Method for extracting organic acid from lemon residues, organic acid and application of organic acid

Abstract

The invention provides a method for extracting organic acid from lemon residues, the organic acid and application of the organic acid, and belongs to the technical field of separation and purification of the organic acid. According to the method, the lemon residues are crushed into slurry, and then the high-concentration organic acid solution is obtained through the steps of enzymolysis reaction, filter pressing, ultrafiltration, nanofiltration, reverse osmosis and reduced pressure distillation. The organic acid solution can be used as an animal feed acidifying agent, and high value-added utilization of the lemon residues is realized. When the organic acid is used as an animal feed acidifier, the average weight gain of animals and the feed utilization rate can be improved, and the daily average feed intake is not increased.

Description

Technical Field

[0001] The invention belongs to the technical field of separation and purification of organic acids, and specifically relates to a method for extracting organic acids by utilizing lemon residues, organic acids and applications of the organic acids. Background Art

[0002] At present, my country's lemon production is close to 3 million tons per year, and the amount of lemon residue produced after lemon processing is huge. Only a small part of these lemon residues are currently used, and most of them are directly piled up outdoors or landfilled, which causes environmental pollution on the one hand and waste of resources on the other hand. At present, the use of lemon residue is mainly used to extract pectin, limonin or prepare biosorbents. For example, the Chinese patent announcement text CN108148108B discloses a method for extracting limonin from lemon peel residue using a guanidine salt ionic liquid aqueous two-phase extraction method, which is specifically used for extracting and preparing limonin from lemon peel residue, and includes the following steps: (1) drying, crushing, enzymolysis, and vacuum concentration of lemon peel residue; (2) the formation and use of a guanidine salt ionic liquid aqueous two-phase extraction system; (3) composite organic solvent re-extraction, vacuum concentration, freeze drying and purification. CN107398252B discloses a method for preparing MgO / carbon composite adsorption material by one-step method using lemon residue and magnesium residue, comprising the following steps: 1) weighing a certain amount of lemon residue and adding it to the magnesium residue solution and stirring at a constant temperature until the water evaporates completely to form a uniform lemon magnesium residue; 2) placing the formed lemon magnesium residue in a N2 atmosphere furnace for high temperature treatment to obtain a MgO / carbon composite material. CN103232555B discloses a method for extracting pectin from lemon peel residue by enzymatic method, first pre-treating the lemon peel residue, then mixing it with a buffer solution with a pH of 4 to 8 at a weight ratio of 1:15 to 1:30, then adding 0.01 to 0.3% enzyme preparation based on the weight of the lemon peel residue, stirring, and extracting at 40 to 70°C for 1 to 5 hours, followed by centrifugation, vacuum concentration, cooling, decolorization, alcohol precipitation, desugaring, drying and crushing to obtain a finished pectin powder product.

[0003] None of these methods involve the utilization of organic acids in lemon slag. Lemon slag contains various amino acids such as lysine, methionine, phenylalanine, leucine, isoleucine, valine, threonine, histidine, arginine, aspartic acid, glutamic acid, glycine, alanine, and serine. Therefore, studying how to improve the utilization rate of organic acids in lemon slag can not only achieve full utilization of lemon slag and expand its application range, but also solve the environmental pollution problem caused by the accumulation of lemon slag. Summary of the invention

[0004] Based on the above problems, the present invention provides a method for extracting organic acid from lemon dregs. The method can extract the organic acid contained in the lemon dregs to the maximum extent, and the organic acid has the advantages of high purity and good palatability.

[0005] Specifically, the present invention adopts the following technical solutions to achieve the above objectives:

[0006] A method for extracting organic acid using lemon residue comprises the following steps:

[0007] S1, crushing lemon residue into slurry, heating the slurry, and adding pectinase and protease to the slurry for enzymolysis reaction;

[0008] S2, filtering the reaction system after the enzymatic hydrolysis reaction in step S1, and sequentially treating the filtrate with an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane to obtain a reverse osmosis concentrate of an organic acid;

[0009] S3, distilling the reverse osmosis concentrate under reduced pressure to obtain an organic acid.

[0010] In a preferred embodiment, the mass percentage of dry matter in the pectinase is 0.3% to 0.5%.

[0011] In a preferred embodiment, the mass percentage of dry matter in the protease is 6% to 10%.

[0012] In a preferred embodiment, the pectinase is at least one of polygalacturonase, pectin lyase and pectinesterase.

[0013] In a preferred embodiment, the protease is an acidic protease and / or a neutral protease.

[0014] In a preferred embodiment, the slurry is heated to 30-50° C. in step S1.

[0015] In a preferred embodiment, the enzymatic hydrolysis reaction time is 2 to 4 hours.

