to 95°C in a container with pressure less than 200mbar, dried for 20min to obtain the neutralized oil.

[0077] Dewaxing: 0.5wt% of perlite was added into the neutralized oil, slowly cooled to 5°C, stirred at low temperature for 20h, then frozen centrifuged and filtered to obtain the dewaxed oil.

[0078] Decolorization: the dewaxed oil was heated to 115°C in an environment with pressure less than 200mbar, 2%(w / w) of compound decolorizing agent (active white clay: activated carbon: attapulgite: bentonite = 10:1:5:1) was added, adsorbed for 30min to obtain the decolorized oil.

[0079] Deodorization: the decolorized oil was vacuumized with pressure of 500pa (5mbar), 2wt% of water vapor was introduced during the process, heated to 245°C for deodorization for 60min to obtain the refined first grade corn oil.

[0080] Example 8

[0081] Degumming: water was added into 500g of crude rapeseed oil (provided by COFCO) for hydration degumming, the amount of water added was 1%(w / w) of the amount of the oil to be processed, reacted at 70°C for 30min, then centrifuged to obtain the degummed oil.

[0082] Neutralization: 0.4wt% of phosphoric acid (85%, w / w) was added into the degummed oil, reacted at 70°C for 45min, then 1.2wt% of sodium hydroxide aqueous solution (liquid caustic concentration was 10wt%) was added, reacted at 75°C for 20min, then centrifuged after heating to 85°C, the centrifuged oil was washed with 4wt%±2wt% of water and 0.2wt%±0.1wt% of phosphoric acid / citric acid, then centrifuged again, the twice centrifuged oil was heated to 95°C in a container with pressure less than 200mbar, dried for 20min to obtain the neutralized oil.

[0083] Decolorization: the neutralized oil was heated to 110°C in an environment with pressure less than 200mbar, 1.5%(w / w) of compound decolorizing agent (active white clay: attapulgite: bentonite = 10:3:1) was added, adsorbed for 30min to obtain the decolorized oil.

[0084] Deodorization: The bleached oil was vacuumed to a pressure of 500 Pa (5 mbar) and 1 wt% steam was introduced during the process. The oil was heated to 240 °C for 90 min to obtain the refined first grade rapeseed oil.

[0085] Example 9

[0086] Neutralization: To 500 g of the crude sunflower oil (provided by COFCO), 0.2 wt% of phosphoric acid (75%, w / w) was added and reacted at 75 °C for 45 min. Then, 1 wt% of sodium hydroxide solution (8 wt% of liquid caustic) was added and reacted at 75 °C for 20 min. The temperature was increased to 85 °C and the oil was centrifuged. The centrifuged oil was washed with 4 wt% ± 2 wt% of water and 0.2 wt% ± 0.1 wt% of phosphoric acid / citric acid. The oil was centrifuged again and dried at 95 °C for 20 min under a pressure of less than 200 mbar to obtain the neutralized oil.

[0087] Dewaxing: The neutralized oil was cooled to 5 °C slowly and stirred at low temperature for 20 h. The oil was frozen and centrifuged to obtain the dewaxed oil.

[0088] Bleaching: The dewaxed oil was heated to 105 °C under an environment of less than 200 mbar. 1% (w / w) of the compounded bleaching agent (active clay: bentonite = 10: 1) was added and adsorbed for 30 min to obtain the bleached oil.

[0089] Deodorization: The bleached oil was vacuumed to a pressure of 500 Pa (5 mbar) and 1 wt% steam was introduced during the process. The oil was heated to 235 °C for 60 min to obtain the refined first grade sunflower oil.

[0090] Comparative Example 1

[0091] Degumming: The crude soybean oil (500 g, provided by COFCO) was degummed by adding water. The amount of water added was 1.2% (w / w) of the amount of the oil to be processed. The mixture was reacted at 75 °C for 30 min and centrifuged to obtain the degummed oil.

[0092] Neutralization: To the degummed oil, 0.45 wt% of phosphoric acid (85%, w / w) was added and reacted at 75 °C for 45 min. Then, 1.5 wt% of sodium hydroxide solution (10 wt% of liquid caustic) was added and reacted at 75 °C for 20 min. The temperature was increased to 85 °C and the oil was centrifuged. The centrifuged oil was washed with 4 wt% ± 2 wt% of water and 0.2 wt% ± 0.1 wt% of phosphoric acid / citric acid. The oil was centrifuged again and dried at 95 °C for 20 min under a pressure of less than 200 mbar to obtain the neutralized oil.

[0093] Deodorization: The bleached oil was vacuumed to 500pa (5mbar), and 0.5wt% steam was introduced during the process. The oil was heated to 240℃ for 90min to get the refined soybean oil.

