Method for temperature swing deodorization of edible oils
By using a variable-temperature deodorization method, combining different temperatures and types of steam, the problem of nutrient loss during the deodorization process of edible oils has been solved, achieving efficient removal of odor substances and retention of nutrients.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JUNAN JINSHENG CEREALS & OILS IND CO LTD
- Filing Date
- 2025-10-31
- Publication Date
- 2026-05-12
AI Technical Summary
During the deodorization process of edible oil, high temperatures cause the loss of nutrients such as vitamin E and phytosterols, and form risky components such as 3-chloropropanol esters and glycidyl esters.
A variable temperature deodorization method is adopted, including pretreatment, low-temperature deodorization, medium-temperature deodorization and high-temperature deodorization stages. Hydroxypropyltrimethylammonium chloride chitosan alkaline solution is used for pretreatment, citric acid steam deodorization is performed at low temperature, ethanol steam deodorization is performed at medium temperature, and L-ascorbic acid palmitate deodorization is performed at high temperature. The temperature and the type and amount of steam are controlled to ensure the retention of nutrients.
It significantly reduces the content of 3-chloropropanol esters and glycidyl esters, while maintaining high levels of vitamin E and phytosterols, thus improving the stability of the deodorization process and the consistency of product quality.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of edible oil refining technology and relates to a method for deodorizing edible oil by temperature variation. Background Technology
[0002] In the refining process of edible oils, deodorization is a crucial step for processing high-grade edible oils. Most of the edible oils we buy in supermarkets are first or second-grade oils. These oils undergo processes such as degumming, deacidification, decolorization, deodorization, and dewaxing in refining equipment to remove impurities and harmful substances, ensuring food safety and improving the color, transparency, and taste of the edible oil.
[0003] In oil refining, deodorization is a key process for removing off-odors. These off-odors include the oil's inherent smell and processing odors. Besides removing these off-odors, deodorization also removes free fatty acids, peroxides, polycyclic aromatic hydrocarbons, and pesticide residues, bringing them to safe levels. It also raises the smoke point of the oil, improves its flavor, and effectively enhances its safety.
[0004] The primary method for deodorizing edible oils is distillation. This process utilizes the significant difference in volatility between odor-causing substances and triglycerides. Under high temperature and high vacuum conditions, distillation removes odor-causing substances, free fatty acids, peroxides, and some heat-sensitive pigments. It also helps remove harmful components such as phthalate plasticizers and polycyclic aromatic hydrocarbons. This is a crucial step in the production of high-grade edible oils.
[0005] However, the high temperatures during the deodorization process of edible oils can also cause the loss of nutrients such as vitamin E and sterols, as well as the formation of risky components such as 3-chloropropanol esters, glycidyl esters, and trans fatty acids. Summary of the Invention
[0006] The main objective of this invention is to provide a method for deodorizing edible oil by changing the temperature. This method can significantly reduce the content of 3-chloropropanol esters and glycidyl esters during the deodorization process of corn oil, while avoiding the loss of nutrients such as vitamin E and phytosterols in corn oil due to high-temperature deodorization.
[0007] The present invention employs the following technical solutions to achieve the above objectives:
[0008] A method for deodorizing edible oil by changing temperature mainly includes the following steps:
[0009] Step 1, Preprocessing stage:
[0010] Add alkali solution to the decolorized corn oil, stir at 30 r / min and 70℃ for about 60 min, cool to room temperature, centrifuge, and take the upper layer of oil to obtain the pretreated corn oil.
[0011] Step 2, Low-temperature deodorization stage:
[0012] Pretreated corn oil is fed into a variable temperature deodorization tower with a vacuum of 0.098-0.099 MPa. The oil is slowly heated to 170-180℃ and steam containing citric acid is introduced while maintaining the temperature for 40-60 minutes. Then the steam is turned off and the oil is kept at the temperature and under vacuum for 10 minutes.
[0013] Step 3, Mesotemperature deodorization stage:
[0014] Maintain a vacuum, heat the oil to 200-210℃, and introduce ethanol vapor while keeping it at this temperature for 20-30 minutes. Then turn off the vapor, keep the oil at this temperature and maintain a vacuum for 10 minutes.
[0015] Step 4, High-temperature deodorization stage:
[0016] Maintain a vacuum, with the oil temperature at 200-210℃. Add L-ascorbic acid palmitate to the oil, stir until dissolved, and then introduce steam. While introducing steam, raise the oil temperature to 250-260℃ within 10 minutes, maintain the temperature for 5-10 minutes, turn off the steam, cool down to 160-180℃, maintain the temperature and keep the vacuum for 10 minutes.
