Method for producing fatty acid and fatty acid

Abstract

The present invention provides a method for producing fatty acids and fatty acids. The method for producing fatty acids of the present invention comprises: a pretreatment step, contacting a soap stock with a first acid to obtain a pretreated soap stock, wherein the ratio of fat to soap in the pretreated soap stock is 1:0.15 to 1:0.55, and the pH of the contact system is 6 to 7.5; an enzymatic reaction step, contacting the pretreated soap stock with a hydrolase for enzymatic reaction to obtain an enzymatic mixture; and an acidification reaction step, contacting the enzymatic mixture obtained in the enzymatic reaction step with a second acid for acidification reaction. The production method of the present invention can greatly reduce the amount of enzyme used and the enzymatic time in the enzymatic reaction, significantly improve the hydrolysis efficiency, and can obtain fatty acids with a high conversion rate in a short time using a small amount of enzyme.

Description

Technical Field

[0001] The invention relates to the field of oil processing, and relates to a method for producing fatty acids and fatty acids, and in particular to a method for producing fatty acids by hydrolyzing soapstock using an enzymatic method and fatty acids produced by the method. Background Art

[0002] Soapstock is a byproduct in the oil refining process, and the total amount accounts for 5-6% of the oil production. Its components mainly include: water, neutral oil (glyceride), soap (sodium fatty acid), free fatty acid, phospholipid and lipid, pigment and other substances, wherein neutral oil and sodium fatty acid salt account for 35-50% of the soapstock mass in total. Therefore, soapstock is a suitable raw material for producing mixed fatty acids, wherein the fatty acid existing in the form of sodium fatty acid salt can be decomposed by sulfuric acid, and the fatty acid existing in the form of neutral oil can be decomposed by hydrolysis. There are three main methods for producing fatty acids from soapstock, namely hydrolysis acidification method, saponification acidolysis method and acid hydrolysis method. Acid hydrolysis method is more adopted in production relative to the other two methods.

[0003] The traditional acid hydrolysis method for preparing fatty acids is to first heat the soap stock to above 90°C, then add 6-8% concentrated sulfuric acid to acidify and layer for several hours or even days to obtain acidified oil, then wash the acidified oil with water, and then use high temperature and high pressure hydrolysis to hydrolyze the glyceride into free fatty acids, and then distill to obtain crude fatty acid products. Although this process is widely used in production, it has the disadvantages of high energy consumption, serious pollution, high equipment requirements for the hydrolysis reaction, and easy occurrence of side reactions during the hydrolysis process, resulting in reduced quality and yield of fatty acid products.

[0004] Therefore, in view of the shortcomings of the acidification hydrolysis method, many documents have reported some new methods, such as hot hydrolysis acidification method (patent application CN201780003789.8), subcritical acetic acid method (patent application CN201210340293.9), short-path distillation acidification method (patent application CN200610086288.4), etc., but these methods all have the disadvantages of complex process flow, catalyst is not easy to obtain or high cost. In addition, after the neutral oil part in the soap stock is completely hydrolyzed by enzyme method, the acidification reaction is carried out again, and the soap stock can be directly converted into fatty acids in one step, avoiding the high temperature and high pressure hydrolysis reaction of the acidified oil, thereby greatly reducing energy consumption, and being a green environmental protection process, but patent application CN200810110995.1 and patent application CN201310185942.7 report the method of hydrolyzing oil or soap stock by enzyme method, the hydrolysis time is up to 36h, the enzyme usage is large, and the glyceride conversion rate in the soap stock is low. Summary of the invention

[0005] Problem that the invention aims to solve

[0006] Existing enzymatic hydrolysis of lipid substances has the disadvantages of low hydrolysis rate (for example, generally around 70%), long reaction time (for example, 1 to 3 days), high enzyme cost (large amount of enzyme used), etc. Therefore, the purpose of the present invention is to provide a method for producing fatty acids, which directly prepares fatty acids by pre-treating soap stock, then enzymatically hydrolyzing and high-temperature acidifying in one pot. The production method of the present invention can greatly reduce the enzyme dosage and enzymatic hydrolysis time in the enzymatic hydrolysis reaction, and significantly improve the hydrolysis efficiency. The present invention can obtain fatty acids with high conversion rate using a small amount of enzyme in a short time.

[0007] Solutions for solving problems

[0008] The present inventors have conducted intensive research to achieve the above-mentioned object, and found that the above-mentioned object can be achieved by implementing the following technical solutions.

[0009] That is, the present invention is as follows.