[0094] Deodorization: The bleached oil was vacuumed to 500pa (5mbar), and 0.5wt% steam was introduced during the process. The oil was heated to 240℃ for 90min to get the refined soybean oil.

[0095] Comparative Example 2

[0096] Degumming: The corn crude oil 500g (provided by COFCO) was degummed by adding water. The amount of water added was 1.5wt% of the amount of oil processed. The reaction was carried out at 75℃ for 30min. After centrifugation, the degummed oil was obtained.

[0097] Neutralization: 0.3wt% of phosphoric acid (85wt%, w / w) was added to the degummed oil, and the reaction was carried out at 75℃ for 45min. Then, 1.5wt% of sodium hydroxide aqueous solution (liquid caustic concentration was 15wt%) was added, and the reaction was carried out at 75℃ for 20min. After warming to 85℃, the oil was centrifuged. The centrifuged oil was washed with 4wt%±2wt% water and 0.2wt%±0.1wt% phosphoric acid / citric acid, and then centrifuged again. The oil obtained after the second centrifugation was heated to 95℃ in a container with a pressure of less than 200mbar, and dried for 20min to obtain the neutralized oil.

[0098] Dewaxing: 0.5wt% perlite was added to the neutralized oil, and slowly cooled to 5℃. The low-temperature stirring was carried out for 20h, and the frozen centrifugal filtration was carried out to obtain the dewaxed oil.

[0099] Bleaching: The dewaxed oil was heated to 110℃ in an environment with a pressure of less than 200mbar, and 1.2wt% of the compounded bleaching agent (activated clay: attapulgite: bentonite = 2:1:1) was added for adsorption for 30min to obtain the bleached oil.

[0100] Deodorization: The bleached oil was vacuumed to 500pa (5mbar), and 0.5wt% steam was introduced during the process. The oil was heated to 240℃ for 90min to get the refined soybean oil.

[0101] Comparative Example 3

[0102] Degumming: The rapeseed crude oil 500g (provided by COFCO) was degummed by adding water. The amount of water added was 1wt% of the amount of oil processed. The reaction was carried out at 75℃ for 30min. After centrifugation, the degummed oil was obtained.

[0103] Neutralization: 0.4wt% of phosphoric acid (85%, w / w) was added into the degummed oil, reacted at 75°C for 45min, then 1.2wt% of sodium hydroxide aqueous solution (liquid caustic concentration was 10wt%) was added, reacted at 75°C for 20min, then centrifuged after heating to 85°C, the centrifuged oil was washed with 4wt%±2wt% of water and 0.2wt%±0.1wt% of phosphoric acid / citric acid, then centrifuged again, the twice centrifuged oil was heated to 95°C in a container with pressure less than 200mbar, dried for 20min to obtain the neutralized oil.

[0104] Decolorization: the neutralized oil was heated to 110°C under the environment with pressure less than 200mbar, 1.1% (w / w) of the compound decolorizing agent (active white clay: attapulgite clay: bentonite = 2:1:1) was added and adsorbed for 30min to obtain the decolorized oil.

[0105] Deodorization: the decolorized oil was vacuumized with pressure of 500pa (5mbar), 1wt% of water vapor was introduced during the process, heated to 240°C for deodorization for 90min to obtain the refined first grade rapeseed oil.

[0106] Comparative Example 4

[0107] Neutralization: 0.2wt% of phosphoric acid (75%, w / w) was added into the crude sunflower oil 500g (provided by COFCO), reacted at 75°C for 45min, then 1wt% of sodium hydroxide aqueous solution (liquid caustic concentration was 8wt%) was added, reacted at 75°C for 20min, then centrifuged after heating to 85°C, the centrifuged oil was washed with 4wt%±2wt% of water and 0.2wt%±0.1wt% of phosphoric acid / citric acid, then centrifuged again, the twice centrifuged oil was heated to 95°C in a container with pressure less than 200mbar, dried for 20min to obtain the neutralized oil.

[0108] Dewaxing: the neutralized oil was added with 0.5wt% of perlite, slowly cooled to 5°C, low-temperature stirred for 20h, then frozen centrifuged and filtered to obtain the dewaxed oil.

[0109] Decolorization: the dewaxed oil was heated to 110°C under the environment with pressure less than 200mbar, 1% (w / w) of the compound decolorizing agent (active white clay: attapulgite clay: bentonite = 2:1:1) was added and adsorbed for 30min to obtain the decolorized oil.

[0110] Deodorization: the decolorized oil was vacuumized with pressure of 500pa (5mbar), 1wt% of water vapor was introduced during the process, heated to 235°C for deodorization for 60min to obtain the refined first grade sunflower oil.

