Method for preparing premixed feed from tryptophan fermentation liquor

Abstract

The invention provides a method for preparing a premixed feed from tryptophan fermentation broth, and belongs to the technical field of animal feeds, the preparation method comprises the following steps: preparing modified corncob, preparing tryptophan methyl ester, carrying out transesterification and granulating, and the transesterification method comprises the following steps: adding the tryptophan methyl ester, the modified corncob and a catalyst K2CO3 into a reactor, uniformly mixing, adding the modified corncob and the catalyst K2CO3 into the reactor, and granulating to obtain the premixed feed. The preparation method comprises the following steps: heating to 110-140 DEG C, then carrying out constant-temperature reaction for 7-9 hours, simultaneously steaming out a reaction byproduct methanol in the reaction process, after the reaction is finished, adding glacial acetic acid and a neutralization catalyst K2CO3, then adding deionized water, standing for layering, and then cleaning and drying an upper-layer product to obtain a modified corncob / tryptophan compound; the premix feed disclosed by the invention is good in stability, colorless tryptophan crystals are separated out within 30 days, and the content of tryptophan is high and is 19.5-21%.

Description

Technical Field

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

[0002] Tryptophan is widely used in food, feed, medicine, agriculture and forestry industries. As a feed additive, it is widely used in animal husbandry. Tryptophan has many functions in animals, including regulating growth, participating in protein synthesis, regulating nutrient metabolism, promoting digestion and absorption, alleviating oxidative stress and improving immunity.

[0003] Adding tryptophan to feed can significantly improve the growth performance, health status and production efficiency of animals. However, adding tryptophan crystals directly to feed will have the following problems: 1. The amount of tryptophan added in the feed is relatively small, 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 adding it directly will affect the palatability of the feed.

[0004] Using feed additive carriers 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 feeds such as barley flour, soybean meal, corn cob powder, wheat bran, wheat meal, defatted rice bran cake powder, rice husk powder, etc. The advantages of organic carriers are that they are widely available, relatively low in price, and have certain nutritional value and palatability. However, organic carriers are easy to absorb moisture and deteriorate, and have a short shelf life. At the same time, the combination of the carrier and the load is unstable, and stratification is prone to occur; common inorganic carriers include minerals such as calcium carbonate, calcium phosphate, silica, diatomaceous earth, zeolite powder, white clay, bentonite, and medical stone. The advantages of inorganic carriers are that they are stable in nature, not easy to deteriorate, not easy to be oxidized, and generally have no adverse effects on animals, but inorganic carriers have poor palatability and have certain requirements on the amount of addition.

[0005] Patent CN101700099B discloses an additive premix feed. In the technical solution, the processing method of the additive premix feed is: adding corn cob particles to concentrated tryptophan fermentation liquid in a stirring state to obtain a wet mixture, and drying the wet mixture to obtain a premix 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 liquid. The combination of tryptophan crystals and corn cobs is not stable, and the tryptophan crystals on the surface of the corn cobs 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 premix feed from tryptophan fermentation broth, so as to achieve the following invention objectives: improve the stability and palatability of the premix feed, improve the absorption and digestion of the feed by animals, and thus improve the feed-to-meat ratio.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a premixed feed from tryptophan fermentation liquid comprises the following steps: 1. Preparation of modified corn cob (1) Preprocessing The corn cob is crushed into particles, then added into deionized water and boiled for 8 to 12 minutes, taken out and dried at 70 to 90° C. for 0.4 to 0.6 hours to obtain a pretreated corn cob; The particle size of the particles is 0.3 to 0.7 mm.

[0008] (2) Modification The pretreated corn cob and sucrose are mixed evenly, and then NaOH solution is added thereto, and after continuous stirring at room temperature for 2.5 to 3.5 hours, epichlorohydrin is slowly added dropwise at 45 to 55° C., and after the addition is completed, the current temperature is maintained and the stirring reaction is continued for 4 to 8 hours, and then the mixture is cooled to room temperature and filtered, and the filter cake is washed with anhydrous ethanol until it is neutral, and then dried at 50 to 70° C. for 0.8 to 1.2 hours to obtain a modified corn cob; The mass ratio of the pretreated corn cob, 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; The time for adding epichlorohydrin dropwise is 40 to 50 minutes.

