Method for degumming corn crude oil by using lipase and phospholipase

Abstract

The invention relates to the technical field of corn oil degumming, in particular to a method for degumming crude corn oil by using lipase and phospholipase, which comprises the following steps: (1) putting the crude corn oil into lipase for enzymolysis reaction; (2) after the reaction, adding citric acid for acidification treatment; (3) adding alkali to adjust the pH value of the system to 4-5 after acidification; (4) adjusting the pH value, adding phospholipase into the system, and carrying out an enzymatic hydrolysis reaction; and (5) after the reaction, heating, preserving heat and separating to obtain the degummed corn oil. According to the method, the lipase is firstly used for pretreatment, so that phospholipase is more efficient in the subsequent degumming process, the phosphorus content in the refined corn oil is reduced, the loss of neutral oil is reduced, and the quality of finished oil is improved.

Description

Technical Field

[0001] The invention relates to the technical field of corn oil degumming, and in particular to a method for degumming corn crude oil by utilizing lipase and phospholipase. Background Art

[0002] Corn oil degumming is an important step in the corn oil refining process. Its main purpose is to remove phospholipids and other colloidal impurities in the oil to improve the purity and stability of the oil. The presence of phospholipids will cause the oil to precipitate during storage, affecting the transparency and flavor of the oil. Through degumming, the stability of corn oil can be significantly improved and its shelf life can be extended.

[0003] The traditional corn oil refining process usually uses a chemical method of acidification for degumming, which has problems such as high energy consumption and serious environmental pollution. In the chemical degumming process, a large amount of acid and alkali are needed to adjust the pH value to promote the hydrolysis of phospholipids and form colloids, and then the colloids are separated by physical methods such as centrifugation. However, this method not only consumes a large amount of chemicals, but also produces a large amount of wastewater, causing serious pollution to the environment. In addition, the chemical degumming process often requires higher temperatures and longer times, resulting in higher energy consumption and increasing production costs.

[0004] In recent years, with the increasing awareness of environmental protection and the continuous improvement of food quality requirements, enzymatic degumming has attracted widespread attention due to its environmental protection and high efficiency.

[0005] Enzymatic degumming mainly uses specific enzymes (such as phospholipases) to hydrolyze phospholipid molecules to achieve the purpose of degumming. This method not only reduces the use of chemicals and reduces environmental pollution, but also has a low operating temperature and relatively low energy consumption. However, single enzymatic degumming has certain limitations in practical applications, such as the degumming effect is not thorough enough, and it is difficult to completely remove the phospholipid components in the oil, resulting in the quality of the finished oil failing to meet high standards. Summary of the invention

[0006] In view of the problem of low removal rate of phosphorus components in corn oil enzymatic degumming, the present invention provides a method for degumming corn crude oil using lipase and phospholipase. First, lipase is used for pretreatment, so that phospholipase is more efficient in the subsequent degumming process, the phosphorus content in refined corn oil is reduced, the loss of neutral oil is reduced, and the quality of finished oil is improved.

[0007] The present invention provides a method for degumming corn crude oil by using lipase and phospholipase, comprising the following steps: (1) Adding lipase to corn oil for enzymatic hydrolysis; (2) Adding citric acid for acidification after the reaction; (3) After acidification, add alkali to adjust the system pH to 4-5; (4) After adjusting the pH value, phospholipase is added to the system for enzymatic hydrolysis; (5) After the reaction, the temperature is raised, kept warm, and separated to obtain degummed corn oil.

[0008] Furthermore, in step (1), the lipase is one of Lipase B and Novozyme 435, and the amount of lipase added is 0.003% to 0.01% of the mass of the crude corn oil.

[0009] Furthermore, in step (1), the temperature of the enzymatic hydrolysis reaction is 30-50°C, and the reaction time is 0.5-2h.

[0010] Furthermore, in step (2), the amount of citric acid added is at least 0.054% by weight of the crude corn oil, and the acidification temperature is 70-90°C.

[0011] Furthermore, in step (4), the phospholipase is at least one of phospholipase A1, phospholipase A2, and phospholipase C, and the amount of phospholipase added is 0.004% to 0.01% by weight of the crude corn oil.

[0012] Furthermore, in step (4), the enzymatic hydrolysis reaction is carried out in a high-speed homogenizer, with a stirring speed of 500-700 rpm, a reaction temperature of 50-70° C., and a reaction time of 1-3 h.

[0013] Furthermore, in step (5), the temperature is raised to 80-90° C. and the heat preservation time is 30-45 min.

[0014] Furthermore, in step (5), separation is performed by using a continuous centrifuge for solid-liquid separation.

