Processing method for debitterizing and deodorizing linseed oil and efficiently retaining antioxidant nutrient linolenol and grease processed by same

Abstract

The invention relates to the field of food processing, and discloses a processing method for debitterizing and deodorizing linseed oil and efficiently retaining antioxidant nutrient linol and grease processed thereof.The method comprises the steps that 1, the linseed oil and a debitterizing agent are mixed to obtain debitterized linseed oil; (2) sequentially carrying out steam quenching and tempering treatment and deodorization treatment on the linseed oil to obtain deodorized linseed oil; wherein the temperature of the deodorization treatment is 45-100 DEG C higher than that of the water vapor quenching and tempering treatment. According to the method, bitter and fishy substances in the linseed oil can be efficiently removed, meanwhile, the loss of alpha-linolenic acid, linolenol (containing tocopherol, PC-8 and polyphenol) and sterol in the linseed oil is reduced, the retention rate of the alpha-linolenic acid, linolenol and sterol in the linseed oil is increased, and then the quality of the linseed oil is improved.

Description

Technical Field

[0001] The invention relates to the field of food processing, and in particular to a method for processing linseed oil to remove bitterness and fishy smell and efficiently retain linseed phenol, an antioxidant nutrient, and processed oil. Background Art

[0002] Flax is one of the world's top ten oil crops. It is mainly distributed in Northwest and North China in China, with Gansu and Ningxia as the main producing areas. It is the fourth largest oil crop after rapeseed, soybeans and peanuts. Flaxseed oil is made from flax seeds after pressing, also known as sesame oil. The obtained flaxseed oil contains a variety of functional active ingredients, such as α-linolenic acid, linoleic acid, vitamins, and flax lignans. Among them, α-linolenic acid helps lower cholesterol and blood lipids, thereby reducing the risk of cardiovascular and cerebrovascular diseases; flax lignans have a preventive effect on estrogen-dependent diseases such as breast cancer, prostate cancer, premenstrual syndrome, and osteoporosis. Therefore, flaxseed oil is popular among the public.

[0003] However, due to factors such as the flaxseed oil production process and its fatty acid composition, existing flaxseed oil products generally have a bitter and fishy taste, which affects the eating experience.

[0004] CN116349739A discloses a method for preparing deodorized linseed oil, which comprises frying linseed at 190-250°C, grinding or ultrafine grinding the fried linseed, adding boiling water and stirring, and then squeezing to obtain modified linseed meal, and finally mixing the modified linseed meal with refined linseed oil that has been degummed, deacidified and deodorized to react at high temperature to obtain linseed oil without or with low fishy smell. Although this method can remove bitter substances, the removal rate of fishy substances is low, and the high-temperature treatment will destroy the nutritional components in the linseed oil, especially the linolenic acid and α-linolenic acid content in the oil.

[0005] CN105112157A discloses a method for removing bitterness and fishy smell from linseed oil, wherein the linseed oil is contacted with a mixture of 5%-10% (by weight of oil) of shelled linseed meal and 1%-3% (by weight of oil) of diatomaceous earth, and stirred for 3h-5h. The method can remove the bitterness and fishy smell of linseed oil, but the method requires shelling of linseeds, and cold pressing of the obtained linseed kernels to obtain linseed oil. The method will cause the loss of linseed lignans and reduce the quality of linseed oil.

[0006] In summary, when removing the bitterness or fishy smell in linseed oil, the prior art focuses more on the changes in the bitter or fishy substances in the linseed oil, but is not clear about the changes in the nutrients in the linseed oil. The partial debittering and fishy removal methods will also cause an imbalance in the ratio of monounsaturated fatty acids (α-linolenic acid) and polyunsaturated fatty acids (linoleic acid) in the linseed oil, as well as the loss of nutrients (such as linolenic acid and sterols), thereby reducing the quality of the linseed oil.

[0007] As living standards improve and health awareness continues to increase, the content of nutrients in linseed oil has also attracted people's attention. Therefore, it is urgent to find a method for preparing linseed oil that can effectively remove bitter and fishy substances in linseed oil while improving the content of nutrients in linseed oil, thereby improving the quality of linseed oil. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems of low removal rate of bitter and fishy substances in linseed oil and serious loss of nutrients (especially α-linolenic acid, linolenic acid and sterols) in the prior art, and to provide a processing method for debittering and removing fishy substances from linseed oil and efficiently retaining the antioxidant nutrient linolenic acid and the processed oil. The method can effectively remove the bitter and fishy substances in linseed oil and improve the retention rate of α-linolenic acid, linolenic acid (including tocopherol, PC-8 and polyphenols) and sterols in linseed oil, thereby improving the quality of linseed oil.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for removing the fishy smell of linseed oil, wherein the method comprises sequentially subjecting the linseed oil to a steam conditioning treatment and a deodorization treatment;

[0010] The temperature of the deodorization treatment is 45-100° C. higher than the temperature of the steam conditioning treatment. The second aspect of the present invention provides a method for removing the bitterness and fishy smell of linseed oil, wherein the method comprises the following steps:

[0011] (1) mixing linseed oil with a debittering agent to obtain debittered linseed oil;

[0012] (2) According to the method of the present invention, the debittered linseed oil is subjected to steam conditioning treatment and deodorization treatment in sequence to obtain deodorized linseed oil.

[0013] The third aspect of the present invention provides linseed oil prepared by the method of the present invention.