[0016] In a preferred embodiment, the pressure of the filter press in step S2 is 3 to 5 MPa.

[0017] In a preferred embodiment, the filtration time in step S2 is 10 to 30 minutes.

[0018] In a preferred embodiment, the air permeability of the filter cloth used in the filter press in step S2 is 30 to 50 L / (m 2 ·s).

[0019] In a preferred embodiment, the molecular weight cut-off of the ultrafiltration membrane in step S2 is 2000-5000 Da.

[0020] In a preferred embodiment, the molecular weight cutoff of the nanofiltration membrane in step S2 is 300 to 500 Da.

[0021] In a preferred embodiment, the molecular weight cut-off of the reverse osmosis membrane in step S2 is 50 to 80 Da.

[0022] In a preferred embodiment, the vacuum degree of the reduced pressure distillation in step S3 is -0.1 to -0.2 MPa.

[0023] In a preferred embodiment, the temperature of the reduced pressure distillation in step S3 is 50-70°C.

[0024] In a preferred embodiment, the time of reduced pressure distillation in step S3 is 60 to 120 minutes.

[0025] The present invention also provides an organic acid extracted according to any one of the above schemes.

[0026] In a preferred embodiment, the concentration of the organic acid is 60% to 70%.

[0027] The present invention also provides the use of the organic acid extracted according to any of the above schemes as a feed acidifier.

[0028] In a preferred embodiment, 5.3% to 6.2% of the organic acid is added to animal feed.

[0029] Compared with the prior art, the technical scheme of the present invention has the following beneficial effects: the present invention uses crushing, enzymolysis, impurity removal, purification, concentration and other processes to treat lemon slag, enzymolyzes macromolecular pectin, protein and the like in the lemon slag into small molecular organic acids, and then separates, purifies and concentrates them through a membrane process to obtain small molecular organic acids with a concentration of 60% to 70%; the organic acids contained in the lemon slag are extracted to the maximum extent, and the obtained organic acids have high concentrations, few impurities and good palatability, and can be used as feed acidifiers. Adding the organic acids accounting for 5.3% to 6.2% of the feed mass to animal feed can make fattening pigs gain at least 6.2% of their average weight in the same feeding time, reduce the feed-to-meat ratio by at least 8%, and basically not increase the feed intake. DETAILED DESCRIPTION

[0030] The following content is combined with the embodiments to clearly and completely describe the technical solution of the present application so that those skilled in the art can fully understand the present application. Obviously, the described embodiments are only some preferred embodiments of the present application, rather than all embodiments. Any equivalent transformation or substitution made to the following implementation modes by those of ordinary skill in the art without creative work belongs to the protection scope of the present application.

[0031] In the following examples, pectinase is a composite pectinase purchased from Shandong Weilan Biotechnology Co., Ltd., with an enzyme activity of 30,000 U / g. Protease is a neutral protease purchased from Hunan Ququ Biotechnology Co., Ltd., with an enzyme activity of 50,000 U / g. The detection method of the organic acid obtained in the examples is carried out in accordance with the provisions of GB / T 22142-2008 "General Requirements for Organic Acids in Feed Additives".

[0032] A specific embodiment of the present invention provides a method for extracting organic acid using lemon residue, comprising the following steps:

[0033] S1. Put lemon slag into a crusher to crush it into slurry, put the lemon slag slurry into a container and heat it in a water bath at a temperature of 30 to 50° C., add pectinase and protease while heating in the water bath, and perform enzymolysis for 2 to 4 hours. Among them, the mass of pectinase accounts for 0.3% to 0.5% of the mass of dry matter in the lemon slag slurry; the mass of protease accounts for 9% to 12% of the mass of dry matter in the lemon slag slurry.

[0034] S2. The lemon slag slurry after enzymatic hydrolysis is then filtered in a hydraulic filter press. The filter pressure is 3-5 MPa, the filter time is 10-30 min, and the air permeability of the filter cloth used in the filter press is 30-50 L / (m 2 ·s). The obtained filtrate is ultrafiltered through an ultrafiltration membrane of 2000-5000Da, the filtrate after ultrafiltration is nanofiltered through a nanofiltration membrane of 300-500Da, the clear liquid after nanofiltration is reverse osmosis through a reverse osmosis membrane of 50-80Da, and a reverse osmosis concentrate containing organic acid is obtained after reverse osmosis.

[0035] S3. The reverse osmosis concentrate is then subjected to reduced pressure low temperature distillation at a distillation temperature of 50 to 70°C, a vacuum degree of -0.1 to -0.2 MPa, and a distillation time of 60 to 120 min. The organic acid concentration in the concentrated solution obtained after reduced pressure low temperature distillation is 60% to 70%.