[0010] [1] A method for producing a fatty acid, the method comprising:

[0011] A pretreatment step, contacting the soap stock with a first acid to obtain a pretreated soap stock, wherein the mass ratio of fat (in terms of glycerides and free fatty acids) to soap (in terms of sodium fatty acids) in the pretreated soap stock is 1:0.15 to 1:0.55, and the pH of the contact system is 6 to 7.5;

[0012] an enzymatic reaction step, wherein the pretreated soapstock is contacted with a hydrolase to perform an enzymatic reaction to obtain an enzymatic mixture; and

[0013] The acidification reaction step is to contact the enzymatic hydrolysis mixture obtained in the enzymatic hydrolysis reaction step with a second acid to carry out an acidification reaction.

[0014] [2] The production method according to [1], wherein the soap stock comprises at least one selected from the group consisting of soybean oil soap stock, cottonseed oil soap stock, corn oil soap stock, rapeseed oil soap stock, sunflower oil soap stock, peanut oil soap stock, rice bran oil soap stock, lard soap stock, beef tallow soap stock and sheep oil soap stock;

[0015] Preferably, the moisture content of the soap stock is 40-60%.

[0016] [3] The method according to [1] or [2], wherein the first acid comprises a strong acid having a pKa of less than 1 and / or a weak acid having a pKa of greater than 4;

[0017] Preferably, the strong acid having a pKa of less than 1 comprises at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid and trichloroacetic acid;

[0018] The weak acid having a pKa greater than 4 comprises at least one selected from the group consisting of acetic acid, citric acid, propionic acid, butyric acid, valeric acid, sorbic acid and lactic acid.

[0019] [4] The production method according to any one of [1] to [3], wherein the mass ratio of fat (calculated as glycerides and free fatty acids) to total emulsifier (calculated as soap and phospholipids) in the pretreated soap stock is 1:0.35 or more.

[0020] [5] The production method according to any one of [1] to [4], wherein the first acid is used in an amount of 1 to 3% by mass relative to the total amount of soapstock.

[0021] [6] The method according to any one of [1] to [5], wherein the hydrolase comprises triglyceride hydrolase and / or partial glyceride hydrolase;

[0022] Preferably, the triglyceride hydrolase comprises at least one triglyceride hydrolase derived from the group consisting of Thermomyces lanuginosus, Candida antarctica, Rhizomucor miehei, Aspergillus niger, Candida plicata and Pseudomonas;

[0023] The partial glyceride hydrolase includes a partial glyceride hydrolase derived from at least one of the group consisting of Penicillium camembert, Penicillium toruloides, Aspergillus oryzae, and Malassezia sphaeroides.

[0024] [7] The method according to any one of [1] to [6], wherein the amount of the hydrolase used is 0.01 to 0.05% by mass relative to the total amount of the soapstock;

[0025] Preferably, the pretreated soapstock and the hydrolase are subjected to an enzymatic hydrolysis reaction at 30-50°C;

[0026] The enzymatic reaction time is 2 to 4 hours.

[0027] [8] The method according to any one of [1] to [7], wherein the second acid comprises a strong acid having a pKa of less than 1;

[0028] Preferably, the second acid comprises at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid and trichloroacetic acid;

[0029] Preferably, the amount of the second acid is 2 to 5% by mass relative to the total amount of the soapstock;

[0030] Preferably, the enzymatic hydrolysis mixture and the second acid are reacted at 80-100° C. for 4-6 hours.

[0031] [9] The production method according to any one of [1] to [8], wherein the soap stock is heated to 30 to 50° C. before the pretreatment step.

[0032]

[10] A fatty acid obtained by the production method according to any one of [1] to [9].

[0033] Effects of the Invention

[0034] By implementing the above technical solution, the present invention can achieve the following technical effects:

[0035] (1) The present invention can significantly reduce the amount of enzyme used in the enzymatic hydrolysis reaction, and the enzyme cost is significantly reduced; the enzymatic hydrolysis time can be significantly shortened from 24 to 36 hours in the traditional enzymatic hydrolysis method to 2 to 4 hours; the enzymatic hydrolysis efficiency is significantly improved. The present invention can obtain fatty acids with a high conversion rate using a small amount of enzyme in a short time.

[0036] (2) The method of preparing fatty acids by directly enzymolysis of soap stock and then acidification at high temperature has a significantly higher final fatty acid yield than the method of first acidifying soap stock to prepare acidified oil and then hydrolyzing it at high temperature and high pressure to prepare fatty acids. At the same time, the present invention also avoids the defects of side reactions that are prone to occur during the process of preparing fatty acids by hydrolyzing acidified oil at high temperature and high pressure, resulting in reduced quality and yield of fatty acid products and high energy consumption.

[0037] (3) The manufacturing method of the present invention has a simple process, is energy-saving and environmentally friendly, can significantly increase the yield of fatty acids compared to the soapstock acid hydrolysis method, and can greatly reduce the generation of high-acid wastewater, thus having important economic benefits.