[0014] Preferably, the content of cyclopeptide E in the linseed oil is ≤6 μg / g, the content of fishy substances is ≤5 μg / g, the content of α-linolenic acid is ≥54wt%, the content of tocopherol in linolenic acid is ≥363 μg / g, the content of PC-8 in linolenic acid is ≥170 μg / g, the content of polyphenols in linolenic acid is ≥10 μg / g, and the content of sterols is ≥5260 μg / g;

[0015] Preferably, the removal rate of cyclopeptide E in the linseed oil is ≥96%, the removal rate of fishy substances is ≥94%, the retention rate of α-linolenic acid is ≥99.5%, the retention rate of tocopherol in linolenic acid is ≥97%, the retention rate of PC-8 in linolenic acid is ≥97%, the retention rate of polyphenols in linolenic acid is ≥55%, and the retention rate of sterols is ≥95%.

[0016] Through the above technical solution, the present invention achieves the following beneficial technical effects:

[0017] (1) The method of the present invention can effectively remove bitter and fishy substances in linseed oil. In a preferred embodiment, the removal rate of cyclopeptide E and fishy substances (volatile aldehydes and ketones) is more than 95%.

[0018] (2) The method of the present invention can retain the content of α-linolenic acid, linolenic acid and sterols in linseed oil to the maximum extent, improve the retention rate of α-linolenic acid, linolenic acid and sterols in linseed oil, and thus improve the quality and applicability of linseed oil. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] In the present invention, "deodorization" and "deodorization" both refer to the removal of fishy substances in oils and fats, and can be used interchangeably.

[0021] A first aspect of the present invention provides a method for removing the fishy smell of linseed oil, wherein the method comprises sequentially subjecting the linseed oil to a steam conditioning treatment and a deodorization treatment;

[0022] The temperature of the deodorization treatment is 45-100° C. higher than the temperature of the steam conditioning treatment.

[0023] Preferably, the temperature of the deodorization treatment is 45-85° C. higher than the temperature of the steam conditioning treatment.

[0024] In the present invention, the temperature difference between the deodorization treatment and the steam conditioning treatment satisfies the above range, which can further enhance the removal effect of fishy substances (volatile aldehydes and ketones), thereby significantly reducing the content of fishy substances in linseed oil.

[0025] According to some embodiments of the present invention, the steam conditioning treatment is carried out by contacting the linseed oil with water vapor, and the mass ratio of the linseed oil to the water vapor is 100:(0.5-2).

[0026] Preferably, the mass ratio of the linseed oil to the water vapor is 100:(0.5-1).

[0027] In the present invention, the increase in moisture content in the linseed oil after conditioning treatment meets the above range, which is more conducive to reducing the proportion of fishy substances (volatile aldehydes and ketones) in the oil and achieving the enhanced removal effect of fishy substances (volatile aldehydes and ketones).

[0028] According to some embodiments of the present invention, the conditions of the steam tempering treatment include: temperature of 105-125° C., pressure of 150-250 kPa, and time of 5-20 min.

[0029] The inventors of the present invention have found that, under low temperature conditions, introducing water vapor into linseed oil for conditioning treatment can further enhance the deodorization effect, thereby improving the quality of the oil.

[0030] In the present invention, there is no special requirement for the equipment for the steam conditioning treatment, as long as it can achieve full mixing of linseed oil and steam, for example, it can be carried out in a conditioning tank.

[0031] According to some embodiments of the present invention, the deodorization method includes single-temperature deodorization and / or dual-temperature deodorization. Single-temperature deodorization refers to deodorization of linseed oil at the same temperature; dual-temperature deodorization refers to the deodorization process of linseed oil including low-temperature deodorization and high-temperature deodorization, and there is no particular limitation on the order of low-temperature deodorization and high-temperature deodorization. For example, linseed oil can be first deodorized at low temperature and then at high temperature, or first deodorized at high temperature and then at low temperature.

[0032] Preferably, the single-temperature deodorization conditions include: temperature of 170-220°C, time of 40-60 min, and pressure of 50 Pa-300 Pa.

[0033] Preferably, the dual-temperature deodorization conditions include: time of 45-60 min, and pressure of 50 Pa-300 Pa.

[0034] More preferably, the dual-temperature deodorization includes low-temperature deodorization and high-temperature deodorization, the temperature of the low-temperature deodorization is 170-190°C, the temperature of the high-temperature deodorization is 15-50°C higher than the temperature of the low-temperature deodorization, and the time of the high-temperature deodorization is 5-15min.

[0035] More preferably, the temperature of the low-temperature deodorization is 170-180°C, and the temperature of the high-temperature deodorization is 15-25°C higher than that of the low-temperature deodorization.

[0036] A second aspect of the present invention provides a method for removing the bitterness and fishy smell of linseed oil, wherein the method comprises the following steps:

[0037] (1) mixing linseed oil with a debittering agent to obtain debittered linseed oil;

[0038] (2) According to the method of the present invention, the debittered linseed oil is subjected to steam conditioning treatment and deodorization treatment in sequence to obtain deodorized linseed oil.

[0039] According to some embodiments of the present invention, the amount of the debittering agent is 1.5 wt%-3 wt%, preferably 1.5 wt%-2.5 wt%, based on the mass of the linseed oil.

[0040] According to some embodiments of the present invention, the ratio of the cumulative specific surface area of ​​the mesopores of the debittering agent to the cumulative specific surface area of ​​the pores of the debittering agent is 85%-100%, preferably 90%-97%.