[0017] Step 5, Post-processing stage:
[0018] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 40-50℃. After filtration and storage, the deodorized oil product is obtained.
[0019] Preferably, the volume ratio of decolorized corn oil to alkaline solution in the pretreatment stage is 10:(0.8-1).
[0020] Preferably, the alkaline solution in the pretreatment stage is a mixed solution of hydroxypropyltrimethylammonium chloride chitosan and NaOH solution.
[0021] More preferably, in the pretreatment stage, the mass fraction of hydroxypropyltrimethylammonium chloride chitosan in the alkaline solution is 5-6%, and the concentration of the NaOH solution is 0.5 mol / L.
[0022] Preferably, the mass fraction of citric acid in the water vapor containing citric acid in the low-temperature deodorization stage is 8-10%.
[0023] Preferably, the amount of water vapor containing citric acid introduced during the low-temperature deodorization stage is 1-1.5 times the oil volume per hour.
[0024] Preferably, the rate of ethanol vapor introduced during the intermediate-temperature deodorization stage is 0.8-1.2 times the oil volume per hour.
[0025] Preferably, the amount of L-ascorbate palmitate added in the high-temperature deodorization stage is 1-1.5 g / kg.
[0026] Preferably, the water vapor flow rate during the high-temperature deodorization stage is 0.5-0.8 times the oil volume per hour.
[0027] The present invention has the following beneficial effects:
[0028] In the edible oil deodorization process described in this invention, the decolorized oil is first pretreated with an alkaline solution containing hydroxypropyltrimethylammonium chloride and chitosan. The purpose is to remove chloride ions and free fatty acids from the decolorized oil. The alkaline solution can also react with some aldehydes present in the decolorized oil to generate salts and alcohols. The salts are removed by sedimentation during the pretreatment stage, and the alcohols are removed during the subsequent low-temperature deodorization process, thus removing as many odor-causing substances as possible during the pretreatment and low-temperature deodorization stages. The low-temperature deodorization stage uses steam containing citric acid. Citric acid neutralizes the residual alkaline solution from the pretreatment process and reacts with the alcohols generated during pretreatment to generate low-boiling-point esters, which are removed at low temperatures. The medium-temperature deodorization uses ethanol steam to remove some free fatty acids and long-chain aldehydes, as well as other medium-boiling-point odor-causing substances, from the corn oil. In the high-temperature deodorization process, L-ascorbic acid palmitate is first added to the oil, and then the oil temperature is rapidly raised to approximately 260°C within a short time. This quickly removes high-boiling-point odor-causing substances from the corn oil, ensuring thorough deodorization. L-Ascorbyl palmitate is usually added to the final finished oil as an antioxidant, but the inventors discovered that using it in the high-temperature deodorization stage can accelerate the high-temperature deodorization process (within 20 minutes) while retaining the beneficial nutrients such as vitamin E and phytosterols in corn oil to the greatest extent, with a vitamin E retention rate of no less than 90% and a phytosterol retention rate of no less than 85%.
[0029] The present invention can significantly improve the stability and controllability of the deodorization process, adapt to the differences in characteristics of different batches of corn oil, and ensure that the quality of each batch of products meets the standards. Detailed Implementation
[0030] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. After reading the present invention, any modifications of the present invention in various equivalent forms by those skilled in the art will fall within the scope of protection of the claims of this application.
[0031] Example 1
[0032] Step 1, Preprocessing stage:
[0033] Add 1L of alkaline solution (a mixture of hydroxypropyltrimethylammonium chloride chitosan and 0.5mol / L NaOH solution, wherein the mass fraction of hydroxypropyltrimethylammonium chloride chitosan is 5%) to 10L of decolorized corn oil, stir at 30r / min and 70℃ for about 60min, cool to room temperature, centrifuge, and take the upper oil layer to obtain the pretreated corn oil;
[0034] Step 2, Low-temperature deodorization stage:
[0035] The pretreated corn oil was fed into a variable temperature deodorization tower with a vacuum maintained at 0.098-0.099 MPa. The heater was turned on and the oil was slowly heated to 180°C. While maintaining the temperature, water vapor containing citric acid (10% by mass) was introduced. The amount of acid-containing steam introduced was 1 times the volume of oil per hour for 60 minutes. Then the steam was turned off and the oil was kept at the temperature and under vacuum for 10 minutes.
[0036] Step 3, Mesotemperature deodorization stage:
[0037] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 200℃, and introduce ethanol vapor while keeping it at the temperature. The amount of ethanol vapor introduced is 1.2 times the volume of oil per hour, and the time is 20 minutes. Then turn off the vapor, keep it at the temperature and maintain the vacuum for 10 minutes.