[0038] (4) The present invention makes full use of soap stock, a by-product in the oil refining process, and increases the utilization of by-products, which has great practical significance for improving the value of the industrial chain. DETAILED DESCRIPTION

[0039] The following is a detailed description of the present invention. The following description of the technical features is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0040] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0041] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0042] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0043] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0044] In this specification, the unit names used are all international standard unit names, and unless otherwise stated, the "%" used indicates weight or mass percentage.

[0045] In this specification, unless otherwise stated, "plurality" means that there are two or more.

[0046] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0047] <First aspect>

[0048] In a first aspect of the present invention, a method for producing a fatty acid is provided, the method comprising:

[0049] A pretreatment step, contacting the soap stock with a first acid to obtain a pretreated soap stock, wherein the mass ratio of fat (in terms of glycerides and free fatty acids) to soap (in terms of sodium fatty acids) in the pretreated soap stock is 1:0.15 to 1:0.55, and the pH of the contact system is 6 to 7.5;

[0050] an enzymatic reaction step, wherein the pretreated soapstock is contacted with a hydrolase to perform an enzymatic reaction to obtain an enzymatic mixture; and

[0051] The acidification reaction step is to contact the enzymatic hydrolysis mixture obtained in the enzymatic hydrolysis reaction step with a second acid to carry out an acidification reaction.

[0052] In the present invention, the fat matter is calculated as glyceride and free fatty acid, the soap is calculated as sodium fatty acid, and the contact system refers to a mixed system of soap stock and the first acid.

[0053] Compared with the traditional enzymatic hydrolysis, the present invention controls the mass ratio of fat (in terms of the total of glycerides and free fatty acids) and soap (in terms of sodium fatty acids) in the soap stock to 1:0.15 to 1:0.55 by pretreating the soap stock, which can greatly reduce the enzyme dosage and enzymatic hydrolysis time in the enzymatic hydrolysis reaction, thereby achieving enzymatic hydrolysis with high enzymatic hydrolysis efficiency using a small amount of enzyme in a short time. In addition, the manufacturing method of the present invention has a simple process, is energy-saving and environmentally friendly, and can significantly improve the yield of fatty acids compared to the traditional soap stock acid hydrolysis method, greatly reduce the generation of high-acid wastewater, and has important economic benefits.

[0054] (Pretreatment process)

[0055] In some preferred embodiments of the present invention, the soap stock may include vegetable oil soap stock and / or animal oil soap stock. As specific examples, for example, soybean oil soap stock, cottonseed oil soap stock, corn oil soap stock, rapeseed oil soap stock, sunflower seed oil soap stock, peanut oil soap stock, rice bran oil soap stock, lard soap stock, beef tallow soap stock, sheep oil soap stock, etc. These can be used alone or in combination of two or more.

[0056] In some preferred embodiments of the present invention, the moisture content of the soap stock is preferably controlled within the range of 40-60%. When the moisture content of the soap stock is less than 40%, the soap stock is a semi-solid system and is not suitable for operation. When the moisture content of the soap stock is greater than 60%, the water content of the soap stock is too high and the total fat content is too low, and it is not economical to use the soap stock to industrially prepare fatty acids.

[0057] In some preferred embodiments of the present invention, before the soap stock is contacted with the first acid, the soap stock is preferably heated to 30-50° C. to better perform the enzymatic hydrolysis reaction described later.

[0058] In some preferred embodiments of the present invention, the first acid may be a strong acid having a pKa of less than 1 and / or a weak acid having a pKa of greater than 4.

[0059] Examples of strong acids having a pKa of less than 1 include sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid, trichloroacetic acid, etc. These may be used alone or in combination of two or more.

[0060] Examples of weak acids having a pKa greater than 4 include acetic acid, citric acid, propionic acid, butyric acid, valeric acid, sorbic acid, and lactic acid, etc. These can be used alone or in combination of two or more.

[0061] In the present invention, by contacting the soap stock with the first acid, the pH of the contact system is adjusted to 6 to 7.5, thereby providing a suitable reaction pH range for the enzymatic hydrolysis reaction described later. In the present invention, by making the first acid contain a strong acid with a pKa less than 1, the strong acid with a pKa less than 1 can react with the sodium fatty acid in the soap stock to generate fatty acids and sodium sulfate in addition to playing a role in adjusting the pH range of the contact system. Therefore, the strong acid with a pKa less than 1 can also play a role in adjusting the ratio of fats (glycerides and free fatty acids) to soaps (sodium fatty acids) in the soap stock, thereby controlling the ratio of fats (glycerides and free fatty acids) to soaps (sodium fatty acids) to 1:0.15 to 1:0.55, thereby promoting the efficiency of the enzymatic hydrolysis reaction described later. The weak acid with a pKa greater than 4 plays a role in adjusting the pH of the system.