[0041] According to some embodiments of the present invention, the ratio of the cumulative volume of the mesopores of the debittering agent to the cumulative volume of the pores of the debittering agent is 70%-85%, preferably 75%-82%.

[0042] In the present invention, the ratio of the cumulative specific surface area of ​​the debittering agent's mesopores to the cumulative specific surface area of ​​the pores refers to the ratio of the specific surface area of ​​the pores of the debittering agent's pores with an internal pore diameter of 2nm-50nm to the specific surface area of ​​the pores of the debittering agent's pores with an internal pore diameter of 0nm-180nm; the ratio of the cumulative volume of the debittering agent's mesopores to the cumulative volume of the pores refers to the ratio of the pore volume of the debittering agent's pores with an internal pore diameter of 2nm-50nm to the pore volume of the debittering agent's pores with an internal pore diameter of 0nm-180nm.

[0043] In the present invention, when the pore structure of the debittering agent meets the above requirements, the debittering agent can efficiently adsorb small molecules, thereby significantly improving the adsorption capacity of the debittering agent for bitter small molecule compounds (cyclopeptide E), so that the debittering agent has a better debittering effect.

[0044] In the present invention, there is no particular limitation on the type of debittering agent, as long as it has the pore structure characteristics defined above. Preferably, the debittering agent can be selected from at least one of activated clay, attapulgite, bentonite, activated carbon and silica gel.

[0045] According to some embodiments of the present invention, the mixing conditions include: temperature of 95-115° C. and time of 30-60 min.

[0046] According to some embodiments of the present invention, the method further comprises degumming and / or deacidifying the linseed oil before mixing with the debittering agent, so that the phosphorus content of the linseed oil is less than 10 ppm.

[0047] The inventors of the present invention have found that the phospholipids naturally contained in linseed oil will affect the adsorption effect of the debittering agent on the bitter substances in linseed oil, thereby affecting the quality of the oil. The phospholipids in linseed oil can be divided into hydrated phospholipids and non-hydrated phospholipids. The hydrated phospholipids are removed by a degumming process, such as by heating water, while the non-hydrated phospholipids cannot be directly removed by a hydration method, and can be removed by a deacidification process, such as by alkali refining deacidification treatment to convert the non-hydrated phospholipids into hydrated phospholipids. In order to ensure the effect of the deacidification process in removing non-hydrated phospholipids, it is necessary to use a water washing method after alkali refining deacidification to enhance the removal effect of non-hydrated phospholipids.

[0048] Preferably, the degumming method comprises: heating the linseed oil to 60-80° C., adding water at the same temperature (the amount of water is 1wt%-2wt% of the mass of the linseed oil), stirring for 10-30 minutes, separating the water phase from the oil phase, thereby removing the hydrophilic phospholipids in the linseed oil to obtain degummed oil.

[0049] Preferably, the deacidification method comprises: adding an alkali solution to the linseed oil, wherein the amount of the alkali solution added (M) is calculated according to the formula M=7.13×10 -4 ×G 油 ×AV 油 The calculation shows that, G 油 is the weight of linseed oil involved in the reaction, AV 油 is the acid value of linseed oil before alkali refining; the mass concentration of the alkali solution is 6%-10%, in order to ensure the effective removal of non-hydratable phospholipids, a certain amount of super alkali can be added on the basis of the amount of alkali solution added in actual operation, and the amount of super alkali is controlled at 0-20wt%, the oil after alkali refining is centrifuged to remove the water phase; the oil is heated to 85-95°C, water at the same temperature is added (the amount of water used is 3wt%-6wt% of the mass of the linseed oil), washed with water for 10-30 minutes, and the water phase in the oil phase is separated to obtain deacidified oil.

[0050] In the present invention, the phosphorus content of linseed oil meets the above range, the phospholipid content in linseed oil is small, and when linseed oil is mixed with a debittering agent, the pores of the debittering agent will not be blocked, the bitter substances in the linseed oil are more easily adsorbed by the debittering agent, and the removal effect of the bitter substances is better.

[0051] In the present invention, in step (2), the steam conditioning treatment and deodorization treatment are the same as those involved in the method described in the present invention, and will not be described in detail here.

[0052] According to some embodiments of the present invention, the method further comprises dewaxing the deodorized linseed oil.

[0053] In the present invention, the linseed oil after debittering and deodorizing still contains wax, which will affect the transparency of the oil and the digestion and absorption rate of the human body, and will also affect the smell and taste of the linseed oil. Therefore, dewaxing the deodorized linseed oil can obtain an oil product with better taste and quality.

[0054] Preferably, the dewaxing method comprises mixing the deodorized linseed oil with a filter aid.

[0055] More preferably, the mass ratio of the deodorized linseed oil to the filter aid is 100:(0.3-0.5).

[0056] More preferably, the filter aid is selected from at least one of diatomaceous earth, bentonite and perlite.

[0057] More preferably, the mixing conditions include: temperature of 4-8°C and time of 10-20h.

[0058] The third aspect of the present invention provides linseed oil prepared by the method of the present invention.

