Thermally sensitive oil upgrading process

Abstract

The present invention discloses a process for improving the quality of heat-sensitive oils. For heat-sensitive oils rich in vitamin E and polyunsaturated fatty acids, a decolorization - medium and low temperature nitrogen and steam alternating stripping deodorization - enzymatic catalysis process is adopted to replace the traditional caustic refining - water washing - decolorization - high temperature steam deodorization process. In view of the problem that the acid value of oils is prone to increase during the decolorization and deodorization processes, the present invention proposes to carry out oil decolorization and deodorization before oil acid reduction. The increase in acid value caused during the oil decolorization and deodorization processes can bind fatty acids back to the glycerol backbone during the subsequent enzymatic catalysis process, thus effectively avoiding raw material loss. To reduce the impact of the conventional high temperature steam deodorization process on the functional substances in heat-sensitive oils, medium and low temperature nitrogen and steam are alternately used for stripping to remove the odor substances in the oils, and the quality of heat-sensitive oils is retained to the greatest extent. This process is applicable to the quality improvement of heat-sensitive functional oil raw materials rich in vitamin E, polyunsaturated fatty acids, etc., and has broad application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of oil and fat chemistry, and specifically relates to a process for improving the quality of heat-sensitive oils and fats. Background Art

[0002] Functional oils and fats rich in vitamin E and polyunsaturated fatty acids (PUFAs) have very important development prospects. Taking functional oils and fats rich in PUFAs (Polyunsaturated Fatty Acids) as an example, a large number of studies have shown that PUFAs, especially EPA (Eicosapentaenoic Acid) and DHA (Docosahexaenoic Acid), play a crucial role in reducing blood lipids, reducing thrombosis, inhibiting cardiovascular and cerebrovascular diseases, preventing cancer, and promoting nerve development and retina formation. Since the human body cannot synthesize them by itself, PUFAs are essential fatty acids for the human body and must be ingested from outside the body. Fish oil and egg yolk are rich in PUFAs. Some oils such as crude palm oil contain rich vitamin E and sterols. Extracting vitamin E and PUFAs directly from these natural functional oil and fat raw materials and further processing them into high-value-added health products have been widely used in the industry. In addition, in recent years, more attention has been paid to directly improving the quality of these functional oil and fat-rich substances and maximizing the retention of functional substances therein. These functional oil and fats can be further directly applied as raw materials or end products in food and cosmetics.

[0003] In the processing of traditional oils and fats (such as soybean oil, rapeseed oil, etc.), in order to improve the quality of the oils and fats, it is often necessary to go through processes such as caustic refining to reduce acidity, water washing, decolorization, and high-temperature steam deodorization to remove free fatty acids, pigments and other substances in the oils and fats respectively. Since the decolorization process often leads to a re-increase in the acid value, there will be a further high-temperature steam deodorization process (the temperature is generally 230-250°C) after decolorization to make the acid value in the final oil meet the requirements of relevant industries. This refining process for conventional oils and fats is not applicable to the refining of oils and fats containing heat-sensitive functional substances. Heat-sensitive functional oils and fats containing polyunsaturated fatty acids, vitamin E, etc. are extremely easy to oxidize and deteriorate during the high-temperature distillation process, seriously affecting the quality of functional oil and fat products. Summary of the Invention

[0004] The present invention aims at the technical problem that the decolorization process easily leads to an increase in the acid value of oils and fats, and provides a new quality improvement process for heat-sensitive oils and fats. The oils and fats are decolorized and deodorized at medium and low temperatures before alkali refining and acid reduction of the oils and fats, so that the increase in the acid value caused by the decolorization and deodorization process of the oils and fats can be combined with the fatty acids back to the glycerol skeleton in the subsequent enzyme catalysis process. At the same time, medium and low temperature nitrogen and water vapor are used for alternating steam stripping deodorization instead of traditional high temperature water vapor deodorization, so that the loss of functional substances such as vitamin E and polyunsaturated fatty acids is reduced to the maximum extent, and the quality and yield of the oils and fats are significantly improved.

[0005] In order to achieve the object of the present invention, the present invention provides a process for improving the quality of heat-sensitive oils and fats, comprising the following steps:

[0006] (1) Decolorizing heat-sensitive oil raw materials;

[0007] (2) The decolorized oil is subjected to alternating steam stripping and deodorization with medium-low temperature water vapor and nitrogen;

[0008] (3) The decolorized and deodorized oil is then upgraded through a lipase-catalyzed reaction.