[0062] Normally, the ratio of fat to soap in the unpretreated soap stock is generally about 1:1.2. The present application controls the ratio of fat (glyceride and free fatty acid) to soap (sodium fatty acid) in the pretreated soap stock to be 1:0.15 to 1:0.55, preferably 1:0.20 to 1:0.40 through the pretreatment process. By setting the ratio of fat (in terms of glyceride and free fatty acid) to soap (in terms of sodium fatty acid) within the above range, the amount of enzyme and the enzymolysis time in the enzymolysis reaction described later can be greatly reduced. For example, the enzymolysis time of the present invention can be greatly shortened from 24 to 36 hours of the traditional enzymolysis method to 2 to 4 hours, and the enzymolysis efficiency is significantly improved. The present invention can use a small amount of enzyme to prepare fatty acids with a high conversion rate in a short time. Under the same reaction time, the ratio of fat (in terms of glyceride and free fatty acid) to soap (in terms of sodium fatty acid) in the pretreated soap stock of the present invention is adopted, and the effect of the subsequent enzymolysis reaction is significantly improved, and the conversion rate of fatty acids is significantly improved.

[0063] In some preferred embodiments of the present invention, the mass ratio of the fat (in terms of glycerides and free fatty acids) to the total emulsifier (in terms of sodium fatty acids and phospholipids, etc.) in the pretreated soap stock is 1:0.35 or more, preferably 1:0.35 to 1:0.75. By setting the ratio of the fat (in terms of glycerides and free fatty acids) to the total emulsifier (in terms of sodium fatty acids and phospholipids, etc.) in the pretreated soap stock within the above range, the subsequent enzymolysis efficiency can be better improved. The total emulsifier is calculated in terms of sodium fatty acids and phospholipids.

[0064] The content of fatty matter (calculated as glycerides and free fatty acids) in soapstock is determined as follows: According to LST1208-1992 Vegetable Oil Production Process Determination Procedure 5.2.13 Determination of Oil Content in Soapstock, the fatty matter content W1 in soapstock is determined by acetone extraction.

[0065] The content of soap (in terms of sodium fatty acid) in soapstock is determined as follows: after adding strong acid to the soapstock to completely acidify it, the total fatty acid content W2 in the soapstock is determined by acetone extraction minus the fatty matter content W1 determined in the soapstock, which is the amount of fatty acids converted from the sodium fatty acid in the soapstock (W2-W1), and then converted to the amount of sodium fatty acid. For example, based on sodium oleate, the mass of sodium fatty acid = (W2-W1) × 304.44 / 282.46).

[0066] The phospholipid content in soapstock is determined as follows: the soapstock is dried and then microwave digested, and the phosphorus content in the soapstock is determined by ICP-OES, which is converted into phospholipid content: phospholipid content = p × 26.31, where p is the phosphorus content.

[0067] In some preferred embodiments of the present invention, the amount of the first acid added is 1 to 3% by mass, preferably 1.5 to 2.5% by mass, relative to the total amount of soapstock (soapstock before pretreatment). By setting the content of the first acid to such a range, the ratio of fat matter (in terms of glycerides and free fatty acids) to soap (in terms of sodium fatty acids) in the soapstock is controlled to be 1:0.15 to 1:0.55, and the pH of the contact system is 6 to 7.5.

[0068] There is no particular limitation on the method of contacting the soap stock with the first acid. For example, conventional contact methods such as a stirrer or a magnetic stirrer may be used.

[0069] There is no particular limitation on the contact time and temperature. From the viewpoint of achieving sufficient contact and controlling the mass ratio of fat (in terms of glycerides and free fatty acids) to soap (in terms of sodium fatty acids) in the pretreated soap stock to be 1:0.15 to 1:0.55, it is preferred to slowly add the first acid to the soap stock at 30 to 50°C and stir for 1 to 2 hours.

[0070] (Enzymatic reaction process)

[0071] As the hydrolase, lipase may be included; preferably, the hydrolase is triglyceride hydrolase and / or partial glyceride hydrolase.

[0072] Examples of hydrolases include: triglyceride hydrolases derived from Thermomyces lanuginosus, Candida antarctic, Rhizomucor miehei, Aspergillus niger, Candida rugosa, and Pseudononas sp.; partial glyceride hydrolases derived from Penicillium camembertii, Penicillium cyclopium, Aspergillus oryzae, and Malassezia globosa, etc. These hydrolases can be used alone or in combination of two or more.