[0009] 2. Preparation of tryptophan methyl ester The tryptophan fermentation liquid is concentrated and crystallized to obtain tryptophan crystals, the tryptophan crystals are added to a reactor containing a reflux device, and then SOCl2 and methanol are added, and after heating and refluxing at 50-70° C. for 0.8-1.2 hours, excess SOCl2 and methanol are removed by rotary evaporation to obtain tryptophan methyl ester; The mass ratio of the tryptophan crystals, SOCl2, and methanol is 3.2-3.6: 2.8-3.2: 0.8-1.2; The temperature of the rotary evaporation is 60-70°C.

[0010] 3. Transesterification reaction Add tryptophan methyl ester, modified corn cob and catalyst K2CO3 into a reactor, stir and mix them evenly at 50-70°C, heat them to 110-140°C, and then react them at a constant temperature for 7-9 hours. During the reaction, methanol, a byproduct of the reaction, is evaporated. After the reaction, glacial acetic acid is added to neutralize the catalyst K2CO3, and then deionized water is added. After standing for 30-50 minutes, the upper layer product is cleaned with hot water at 60-80°C, and dried at 40-50°C to obtain a modified corn cob / tryptophan complex. The mass ratio of tryptophan, modified corncob and catalyst K2CO3 is 0.4-0.6: 2.8-3.2: 0.8-1.2; The mass ratio of tryptophan, glacial acetic acid and deionized water is 0.8-1.2: 0.1-0.3: 2.7-2.9; The stirring rate is 60-70 r / min.

[0011] 4. Granulation The modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate and water are uniformly mixed to form a wet mixture, the wet mixture is formed into granules by a granulator, and the premixed feed is obtained after drying at 55 to 65° C. for 2 to 4 hours; The mass ratio of the modified corncob / 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, wherein 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.

[0012] Compared with the prior art, the present invention has the following beneficial effects: Under the action of epichlorohydrin, the pretreated corncob is connected with sucrose through an ether bond to obtain a modified corncob. The sucrose molecules in the modified corncob contain multiple active hydroxyl groups, which react with tryptophan methyl ester through an ester exchange reaction to obtain a modified corncob / tryptophan complex. Among them, (1) tryptophan is connected to sucrose in the modified corn cob 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 are precipitated within 30 days; (2) The sucrose in the modified corncob contains multiple hydroxyl groups, which can be connected to 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%; (3) The ester group can enhance the antioxidant activity 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 pig (the experiment used weaned piglets) is 1204-1238g; (4) After the premixed feed is eaten, the ester bond is hydrolyzed in gastric acid to produce tryptophan, which can promote the digestion and absorption of the basic diet. The feed-to-meat ratio is low, at 1.98-2.07%; the diarrhea rate is low, at 1.6-2.1%. DETAILED DESCRIPTION

[0013] Example 1 1. Preparation of modified corn cob (1) Preprocessing The corn cob was crushed, passed through a 0.5 mm sieve, and then added into deionized water and boiled for 10 min. After being taken out, it was dried at 80°C for 0.5 h to obtain the pretreated corn cob; (2) Modification The pretreated corn cob and sucrose were mixed evenly, and then NaOH solution was added thereto. After continuous stirring at room temperature for 3 hours, epichlorohydrin was slowly added dropwise at 50°C. After the addition was completed, the current temperature was maintained and stirred for 6 hours, and then cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol until neutral, and then dried at 60°C for 1 hour to obtain a modified corn cob; The mass ratio of the pretreated corn cob, sucrose, NaOH solution and epichlorohydrin is 1:1.2:65:7.1; The mass fraction of the NaOH solution is 40%; The stirring rate is 80r / min; The time for adding epichlorohydrin dropwise is 45 minutes.