[0059] Preferably, the content of cyclopeptide E in the linseed oil is ≤6 μg / g, the content of fishy substances is ≤5 μg / g, the content of α-linolenic acid is ≥54wt%, the content of tocopherol in linolenic acid is ≥363 μg / g, the content of PC-8 in linolenic acid is ≥170 μg / g, the content of polyphenols in linolenic acid is ≥10 μg / g, and the content of sterols is ≥5260 μg / g;

[0060] Preferably, the removal rate of cyclopeptide E in the linseed oil is ≥96%, the removal rate of fishy substances is ≥94%, the retention rate of α-linolenic acid is ≥99.5%, the retention rate of tocopherol in linolenic acid is ≥97%, the retention rate of PC-8 in linolenic acid is ≥97%, the retention rate of polyphenols in linolenic acid is ≥55%, and the retention rate of sterols is ≥95%.

[0061] In the present invention, fishy substances refer to the sum of volatile aldehyde and ketone small molecule compounds; flax phenol refers to the general term for tocopherols and polyphenols, among which tocopherols refer to the sum of tocopherol, tocotrienols, PC-8 (Plastochromanol-8, a natural compound with a similar structure to γ-tocopherol) and its series of derivatives; polyphenols refer to the sum of free and bound polyphenols including flax lignans; sterols refer to the sum of free and esterified forms of 4-demethyl sterol compounds (including sterols, stanols and enols).

[0062] In the present invention, flaxseed is a commercial product. At present, the main producing areas of flaxseed are Russia, Kazakhstan, Canada and China, and the varieties are various. The flaxseed produced by different manufacturers has different origins or varieties, resulting in different polyphenol contents in flaxseed, and the polyphenol contents in crude flaxseed oil obtained from flaxseed are also different. The inventors of the present invention found that phenylalanine is a precursor substance for the synthesis of polyphenols, and the content of polyphenols in crude flaxseed oil is related to the content of phenylalanine in flaxseed. When the content of phenylalanine in flaxseed is greater than 1wt%, the content of polyphenols in crude flaxseed oil is high; when the content of phenylalanine in flaxseed is less than 1wt%, the content of polyphenols in crude flaxseed oil is low. The method of the present invention has no particular limitation on the polyphenol content in flaxseed (or crude flaxseed oil). The method of the present invention can retain the polyphenol content in the flaxseed oil to the maximum extent by treating crude flaxseed oil with different polyphenol contents, and improve the retention rate of polyphenols in the flaxseed oil. In particular, when the method of the present invention is used to treat flaxseed (or crude flaxseed oil) with a low polyphenol content, the loss of polyphenol content in the flaxseed oil is less, and the retention rate of polyphenols is higher.

[0063] According to a particularly preferred embodiment of the present invention, a method for removing the bitterness and fishy smell of linseed oil is provided, the method comprising the following steps:

[0064] (1) heating the degummed and deacidified linseed oil to 100-110° C., adding activated clay to the linseed oil, and performing a debittering treatment for 30-60 minutes to obtain debittered linseed oil;

[0065] The ratio of the cumulative specific surface area of ​​the mesopores of the activated clay to the cumulative specific surface area of ​​the pores of the activated clay is 90%-97%, and the ratio of the cumulative volume of the mesopores of the activated clay to the cumulative volume of the pores of the activated clay is 75%-85%.

[0066] The amount of activated clay added is 1.5wt%-2wt% of the mass of deacidified linseed oil;

[0067] (2) heating the debittered linseed oil to 110-120° C., delivering water vapor to the conditioning tank, controlling the pressure in the conditioning tank to 150-250 kPa, and fully mixing the debittered linseed oil and the water vapor for 5-20 minutes to obtain the tempered linseed oil;

[0068] The mass ratio of debittered linseed oil to water vapor is 100:0.5-1;

[0069] (3) transferring the conditioned linseed oil to a deodorizing tower, and removing the fishy smell by a dual-temperature deodorizing process (first low-temperature deodorizing and then high-temperature deodorizing) to obtain deodorized linseed oil;

[0070] Among them, the dual-temperature deodorization time is 50-60min, the high-temperature deodorization time is 5-10min, the low-temperature deodorization temperature is controlled to be 170-180℃, the high-temperature deodorization temperature is 20℃-30℃ higher than the low-temperature deodorization temperature, and the deodorization tower pressure is 100-200Pa;

[0071] (5) adding diatomaceous earth to the deodorized linseed oil, cooling the temperature to 4-8° C. and maintaining the temperature for 10-20 hours, and filtering to obtain the finished linseed oil;

[0072] Wherein, the mass ratio of linseed oil to diatomaceous earth is 100:(0.3-0.5).

[0073] The present invention will be described in detail below through examples.

[0074] Flax seeds 1 were purchased from Yiwu Shanbao Supply Chain Management Co., Ltd. The phenylalanine content in flax seeds 1 was 1.15%. The crude flax seed oil (Preparation Example 1) obtained by pressing flax seeds 1 had a high polyphenol content (89.9 μg / g).

[0075] Flaxseed 2 was purchased from Qingdao Dehui Marine Biotechnology Co., Ltd. The phenylalanine content in flaxseed 2 was 0.8%. The crude flaxseed oil (Preparation Example 2) obtained by pressing flaxseed 2 had a low polyphenol content (21.6 μg / g).

[0076] Activated clay, activated carbon, attapulgite and bentonite were purchased from Huangshan Baiyue Activated Clay Co., Ltd., Chongqing Feiyang Environmental Protection Technology Co., Ltd., Jiangsu Shenlite Biotechnology Co., Ltd. and Zhangjiakou Saibei Chemical Co., Ltd., respectively.

