A method for preparing a premixed feed from tryptophan fermentation broth

Abstract

The present invention provides a method for preparing a premixed feed from a tryptophan fermentation broth, belonging to the technical field of animal feeds. The preparation method includes preparing modified corncobs, preparing methyl tryptophan, transesterification reaction, and granulation. The method for the transesterification reaction is to add methyl tryptophan, modified corncobs, and catalyst K 2 CO 3 into a reactor, mix them evenly, heat up to 110-140 °C, and then carry out a constant-temperature reaction for 7-9 h. During the reaction process, the reaction by-product methanol is distilled out simultaneously. After the reaction is completed, glacial acetic acid is added to neutralize catalyst K 2 CO 3 , and then deionized water is added. After standing and separating layers, the upper-layer product is washed clean and dried to obtain a modified corncob / tryptophan complex. The premixed feed of the present invention has good stability, no tryptophan crystals precipitate within 30 days, and has a high tryptophan content of 19.5-21%.

Description

Technical Field

[0001] The present invention belongs to the technical field of animal feed, and particularly relates to a method for preparing a premixed feed from a tryptophan fermentation broth. Background Art

[0002] Tryptophan is widely used in industries such as food, feed, medicine, agriculture and forestry. As a feed additive, it has a wide range of applications in the livestock industry. Tryptophan has various functions in animals, such as regulating growth, participating in protein synthesis, regulating nutrient metabolism, promoting digestion and absorption, alleviating oxidative stress and enhancing immunity.

[0003] Adding tryptophan to feed can significantly improve the growth performance, health status and production efficiency of animals. However, directly adding tryptophan crystals to feed has the following problems: 1. The addition amount of tryptophan accounts for a relatively small proportion in the feed, so it is not easy to mix evenly with the feed, and tryptophan cannot be evenly supplemented into each animal's body; 2. Tryptophan tastes slightly bitter, and directly adding it will affect the palatability of the feed.

[0004] Using a feed additive carrier to load tryptophan can improve the above problems, which is a commonly used method in the prior art. At present, feed additive carriers are mainly divided into two categories: organic carriers and inorganic carriers. Common organic carriers include plant-based feeds such as barley flour, soybean meal powder, corncob powder, wheat bran, wheat coarse powder, defatted rice bran cake powder, rice hull powder, rice husk powder, etc. The advantages of organic carriers are wide sources, relatively low prices, and certain nutritional value and palatability. However, organic carriers are prone to moisture absorption and deterioration, have a short shelf life, and the combination between the carrier and the loaded substance is unstable, and layering is likely to occur; common inorganic carriers include minerals such as calcium carbonate, calcium phosphate, silicon dioxide, diatomaceous earth, zeolite powder, kaolin, bentonite, and medical stone. The advantages of inorganic carriers are stable properties, not easy to deteriorate, not easy to be oxidized, and generally have no adverse effects on animals. However, inorganic carriers have poor palatability and certain requirements for the addition amount.

[0005] Patent CN101700099B discloses an additive premixed feed. In this technical solution, the processing method of the additive premixed feed is: adding corncob particles to the concentrated tryptophan fermentation broth in a stirring state to obtain a wet mixture, and drying the wet mixture to obtain the premixed feed. However, the solubility of tryptophan in water is very small, so there will be a large number of tryptophan crystal particles in the concentrated fermentation broth. The combination between the tryptophan crystals and the corncob is not stable, and the tryptophan crystals on the surface of the corncob will affect the palatability. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for preparing a premixed feed from a tryptophan fermentation broth, achieving the following invention objectives: improving the stability and palatability of the premixed feed, enhancing the absorption and digestion of the feed by animals, and thus improving the feed conversion ratio.

[0007] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0008] A method for preparing a premixed feed from a tryptophan fermentation broth, comprising the following steps:

[0009] 1. Preparation of modified corncob

[0010] (1) Pretreatment

[0011] Crush the corncob into particles, then add it to deionized water and boil for 8 - 12 min. After fishing out, dry it at 70 - 90 °C for 0.4 - 0.6 h to obtain pretreated corncob;

[0012] The particle size of the particles is 0.3 - 0.7 mm.