[0009] Wherein, the temperature for the alternating stripping and deodorization of low-temperature water vapor and nitrogen in step (2) is 100°C to 120°C.

[0010] Furthermore, step (1) is carried out using kaolin, activated carbon, and diatomaceous earth alone or in combination to obtain decolorized oil.

[0011] Furthermore, step (2) is specifically as follows: the decolorized oil is deodorized at 105°C nitrogen for 30 minutes, then deodorized at 110°C water vapor for 30 minutes, then deodorized at 115°C nitrogen for 40 minutes, then deodorized at 120°C water vapor for 30 minutes, and finally deodorized at 120°C nitrogen for 30 minutes.

[0012] In the present invention, the lipase-catalyzed reaction can be carried out with or without the addition of glycerol.

[0013] Step (3) comprises: placing the decolorized and deodorized oil and immobilized lipase in an enzyme reactor, and introducing online dehydration during the enzyme catalytic reaction so that the acid value of the oil is finally lower than 0.5 mg KOH / g oil.

[0014] Furthermore, step (3) is specifically as follows: adding decolorized and deodorized oil, 0-1.2 times the molar number of free fatty acids in the oil and glycerol and 200-4000 standard enzyme activity units of lipase based on the mass of the oil into a primary or multi-stage enzyme reactor, controlling the temperature at 35°C-55°C, and reacting for 5-20 hours.

[0015] Preferably, online dehydration is to carry out moisture removal under the action of an exogenous gas such as nitrogen or carbon dioxide; the dehydration process is carried out in a system with or without vacuum.

[0016] In the present invention, the heat-sensitive oil includes but is not limited to functional oils rich in vitamin E and polyunsaturated fatty acids.

[0017] The heat-sensitive oil can be selected from at least one of shea butter, fish oil, cocoa butter, palm oil, yeast oil, microalgae oil, etc.

[0018] The lipase can be at least one of lipases derived from Candida antarctica, Thermomyces lanuginosus, Aspergillus niger, Aspergillus oryzae, Rhizomucor miehei or Rhizopus oryzae.

[0019] By means of the above technical solution, the present invention has at least the following advantages and beneficial effects:

[0020] The present invention provides a new process for improving the quality and yield of heat-sensitive functional oils. According to the characteristics of the heat-sensitive oil raw materials, the present invention first proposes a process of "decolorization - medium and low temperature nitrogen and steam alternating stripping deodorization - enzyme catalysis". By changing the order of the decolorization, deodorization and acid value reduction processes, the increase in acid value caused during the oil decolorization and deodorization processes can be solved together in the subsequent acid value reduction process, simplifying the process; at the same time, enzyme catalysis replaces the traditional alkali refining for acid value reduction. Through the catalytic action of the enzyme, the fatty acids in the oil are combined back to the glycerol backbone to form glycerides, which is carried out at normal temperature and pressure. No acids and alkalis are introduced during the process and no water washing is required, significantly improving the oil yield. At the same time, medium and low temperature (temperature not exceeding 120°C) nitrogen and steam alternating stripping deodorization is used instead of traditional high temperature (generally 230 - 250°C) steam deodorization, maximizing the retention of the quality of heat-sensitive functional substances including vitamin E and polyunsaturated fatty acids. This process has low energy consumption, simple process operation, environmental protection, and high retention rate of heat-sensitive functional substances, and is very suitable for the refining of heat-sensitive functional oils. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of improving the quality of oil by introducing online dehydration during the lipase-catalyzed reaction process in a preferred embodiment of the present invention. Among them, the medium in the absorption tank is water, which is used for absorbing the oil that may be carried out during the stripping process, and the vacuum system is used to maintain the vacuum condition in the reactor. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention provides a new process for improving the quality and yield of heat-sensitive functional oils. The "decolorization - medium and low temperature nitrogen and steam stripping deodorization - enzyme catalysis" process is used to improve the quality of heat-sensitive functional oils. Aiming at the technical problem that the acid value of oils is likely to increase during the conventional decolorization and deodorization processes, the present invention proposes to carry out decolorization and deodorization of oils before acid reduction. The increase in acid value caused during the decolorization and deodorization of oils can be utilized in the subsequent enzyme catalysis process to bind fatty acids back to the glycerol backbone by means of the enzyme catalysis function, thereby significantly improving the oil yield. At the same time, the medium and low temperature nitrogen and steam alternating stripping deodorization process is used to remove odor substances in the oils. This way of intermittently supplementing nitrogen at medium and low temperatures maximally retains the quality of heat-sensitive functional oils. Compared with the conventional high-temperature steam deodorization process, the present invention significantly improves the oil yield and maximally retains the heat-sensitive functional substances in the oils. Throughout the process, no chemical acids or alkalis are used, no water washing is required, the process is simple, the oil yield is greater than 97%, and the retention rate of functional substances such as vitamin E and polyunsaturated fatty acids in the oils exceeds 98%. This process is applicable to the quality improvement of heat-sensitive functional oil raw materials rich in vitamin E, polyunsaturated fatty acids, etc., and has very good industrial promotion and application prospects.