[0014] 2. Preparation of tryptophan methyl ester The tryptophan fermentation liquid is concentrated and crystallized to obtain tryptophan crystals, the tryptophan crystals are added to a reactor containing a reflux device, and then SOCl2 and methanol are added, and after heating and refluxing at 60° C. for 1 hour, excess SOCl2 and methanol are removed by rotary evaporation to obtain tryptophan methyl ester; The mass ratio of the tryptophan crystals, SOCl2, and methanol is 3.4:3:1; The temperature of the rotary evaporation is 65°C.

[0015] 3. Transesterification reaction Tryptophan methyl ester, modified corn cob and catalyst K2CO3 were added into the reactor, stirred and mixed at 60°C, then heated to 130°C and reacted at a constant temperature for 8 hours. During the reaction, the by-product methanol was evaporated. After the reaction, glacial acetic acid was added to neutralize the catalyst K2CO3, and then deionized water was added. After standing for 40 minutes, the upper layer product was cleaned with hot water at 70°C and dried at 45°C to obtain a modified corn cob / tryptophan complex. The mass ratio of tryptophan, modified corncob and catalyst K2CO3 is 0.5:3:1; The mass ratio of tryptophan, glacial acetic acid and deionized water is 1:0.2:2.8; The stirring rate is 65 r / min.

[0016] 4. Granulation The modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate and water are uniformly mixed to form a wet mixture, the wet mixture is formed into granules by a granulator, and the premixed feed is obtained after drying at 60° C. for 3 hours; The mass ratio of the modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate, and water is 1:5:0.03:0.1:0.8:3; The complex vitamin comprises vitamin A, vitamin E, vitamin B3 and vitamin B6, wherein the mass ratio of vitamin A, vitamin E, vitamin B3 and vitamin B6 is 1.46:4:3.5:1.04.

[0017] Example 2 1. Preparation of modified corn cob (1) Preprocessing The corn cob was crushed, passed through a 0.3 mm sieve, and then added into deionized water and boiled for 8 min. After being taken out, it was dried at 70°C for 0.4 h to obtain the pretreated corn cob. (2) Modification The pretreated corn cob and sucrose were mixed evenly, and then NaOH solution was added thereto. After continuous stirring at room temperature for 2.5 hours, epichlorohydrin was slowly added dropwise at 45°C. After the addition was completed, the current temperature was maintained and stirred for 4 hours, and then cooled to room temperature, filtered, and the filter cake was washed with anhydrous ethanol until neutral, and then dried at 50°C for 0.8 hours to obtain a modified corn cob; The mass ratio of the pretreated corn cob, sucrose, NaOH solution and epichlorohydrin is 0.8:1.1:60:6.9; The mass fraction of the NaOH solution is 30%; The stirring rate is 70r / min; The time for adding epichlorohydrin dropwise is 40 minutes.

[0018] 2. Preparation of tryptophan methyl ester The tryptophan fermentation liquid is concentrated and crystallized to obtain tryptophan crystals, the tryptophan crystals are added to a reactor containing a reflux device, and then SOCl2 and methanol are added, and after heating and refluxing at 50° C. for 0.8 h, excess SOCl2 and methanol are removed by rotary evaporation to obtain tryptophan methyl ester; The mass ratio of the tryptophan crystals, SOCl2, and methanol is 3.2:2.8:0.8; The temperature of the rotary evaporation is 60°C.

[0019] 3. Transesterification reaction Tryptophan methyl ester, modified corncob and catalyst K2CO3 were added into the reactor, stirred and mixed evenly at 50°C, then heated to 110°C and reacted at a constant temperature for 7 hours. During the reaction, the by-product methanol was evaporated. After the reaction, glacial acetic acid was added to neutralize the catalyst K2CO3, and then deionized water was added. After standing for 30 minutes, the upper layer product was cleaned with hot water at 60°C and dried at 40°C to obtain a modified corncob / tryptophan complex. The mass ratio of tryptophan, modified corncob and catalyst K2CO3 is 0.4:2.8:0.8; The mass ratio of tryptophan, glacial acetic acid and deionized water is 0.8:0.1:2.7; The stirring rate is 60 r / min.