[0013] (2) Modification

[0014] Mix the pretreated corncob and sucrose evenly, then add NaOH solution thereto, continuously stir at room temperature for 2.5 - 3.5 h, slowly drop epichlorohydrin at 45 - 55 °C. After the dropping is completed, maintain the current temperature and continue to stir and react for 4 - 8 h, then cool to room temperature, filter, wash the filter cake with absolute ethanol until neutral, and dry it at 50 - 70 °C for 0.8 - 1.2 h to obtain modified corncob;

[0015] The mass ratio of the pretreated corncob, sucrose, NaOH solution, and epichlorohydrin is 0.8 - 1.2∶1.1 - 1.3∶60 - 70∶6.9 - 7.3;

[0016] The mass fraction of the NaOH solution is 30 - 50%;

[0017] The stirring rate is 70 - 90 r / min;

[0018] The time for dropping epichlorohydrin is 40 - 50 min.

[0019] 2. Preparation of tryptophan methyl ester

[0020] Concentrate and crystallize the tryptophan fermentation broth to obtain tryptophan crystals. Add the tryptophan crystals to a reactor equipped with a reflux device, then add SOCl 2 and methanol, heat and reflux at 50 - 70 °C for 0.8 - 1.2 h, then rotary evaporate to remove the excess SOCl 2 and methanol to obtain tryptophan methyl ester;

[0021] The mass ratio of the tryptophan crystal, SOCl 2 , and methanol is 3.2 - 3.6:2.8 - 3.2:0.8 - 1.2;

[0022] The temperature of the rotary evaporation is 60 - 70 °C.

[0023] 3. Transesterification reaction

[0024] Put methyl tryptophan, modified corncob, and catalyst K 2 CO 3 into the reactor. After stirring and mixing evenly at 50 - 70 °C, raise the temperature to 110 - 140 °C, and then keep the temperature constant for reaction for 7 - 9 h. During the reaction process, the reaction by-product methanol is distilled out simultaneously. After the reaction ends, add glacial acetic acid to neutralize the catalyst K 2 CO 3 , then add deionized water. After standing for 30 - 50 min, wash the upper product with hot water at 60 - 80 °C, and dry it at 40 - 50 °C to obtain the modified corncob / tryptophan complex;

[0025] The mass ratio of the tryptophan, modified corncob, and catalyst K 2 CO 3 is 0.4 - 0.6:2.8 - 3.2:0.8 - 1.2;

[0026] The mass ratio of the tryptophan, glacial acetic acid, and deionized water is 0.8 - 1.2:0.1 - 0.3:2.7 - 2.9;

[0027] The stirring rate is 60 - 70 r / min.

[0028] 4. Granulation

[0029] Mix the modified corncob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water evenly to form a wet mixture. Form the wet mixture into granules through a granulator, and dry it at 55 - 65 °C for 2 - 4 h to obtain the premixed feed;

[0030] The mass ratio of the modified corncob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water is 0.8 - 1.2:4 - 6:0.02 - 0.04:0.08 - 0.12:0.7 - 0.9:2 - 4;

[0031] The compound vitamins include vitamin A, vitamin E, vitamin B3, and vitamin B6. The mass ratio of vitamin A, vitamin E, vitamin B3, and vitamin B6 is 1.4 - 1.5:3.5 - 4.5:3.3 - 3.7:1.02 - 1.06.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] Under the action of epichlorohydrin, pretreated corncobs are connected to sucrose through ether bonds to obtain modified corncobs. The sucrose molecules in the modified corncobs contain multiple active hydroxyl groups, and through transesterification reaction with methyl tryptophan, a modified corncob / tryptophan complex is obtained;

[0034] Among them, (1) Tryptophan is connected to the sucrose in the modified corncob through an ester bond, and the combination is stable. Therefore, the obtained premixed feed has good stability and a long shelf life, and no tryptophan crystals precipitate within 30 days;

[0035] (2) The sucrose in the modified corncob contains multiple hydroxyl groups, which can connect multiple tryptophans. The modified corncob has a high loading capacity for tryptophan, and the tryptophan content in the obtained premixed feed reaches 19.5-21%;