[0023] The decolorization and deodorization processes are placed before the acid reduction process. Enzyme-catalyzed acid reduction is used instead of traditional caustic refining acid reduction, and medium and low temperature nitrogen and steam alternating stripping are used instead of traditional high-temperature steam stripping. This invention maximally retains heat-sensitive functional substances. Specifically, aiming at the technical problem that the acid value of oils is likely to increase during the decolorization and deodorization processes of oils, the present invention proposes to first carry out decolorization and deodorization of heat-sensitive oils, so that the increase in acid value caused during the decolorization and deodorization of oils can be solved together in the subsequent acid reduction process. The acid reduction process uses enzyme catalysis instead of traditional caustic refining acid reduction. Through the catalytic action of the enzyme, the fatty acids in the oils are bound back to the glycerol backbone to form glycerides. It is carried out at normal temperature and pressure, no acids or alkalis are introduced during the process, no water washing is required, and the oil yield is significantly improved. At the same time, medium and low temperature nitrogen and steam alternating stripping deodorization are used instead of traditional high-temperature steam deodorization, which not only ensures the effective removal of odor substances, but also maximally retains the quality of heat-sensitive functional substances including vitamin E and polyunsaturated fatty acids.

[0024] The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well-known to those skilled in the art, and the raw materials used are all commercially available products.

[0025] Example 1

[0026] Thermally sensitive functional oils containing vitamin E and polyunsaturated fatty acids, such as microalgae oil, crude fish oil, crude palm oil, crude cocoa butter, crude shea butter, yeast oil, etc., are decolorized. The adsorbent can be clay, diatomaceous earth, activated carbon (used alone or in combination). The addition amount of the adsorbent is 3% based on the oil weight, the adsorption time is 3 hours, the temperature is 80 °C, and the acid value of the decolorized oil is 4 - 24 mg KOH / g oil.

[0027] Example 2

[0028] The decolorized microalgae oil, fish oil, palm oil, cocoa butter oil, shea butter oil, and yeast oil obtained in Example 1 are further subjected to medium and low temperature nitrogen and steam alternating stripping deodorization: 105 °C, nitrogen stripping for 30 minutes, then 110 °C, steam stripping for 30 minutes, further 115 °C nitrogen stripping for 40 minutes, 120 °C steam stripping for 30 minutes, 120 °C nitrogen stripping for 30 minutes, or 110 °C, nitrogen stripping for 30 minutes, then 115 °C, steam stripping for 30 minutes, further 115 °C nitrogen stripping for 40 minutes, 120 °C steam stripping for 30 minutes, 120 °C nitrogen stripping for 30 minutes. After deodorization, the acid value of the oil is 6 - 30 mg KOH / g oil.

[0029] Example 3

[0030] 40 g of the decolorized and deodorized microalgae oil (acid value 30 mg KOH / g) obtained in Example 2 is placed in an enzyme reactor, and glycerol at a multiple of 1.2 times the molar number of free fatty acids and immobilized lipase from Candida antarctica with 4000 standard enzyme activities per unit mass of oil are added, and the temperature is controlled at 35 °C for reaction. During the reaction, on-line dehydration as shown in Figure 1 is carried out (nitrogen or carbon dioxide is introduced from the bottom of the reactor, and it can be carried out under vacuum conditions). After reacting for 5 hours, the acid value of the oil is 0.48 mg KOH / g oil, the retention rates of polyunsaturated fatty acids and vitamin E are 98.6% and 98.0% respectively, and the oil yield is 98%.