[0111] The experimental results of the above examples and comparative examples are as follows:

[0112]

[0113] The freezing test method refers to the national standard GB / T 35877-2018.

[0114] The measurement method of the specific surface area and the large pore volume of the decolorizing agent refers to the national standard GB / T 19587-2017.

[0115] In the comparative examples, the two indicators of the specific surface area of the decolorizing agent per unit weight of oil and the large pore volume per unit weight of oil or all are lower than the recommended values, or one is lower than the recommended value, and the freezing test duration of the oil is at a lower level. By adjusting the selection, ratio and amount of the decolorizing agent and the like, when both the two indicators are higher than the recommended values, the freezing test duration of the oil can be greatly improved, and the quality of the oil can be improved.

Claims

1. A processing method for improving the antifreeze properties of edible oils, the processing method comprising the following steps: (1) Optional degumming process: optional degumming of the raw oil of edible oil; (2) Neutralization section: The oil obtained in the above steps is neutralized by adding phosphoric acid and sodium hydroxide solution in sequence; (3) Optional dewaxing stage: The oil obtained in the above steps is optionally dewaxed; (4) Decolorization stage: The oil obtained in the preceding steps is decolorized by adding a decolorizing agent, wherein the decolorizing agent is selected from at least two of activated clay, activated carbon, attapulgite, and bentonite, and the total surface area of ​​the decolorizing agent / oil weight is 150m². 2 The decolorizing agent has a macropore volume / oil weight ratio greater than 0.024 cm³ / 100g of oil. 3 / 100g oil; and (5) Deodorization section: Deodorize the oil obtained in the above steps.

2. The processing method as described in claim 1, wherein, The total surface area of ​​the decolorizing agent / oil weight is 170m². 2 / 100g or more of oil.

3. The processing method as described in claim 1 or 2, wherein, The edible oils include vegetable oils and animal oils.

4. The processing method as described in claim 3, wherein, The edible oil is a vegetable oil.

5. The processing method as described in claim 4, wherein, The vegetable oils include soybean oil, sunflower seed oil, corn oil, rapeseed oil, rice bran oil, peanut oil, flaxseed oil, cottonseed oil, palm oil, olive oil, camellia oil, safflower seed oil, perilla seed oil, tea seed oil, castor seed oil, coconut oil, wheat germ oil, walnut oil, grape seed oil, and sesame seed oil.

6. The processing method as described in claim 4, wherein, The vegetable oils mentioned are soybean oil, corn oil, rapeseed oil, sunflower seed oil, and rice bran oil.

7. The processing method as described in claim 4, wherein, The vegetable oil is soybean oil.

8. The processing method as described in claim 1 or 2, wherein, In step (4), the overall specific surface area of ​​the decolorizing agent is 50m². 2 / g-1000m 2 The decolorizing agent has a macropore volume of 0.015 cm³ / g; the overall decolorizing agent macropore volume is between / g and / g. 3 / g-0.035cm 3 Between / g.

9. The processing method as described in claim 8, wherein, In step (4), the overall specific surface area of ​​the decolorizing agent is 150 m². 2 / g-500m 2 The decolorizing agent has a macropore volume of 0.020 cm³ / g; 3 / g-0.030cm 3 Between / g.

10. The processing method as described in claim 1 or 2, wherein, The amount of the decolorizing agent added is 0.5wt%-2.5wt% of the amount of the processed oil.

11. The processing method as described in claim 10, wherein, The amount of the decolorizing agent added is 0.8wt%-2wt% of the amount of the processed oil.

12. The processing method as described in claim 1 or 2, wherein, The decolorizing agent is selected from activated clay + bentonite; activated clay + attapulgite; activated clay + activated carbon + attapulgite + bentonite; activated carbon + attapulgite + bentonite; or activated clay + attapulgite + bentonite.

13. The processing method as described in claim 12, wherein, When the decolorizing agent contains activated clay and attapulgite, the mass ratio of activated clay to attapulgite is (1-5):1; when the decolorizing agent contains activated clay and bentonite, the mass ratio of activated clay to bentonite is (3-15):1; when the decolorizing agent contains activated clay, activated carbon, attapulgite, and bentonite, the mass ratio of activated clay, activated carbon, attapulgite, and bentonite is (3-10):1:(2-5):1; when the decolorizing agent contains activated carbon, attapulgite, and bentonite, the mass ratio of activated carbon, attapulgite, and bentonite is (1-2):5:1; when the decolorizing agent contains activated clay, attapulgite, and bentonite, the mass ratio of activated clay, attapulgite, and bentonite is (3-10):(1-3):

1.

14. The processing method as described in claim 1 or 2, wherein, In step (1), degumming is carried out by hydration degumming, and the degumming conditions are a temperature of 65-80℃; the amount of water added is 0.5wt%-2wt% of the amount of the processed oil.