[0015] The beneficial effects of the present invention are: (1) The present invention can release more free fatty acids through lipase enzymatic pretreatment, and these free fatty acids are more easily removed in the subsequent phospholipase degumming process, thereby improving the degumming efficiency.

[0016] (2) The enzymatic pretreatment of the lipase of the present invention releases free fatty acids, which can change the structure of the oil and create favorable conditions for the subsequent phospholipase degumming, making the phospholipase more efficient in the degumming process, reducing the loss of neutral oil, and thus improving the quality of the finished oil.

[0017] (3) Compared with the traditional chemical degumming method, the present invention reduces the energy consumption in the heating and cooling processes and reduces the overall energy consumption. At the same time, the present invention reduces the use of acid and alkali chemicals and reduces the impact of chemicals on the environment.

[0018] (4) The present invention can significantly improve the degumming efficiency, reduce the generation of by-products, and improve the yield and quality of the final product by using lipase and phospholipase in combination.

[0019] (5) The method of the present invention is simple to operate, easy to realize automatic control, and suitable for large-scale industrial production. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0021] Example 1 2 tons of corn crude oil (phosphorus content 245.42ppm) were heated to 40℃, lipase Novozyme 435 (manufacturer: Novozymes, added in an amount of 0.005wt%) was added, and the reaction was carried out at 500rpm and 40℃ for 1h. The corn crude oil pretreated with lipase was heated to 70℃ by a heat exchanger, citric acid solution was added and homogenized at high speed in an acidification reaction tank. The mass of citric acid contained in the citric acid solution was 0.061% of the mass of corn crude oil. The reaction was stirred for 30min under this condition for acidification. After the acidified corn crude oil came out of the acidification reaction tank, it was cooled to 50℃ by a heat exchanger, and then a 4% sodium hydroxide solution was added at a concentration of 6.4L per ton of oil to adjust the system pH to 4~5. At the same time, soft water below 55℃ was added at a concentration of 20L per ton of oil, and stirring was continued for 5min at 50℃ and 500rpm. Then, phospholipase A1 (addition amount is 0.005wt%) was added, and a high-speed homogenizer was used for homogenization. After homogenization and mixing, it was put into the enzyme reaction tank, stirred and kept at 50°C for enzymatic reaction, the stirring speed was 500rpm, and the reaction time was 2h. After the enzymatic reaction, the crude oil was heated to 80°C by a heat exchanger and then entered the temporary storage tank, where it was kept warm for 30min. Finally, a continuous centrifuge was used to separate the reaction products, and the oil phase was recovered to obtain degummed corn oil (phosphorus content 8.86ppm).

[0022] Example 2 1.5 tons of corn crude oil (phosphorus content 575.42ppm) was heated to 30℃, lipase Novozyme 435 (manufacturer: Novozymes, added in an amount of 0.003wt%) was added, and the reaction was carried out at 500rpm and 30℃ for 1h. The corn crude oil pretreated with lipase was heated to 80℃ by a heat exchanger, citric acid solution was added and homogenized at high speed in an acidification reaction tank. The mass of citric acid contained in the citric acid solution was 0.054% of the mass of corn crude oil. Under this condition, the reaction was stirred for 30min for acidification. After the acidified corn crude oil came out of the acidification reaction tank, it was cooled to 50℃ by a heat exchanger, and then a 4% sodium hydroxide solution was added at a concentration of 6.0L per ton of oil to adjust the system pH to 4~5. At the same time, soft water below 55℃ was added at a concentration of 20L per ton of oil, and stirring was continued for 5min at 50℃ and 500rpm. Then, phospholipase A2 (0.01wt%) was added, and the mixture was homogenized using a high-speed homogenizer. After being uniformly mixed, the mixture was put into the enzyme reaction tank, stirred and kept at 60°C for enzymatic reaction. The stirring speed was 600rpm and the reaction time was 1h. After the enzymatic reaction, the crude oil was heated to 90°C by a heat exchanger and then put into a temporary storage tank for 40min of heat preservation. Finally, the reaction product was separated by a continuous centrifuge, and the oil phase was recovered to obtain degummed corn oil (phosphorus content 5.32ppm).