[0031] Example 4

[0032] 40 g of the decolorized and deodorized shea butter oil (acid value 15 mg KOH / g) obtained in Example 2 is placed in an enzyme reactor, and glycerol at a multiple of 1 times the molar number of free fatty acids and immobilized lipase from Aspergillus oryzae with 200 standard enzyme activities per unit mass of oil are added, and the temperature is controlled at 48 °C. During the reaction, as in Figure 1Online dehydration as shown (nitrogen or carbon dioxide is introduced from the bottom of the reactor, and it can be carried out under vacuum conditions). The reaction lasts for 20 hours, the acid value of the oil is 0.45 mg KOH / g oil, the retention rates of polyunsaturated fatty acids and vitamin E are 98.5% and 98.2% respectively, and the oil yield is 98.5%.

[0033] Example 5

[0034] 40 g of decolorized and deodorized palm oil (acid value 6 mg KOH / g) obtained in Example 2 was placed in an enzyme reactor, and immobilized lipase from Rhizomucor miehei with 500 standard enzyme activities per unit mass of oil and immobilized lipase from Candida antarctica with 2000 standard enzyme activities per unit mass of oil were added, and the temperature was controlled at 40 °C. During the reaction, online dehydration as shown Figure 1 was carried out (nitrogen or carbon dioxide is introduced from the bottom of the reactor, and it can be carried out under vacuum conditions). The reaction lasted for 5 hours, the final acid value of the oil was 0.32 mg KOH / g oil, the retention rates of polyunsaturated fatty acids and vitamin E were 98.6% and 98.2% respectively, and the oil yield was 98.5%.

[0035] Example 6

[0036] 40 g of decolorized and deodorized microalgae oil (acid value 8 mg KOH / g) obtained in Example 2 was placed in an enzyme reactor, and glycerol at a multiple of 1 times the molar number of free fatty acids, immobilized lipase from Candida antarcticar with 500 standard enzyme activities per unit mass of oil, and immobilized lipase from Aspergillus oryzae with 2500 standard enzyme activities per unit mass of oil were added, and the temperature was controlled at 55 °C. During the reaction, online dehydration as shown Figure 1 was carried out (nitrogen or carbon dioxide is introduced from the bottom of the reactor, and it can be carried out under vacuum conditions). The reaction lasted for 6 hours, the final acid value of the oil was 0.42 mg KOH / g oil, the retention rates of polyunsaturated fatty acids and vitamin E were 98.0% and 98.4% respectively, and the oil yield was 98%.

[0037] Example 7

[0038] 40 g of decolorized and deodorized cocoa oil (acid value 30 mg KOH / g) obtained in Example 2 was placed in an enzyme reactor, and glycerol at a multiple of 1.2 times the molar number of free fatty acids and immobilized lipase from Aspergillus oryzae with 2500 standard enzyme activities per unit mass of oil were added, and the temperature was controlled at 35 °C. During the reaction, online dehydration as shown Figure 1Online dehydration as shown (nitrogen or carbon dioxide is introduced from the bottom of the reactor, and it can be carried out under vacuum conditions). The reaction lasts for 14 hours. The final acid value of the oil is 0.35 mg KOH / g oil, and the retention rates of polyunsaturated fatty acids and vitamin E are 98.2% and 98% respectively, and the oil yield is 97.5%.

[0039] Comparative Example 1: 40 g of cocoa oil (acid value 30 mg KOH / g) was subjected to NaOH alkaline refining deacidification, water washing, decolorization, and deodorization processes ((250 °C). The final acid value of the oil was 0.38 mg KOH / g oil, and the retention rates of polyunsaturated fatty acids and vitamin E were 86.5% and 88% respectively, and the oil yield was 80%.

[0040] Example 8

[0041] 20 g of the decolorized and deodorized microalgae oil obtained in Example 2 and 20 g of palm oil (the acid value after mixing is 16 mg KOH / g) were placed in an enzyme reactor, and 0.5 times the molar number of free fatty acids of glycerol and immobilized lipase derived from Aspergillus niger with 1200 standard enzyme activities per unit mass of oil and immobilized lipase derived from Thermomyces lanuginosus with 2800 standard enzyme activities were added, and the temperature was controlled at 55 °C. During the reaction, online dehydration as shown Figure 1 (nitrogen or carbon dioxide is introduced from the bottom of the reactor, and it can be carried out under vacuum conditions) was carried out. The reaction lasted for 8 hours. The final acid value of the oil was 0.42 mg KOH / g oil, and the retention rates of polyunsaturated fatty acids and vitamin E were 98.5% and 98.5% respectively, and the oil yield was 97.4%.