[0077] The ratio of the cumulative specific surface area of ​​the debittering agent's mesopores to the cumulative specific surface area of ​​the pores (%) = 100% × (specific surface area of ​​the debittering agent's pores with an internal pore diameter of 2nm-50nm / specific surface area of ​​the debittering agent's pores with an internal pore diameter of 0nm-180nm).

[0078] The ratio of the cumulative volume of the debittering agent's mesopores to the cumulative volume of the pores (%) = 100% × (the volume of the debittering agent's pores with an internal pore diameter of 2nm-50nm / the volume of the debittering agent's pores with an internal pore diameter of 0nm-180nm).

[0079] The pore specific surface area of ​​the debitter channel with an internal pore diameter of 0nm-180nm, the pore specific surface area of ​​the debitter channel with an internal pore diameter of 0nm-180nm, the pore volume of the debitter channel with an internal pore diameter of 2nm-50nm and the pore volume of the debitter channel with an internal pore diameter of 0nm-180nm are determined in accordance with "GB / T19587-2017 Determination of the Specific Surface Area of ​​Solid Substances by Gas Adsorption BET Method".

[0080] The phosphorus content of degummed / deacidified linseed oil was determined using "GB 5009.87-2016 National Food Safety Standard Determination of Phosphorus in Foods - Method 1 - Molybdenum Blue Spectrophotometry".

[0081] The moisture content of degummed / deacidified linseed oil was determined according to the method of GB / T 6283-2008 Determination of Moisture Content in Chemical Products - Karl Fischer Method (General Method) using a Swiss Metrohm (915KF) Karl Fischer Moisture Analyzer.

[0082] Unless otherwise specified, all materials were purchased from the market.

[0083] Preparation Example 1

[0084] The flax seeds 1 roasted at 60° C. for 40 min were poured into a screw press for cold pressing. After filtering, crude flax seed oil was obtained. The polyphenol content in the crude flax seed oil was 89.9 μg / g.

[0085] Preparation Example 2

[0086] The flax seeds 2 roasted at 60° C. for 40 min were poured into a screw press for cold pressing. After filtering, crude flax seed oil was obtained. The polyphenol content in the crude flax seed oil was 21.6 μg / g.

[0087] Example 1

[0088] This example is used to illustrate the use of the method of the present invention to remove the bitterness and fishy smell from linseed oil.

[0089] (1) Degumming: adding hot water at the same temperature (the amount of hot water added is 1.5 wt% of the mass of the crude linseed oil) heated to 75° C. to the crude linseed oil (Preparation Example 1), stirring for 30 min to separate phospholipids, and obtaining degummed linseed oil;

[0090] (2) deacidification: adding a sodium hydroxide solution (the mass concentration of the sodium hydroxide solution is 10%) to the above degummed linseed oil, wherein the amount of the sodium hydroxide solution added is 10wt% of the mass of the degummed linseed oil, and the oil after alkali refining is centrifuged to separate the soap stock, and then the separated liquid is heated to 90° C., and then 4wt% of the mass of the degummed linseed oil is added to the separated liquid. The separated liquid is washed with water for 10 minutes to obtain deacidified linseed oil;

[0091] Among them, the phosphorus content of deacidified linseed oil is 3.2ppm;

[0092] (3) debittering: heating the deacidified linseed oil to 105° C., adding activated white clay to the deacidified linseed oil, and debittering for 30 minutes to obtain debittered linseed oil;

[0093] Wherein, the moisture content in the debittered linseed oil is 0.1wt%;

[0094] The amount of activated clay added is 2wt% of the mass of deacidified linseed oil;

[0095] Among them, the proportion of the cumulative specific surface area of ​​the mesopores of the activated clay to the cumulative specific surface area of ​​the pores is 91.3%, and the proportion of the cumulative volume of the mesopores of the activated clay to the cumulative volume of the pores is 79.3%;

[0096] (4) Conditioning: The debittered linseed oil is heated to 115°C and then transferred to a conditioning tank. Water vapor is transported into the conditioning tank (the mass ratio of debittered linseed oil to water vapor is 100:1). The pressure in the conditioning tank is controlled to be 200 kPa. The debittered linseed oil and water vapor are fully mixed for 10 minutes to obtain tempered linseed oil.

[0097] (5) removing fishy smell: transferring the conditioned linseed oil to a deodorizing tower, and using a dual-temperature deodorization process (first low-temperature deodorization and then high-temperature deodorization) to remove the fishy smell, thereby obtaining deodorized linseed oil;

[0098] The temperature of low-temperature deodorization is controlled to be 180°C and maintained for 50 minutes, and the temperature of high-temperature deodorization is controlled to be 200°C and maintained for 10 minutes. During the fishy smell removal process, the pressure of the deodorization tower is 200Pa.

[0099] (6) Dewaxing: Add diatomaceous earth to the deodorized linseed oil, cool it to 4°C and keep it for 10 h, and filter it to obtain the finished linseed oil A1;

[0100] The amount of diatomaceous earth used is 0.5wt% of the deodorized linseed oil.

[0101] Example 2

[0102] This example is used to illustrate the use of the method of the present invention to remove the bitterness and fishy smell from linseed oil.