[0020] 4. Granulation The modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate and water are uniformly mixed to form a wet mixture, the wet mixture is formed into granules by a granulator, and the premixed feed is obtained after drying at 55° C. for 2 hours; The mass ratio of the modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate, and water is 0.8:4:0.02:0.08:0.7:2; The complex vitamin comprises vitamin A, vitamin E, vitamin B3 and vitamin B6, wherein the mass ratio of vitamin A, vitamin E, vitamin B3 and vitamin B6 is 1.4:3.5:3.3:1.02.

[0021] Example 3 1. Preparation of modified corn cob (1) Preprocessing The corn cob was crushed, passed through a 0.7 mm sieve, and then added into deionized water and boiled for 12 min. After being taken out, it was dried at 90°C for 0.6 h to obtain the pretreated corn cob. (2) Modification The pretreated corn cob and sucrose were mixed evenly, and then NaOH solution was added thereto. After continuous stirring at room temperature for 3.5 hours, epichlorohydrin was slowly added dropwise at 55°C. After the addition was completed, the current temperature was maintained and stirred for 8 hours. Then, the mixture was cooled to room temperature and filtered. The filter cake was washed with anhydrous ethanol until it was neutral, and then dried at 70°C for 1.2 hours to obtain a modified corn cob. The mass ratio of the pretreated corn cob, sucrose, NaOH solution and epichlorohydrin is 1.2:1.3:70:7.3; The mass fraction of the NaOH solution is 50%; The stirring rate is 90r / min; The time for adding epichlorohydrin dropwise is 50 minutes.

[0022] 2. Preparation of tryptophan methyl ester The tryptophan fermentation liquid is concentrated and crystallized to obtain tryptophan crystals, the tryptophan crystals are added to a reactor containing a reflux device, and then SOCl2 and methanol are added, and after heating and refluxing at 70°C for 1.2 hours, excess SOCl2 and methanol are removed by rotary evaporation to obtain tryptophan methyl ester; The mass ratio of the tryptophan crystals, SOCl2, and methanol is 3.6:3.2:1.2; The temperature of the rotary evaporation is 70°C.

[0023] 3. Transesterification reaction Tryptophan methyl ester, modified corncob and catalyst K2CO3 were added into the reactor, stirred and mixed evenly at 70°C, then heated to 140°C and reacted at a constant temperature for 9 hours. During the reaction, the by-product methanol was evaporated. After the reaction, glacial acetic acid was added to neutralize the catalyst K2CO3, and then deionized water was added. After standing for 50 minutes, the upper layer product was cleaned with hot water at 80°C and dried at 50°C to obtain a modified corncob / tryptophan complex. The mass ratio of tryptophan, modified corncob and catalyst K2CO3 is 0.6:3.2:1.2; The mass ratio of tryptophan, glacial acetic acid and deionized water is 1.2:0.3:2.9; The stirring rate is 70 r / min.

[0024] 4. Granulation The modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate and water are uniformly mixed to form a wet mixture, the wet mixture is formed into granules by a granulator, and the premixed feed is obtained after drying at 65° C. for 4 hours; The mass ratio of the modified corncob / tryptophan complex, bran, sodium alginate, complex vitamins, calcium phosphate, and water is 1.2:6:0.04:0.12:0.9:4; The complex vitamin comprises vitamin A, vitamin E, vitamin B3 and vitamin B6, wherein the mass ratio of vitamin A, vitamin E, vitamin B3 and vitamin B6 is 1.5:4.5:3.7:1.06.