[0036] (3) The ester group can enhance the antioxidant property of the modified corncob / tryptophan complex and improve the taste. Therefore, the obtained premixed feed has good palatability, and the average daily feed intake per piglet (weaned piglets were used in the experiment) reaches 1204-1238 g;

[0037] (4) After the premixed feed is eaten, the ester bond is hydrolyzed in gastric acid to obtain tryptophan. Tryptophan can promote the digestion and absorption of the basal diet, with a low feed-to-meat ratio of 1.98-2.07%; and a low diarrhea rate of 1.6-2.1%. Detailed implementation mode

[0038] Example 1

[0039] 1. Preparation of modified corncobs

[0040] (1) Pretreatment

[0041] The corncobs are crushed and sieved through a 0.5 mm sieve, then added to deionized water and boiled for 10 min, fished out and dried at 80 °C for 0.5 h to obtain pretreated corncobs;

[0042] (2) Modification

[0043] The pretreated corncobs and sucrose are mixed evenly, then NaOH solution is added thereto, and after continuously stirring at room temperature for 3 h, epichlorohydrin is slowly added dropwise at 50 °C. After the addition is completed, the reaction is continued by stirring at the current temperature for 6 h, then cooled to room temperature, filtered, and the filter cake is washed with absolute ethanol until neutral and then dried at 60 °C for 1 h to obtain modified corncobs;

[0044] The mass ratio of the pretreated corncobs, sucrose, NaOH solution, and epichlorohydrin is 1∶1.2∶65∶7.1;

[0045] The mass fraction of the NaOH solution is 40%;

[0046] The stirring rate is 80 r / min;

[0047] The time for dropping epichlorohydrin is 45 min.

[0048] 2. Preparation of tryptophan methyl ester

[0049] Concentrate and crystallize the tryptophan fermentation broth to obtain tryptophan crystals. Add the tryptophan crystals to a reactor equipped with a reflux device, and then add SOCl 2 and methanol. After heating under reflux at 60 °C for 1 h, rotary evaporate to remove the excess SOCl 2 and methanol to obtain tryptophan methyl ester;

[0050] The mass ratio of the tryptophan crystals, SOCl 2 , and methanol is 3.4∶3∶1;

[0051] The temperature of the rotary evaporation is 65 °C.

[0052] 3. Transesterification reaction

[0053] Add tryptophan methyl ester, modified corn cob, and catalyst K 2 CO 3 to the reactor. After stirring and mixing evenly at 60 °C, raise the temperature to 130 °C, and then keep the temperature constant for 8 h. During the reaction, the reaction by-product methanol is distilled out simultaneously. After the reaction is completed, add glacial acetic acid to neutralize the catalyst K 2 CO 3 , then add deionized water. After standing for 40 min, wash the upper layer product with hot water at 70 °C and dry it at 45 °C to obtain the modified corn cob / tryptophan complex;

[0054] The mass ratio of the tryptophan, modified corn cob, and catalyst K 2 CO 3 is 0.5∶3∶1;

[0055] The mass ratio of the tryptophan, glacial acetic acid, and deionized water is 1∶0.2∶2.8;

[0056] The stirring rate is 65 r / min.

[0057] 4. Granulation

[0058] Mix the modified corn cob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water evenly to form a wet mixture. Form the wet mixture into pellets through a granulator and dry them at 60 °C for 3 h to obtain the premixed feed;

[0059] The mass ratio of the modified corncob / tryptophan complex, bran, sodium alginate, compound vitamins, calcium phosphate, and water is 1:5:0.03:0.1:0.8:3;

[0060] The compound vitamins include vitamin A, vitamin E, vitamin B3, and vitamin B6, and the mass ratio of vitamin A, vitamin E, vitamin B3, and vitamin B6 is 1.46:4:3.5:1.04.