[0038] Step 4, High-temperature deodorization stage:
[0039] Maintain a vacuum of 0.098-0.099 MPa and an oil temperature of 200℃. Add 1.5 g / kg of L-ascorbic acid palmitate to the oil, stir to dissolve, and then introduce steam at a rate of 0.5 times the oil volume per hour. While introducing steam, raise the oil temperature to 250℃ within 10 minutes, maintain the temperature for 10 minutes, turn off the steam, cool down to 160℃, maintain the temperature and vacuum for 10 minutes.
[0040] Step 5, Post-processing stage:
[0041] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 40°C. After filtration and storage, the deodorized oil product is obtained.
[0042] Example 2
[0043] Step 1, Preprocessing stage:
[0044] Add 0.8L of alkaline solution (a mixture of hydroxypropyltrimethylammonium chloride chitosan and 0.5mol / L NaOH solution, wherein the mass fraction of hydroxypropyltrimethylammonium chloride chitosan is 6%) to 10L of decolorized corn oil, stir at 30r / min and 70℃ for about 60min, cool to room temperature, centrifuge, and take the upper oil layer to obtain the pretreated corn oil;
[0045] Step 2, Low-temperature deodorization stage:
[0046] Pretreated corn oil is fed into a variable temperature deodorization tower with a vacuum maintained at 0.098-0.099 MPa. The heater is turned on and the oil is slowly heated to 170°C. While maintaining the temperature, water vapor containing citric acid (8% by mass) is introduced. The amount of acid-containing steam introduced is 1.5 times the volume of oil per hour for 40 minutes. Then the steam is turned off and the oil is kept at the temperature and under vacuum for 10 minutes.
[0047] Step 3, Mesotemperature deodorization stage:
[0048] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 210℃, and introduce ethanol vapor while keeping it at the temperature. The amount of ethanol vapor introduced is 0.8 times the volume of oil per hour, and the time is 30 minutes. Then turn off the vapor, keep it at the temperature and maintain the vacuum for 10 minutes.
[0049] Step 4, High-temperature deodorization stage:
[0050] Maintain a vacuum of 0.098-0.099 MPa and an oil temperature of 210°C. Add 1 g / kg of L-ascorbic acid palmitate to the oil, stir to dissolve, and then introduce steam at a rate of 0.8 times the oil volume per hour. While introducing steam, raise the oil temperature to 260°C within 10 minutes, hold for 5 minutes, turn off the steam, cool down to 180°C, hold for 10 minutes while maintaining a vacuum.
[0051] Step 5, Post-processing stage:
[0052] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 50°C. After filtration and storage, the deodorized oil product is obtained.
[0053] Example 3
[0054] Step 1, Preprocessing stage:
[0055] Add 0.9L of alkaline solution (a mixture of hydroxypropyltrimethylammonium chloride chitosan and 0.5mol / L NaOH solution, wherein the mass fraction of hydroxypropyltrimethylammonium chloride chitosan is 5%) to 10L of decolorized corn oil, stir at 30r / min and 70℃ for about 60min, cool to room temperature, centrifuge, and take the upper oil layer to obtain the pretreated corn oil;
[0056] Step 2, Low-temperature deodorization stage:
[0057] Pretreated corn oil is fed into a variable temperature deodorization tower with a vacuum maintained at 0.098-0.099 MPa. The heater is turned on and the oil is slowly heated to 170°C. While maintaining the temperature, water vapor containing citric acid (9% by mass) is introduced. The amount of acid-containing steam introduced is 1.2 times the volume of oil per hour for 50 minutes. Then the steam is turned off and the oil is kept at the temperature and under vacuum for 10 minutes.
[0058] Step 3, Mesotemperature deodorization stage:
[0059] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 210℃, and introduce ethanol vapor while keeping it at the temperature. The amount of ethanol vapor introduced is 1 times the volume of oil per hour, and the time is 25 minutes. Then turn off the vapor, keep it at the temperature and maintain the vacuum for 10 minutes.
[0060] Step 4, High-temperature deodorization stage:
[0061] Maintain a vacuum of 0.098-0.099 MPa and an oil temperature of 210°C. Add 1.3 g / kg of L-ascorbic acid palmitate to the oil, stir to dissolve, and then introduce steam at a rate of 0.7 times the oil volume per hour. While introducing steam, raise the oil temperature to 250°C within 10 minutes, maintain the temperature for 8 minutes, turn off the steam, cool down to 170°C, maintain the temperature and vacuum for 10 minutes.