[0103] (1) Degumming: adding hot water at the same temperature (the amount of hot water added is 2 wt% of the mass of the crude linseed oil) heated to 60° C. to the crude linseed oil (Preparation Example 1), stirring for 30 min to separate phospholipids, and obtaining degummed linseed oil;

[0104] (2) deacidification: adding a sodium hydroxide solution (the mass concentration of the sodium hydroxide solution is 6%) to the above degummed linseed oil, wherein the amount of the sodium hydroxide solution added is 15wt% of the mass of the degummed linseed oil, and the oil after alkali refining is centrifuged to separate the soap stock, and then the separated liquid is heated to 95° C., and then isothermal hot water (6wt% of the mass of the degummed linseed oil) is added to the separated liquid, and the separated liquid is washed with water for 15 minutes to obtain deacidified linseed oil;

[0105] Among them, the phosphorus content of deacidified linseed oil is 5.7ppm;

[0106] (3) debittering: the deacidified linseed oil is heated to 115° C., a debittering agent (the mass ratio of activated clay to silica gel is 9:1) is added to the deacidified linseed oil, and debittering is performed for 40 minutes to obtain debittered linseed oil;

[0107] Wherein, the moisture content in the debittered linseed oil is 0.1wt%;

[0108] The amount of the debittering agent added is 1.5wt% of the mass of the deacidified linseed oil;

[0109] Among them, the proportion of the cumulative specific surface area of ​​the mesopores of the debittering agent to the cumulative specific surface area of ​​the pores is 95.3%, and the proportion of the cumulative volume of the mesopores of the debittering agent to the cumulative volume of the pores is 83.6%;

[0110] (4) Conditioning: The debittered linseed oil is heated to 125°C and then transferred to a conditioning tank. Water vapor is transported into the conditioning tank (the mass ratio of debittered linseed oil to water vapor is 100:0.5). The pressure in the conditioning tank is controlled to be 250 kPa. The debittered linseed oil and water vapor are fully mixed for 5 minutes to obtain tempered linseed oil.

[0111] (5) removing fishy smell: transferring the conditioned linseed oil to a deodorizing tower, and removing the fishy smell by a single-temperature deodorizing process to obtain deodorized linseed oil;

[0112] The temperature of the single-temperature deodorization is controlled to be 200°C and maintained for 50 minutes. During the odor removal process, the pressure of the deodorization tower is 250Pa.

[0113] (6) Dewaxing: Add diatomaceous earth to the deodorized linseed oil, cool it to 8°C and keep it for 20 hours, and filter it to obtain the finished linseed oil A2;

[0114] The amount of diatomaceous earth used is 0.3wt% of the deodorized linseed oil.

[0115] Example 3

[0116] This example is used to illustrate the use of the method of the present invention to remove the bitterness and fishy smell from linseed oil.

[0117] (1) Degumming: adding hot water at the same temperature (the amount of hot water added is 1 wt% of the mass of the crude linseed oil) heated to 80° C. to the crude linseed oil (Preparation Example 1), stirring for 30 min to separate phospholipids, thereby obtaining degummed linseed oil;

[0118] (2) deacidification: adding a sodium hydroxide solution (the mass concentration of the sodium hydroxide solution is 8%) to the above degummed linseed oil, wherein the amount of the sodium hydroxide solution added is 5wt% of the mass of the degummed linseed oil, and the oil after alkali refining is centrifuged to separate the soap stock, and then the separated liquid is heated to 85° C., and then 3wt% of the mass of the degummed linseed oil is added to the separated liquid. The separated liquid is washed with water for 15 minutes to obtain deacidified linseed oil;

[0119] Among them, the phosphorus content of deacidified linseed oil is 9.3ppm;

[0120] (3) debittering: heating the deacidified linseed oil to 95° C., adding attapulgite to the deacidified linseed oil, and debittering for 60 min to obtain debittered linseed oil;

[0121] The moisture content of debittered linseed oil is 0.3wt%;

[0122] The addition amount of attapulgite is 2wt% of the mass of deacidified linseed oil;

[0123] Among them, the proportion of the cumulative specific surface area of ​​the mesopores of attapulgite to the cumulative specific surface area of ​​the pores is 87.9%, and the proportion of the cumulative volume of the mesopores of attapulgite to the cumulative volume of the pores is 75.1%;

[0124] (4) Conditioning: The debittered linseed oil is heated to 105°C and then transferred to a conditioning tank. Water vapor is transported into the conditioning tank (the mass ratio of debittered linseed oil to water vapor is 100:1). The pressure in the conditioning tank is controlled to be 150 kPa. The debittered linseed oil and water vapor are fully mixed for 20 minutes to obtain tempered linseed oil.

[0125] (5) removing fishy smell: transferring the conditioned linseed oil to a deodorizing tower, and removing the fishy smell by a single-temperature deodorizing process to obtain deodorized linseed oil;

[0126] The temperature of the single-temperature deodorization is controlled to be 220°C and maintained for 60 minutes. During the odor removal process, the pressure of the deodorization tower is 200Pa.

[0127] (6) Dewaxing: Add diatomaceous earth to the deodorized linseed oil, cool it to 6°C and keep it for 15 hours, and filter it to obtain the finished linseed oil A3;

[0128] The amount of diatomaceous earth used is 0.5wt% of the deodorized linseed oil.

[0129] Example 4

[0130] The method of Example 1 was followed, except that the crude linseed oil was the crude oil obtained in Preparation Example 2, to obtain finished linseed oil A4.

[0131] Example 5

[0132] The method of Example 1 was followed, except that the degummed linseed oil was not subjected to deacidification treatment, and the phosphorus content of the degummed linseed oil was 6 ppm, to obtain finished linseed oil A5.