[0036] Example 1

[0037] A method for extracting organic acid using lemon residue comprises the following steps:

[0038] S1. Put lemon slag into a crusher to crush it into slurry, put the lemon slag slurry into a container and heat it in a water bath at a temperature of 30°C, and add composite pectinase and neutral protease to perform enzymolysis for 4 hours while heating in the water bath. The mass of pectinase accounts for 0.5% of the mass of dry matter in the lemon slag slurry; the mass of protease accounts for 10% of the mass of dry matter in the lemon slag slurry.

[0039] S2. The lemon residue slurry after enzymatic hydrolysis is then filtered in a hydraulic filter press. The filter pressure is 3 MPa, the filter time is 30 min, and the air permeability of the filter cloth used in the filter press is 50 L / (m 2 ·s). The obtained filtrate is ultrafiltered through a 5000Da ultrafiltration membrane, the filtrate after ultrafiltration is nanofiltered through a 500Da nanofiltration membrane, the clear liquid after nanofiltration is reverse osmosis through an 80Da reverse osmosis membrane, and a reverse osmosis concentrate containing organic acid is obtained after reverse osmosis.

[0040] S3, the reverse osmosis concentrate is then distilled at reduced pressure and low temperature, the distillation temperature is 50°C, the vacuum degree is -0.2MPa, the distillation time is 120min, and the mass concentration of organic acid in the concentrate obtained after reduced pressure and low temperature distillation is 70%. The organic acid can be processed into feed acidifier.

[0041] Example 2

[0042] A method for extracting organic acid using lemon residue comprises the following steps:

[0043] S1. Put lemon slag into a crusher and crush it into slurry. Put the lemon slag slurry into a container and heat it in a water bath at 40°C. Add compound pectinase and neutral protease while heating in the water bath, and perform enzymolysis for 3 hours. Among them, the mass of pectinase accounts for 0.4% of the mass of dry matter in the lemon slag slurry; the mass of protease accounts for 8% of the mass of dry matter in the lemon slag slurry.

[0044] S2. The lemon residue slurry after enzymatic hydrolysis is then filtered in a hydraulic filter press. The filter pressure is 4 MPa, the filter time is 20 min, and the air permeability of the filter cloth used in the filter press is 40 L / (m 2 ·s). The obtained filtrate is ultrafiltered through a 3000Da ultrafiltration membrane, the filtrate after ultrafiltration is nanofiltered through a 400Da nanofiltration membrane, the clear liquid after nanofiltration is reverse osmosis through a 70Da reverse osmosis membrane, and a reverse osmosis concentrate containing organic acid is obtained after reverse osmosis.

[0045] S3. The reverse osmosis concentrate is then distilled at reduced pressure and low temperature, the distillation temperature is 60°C, the vacuum degree is -0.15MPa, the distillation time is 100min, and the organic acid concentration in the concentrate obtained after reduced pressure and low temperature distillation is 67%. The organic acid can be processed into feed acidifier.

[0046] Example 3

[0047] A method for extracting organic acid using lemon residue comprises the following steps:

[0048] S1. Put lemon slag into a crusher and crush it into slurry. Put the lemon slag slurry into a container and heat it in a water bath at a temperature of 50°C. Add compound pectinase and neutral protease while heating in the water bath, and perform enzymolysis for 2 hours. Among them, the mass of pectinase accounts for 0.3% of the mass of dry matter in the lemon slag slurry; the mass of protease accounts for 6% of the mass of dry matter in the lemon slag slurry.

[0049] S2. The lemon residue slurry after enzymatic hydrolysis is then filtered in a hydraulic filter press. The filter pressure is 5 MPa, the filter time is 10 min, and the air permeability of the filter cloth used in the filter press is 30 L / (m 2·s). The obtained filtrate is ultrafiltered through a 2000Da ultrafiltration membrane, the filtrate after ultrafiltration is nanofiltered through a 300Da nanofiltration membrane, the clear liquid after nanofiltration is reverse osmosis through a 50Da reverse osmosis membrane, and a reverse osmosis concentrate containing organic acid is obtained after reverse osmosis.

[0050] S3, the reverse osmosis concentrate is then distilled at reduced pressure and low temperature, the distillation temperature is 70°C, the vacuum degree is -0.1MPa, the distillation time is 60min, and the organic acid concentration in the concentrate obtained after reduced pressure and low temperature distillation is 60%. The organic acid can be processed into feed acidifier.

[0051] It should be noted that the inventors studied a variety of pectinases and proteases during the experiment and finally found that when the pectinase is any one or a combination of polygalacturonase, pectin lyase and pectinesterase, the same effect as the composite pectinase in the embodiment can be achieved. When the protease is an acid protease or a mixture of an acid protease and a neutral protease, the same effect as the neutral protease in the embodiment can be achieved.