[0062] Step 5, Post-processing stage:
[0063] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 40°C. After filtration and storage, the deodorized oil product is obtained.
[0064] Comparative Example 1
[0065] Step 1, Low-temperature deodorization stage:
[0066] The decolorized corn oil was fed into a variable temperature deodorization tower with a vacuum maintained at 0.098-0.099 MPa. The heater was turned on and the oil was slowly heated to 170°C. Water vapor was introduced while the oil was kept at the temperature. The water vapor introduction rate was 1.2 times the oil volume / h for 50 minutes. Then the water vapor was turned off and the oil was kept at the temperature and under vacuum for 10 minutes.
[0067] Step 2, Mesotemperature deodorization stage:
[0068] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 210℃, and introduce ethanol vapor while keeping it at the temperature. The amount of ethanol vapor introduced is 1 times the volume of oil per hour, and the time is 30 minutes. Then turn off the vapor, keep it at the temperature and maintain the vacuum for 10 minutes.
[0069] Step 3, High-temperature deodorization stage:
[0070] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 250°C, and introduce steam while keeping it at the same temperature. The steam introduction rate is 0.7 times the oil volume per hour, and the time is 20 minutes.
[0071] Step 4, Post-processing stage:
[0072] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 40°C. After filtration and storage, the deodorized oil product is obtained.
[0073] Comparative Example 2
[0074] Step 1, Low-temperature deodorization stage:
[0075] The decolorized corn oil was fed into a variable temperature deodorization tower with a vacuum maintained at 0.098-0.099 MPa. The heater was turned on and the oil was slowly heated to 180°C. While maintaining the temperature, water vapor containing citric acid (9% by mass) was introduced. The amount of acidic vapor introduced was 1.2 times the volume of the oil per hour for 50 minutes. Then the steam was turned off and the oil was kept at the temperature and under vacuum for 10 minutes.
[0076] Step 2, High-Temperature Deodorization Stage:
[0077] Maintain a vacuum of 0.098-0.099 MPa and an oil temperature of 180°C. Add 1.3 g / kg of L-ascorbic acid palmitate to the oil, stir to dissolve, and then introduce steam at a rate of 0.7 times the oil volume per hour. While introducing steam, raise the oil temperature to 250°C within 30 minutes, hold for 5 minutes, turn off the steam, cool down to 180°C, hold for 10 minutes while maintaining a vacuum.
[0078] Step 4, Post-processing stage:
[0079] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 40°C. After filtration and storage, the deodorized oil product is obtained.
[0080] Comparative Example 3
[0081] Step 1, Preprocessing stage:
[0082] Add 0.9L of alkaline solution (a mixture of hydroxypropyltrimethylammonium chloride chitosan and 0.5mol / L NaOH solution, wherein the mass fraction of hydroxypropyltrimethylammonium chloride chitosan is 5%) to 10L of decolorized corn oil, stir at 30r / min and 70℃ for about 60min, cool to room temperature, centrifuge, and take the upper oil layer to obtain the pretreated corn oil;
[0083] Step 2, Low-temperature deodorization stage:
[0084] Pretreated corn oil is fed into a variable temperature deodorization tower with a vacuum maintained at 0.098-0.099 MPa. The heater is turned on and the oil is slowly heated to 170°C. Steam is introduced while the oil is kept at the temperature. The steam flow rate is 1.2 times the oil volume / h and the time is 50 min. Then the steam is turned off and the oil is kept at the temperature and under vacuum for 10 min.
[0085] Step 3, Mesotemperature deodorization stage:
[0086] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 210°C, and introduce ethanol vapor while keeping it at the temperature. The amount of ethanol vapor introduced is 1 times the volume of the oil per hour, and the time is 30 minutes. Then turn off the vapor, keep the oil at the temperature and maintain the vacuum for 10 minutes.
[0087] Step 4, High-temperature deodorization stage:
[0088] Maintain a vacuum of 0.098-0.099 MPa, heat the oil to 260°C, introduce steam at a rate of 0.7 times the oil volume per hour for 20 minutes, turn off the steam, cool down to 170°C, and maintain the temperature and vacuum for 10 minutes.
[0089] Step 5, Post-processing stage:
[0090] The corn oil that has undergone temperature-controlled deodorization is sent to a cooler and cooled by circulating water to reduce the oil temperature to 40°C. After filtration and storage, the deodorized oil product is obtained.
[0091] Performance testing
[0092] I. Changes in chloride ions, 3-chloropropanol esters, and glycidyl esters during different deodorization treatments of corn oil
[0093] The decolorized oil, the oil after low-temperature deodorization, and the deodorized oil product from Examples 1-3 and Comparative Examples 1-3 were taken respectively, and the contents of chloride ion 3-chloropropanol ester and glycidyl ester were detected. The results are shown in Table 1, Table 2, and Table 3.