[0042] Comparative Example 2: 20 g of microalgae oil and 20 g of palm oil (the acid value after mixing is 16 mg KOH / g) were subjected to NaOH alkaline refining deacidification, water washing, decolorization, and deodorization processes (230 °C). The final acid value of the oil was 0.45 mg KOH / g oil, and the retention rates of polyunsaturated fatty acids and vitamin E were 88.5% and 92% respectively, and the oil yield was 85%.

[0043] The present invention provides a new process for improving the quality and yield of heat-sensitive oils. For heat-sensitive oils rich in vitamin E and polyunsaturated fatty acids, the process of "bleaching - medium and low temperature nitrogen and steam alternating stripping deodorization - enzyme catalysis" is adopted to replace the traditional process of "alkali refining - water washing - bleaching - high temperature steam deodorization". In view of the technical problem that the acid value of oils is likely to increase during the bleaching and deodorization processes, the present invention proposes to carry out oil bleaching and deodorization before acid reduction of the oils. The increase in acid value caused during the oil bleaching and deodorization processes can bind fatty acids back to the glycerol backbone during the subsequent enzyme catalysis process, thus effectively avoiding raw material loss. The conventional high temperature steam deodorization process has a great impact on functional substances in heat-sensitive oils such as vitamin E and polyunsaturated fatty acids. The present invention proposes to use medium and low temperature nitrogen and steam to alternately strip and remove odor substances in the oils, retaining the quality of heat-sensitive oils to the greatest extent. While significantly improving the oil yield, the present invention significantly enhances the maximum retention of heat-sensitive functional substances in the oils. The oil yield is greater than 97%, and the retention rates of functional substances such as vitamin E and polyunsaturated fatty acids in the oils exceed 98%. This process is applicable to the quality improvement of heat-sensitive functional oil raw materials rich in vitamin E, polyunsaturated fatty acids, etc., and has very good prospects for industrial promotion and application.

[0044] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A process for improving the quality of heat-sensitive oils, characterized in that, Comprising the following steps: (1) Decolorize the heat-sensitive oil raw material; (2) Subject the decolorized oil to alternate steam stripping and nitrogen stripping at medium and low temperatures; (3) Improve the quality of the decolorized and deodorized oil through lipase-catalyzed reaction; Step (2) specifically is: The decolorized oil is deodorized with nitrogen at 105°C for 30 minutes, then deodorized with steam at 110°C for 30 minutes, then deodorized with nitrogen at 115°C for 40 minutes, then deodorized with steam at 120°C for 30 minutes, and finally deodorized with nitrogen at 120°C for 30 minutes; The heat-sensitive oil includes functional oils rich in vitamin E and polyunsaturated fatty acids.

2. The process according to claim 1, characterized in that, Step (1) is carried out using bentonite, activated carbon, diatomaceous earth alone or in combination to obtain decolorized oil.

3. The process according to claim 1, characterized in that, Step (3) carries out the lipase-catalyzed reaction in the presence of glycerol.

4. The process according to claim 1, characterized in that, Step (3) includes: Placing the decolorized and deodorized oil and immobilized lipase in an enzyme reactor, and introducing on-line dehydration during the enzyme-catalyzed reaction, so that the acid value of the oil is finally lower than 0.5mgKOH / g oil.

5. The process according to claim 4, characterized in that, Step (3) specifically is: Add the decolorized and deodorized oil to a single-stage or multi-stage enzyme reactor, glycerol based on 0 - 1.2 times the molar number of free fatty acids in the oil, and lipase based on 200 - 4000 standard enzyme activity units based on the mass of the oil, control the temperature at 35°C - 55°C, and react for 5 - 20 hours.

6. The process according to claim 4, characterized in that, On-line dehydration is to carry out dehydration by taking out water under the action of an external gas nitrogen or carbon dioxide; the dehydration process is carried out in a system with or without vacuum.

7. The process according to any one of claims 1-6, characterized in that, The heat-sensitive oil is selected from at least one of shea butter, fish oil, cocoa butter, palm oil, yeast oil, and microalgae oil.

8. The process according to any one of claims 1 to 6, characterized in that, The lipase is derived from at least one of lipases of Candida antarctica, Thermomyces lanuginosus, Aspergillus niger, Aspergillus oryzae, Rhizomucor miehei, or Rhizopus oryzae.

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