[0052] Application of organic acids

[0053] The organic acid prepared in Examples 1 to 3 was mixed with the 6214-50 type large pig complete feed produced by Shenyang Dabeinong Feed Co., Ltd., and the mass of the organic acid was added at 5.3% to 6.2% of the mass of the large pig complete feed. After adding, the average organic acid content of the mixed feed was 7.1%. 80 fattening pigs with similar weight and health were selected and divided into 2 groups. The control group was fed with the purchased large pig complete feed, and the test group was fed with the purchased large pig complete feed plus the organic acid of Examples 1 to 3. After feeding for 38 days, the weight, feed intake and feed usage of the fattening pigs were recorded, and the average weight gain rate and feed utilization rate of each fattening pig were calculated. The results are shown in Table 1.

[0054] Table 1 Experimental results of using organic acids as feed acidifiers

[0055] Control group Example 1 Example 2 Example 3 The mass ratio of organic acid addition to pig feed 0 5.3％ 5.5％ 6.2％ Final mass percentage of organic acids in pig feed 3.8％ 7.1％ 7.1％ 7.1％ Initial weight per head (kg) 77.0 74.1 76.9 77.9 Average weight per head (kg) 111.0 112.8 114.7 114.0 Weight gain per head (kg) 34.0 38.7 37.8 36.1 Total feed consumption (kg) 2320.5 2210.5 2357.0 2376.0 Feed consumption per head (kg) 110.50 110.53 112.24 108.00 Feed-to-meat ratio in the test area 3.25 2.86 2.97 2.99

[0056] As can be seen from Table 1, the average of the fattening pigs fed with the organic acid prepared in the examples of the present application as a feed acidifier is significantly higher than that of the control group, and the feed-to-meat ratio is significantly lower than that of the control group; the difference in feed consumption per head is not large. This shows that when the organic acid prepared according to the method of the present invention is used as a feed acidifier, it can improve the growth performance and feed conversion rate of fattening pigs, and has no significant effect on the feed intake of the pigs.

[0057] The above-described embodiments are only preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. For any person skilled in the art, the present application may have various changes and modifications. Any simple equivalent changes and modifications made based on the scope of protection of the present application and the contents of the specification should be included in the scope of protection of the present application.

Claims

1. A method for extracting organic acid using lemon residue, characterized in that: The following steps are involved: S1, crushing lemon residue into slurry, heating the slurry, and adding pectinase and protease to the slurry for enzymolysis reaction; S2, filtering the reaction system after the enzymatic hydrolysis reaction in step S1, and sequentially treating the filtrate with an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane to obtain a reverse osmosis concentrate of an organic acid; S3, distilling the reverse osmosis concentrate under reduced pressure to obtain an organic acid.

2. The method for extracting organic acid from lemon residue according to claim 1, characterized in that: The mass percentage of the pectinase in the dry matter in the slurry is 0.3% to 0.5%; or / and the mass percentage of the protease in the dry matter in the slurry is 6% to 10%.

3. The method for extracting organic acid from lemon residue according to claim 1, characterized in that: In step S1, the slurry is heated to 30-50° C.; or / and the enzymatic reaction time is 2-4 hours.

4. The method for extracting organic acid from lemon residue according to claim 1, characterized in that: The pressure of the filtration in step S2 is 3-5 MPa; or / and the time of the filtration in step S2 is 10-30 min.

5. The method for extracting organic acid from lemon residue according to claim 1, characterized in that: The air permeability of the filter cloth used in the filter press in step S2 is 30 to 50 L / (m 2 ·s).

6. The method for extracting organic acid from lemon residue according to claim 1, characterized in that: The molecular weight cutoff of the ultrafiltration membrane in step S2 is 2000-5000Da; or / and the molecular weight cutoff of the nanofiltration membrane in step S2 is 300-500Da; or / and the molecular weight cutoff of the reverse osmosis membrane in step S2 is 50-80Da.

7. The method for extracting organic acid using lemon residue according to claim 1, characterized in that: The pectinase is at least one of polygalacturonase, pectin lyase and pectinesterase; or / and the protease is acidic protease or / and neutral protease.

8. The method for extracting organic acid using lemon residue according to claim 1, characterized in that: The vacuum degree of the reduced pressure distillation in step S3 is -0.1 to -0.2 MPa; or / and the temperature of the reduced pressure distillation in step S3 is 50 to 70° C.; or / and the time of the reduced pressure distillation in step S3 is 60 to 120 min.

9. The organic acid extracted by the method according to any one of claims 1 to 8.

10. Use of the organic acid extracted by the method according to any one of claims 1 to 8 as a feed acidifier.