[0094] Table 1. Comparison of chloride ion content (mg / kg) in different oil samples
[0095]
[0096] Table 2 Comparison of 3-chloropropanol ester content in different oil samples (mg / kg)
[0097]
[0098] Table 3 Comparison of glycidyl ester content in different oil samples (mg / kg)
[0099]
[0100] As can be seen from the results in Tables 1, 2, and 3, the decolorized oils in Examples 1-3 of this invention, after pretreatment and low-temperature deodorization, can significantly reduce the chloride ion content in the oil. The reduction of chloride ions can effectively reduce the formation of 3-chloropropanol esters in the oil during the deodorization process, thus reducing the 3-chloropropanol ester content in the deodorized oil. In addition, the increase in glycidyl ester content in the oil samples treated by the deodorization process of this invention is relatively small, and the effect is significantly better than the deodorization methods of Comparative Examples 1-3.
[0101] II. The Effects of Different Deodorization Processes on Vitamin E and Phytosterols in Corn Oil
[0102] The decolorized and deodorized oil products from Examples 1-3 and Comparative Examples 1-3 were taken respectively, and the contents of total vitamin E and total sterols in two states (lipid sterols and free sterols) were tested. The results are shown in Tables 4 and 5.
[0103] Table 4 Comparison of total vitamin E content (mg / kg) in different oil samples
[0104]
[0105] Table 5 Comparison of phytosterol content in different oil samples (mg / kg)
[0106]
[0107] As can be seen from the results in Tables 4 and 5, the deodorized oil obtained by the deodorization method described in Examples 1-3 of this invention has a high retention rate of VE and sterols and a low loss.
Claims
1. A method for temperature swing deodorization of an edible oil, characterized by, The method comprises the following steps: Step 1, pretreatment stage: Add alkali liquor to the decolorized corn oil, stir at 30 r / min and 70℃ for 60 min, cool to room temperature, centrifuge, and take the upper oil product, to obtain the pretreated corn oil; the alkali liquor is a mixed solution of hydroxypropyltrimethylammonium chloride chitosan and NaOH solution, the mass fraction of hydroxypropyltrimethylammonium chloride chitosan in the alkali liquor is 5-6%, and the concentration of the NaOH solution is 0.5 moL / L; Step 2, low-temperature deodorization stage: Put the pretreated corn oil into a variable-temperature deodorization tower with a vacuum degree of 0.098-0.099 MPa, heat the oil to 170-180℃, and pass in water vapor containing citric acid under the condition of heat preservation for 40-60 min, then close the vapor, keep heat preservation and vacuum for 10 min; Step 3, medium-temperature deodorization stage: Keep the vacuum, and heat the oil to 200-210℃, then pass in ethanol vapor under the condition of heat preservation for 20-30 min, then close the vapor, keep heat preservation and vacuum for 10 min; Step 4, high-temperature deodorization stage: Keep the vacuum, heat the oil to 200-210℃, add L-ascorbyl palmitate to the oil, stir to dissolve, then pass in water vapor, increase the oil temperature to 250-260℃ within 10 min under the condition of passing in the vapor, keep heat preservation for 5-10 min, close the vapor, cool to 160-180℃, keep heat preservation and vacuum for 10 min; Step 5, post-treatment stage: Put the corn oil after variable-temperature deodorization into a cooler, cool the oil to 40-50℃ by circulating water cooling, filter, and store, to obtain the deodorized oil product.
2. The deodorization process according to claim 1, characterized in that, The volume ratio of the decolorized corn oil to the alkali liquor in the pretreatment stage is 10:(0.8-1).
3. The deodorization process of claim 1, wherein, The mass fraction of citric acid in the water vapor containing citric acid in the low-temperature deodorization stage is 8-10%.
4. The deodorization process of claim 1, wherein, The passing-in amount of the water vapor containing citric acid in the low-temperature deodorization stage is 1-1.5 times the volume of the oil per hour.
5. The deodorization process of claim 1 wherein, The passing-in amount of the ethanol vapor in the medium-temperature deodorization stage is 0.8-1.2 times the volume of the oil per hour.
6. The deodorization process of claim 1 wherein, The adding amount of L-ascorbyl palmitate in the high-temperature deodorization stage is 1-1.5 g / kg.
7. The deodorization process of claim 1 wherein, The passing-in amount of the water vapor in the high-temperature deodorization stage is 0.5-0.8 times the volume of the oil per hour.