[0133] Example 6

[0134] Finished linseed oil A6 was obtained by the method of Example 1 except that the ratio of the cumulative specific surface area of ​​the mesopores of the activated clay to the cumulative specific surface area of ​​the channels was 85.3%, and the ratio of the cumulative volume of the mesopores of the activated clay to the cumulative volume of the channels was 73.6%.

[0135] Example 7

[0136] Finished linseed oil A7 was obtained by the method of Example 1 except that the ratio of the cumulative specific surface area of ​​the mesopores of the activated clay to the cumulative specific surface area of ​​the channels was 81.2%, and the ratio of the cumulative volume of the mesopores of the activated clay to the cumulative volume of the channels was 65.1%.

[0137] Example 8

[0138] Finished linseed oil A8 was obtained by the method of Example 1 except that the ratio of the cumulative specific surface area of ​​the mesopores of the activated clay to the cumulative specific surface area of ​​the channels was 25.2%, and the ratio of the cumulative volume of the mesopores of the activated clay to the cumulative volume of the channels was 55.1%.

[0139] Example 9

[0140] The method of Example 1 was followed, except that the amount of activated clay added was 3.5 wt % of the mass of the deacidified linseed oil, to obtain finished linseed oil A9.

[0141] Example 10

[0142] The method of Example 1 is followed, except that the mass ratio of debittered linseed oil to water vapor is 100:3, to obtain finished linseed oil A10.

[0143] Embodiment 11

[0144] The method of Example 1 was followed, except that the temperature of the conditioning treatment was 140° C., to obtain finished linseed oil A11.

[0145] Example 12

[0146] The method of Example 1 is followed, except that the temperature of high-temperature deodorization is 10° C. higher than that of low-temperature deodorization, to obtain finished linseed oil A12.

[0147] Embodiment 13

[0148] The method of Example 1 is followed, except that the linseed oil is not subjected to debittering treatment, to obtain finished linseed oil A13.

[0149] Comparative Example 1

[0150] The method of Example 1 was followed, except that the linseed oil was not subjected to conditioning treatment but the low-temperature deodorization time was extended to 60 min, and the total time of conditioning treatment and low-temperature deodorization was consistent with that of Example 1, to obtain finished linseed oil B1.

[0151] Comparative Example 2

[0152] The method of Example 1 is followed, except that no water vapor is conveyed into the conditioning tank, to obtain finished linseed oil B2.

[0153] Test Example 1

[0154] The contents of cyclopeptide E, fishy substances, α-linolenic acid, vitamin E, sterols and polyphenols in the crude linseed oil of Preparation Examples 1-2 and the finished linseed oil of the above examples and comparative examples were tested respectively (the results are shown in Table 1), and the removal rates of cyclopeptide E and fishy substances in the finished linseed oil and the retention rates of α-linolenic acid, vitamin E, sterols and polyphenols were calculated.

[0155] Fishy substances refer to the sum of volatile aldehyde and ketone small molecule compounds; flaxenol refers to the general term for tocopherols and polyphenols, among which tocopherols refer to the sum of tocopherol, tocotrienols, PC-8 (Plastochromanol-8, a natural compound with a similar structure to γ-tocopherol) and its series of derivatives; polyphenols refer to the sum of free and bound polyphenols including flax lignans; sterols refer to the sum of free and esterified forms of 4-demethylsterol compounds (including sterols, stanols and enols).

[0156] The content of cyclopeptide E was determined according to the method in "Determination of cyclopeptide A and cyclopeptide E in flaxseed oil in grain and oil inspection (Draft for comments)".

[0157] The content of fishy substances was determined according to the method of "T / CCOA 68-2023 Determination of Volatile Flavor Components in Edible Vegetable Oils by Headspace Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry".

[0158] The content of α-linolenic acid is determined according to the method of "GB 5009.168-2016 National Food Safety Standard Determination of Fatty Acids in Foods - Normalization Method, Method 3".

[0159] The tocopherol content is determined according to the method of "GB 5009.82-2016 National Food Safety Standard Determination of Vitamin A, D and E in Food Method 2".

[0160] The content of PC-8 is determined in accordance with "GB / T 26635-2011 Determination of Tocopherol and Tocotrienol Content in Animal and Plant Oils and Fats - High Performance Liquid Chromatography".

[0161] The content of polyphenols is determined in accordance with “LS / T 6119-2017 Grain and Oil Inspection-Determination of Polyphenols in Vegetable Oils-Spectrophotometric Method”.

[0162] The sterol content is determined according to the method of "GB / T 25223-2010 Determination of sterol composition and total sterol content in animal and plant oils and fats - Gas chromatography".

[0163] The removal rate of cyclopeptide E=100%×(the content of cyclopeptide E in crude linseed oil-the content of cyclopeptide E in finished linseed oil) / the content of cyclopeptide E in crude linseed oil.

[0164] Removal rate of fishy substances=100%×(content of fishy substances in crude linseed oil-content of fishy substances in finished linseed oil) / content of fishy substances in crude linseed oil.

[0165] The retention rate of α-linolenic acid (%) = 100% × (the content of α-linolenic acid in the product / the content of α-linolenic acid in the crude oil).

[0166] Tocopherol retention rate (%) = 100% × (tocopherol content in the product / tocopherol content in the crude oil).

[0167] PC-8 retention rate (%) = 100% × (PC-8 content in the product / PC-8 content in the crude oil).