[0073] In some preferred embodiments of the present invention, the amount of the hydrolase is 0.01 to 0.05% by mass, preferably 0.01 to 0.03% by mass, relative to the total amount of soapstock (soapstock before pretreatment). By setting the amount of the hydrolase to such a range, the enzymatic efficiency can be improved and the enzyme cost can be reduced.

[0074] In the present invention, since the soap stock is pretreated, the ratio of fat (calculated as glyceride and free fatty acid) to soap (calculated as sodium fatty acid) in the pretreated soap stock is 1:0.15 to 1:0.55. Compared with the traditional enzymatic hydrolysis method of soap stock, the present invention can greatly reduce the amount of hydrolase used, can achieve an enzymatic hydrolysis reaction with high enzymatic hydrolysis efficiency with a small amount of hydrolase, and significantly reduce the enzyme cost.

[0075] In some preferred embodiments of the present invention, the enzymatic reaction time is preferably 2 to 4 hours, more preferably 2 to 3 hours. In the present invention, since the soap stock is pretreated, the ratio of fat (in terms of glycerides and free fatty acids) to soap (in terms of fatty acid sodium) in the pretreated soap stock is 1:0.15 to 1:0.55. Compared with the traditional enzymatic hydrolysis method of soap stock, the present invention can greatly shorten the enzymatic hydrolysis time, can perform enzymatic hydrolysis reaction with high enzymatic hydrolysis efficiency in a short enzymatic hydrolysis time, and has important economic benefits.

[0076] The enzymatic reaction temperature is not particularly limited as long as the reaction is carried out at a temperature that does not inactivate the enzyme. From the viewpoint of sufficient reaction, the pretreated soapstock is preferably reacted with the hydrolase at 30 to 50°C.

[0077] There is no particular limitation on the contacting method of the pretreated soapstock with the hydrolase, and for example, conventional contacting methods such as a stirrer or a magnetic stirrer may be used.

[0078] (Acidification reaction process)

[0079] In the acidification reaction step, the enzymatic hydrolysis mixture obtained in the enzymatic hydrolysis reaction step is contacted with a second acid to perform an acidification reaction.

[0080] In some preferred embodiments of the present invention, the second acid preferably comprises a strong acid having a pKa of less than 1. Examples of strong acids having a pKa of less than 1 include sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid, trichloroacetic acid, etc. These acids may be used alone or in combination of two or more.

[0081] In some preferred embodiments of the present invention, the amount of the second acid is 2-5% by mass, preferably 2.5-4% by mass, relative to the total amount of soapstock before pretreatment. By setting the amount of the second acid to such a range, the acidification reaction can be effectively promoted to obtain fatty acids with a high yield, and the separation speed is accelerated, so that the separation speed of the fatty acid oil phase and the water phase is faster, which is conducive to industrial operation.

[0082] The temperature and time of the acidification reaction are not particularly limited. In some preferred embodiments of the present invention, from the viewpoint of sufficient reaction, the enzymatic hydrolysis mixture obtained in the enzymatic hydrolysis reaction step is preferably reacted with the second acid at 80-100° C. for 4-6 hours.

[0083] In some other embodiments of the present invention, after the acidification reaction step, the production method of the present invention preferably further comprises a separation step to separate and recover fatty acids.

[0084] There is no particular limitation on the separation method, and centrifugation, stratification and the like may be used alone or in combination according to the specific conditions of the system after actual contact.

[0085] In some specific embodiments of the present invention, the system after the acidification reaction step can be centrifuged to separate fatty acids from the mixed system obtained in the acidification reaction step. More specifically, the mixed system obtained from the acidification reaction step is centrifuged to separate the oil phase and the water phase, and the upper oil phase is separated to obtain fatty acids.

[0086] In some specific embodiments of the present invention, the centrifugal treatment can be performed by using a centrifuge to separate the above system to obtain a system containing an oil phase and an aqueous phase. There is no particular limitation on the centrifugal conditions, for example, a centrifugal rate of 5000 to 10000 rpm / min and a centrifugal time of 1 to 10 min can be used.

[0087] In the production method of the present invention, the conversion rate of soapstock (more specifically, glyceride in soapstock) into fatty acids is 90% or more, preferably 91% or more, more preferably 92% or more, and further preferably 93% or more. Compared with the traditional method of preparing fatty acids from soapstock, the production method of the present invention can use a small amount of hydrolase in a short time to obtain fatty acids with a high conversion rate, which has important economic benefits.

[0088] <Second Aspect>

[0089] In the second aspect of the present invention, the present invention provides a fatty acid. The fatty acid of the present invention can be obtained by the method disclosed in the first aspect of the present invention. The fatty acid obtained by the method has the characteristics of high quality and can be widely used in industries such as washing, medicine, food, textile printing and dyeing, daily chemical industry, petrochemical industry, rubber and plastic processing, mining, transportation, casting, metal processing, ink, coating and pigment.