15. The processing method as described in claim 14, wherein, In step (1), degumming is carried out by hydration degumming, and the degumming conditions are a temperature of 70-75℃; the amount of water added is 0.5wt%-1wt% of the amount of the processed oil.

16. The processing method as described in claim 1 or 2, wherein, In step (2), at a temperature of 65-80°C, 0.01wt%-0.07wt% of 75wt%-85wt% phosphoric acid of the amount of the processed oil is added to the oil and reacted for 30-50 minutes. Then, 0.5wt%-2wt% of 6wt%-16wt% sodium hydroxide solution of the amount of the processed oil is added and reacted for 10-25 minutes. After the oil undergoes the acid-base reaction, it is heated to 85-90°C and centrifuged, and then washed with water.

17. The processing method as described in claim 16, wherein, In step (2), at a temperature of 70-75°C, 0.01wt%-0.07wt% of 75wt%-85wt% phosphoric acid of the amount of the processed oil is added to the oil and reacted for 30-50 minutes. Then, 0.5wt%-2wt% of 6wt%-16wt% sodium hydroxide solution of the amount of the processed oil is added and reacted for 10-25 minutes. After the oil undergoes the acid-base reaction, it is heated to 85-90°C and centrifuged, and then washed with water.

18. The processing method as described in claim 16, wherein, Water is added and phosphoric acid / citric acid is used for washing, wherein the amount of water added is 4wt% ± 2wt% of the amount of the processed oil, and the amount of phosphoric acid / citric acid added is 0.2wt% ± 0.1wt% of the amount of the processed oil, wherein the phosphoric acid / citric acid is 75wt%-85wt% phosphoric acid, citric acid monohydrate or a combination thereof.

19. The processing method as described in claim 1 or 2, wherein, In step (3), dewaxing is carried out by low-temperature crystallization filtration. 0.1wt%-2wt% of a crystallizer is added to the oil to be dewaxed, and the temperature is cooled to 0-10℃ for 5-20 hours.

20. The processing method as described in claim 1 or 2, wherein, In step (3), dewaxing is carried out by low-temperature crystallization filtration. 0.1wt%-0.5wt% of a crystallizing agent is added to the oil to be dewaxed, and the temperature is cooled to 4-8℃ for 15-20 hours.

21. The processing method as described in claim 19, wherein, The crystallizing agent is diatomaceous earth and / or perlite.

22. The processing method as described in claim 1 or 2, wherein, In step (4), the decolorization temperature is 100-120℃; the decolorization time is 30-60min; and the decolorization vacuum degree is 10-200mbar.

23. The processing method as described in claim 22, wherein, In step (4), the decolorization temperature is 105-115℃; the decolorization time is 30-60min; and the decolorization vacuum degree is 10-200mbar.

24. The processing method as described in claim 1 or 2, wherein, In step (5), deodorization is carried out under vacuum and high temperature conditions. The vacuum degree of the deodorization tank is 0-500 Pa; the deodorization time is 30-120 min; the deodorization temperature is 220-250℃; and the steam volume is 0.3wt%-2wt%.

25. The processing method as described in claim 24, wherein, In step (5), deodorization is carried out under vacuum and high temperature conditions. The vacuum degree of the deodorization tank is 0-500 Pa; the deodorization time is 50-90 min; the deodorization temperature is 235-245℃; and the steam volume is 0.3wt%-2wt%.

26. The use of decolorizing agents to improve the antifreeze properties of edible oils, among which, The decolorizing agent is selected from at least two of activated clay, activated carbon, attapulgite, and bentonite, and the overall specific surface area of ​​the decolorizing agent is 50 m². 2 / g-1000m 2 The decolorizing agent has a macropore volume of 0.015 cm³ / g; the overall decolorizing agent macropore volume is between / g and / g. 3 / g-0.035cm 3 Between / g; when the decolorizing agent is added to the oil, the total surface area of ​​the decolorizing agent / oil weight is 150m². 2 The decolorizing agent has a macropore volume / oil weight ratio of over 100g and a total volume of oil greater than 0.024cm³. 3 / 100g oil.

27. The use as described in claim 26, wherein, The overall decolorizing agent has a specific surface area of ​​150m². 2 / g-500m 2 The decolorizing agent has a macropore volume of 0.020 cm³ / g; 3 / g-0.030cm 3 Between / g; when the decolorizing agent is added to the oil, the total surface area of ​​the decolorizing agent / oil weight is 170m². 2 The decolorizing agent has a macropore volume / oil weight ratio of over 100g and a total volume of oil greater than 0.024cm³. 3 / 100g oil.

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