[0061] Example 2

[0062] 1. Preparation of modified corncob

[0063] (1) Pretreatment

[0064] Crush the corncob, pass it through a 0.3 mm sieve, then add it to deionized water and boil for 8 min. After fishing it out, dry it at 70 °C for 0.4 h to obtain pretreated corncob;

[0065] (2) Modification

[0066] Mix the pretreated corncob and sucrose evenly, then add NaOH solution to it. After continuously stirring at room temperature for 2.5 h, slowly drop epichlorohydrin at 45 °C. After the dropping is completed, continue to stir and react at the current temperature for 4 h, then cool to room temperature, filter, wash the filter cake with absolute ethanol until neutral, and then dry it at 50 °C for 0.8 h to obtain modified corncob;

[0067] The mass ratio of the pretreated corncob, sucrose, NaOH solution, and epichlorohydrin is 0.8:1.1:60:6.9;

[0068] The mass fraction of the NaOH solution is 30%;

[0069] The stirring rate is 70 r / min;

[0070] The time for dropping epichlorohydrin is 40 min.

[0071] 2. Preparation of tryptophan methyl ester

[0072] Concentrate and crystallize the tryptophan fermentation broth to obtain tryptophan crystals. Add the tryptophan crystals to a reactor equipped with a reflux device, then add SOCl 2 and methanol, heat and reflux at 50 °C for 0.8 h, then rotary evaporate to remove the excess SOCl 2 and methanol to obtain tryptophan methyl ester;

[0073] The mass ratio of the tryptophan crystals, SOCl 2 and methanol is 3.2:2.8:0.8;

[0074] The temperature of the rotary evaporation is 60 °C.

[0075] 3. Transesterification reaction

[0076] Add methyl tryptophan, modified corn cob, and catalyst K 2 CO 3 into the reactor. After stirring and mixing evenly at 50 °C, raise the temperature to 110 °C, then keep the temperature constant for 7 h. During the reaction process, the reaction by-product methanol is distilled out simultaneously. After the reaction is completed, add glacial acetic acid to neutralize catalyst K 2 CO 3 , then add deionized water. After standing for 30 min, wash the upper layer product with hot water at 60 °C and dry it at 40 °C to obtain the modified corn cob / tryptophan complex;

[0077] The mass ratio of the tryptophan, modified corn cob, and catalyst K 2 CO 3 is 0.4∶2.8∶0.8;

[0078] The mass ratio of the tryptophan, glacial acetic acid, and deionized water is 0.8∶0.1∶2.7;

[0079] The stirring rate is 60 r / min.

[0080] 4. Granulation

[0081] Mix the modified corn cob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water evenly to form a wet mixture. Form the wet mixture into granules through a granulator and dry it at 55 °C for 2 h to obtain the premixed feed;

[0082] The mass ratio of the modified corn cob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water is 0.8∶4∶0.02∶0.08∶0.7∶2;

[0083] The compound vitamins include vitamin A, vitamin E, vitamin B3, and vitamin B6. The mass ratio of vitamin A, vitamin E, vitamin B3, and vitamin B6 is 1.4∶3.5∶3.3∶1.02.

[0084] Example 3

[0085] 1. Preparation of modified corn cob

[0086] (1) Pretreatment

[0087] Crush the corn cob, pass it through a 0.7-mm sieve, then add it to deionized water and boil for 12 min. After fishing it out, dry it at 90 °C for 0.6 h to obtain the pretreated corn cob;

[0088] (2) Modification

[0089] Mix the pretreated corncob and sucrose evenly, then add NaOH solution to it. After continuously stirring at room temperature for 3.5 h, slowly add epichlorohydrin at 55 °C. After the addition is complete, maintain the current temperature and continue stirring and reacting for 8 h. Then cool to room temperature, filter, wash the filter cake with absolute ethanol until neutral, and dry it at 70 °C for 1.2 h to obtain the modified corncob;

[0090] The mass ratio of the pretreated corncob, sucrose, NaOH solution, and epichlorohydrin is 1.2∶1.3∶70∶7.3;

[0091] The mass fraction of the NaOH solution is 50%;

[0092] The stirring rate is 90 r / min;

[0093] The time for adding epichlorohydrin dropwise is 50 min.