[0090] Example

[0091] The embodiments of the present invention will be described in detail below in conjunction with examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out under normal conditions or conditions recommended by the manufacturer. Unless otherwise specified, the materials or instruments used are all commercially available conventional products.

[0092] Determination of the content of fat (calculated as glycerides and free fatty acids) in soapstock: According to LST1208-1992 Vegetable Oil Production Process Determination Procedure 5.2.13 Determination of Oil Content in Soapstock, the fat content W1 in soapstock is determined by acetone extraction.

[0093] Method for detecting the content of sodium fatty acids in soap stock: After adding strong acid to the soap stock to completely acidify it, acetone extraction is used to determine the total fatty acid content W2 in the soap stock minus the fat content W1 determined in the soap stock, which is the amount of fatty acids converted from the sodium fatty acids in the soap stock (W2-W1), which is converted into the amount of sodium fatty acids. For example, based on sodium oleate, the mass of sodium fatty acids = (W2-W1) × 304.44 / 282.46).

[0094] Determination of phospholipid content in soapstock: After drying the soapstock, microwave digestion was performed and the phosphorus content in the soapstock was determined by ICP-OES, which was converted into phospholipid content: phospholipid content = p × 26.31, where p is the phosphorus content.

[0095] Example 1

[0096] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 3 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 6.0, and the mass ratio of fat to soap in the pretreated soap stock is 1:0.15.

[0097] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0098] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 2 g of 98% concentrated sulfuric acid was added, and the reaction was acidified for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm, and the content of triglyceride, diglyceride and monoglyceride in the upper oil phase was determined by gas chromatography to be 0.95%, 1.11% and 0.79% respectively. The acid value of the oil phase was determined by acid-base titration to be 192.39 mgKOH / g, and the glyceride conversion rate was 93.98%.

[0099] Example 2

[0100] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 2.5 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 6.7, and the ratio of fat to soap in the pretreated soap stock is 1:0.28.

[0101] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0102] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 2.5 g of 98% concentrated sulfuric acid was added, and the reaction was acidified for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm, and the content of triglycerides, diglycerides and monoglycerides in the upper oil phase was determined by gas chromatography to be 1.33%, 1.10% and 0.74%, respectively. The acid value of the oil phase was determined by acid-base titration to be 191.06 mgKOH / g, and the glyceride conversion rate was 93.31%.

[0103] Example 3

[0104] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 2 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 7.1, and the ratio of fat to soap in the pretreated soap stock is 1:0.40.

[0105] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0106] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 3 g of 98% concentrated sulfuric acid was added, and the reaction was acidified for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm, and the content of triglyceride, diglyceride and monoglyceride in the upper oil phase was determined by gas chromatography to be 1.43%, 1.22% and 0.62%, respectively. The acid value of the oil phase was determined by acid-base titration to be 190.33 mgKOH / g, and the glyceride conversion rate was 93.10%.

[0107] Example 4

[0108] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 1.5 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 7.5, and the ratio of fat to soap in the pretreated soap stock is 1:0.55.

[0109] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0110] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 3.5 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 1.89%, 1.31%, and 1.04%, respectively. The acid value of the oil phase was determined by acid-base titration to be 189.21 mgKOH / g, and the glyceride conversion rate was 91.01%.

[0111] Comparative Example 1

[0112] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 3 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 6.0. At the same time, add 10 g of oleic acid to adjust the ratio of fat to soap in the soap stock to 1:0.10.

[0113] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0114] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 2 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 11.64%, 1.12%, and 1.18%, respectively. The acid value of the oil phase was determined by acid-base titration to be 168.34 mgKOH / g, and the glyceride conversion rate was 69.28%.

[0115] Comparative Example 2

[0116] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 1 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and at the same time add 2.5 g of glacial acetic acid, stir at 200 rpm for 2 hours, adjust the pH value of the soap stock system to 6.0, and the ratio of fat to soap in the soap stock is 1:0.75.

[0117] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0118] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 4 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 16.36%, 1.42%, and 1.05%, respectively. The acid value of the oil phase was determined by acid-base titration to be 157.87 mgKOH / g, and the glyceride conversion rate was 59.78%.

[0119] Comparative Example 3

[0120] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 5 g of glacial acetic acid into the soybean oil soap stock, stir at 200 rpm for 2 h, adjust the pH value of the soap stock system to 6.0, and the ratio of fat to soap in the soap stock is 1:1.15.

[0121] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0122] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 5 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 26.40%, 2.37%, and 1.84%, respectively. The acid value of the oil phase was determined by acid-base titration to be 140.35 mgKOH / g, and the glyceride conversion rate was 40.03%.