[0168] The retention rate of polyphenols (%) = 100% × (polyphenol content in the product / polyphenol content in the crude oil).

[0169] Sterol retention rate (%) = 100% × (sterol content in the product / sterol content in the crude oil).

[0170] Table 1

[0171]

[0172]

[0173] By comparing Examples 1-4 with Examples 5-13, it can be seen that the linseed oil prepared by the preferred debittering and fishy smell removal method of the present invention has a higher removal rate of cyclopeptide E and fishy substances, and the retention rate of α-linolenic acid, linolenic acid and sterols in the linseed oil is also higher, which further improves the quality and applicability of the linseed oil.

[0174] Compared with the embodiments, in Comparative Example 1, no conditioning treatment was performed, and the removal rate of fishy substances in the obtained oil product decreased, and the retention rate of α-linolenic acid, linolenic acid and sterols in the oil product also decreased; in Comparative Example 2, no water vapor was transported during the conditioning treatment, and the removal rate of fishy substances in the obtained oil product decreased significantly.

[0175] In summary, this method can effectively remove bitter and fishy substances in linseed oil, reduce the loss of α-linolenic acid, linolenic acid and sterols in linseed oil, increase the retention rate of α-linolenic acid, linolenic acid and sterols in linseed oil, and thus improve the quality of linseed oil.

[0176] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for removing the fishy smell of linseed oil, It is characterized in that The method comprises sequentially subjecting linseed oil to steam conditioning treatment and deodorization treatment; The temperature of the deodorization treatment is 45-100° C. higher than the temperature of the steam conditioning treatment.

2. The method according to claim 1, in, The steam conditioning treatment is carried out by contacting the linseed oil with water vapor, wherein the mass ratio of the linseed oil to the water vapor is 100:(0.5-2); And / or, the conditions of the heat treatment include: temperature of 105-125° C., pressure of 150-250 kPa, and time of 5-20 min.

3. The method according to claim 1 or 2, in, The deodorization method includes single-temperature deodorization and / or dual-temperature deodorization; Preferably, the single-temperature deodorization conditions include: temperature of 170-220°C, time of 40-60 min, and pressure of 50 Pa-300 Pa; Preferably, the dual-temperature deodorization conditions include: time of 45-60 min, pressure of 50 Pa-300 Pa; More preferably, the dual-temperature deodorization includes low-temperature deodorization and high-temperature deodorization, the temperature of the low-temperature deodorization is 170-190°C, the temperature of the high-temperature deodorization is 15°C-50°C higher than the temperature of the low-temperature deodorization, and the time of the high-temperature deodorization is 5-15min.

4. A method for removing the bitterness and fishy smell of linseed oil, It is characterized in that The method comprises the following steps: (1) mixing linseed oil with a debittering agent to obtain debittered linseed oil; (2) The debittered linseed oil is subjected to a steam conditioning treatment and a deodorization treatment in sequence according to the method according to any one of claims 1 to 3.

5. The method according to claim 4, in, Based on the mass of the linseed oil, the amount of the debittering agent is 1.5wt%-3wt%.

6. The method according to claim 4 or 5, in, The ratio of the cumulative specific surface area of ​​the mesopores of the debittering agent to the cumulative specific surface area of ​​the pores of the debittering agent is 85%-100%, preferably 90%-97%; and / or, the ratio of the cumulative volume of the mesopores of the debittering agent to the cumulative volume of the pores of the debittering agent is 70%-85%, preferably 75%-85%; Preferably, the debittering agent is selected from at least one of activated clay, attapulgite, bentonite, activated carbon and silica gel.

7. The method according to any one of claims 4 to 6, in, The conditions for mixing with the debittering agent include: temperature of 95-115°C and time of 30-60 minutes.

8. The method according to any one of claims 4 to 5, in, The method further comprises degumming and / or deacidifying the linseed oil before mixing with the debittering agent, so that the phosphorus content of the linseed oil is less than 10 ppm.

9. The method according to claim 4, in, The method further comprises dewaxing the linseed oil after the deodorization treatment; Preferably, the dewaxing treatment method comprises mixing the deodorized linseed oil with a filter aid; More preferably, the mass ratio of the deodorized linseed oil to the filter aid is 100:(0.3-0.5); More preferably, the filter aid is selected from at least one of diatomaceous earth, bentonite and perlite; More preferably, the conditions for mixing with the filter aid include: temperature of 4-8° C. and time of 10-20 h.

10. A linseed oil, It is characterized in that The linseed oil is prepared by the method according to any one of claims 4 to 9; Preferably, the content of cyclopeptide E in the linseed oil is ≤6 μg / g, the content of fishy substances is ≤5 μg / g, the content of α-linolenic acid is ≥54wt%, the content of tocopherol in linolenic acid is ≥363 μg / g, the content of PC-8 in linolenic acid is ≥170 μg / g, the content of polyphenols in linolenic acid is ≥10 μg / g, and the content of sterols is ≥5260 μg / g; Preferably, the removal rate of cyclopeptide E in the linseed oil is ≥96%, the removal rate of fishy substances is ≥94%, the retention rate of α-linolenic acid is ≥99.5%, the retention rate of tocopherol in linolenic acid is ≥97%, the retention rate of PC-8 in linolenic acid is ≥97%, the retention rate of polyphenols in linolenic acid is ≥55%, and the retention rate of sterols is ≥95%.

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