[0023] Example 3 2.3 tons of corn crude oil (phosphorus content 875.42ppm) was heated to 50℃, lipase Novozyme 435 (manufacturer: Novozymes, added in an amount of 0.01wt%) was added, and the reaction was carried out at 500rpm and 50℃ for 1h. The corn crude oil pretreated with lipase was heated to 90℃ by a heat exchanger, citric acid solution was added and homogenized at high speed in an acidification reaction tank. The mass of citric acid contained in the citric acid solution was 0.072% of the mass of corn crude oil. Under this condition, the reaction was stirred for 40min for acidification. After the acidified corn crude oil came out of the acidification reaction tank, it was cooled to 50℃ by a heat exchanger, and then a 4% sodium hydroxide solution was added at a concentration of 6.2L per ton of oil to adjust the system pH to 4~5. At the same time, soft water below 55℃ was added at a concentration of 20L per ton of oil, and stirring was continued for 5min at 50℃ and 500rpm. Then, phospholipase C (added amount is 0.004wt%) was added, and a high-speed homogenizer was used for homogenization. After homogenization and mixing, it was put into the enzyme reaction tank, stirred and kept at 70℃ for enzymatic reaction, the stirring speed was 700rpm, and the reaction time was 3h. After the enzymatic reaction, the crude oil was heated to 85℃ by the heat exchanger and then entered the temporary storage tank, where it was kept warm for 35min. Finally, a continuous centrifuge was used to separate the reaction products, and the oil phase was recovered to obtain degummed corn oil (phosphorus content 4.82ppm).

[0024] Comparative Example 1 2 tons of corn crude oil (phosphorus content 245.42ppm) were heated to 70℃, 0.24L of 45% citric acid solution was added per ton of oil and homogenized at high speed in the acidification reaction tank. Under this condition, the reaction was stirred for 30min for acidification. After the acidified corn crude oil came out of the acidification reaction tank, it was cooled to 50℃ through a heat exchanger, and then 6.4L of 4% sodium hydroxide solution was added per ton of oil to adjust the pH value of the system to 4~5. At the same time, soft water below 55℃ was added per ton of oil at 20L, and stirring was continued for 5min at 50℃ and 500rpm. Then, phospholipase A1 (added amount was 0.005wt%) was added, and homogenized with a high-speed homogenizer. After homogenization and mixing, it entered the enzyme reaction tank, stirred and kept warm at 50℃ for enzymatic reaction, the stirring speed was 500rpm, and the reaction time was 2h. The crude oil after the enzymatic reaction was heated to 80°C through a heat exchanger and then entered into a temporary storage tank, where it was kept warm for 30 minutes. Finally, a continuous centrifuge was used to separate the reaction products, and the oil phase was recovered to obtain degummed corn oil (phosphorus content: 65.11 ppm).

[0025] It can be seen from Examples 1-3 that the degumming method provided by the present invention can significantly reduce the phosphorus content in corn oil. At the same time, it can be seen from Comparative Example 1 that the phosphorus content of the degummed corn oil without lipase pretreatment is 65.11 ppm, which is significantly greater than the phosphorus content of the corn oil obtained under the same phospholipase treatment conditions in Example 1, indicating that the combined use of lipase and phospholipase of the present invention can significantly improve the degumming effect and improve the yield and quality of the final product.

[0026] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A method for degumming corn crude oil using lipase and phospholipase, characterized in that: The steps include: (1) Adding lipase to corn oil for enzymatic hydrolysis; (2) Adding citric acid for acidification after the reaction; (3) After acidification, add alkali to adjust the system pH to 4-5; (4) After adjusting the pH value, phospholipase is added to the system for enzymatic hydrolysis; (5) After the reaction, the temperature is raised, kept warm, and separated to obtain degummed corn oil.

2. The method for degumming crude corn oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (1), the lipase is one of Lipase B and Novozyme 435, and the amount of lipase added is 0.003% to 0.01% of the mass of the crude corn oil.

3. The method for degumming corn crude oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (1), the temperature of the enzymatic hydrolysis reaction is 30-50°C, and the reaction time is 0.5-2h.

4. The method for degumming crude corn oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (2), the amount of citric acid added is at least 0.054% of the mass of the crude corn oil, and the acidification temperature is 70-90°C.

5. The method for degumming crude corn oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (4), the phospholipase is at least one of phospholipase A1, phospholipase A2, and phospholipase C, and the amount of phospholipase added is 0.004% to 0.01% by weight of the crude corn oil.

6. The method for degumming corn crude oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (4), the enzymatic hydrolysis reaction is carried out in a high-speed homogenizer, the stirring speed is 500-700 rpm, the reaction temperature is 50-70° C., and the reaction time is 1-3 h.

7. The method for degumming corn crude oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (5), the temperature is raised to 80-90° C. and the heat preservation time is 30-45 minutes.

8. The method for degumming corn crude oil using lipase and phospholipase as claimed in claim 1, characterized in that: In step (5), separation is performed by using a continuous centrifuge for solid-liquid separation.