[0123] Comparative Example 4

[0124] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 2 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 7.1. At the same time, add 70 g of oleic acid to adjust the ratio of fat to soap in the soap stock to 1:0.10.

[0125] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0126] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 2 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 16.44%, 2.12%, and 1.18%, respectively. The acid value of the oil phase was determined by acid-base titration to be 162.23 mgKOH / g, and the glyceride conversion rate was 61.02%.

[0127] Comparative Example 5

[0128] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 1 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and at the same time add 1.8 g of glacial acetic acid, stir at 200 rpm for 2 hours, adjust the pH value of the soap stock system to 7.1, and the ratio of fat to soap in the soap stock is 1:0.75.

[0129] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0130] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 4 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 20.45%, 3.41%, and 2.26%, respectively. The acid value of the oil phase was determined by acid-base titration to be 151.34 mgKOH / g, and the glyceride conversion rate was 49.52%.

[0131] Comparative Example 6

[0132] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 3.2 g of glacial acetic acid into the soybean oil soap stock, stir at 200 rpm for 2 h, adjust the pH value of the soap stock system to 7.1, and the ratio of fat to soap in the soap stock is 1:1.15.

[0133] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0134] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 5 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 28.45%, 5.49%, and 2.03%. The acid value of the oil phase was determined by acid-base titration to be 134.15 mgKOH / g, and the glyceride conversion rate was 31.80%.

[0135] Comparative Example 7

[0136] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 3 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 6.0. At the same time, add 10 g of oleic acid and 1.7 g of lecithin PC, and adjust the ratio of fat to total emulsifier in the soap stock system to 1:0.5, and the ratio of fat to soap to 1:0.10.

[0137] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0138] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 2 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 10.75%, 1.35%, and 1.68%, respectively. The acid value of the oil phase was determined by acid-base titration to be 170.21 mgKOH / g, and the glyceride conversion rate was 70.50%.

[0139] Comparative Example 8

[0140] Add 100 g of soybean oil soap stock with a water content of 53.5% into a 250 mL conical flask, place it in a 40°C magnetic stirring water bath, slowly add 2 g of 98% concentrated sulfuric acid to the soybean oil soap stock, and stir at 200 rpm for 2 hours. At this time, the pH value of the soap stock system is 7.1. At the same time, add 70 g of oleic acid and 35 g of lecithin PC, and adjust the ratio of fat to total emulsifier in the soap stock to 1:0.75, and the ratio of fat to soap to 1:0.10.

[0141] To the pretreated soap stock, 0.01% of triglyceride hydrolase Eversa 2.0 (manufactured by Novozymes, Eversa transform 2.0) and 0.01% of partial glyceride hydrolase G50 (manufactured by Amano, Amano G50) were added to the total amount of soybean oil soap stock and reacted for 2 hours.

[0142] After the enzymatic hydrolysis reaction was completed, the temperature was raised to 85°C, 2 g of 98% concentrated sulfuric acid was added, and the acidification reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged at 5000 rpm. The triglyceride content, diglyceride content, and monoglyceride content in the upper oil phase were determined by gas chromatography to be 25.21%, 2.63%, and 1.44%, respectively. The acid value of the oil phase was determined by acid-base titration to be 143.01 mgKOH / g, and the glyceride conversion rate was 41.20%.

[0143] The pH of the contact system in the pretreatment process of Examples 1 to 4 and Comparative Examples 1 to 8, the mass ratio of fat matter to soap in the soap stock after pretreatment, the mass ratio of fat matter to total emulsifier in the soap stock after pretreatment, the acid value of the obtained fatty acid, and the glyceride conversion rate are shown in Tables 1 to 2.

[0144] Table 1

[0145]

[0146] Table 2

[0147]

[0148] As can be seen from Table 1, Examples 1 to 4 adjust the ratio of fat to soap in the soap stock within the range of 1:0.15 to 1:0.55 through the pretreatment process, and the amount of enzyme used in the enzymatic hydrolysis reaction is greatly reduced, and the enzymatic hydrolysis time can be greatly shortened from 24 to 36 hours of the traditional enzymatic hydrolysis method to 2 to 4 hours, and the glyceride conversion rate is greater than 90%. It can be seen that Examples 1 to 4 can obtain fatty acids with a high glyceride conversion rate in a short time using a small amount of enzyme.

[0149] In contrast, in Comparative Examples 1 to 6, since the ratio of fat to soap in the soapstock was not within the range of 1:0.15 to 1:0.55, the glyceride conversion rate was significantly reduced, and fatty acids could not be obtained at a high glyceride conversion rate using a small amount of enzyme in a short time.