[0025] Comparative Example 1 On the basis of Example 1, the modification of the pretreated corn cob in step 1 was omitted, and the modified corn cob was replaced with the pretreated corn cob, and the remaining steps were the same.

[0026] Comparative Example 2 On the basis of Example 1, step 2 of preparing tryptophan methyl ester is omitted, and step 3 is changed to uniformly mixing the modified corn cob with the tryptophan fermentation liquid to obtain a wet mixture, and drying the wet mixture to obtain a premixed feed; The mass ratio of the modified corn cob to the tryptophan fermentation liquid is 1:6; The mass fraction of tryptophan in the tryptophan fermentation broth is 20%.

[0027] Test example The following data were tested on the premixed feeds prepared in Examples 1 to 3 and Comparative Examples 1 to 2. The test results are shown in Table 1.

[0028] Data 1: The appearance of the premixed feed after 30 days to see if there is any precipitation of tryptophan crystals; Data 2, tryptophan content in premixed feed; The method for detecting the tryptophan content in the premixed feed is as follows: adding the premixed feed, stirring and dissolving, and then detecting by an amino acid analyzer to obtain the tryptophan content; Data 3: Performance of animals (weaned piglets in this experiment) after adding premixed feed to the basic diet, including average daily feed intake, feed-to-meat ratio, and diarrhea rate within 30 days; The basic diet includes 55% corn, 25% soybean meal, 5% fish meal, 5% soybean protein powder, 8.4% fish oil, 1% calcium hydrogen phosphate, 0.3% salt, 0.12% vitamins, and 0.18% trace elements.

[0029] Table 1

[0030] It can be seen from the above results that compared with Example 1, Comparative Example 1 did not modify the pretreated corn cob, the chemical properties of the hydroxyl groups on the surface of the pretreated corn cob were stable, so the ester bond formed with tryptophan was small, and part of the tryptophan was physically combined with the pretreated corn cob; in Comparative Example 2, the pretreated corn cob and tryptophan were all physically combined; therefore, the premixed feed obtained in Comparative Examples 1 and 2 had a small tryptophan content and crystals precipitated on the surface, which led to poor palatability, reduced average daily feed intake, increased feed-to-meat ratio, poor digestion and absorption of the basal diet, and increased 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, transesterification 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 the ester exchange reaction is as follows: tryptophan methyl ester, modified corn cob, and catalyst K2CO3 are added into a reactor and mixed evenly, then the temperature is raised to 110-140° C., and then the reaction is carried out at a constant temperature for 7-9 hours, and the reaction byproduct methanol is evaporated 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 stratification, the upper layer product is cleaned and dried to obtain a modified corn cob / tryptophan complex.

2. The method for preparing a premixed feed from tryptophan fermentation broth according to claim 1, characterized in that: 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 NaOH solution is 30-50%, the stirring rate is 70-90 r / min, and the time for dripping epichlorohydrin is 40-50 min.

3. The method for preparing a premixed feed from tryptophan fermentation broth according to claim 1, characterized in that: 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.

4. The method for preparing a premixed feed from tryptophan fermentation liquid according to claim 1, characterized in that: The method for preparing tryptophan methyl ester comprises the following steps: concentrating and crystallizing a tryptophan fermentation liquid to obtain tryptophan crystals; adding the tryptophan crystals into a reactor having a reflux device; then adding SOCl2 and methanol; heating and reflux at 50 to 70° C. for 0.8 to 1.2 hours; and then removing excess SOCl2 and methanol by rotary evaporation to obtain tryptophan methyl ester.

5. The method for preparing a premixed feed from tryptophan fermentation liquid according to claim 4, 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.

6. The method for preparing a premixed feed from tryptophan fermentation liquid 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.

7. The method for preparing a premixed feed from tryptophan fermentation liquid according to claim 6, 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.

8. The method for preparing a premixed feed from tryptophan fermentation liquid 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.

9. The method for preparing a premixed feed from tryptophan fermentation liquid according to claim 8, 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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