[0094] 2. Preparation of tryptophan methyl ester

[0095] Concentrate and crystallize the tryptophan fermentation broth to obtain tryptophan crystals. Add the tryptophan crystals to a reactor equipped with a reflux device, and then add SOCl 2 and methanol. After heating under reflux at 70 °C for 1.2 h, rotary evaporate to remove the excess SOCl 2 and methanol to obtain tryptophan methyl ester;

[0096] The mass ratio of the tryptophan crystals, SOCl 2 , and methanol is 3.6∶3.2∶1.2;

[0097] The temperature of the rotary evaporation is 70 °C.

[0098] 3. Transesterification reaction

[0099] Add tryptophan methyl ester, modified corncob, and catalyst K 2 CO 3 to the reactor. After stirring and mixing evenly at 70 °C, raise the temperature to 140 °C, and then keep the temperature constant and react for 9 h. During the reaction process, simultaneously distill out the reaction by-product methanol. After the reaction is completed, add glacial acetic acid to neutralize the catalyst K 2 CO 3 , then add deionized water, let it stand for 50 min, wash the upper product with hot water at 80 °C, and dry it at 50 °C to obtain the modified corncob / tryptophan complex;

[0100] The mass ratio of tryptophan, modified corncob, and catalyst K 2 CO 3 is 0.6∶3.2∶1.2;

[0101] The mass ratio of the tryptophan, glacial acetic acid, and deionized water is 1.2∶0.3∶2.9;

[0102] The stirring rate is 70 r / min.

[0103] 4. Granulation

[0104] Mix the modified corncob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water evenly to form a wet mixture, and form granules from the wet mixture through a granulator, and obtain a premixed feed after drying at 65°C for 4 h;

[0105] The mass ratio of the modified corncob / tryptophan complex, wheat bran, sodium alginate, compound vitamins, calcium phosphate, and water is 1.2∶6∶0.04∶0.12∶0.9∶4;

[0106] The compound vitamins include vitamin A, vitamin E, vitamin B3, and vitamin B6, and the mass ratio of vitamin A, vitamin E, vitamin B3, and vitamin B6 is 1.5∶4.5∶3.7∶1.06.

[0107] Comparative Example 1

[0108] On the basis of Example 1, omit the modification of the pretreated corncob in Step 1, and change the modified corncob to the pretreated corncob, and the other steps are the same.

[0109] Comparative Example 2

[0110] On the basis of Example 1, omit the preparation of tryptophan methyl ester in Step 2, and change Step 3 to mix the modified corncob and the tryptophan fermentation broth evenly to obtain a wet mixture, and dry the wet mixture to obtain a premixed feed;

[0111] The mass ratio of the modified corncob to the tryptophan fermentation broth is 1∶6;

[0112] The mass fraction of tryptophan in the tryptophan fermentation broth is 20%.

[0113] Test Example

[0114] The following data of the premixed feeds prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were detected, and the detection results are shown in Table 1.

[0115] Data 1. Whether tryptophan crystals precipitate on the appearance of the premixed feed after 30 days;

[0116] Data 2. The content of tryptophan in the premixed feed;

[0117] The detection method for the content of tryptophan in the premixed feed is as follows: add the premixed feed, stir and dissolve it, and then detect it with an amino acid analyzer to obtain the content of tryptophan;

[0118] Data 3. The performance of animals (weaned piglets were used in this experiment) after adding the premixed feed to the basal diet, including the average daily feed intake, feed-to-gain ratio, and diarrhea rate within 30 days;

[0119] The basal diet includes 55% corn, 25% soybean meal, 5% fish meal, 5% soy protein powder, 8.4% fish oil, 1% calcium hydrogen phosphate, 0.3% salt, 0.12% vitamins, and 0.18% trace elements.

[0120] Table 1

[0121]

[0122] It can be seen from the above results that compared with Example 1, in Comparative Example 1, the pretreated corncob was not modified, and the chemical properties of the hydroxyl groups on the surface of the pretreated corncob were stable. Therefore, fewer ester bonds were formed with tryptophan, and part of the tryptophan was physically combined with the pretreated corncob; in Comparative Example 2, the pretreated corncob and tryptophan were all physically combined; as a result, the content of tryptophan in the premixed feed obtained in Comparative Example 1 and Comparative Example 2 was low, and crystals precipitated on the surface, which further led to poor palatability, a decrease in the average daily feed intake, an increase in the feed-to-gain ratio, a poor digestion and absorption effect on the basal diet, and an increase in the diarrhea rate.