[0150] In addition, although the prior art mentions that adding an emulsifier to oil hydrolysis can increase the hydrolysis rate, in Comparative Examples 7 to 8, since the ratio of fat to soap in the soap stock is not in the range of 1:0.15 to 1:0.55, even if 1.7 g and 35 g of lecithin PC are added respectively, so that the ratio of fat to total emulsifier in the soap stock is the same as in Example 1 and Example 3, as shown in Table 2, in Comparative Examples 7 to 8, even if the emulsifier is added, the technical problem of shortening the reaction time cannot be solved. In Comparative Examples 7 to 8, the glyceride conversion rate is only 70.50% and 41.20% within the enzymatic reaction time of 2 h, and fatty acids cannot be obtained with a high glyceride conversion rate using a small amount of enzyme in a short time.

[0151] Industrial Applicability

[0152] The manufacturing method of the present invention can greatly reduce the amount of enzyme used in the enzymatic hydrolysis reaction, and the enzyme cost is significantly reduced; the enzymatic hydrolysis time can be greatly shortened from 24 to 36 hours in the traditional enzymatic hydrolysis method to 2 to 4 hours; and the enzymatic hydrolysis efficiency is significantly improved. The present invention can obtain fatty acids with a high conversion rate using a small amount of enzyme in a short time. In addition, the manufacturing method of the present invention has a simple process, is energy-saving and environmentally friendly, can significantly improve the yield of fatty acids compared to the soapstock acid hydrolysis method, and can significantly reduce the generation of high-acid wastewater, and has important economic benefits.

Claims

1. A method for producing a fatty acid, characterized in that: The method comprises: A pretreatment step, contacting the soap stock with a first acid to obtain a pretreated soap stock, wherein the mass ratio of the fat matter calculated as glyceride and free fatty acid to the soap calculated as sodium fatty acid in the pretreated soap stock is 1:0.15 to 1:0.55, and the pH of the contact system is 6 to 7.5; an enzymatic reaction step, wherein the pretreated soapstock is contacted with a hydrolase to perform an enzymatic reaction to obtain an enzymatic mixture; and an acidification reaction step, wherein the enzymatic hydrolysis mixture obtained in the enzymatic hydrolysis reaction step is contacted with a second acid to perform an acidification reaction, The first acid comprises a strong acid having a pKa of less than 1, The strong acid having a pKa of less than 1 comprises at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid and trichloroacetic acid, The hydrolase is triglyceride hydrolase and partial glyceride hydrolase. The pretreated soapstock and the hydrolase are subjected to an enzymatic reaction at 30-50° C. The enzymatic reaction time is 2 to 4 hours. The second acid comprises a strong acid having a pKa less than 1, The second acid includes at least one selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid and trichloroacetic acid.

2. The manufacturing method according to claim 1, characterized in that: The soap stock comprises at least one selected from the group consisting of soybean oil soap stock, cottonseed oil soap stock, corn oil soap stock, rapeseed oil soap stock, sunflower oil soap stock, peanut oil soap stock, rice bran oil soap stock, lard soap stock, beef tallow soap stock and sheep oil soap stock.

3. The manufacturing method according to claim 1, characterized in that: The moisture content of the soap stock is 40-60%.

4. The manufacturing method according to claim 1 or 2, characterized in that: The mass ratio of the fat matter calculated as glyceride and free fatty acid to the total emulsifier calculated as soap and phospholipid in the pretreated soap stock is 1:0.35 or more.

5. The manufacturing method according to claim 1 or 2, characterized in that: The usage of the first acid is 1 to 3% by mass relative to the total amount of soapstock.

6. The manufacturing method according to claim 1 or 2, characterized in that: The triglyceride hydrolase comprises at least one triglyceride hydrolase derived from the group consisting of Thermomyces lanuginosus, Candida antarctica, Rhizomucor miehei, Aspergillus niger, Candida plicata and Pseudomonas; The partial glyceride hydrolase includes a partial glyceride hydrolase derived from at least one of the group consisting of Penicillium camembert, Penicillium toruloides, Aspergillus oryzae, and Malassezia sphaeroides.

7. The manufacturing method according to claim 1 or 2, characterized in that: The amount of the hydrolase used is 0.01 to 0.05 mass % relative to the total amount of the soapstock.

8. The manufacturing method according to claim 1 or 2, characterized in that: The amount of the second acid used is 2 to 5% by mass relative to the total amount of the soapstock.

9. The manufacturing method according to claim 1 or 2, characterized in that: The enzymatic hydrolysis mixture and the second acid are reacted at 80-100° C. for 4-6 hours.

10. The manufacturing method according to claim 1 or 2, characterized in that: Before the pretreatment process, the soap stock is heated to 30-50°C.

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