Claims

1. A method for preparing a premixed feed from tryptophan fermentation broth, characterized in that: The preparation method comprises preparing modified corn cobs, preparing tryptophan methyl ester, ester exchange reaction, and granulation; The method for preparing modified corncob includes pretreatment and modification; The modification method comprises the following steps: uniformly mixing the pretreated corn cob and sucrose, then adding a NaOH solution thereto, stirring continuously for 2.5 to 3.5 hours at room temperature, slowly dropping epichlorohydrin at 45 to 55° C., and after the dropping is completed, maintaining the temperature at 45 to 55° C. and continuing to stir and react for 4 to 8 hours, then cooling to room temperature, filtering, washing, and drying to obtain a modified corn cob; The method for preparing tryptophan methyl ester is to concentrate and crystallize the tryptophan fermentation broth to obtain tryptophan crystals, add the tryptophan crystals to a reactor containing a reflux device, then add SOCl2 and methanol, heat and reflux at 50 to 70°C for 0.8 to 1.2h, and then remove excess SOCl2 and methanol by rotary evaporation to obtain tryptophan methyl ester; The transesterification reaction method comprises the following steps: adding tryptophan methyl ester, modified corncob and catalyst K2CO3 into a reactor and mixing them evenly, heating the reactor to 110-140° C., and then reacting the reactor at a constant temperature for 7-9 hours, while simultaneously evaporating the reaction byproduct methanol during the reaction process. After the reaction is completed, glacial acetic acid is added to neutralize the catalyst K2CO3 to make the solution neutral, and then deionized water is added. After standing and stratifying, the upper layer product is cleaned and dried to obtain a modified corncob / tryptophan complex. In the modification method, the mass ratio of pretreated corn cobs, sucrose, NaOH solution, and epichlorohydrin is 0.8-1.2:1.1-1.3:60-70:6.9-7.3, the mass fraction of the NaOH solution is 30-50%, the stirring rate is 70-90 r / min, and the time for dripping epichlorohydrin is 40-50 min; In the transesterification method, the mass ratio of tryptophan methyl ester, modified corn cob, catalyst K2CO3 and deionized water is 0.4-0.6: 2.8-3.2: 0.8-1.2: 2.7-2.

9.

2. The method for preparing a premixed feed from tryptophan fermentation broth according to claim 1, characterized in that: In the method for preparing tryptophan methyl ester, the mass ratio of tryptophan crystals, SOCl2, and methanol is 3.2-3.6:2.8-3.2:0.8-1.2, and the rotary evaporation temperature is 60-70°C.

3. The method for preparing a premixed feed from tryptophan fermentation broth according to claim 1, characterized in that: In the method for preparing the modified corn cob, the pretreatment method is to crush the corn cob into particles, and then boil and dry them to obtain the pretreated corn cob.

4. The method for preparing a premixed feed from tryptophan fermentation broth according to claim 3, characterized in that: In the pretreatment method, the particle size of the particles is 0.3-0.7 mm, the boiling time is 8-12 min, the drying temperature is 70-90° C., and the drying time is 0.4-0.6 h.

5. The method for preparing a premixed feed from tryptophan fermentation broth according to claim 1, characterized in that: The granulation method comprises the following steps: uniformly mixing the modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate and water to form a wet mixture, passing the wet mixture through a granulator to form granules, and drying the granules to obtain a premixed feed.

6. The method for preparing a premixed feed from tryptophan fermentation liquid according to claim 5, characterized in that: In the granulation method, the mass ratio of the modified corn cob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate and water is 0.8-1.2: 4-6: 0.02-0.04: 0.08-0.12: 0.7-0.9: 2-4, the complex vitamins include vitamin A, vitamin E, vitamin B3 and vitamin B6, and the mass ratio of vitamin A, vitamin E, vitamin B3 and vitamin B6 is 1.4-1.5: 3.5-4.5: 3.3-3.7: 1.02-1.06.

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