CN106047954B - Method for producing lactic acid and co-producing protein feed through circulating fermentation - Google Patents
Method for producing lactic acid and co-producing protein feed through circulating fermentation Download PDFInfo
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Abstract
The invention belongs to the technical field of lactic acid fermentation, and particularly relates to a method for producing lactic acid and coproducing protein feed through circulating fermentation. The method of the invention is based on the existing lactic acid production process of simultaneous saccharification and fermentation, combines the pretreatment method of lactic acid fermentation thallus residues to realize the recycling of thallus, utilizes a single batch of strains to realize multi-cycle fermentation, solves the problem of fermentation waste residue outlet, reduces the consumption of raw and auxiliary materials, and realizes the recycling of resources by recycling a composite medium. In addition, the method for producing lactic acid and coproducing protein feed by circulating fermentation introduces an automatic plate-and-frame filtration technology to quickly separate corn starch residues in the sugar production process; meanwhile, the separated corn starch residue is subjected to solid state fermentation to co-produce protein feed, so that the amino acid content can be obviously improved, and all components in the starch residue are digested and absorbed by animals to prepare the corn protein feed with high added value.
Description
Technical Field
The invention belongs to the technical field of lactic acid fermentation, and particularly relates to a method for producing lactic acid and coproducing protein feed through circulating fermentation.
Background
Lactic acid is one of three major organic acids (including lactic acid, citric acid and acetic acid), is an organic acid prepared by using starch as a raw material and performing microbial fermentation and refining, and is widely applied to the fields of food, medicine, chemical industry and the like.
In the field of food industry, lactic acid is widely used as an acidulant and a preservative in the food industry because it is soft and stable in acidity, and therefore, the consumption amount of lactic acid in the food industry accounts for about 60% of the total consumption amount of lactic acid in the world. Since the human body only has enzymes for metabolizing L-lactic acid, D-lactic acid cannot be absorbed by the human body, and excessive use of D-lactic acid is toxic to the human body. Therefore, the world health organization advocates that L-lactic acid is used as a food additive and an internal medicine to replace DL-lactic acid which is generally used at present. Meanwhile, the use of phosphoric acid to adjust the pH of wort has been banned in the field of beer production, but L-lactic acid has been used as an adjusting agent. It has been investigated that one fourth of the world's lactic acid is used to produce stearoyllactic acid, while its salts are used in large quantities for bread production due to the longer shelf life of bread. In addition, the lactic acid is added into the tobacco, so that the humidity of the tobacco can be kept, and the quality of the cigarette can be improved.
In the field of pharmaceutical industry, lactic acid, particularly L-lactic acid, has a strong bactericidal effect, even higher than that of common disinfectants such as citric acid, tartaric acid, succinic acid and the like, and can be used as a disinfectant in places such as operating rooms, wards, laboratories, workshops and the like. Research shows that the infusion compounded with L-lactic acid, sodium L-lactate, glucose, amino acid, etc. can treat acidosis and hyperkalemia, and L-ferric lactate, sodium L-lactate and calcium L-lactate are excellent medicine for replenishing metal elements.
In the fields of chemical industry and the like, lactic acid is used as a deliming agent in the leather industry and also for treating textile fibres to make them easily tintable, to increase gloss and to make them soft to the touch. Ethyl lactate as a "green solvent" can be used as a fine metal cleaner in the electronics, aerospace, and semiconductor industries. In cosmetics, lactic acid, sodium lactate and calcium lactate can provide moisture-keeping property, and phthalyl zirconium lactate is effective emulsifier, material filler and stabilizer in cosmetics and health products, and can improve skin structure, prevent aging, and protect skin.
With global warming, increasing environmental pollution and increasing shortage of petroleum resources, the development of clean energy and environment-friendly materials is currently a very urgent task in China. Among the numerous degradable polymers, polylactic acid has become the green environmental material with the greatest development prospect in the 21 st century. The production of L-lactic acid, a synthetic material of polylactic acid, directly affects the synthesis of polylactic acid. Therefore, it can be said that the development of L-lactic acid technology and industry is an important prerequisite for the development of polylactic acid industry.
At present, most of the processes for producing L-lactic acid at home and abroad use corn starch as a main raw material and prepare the L-lactic acid by fermenting with proper lactic acid bacteria. In the industrial production process of lactic acid fermentation in China, saccharification and fermentation procedures are mostly carried out step by step, so that the production period of lactic acid is long, a plurality of operation units are needed, and continuous production is difficult; in the prior patents and documents, technologies for producing lactic acid by simultaneous saccharification and fermentation are also proposed, the processes are different due to different raw materials, and due to the limitation of the pH value required by fermentation, the simultaneous saccharification and fermentation is difficult to control, so that the residual sugar content of fermentation liquor is high, the utilization rate of sugar is low, the separation and purification of the fermentation liquor are difficult, and the industrial implementation is difficult. On the basis, Chinese patent CN103789362A discloses a method for producing lactic acid by pre-saccharification and synchronous saccharification and fermentation, which comprises the following steps: (1) preparing raw materials: removing impurities from corn, pulverizing, mixing, spraying for liquefaction, and filtering; preparing liquefied sugar liquid with the DE value of 22-28%, wherein the total sugar content in the liquefied sugar liquid is 120-180 g/L; (2) pre-saccharification: adding the liquefied sugar solution into a sterilized fermentation tank for pre-saccharification to obtain a fermentation solution; (3) saccharifying and fermenting simultaneously. The method can obviously shorten the saccharification time and further shorten the production period of the lactic acid, but after the fermentation separation product is carried out, the thallus dregs obtained by fermentation contain not only the thallus but also the unconsumed nutrition and other metal ions such as calcium, on one hand, the nutrient substances in the fermentation culture medium are wasted, and simultaneously, the problem of fermentation waste residue pollution exists, and the resource waste is caused.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a method for producing lactic acid and coproducing protein feed by circulating fermentation.
In order to solve the technical problems, the method for producing lactic acid and coproducing protein feed by circulating fermentation comprises the following steps:
(1) preparing raw materials: removing impurities from corn, pulverizing, mixing, spraying to liquefy to obtain corn slurry, filtering, and separating to obtain liquefied sugar solution and corn starch residue;
(2) pre-saccharification: adding the prepared liquefied sugar liquid into a fermentation tank, and adding saccharifying enzyme for pre-saccharification treatment to obtain fermentation liquid;
(3) after the pre-saccharification is finished, adding yeast extract into the fermentation liquid, inoculating lactobacillus liquid and saccharifying enzyme to perform synchronous saccharification and fermentation, and detecting the yield of lactic acid;
(4) filtering the obtained fermentation liquid, pretreating the obtained solid thallus dregs with a composite medium, and filtering and separating the pretreated thallus dregs to obtain soluble nutrient substances and insoluble impurities; meanwhile, the soluble nutrient substances obtained after filtration and separation are circulated to a fermentation tank for the next circulation of fermentation;
the composite medium comprises ammonium sulfate, ethylene diamine tetraacetic acid disodium salt, sodium dodecyl sulfate and sodium citrate;
(5) and (2) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus for solid state fermentation, drying the corn starch protein slurry obtained by fermentation in a rotary drum, and crushing to obtain the protein feed.
In the composite medium, the mass ratio of the ammonium sulfate to the disodium ethylene diamine tetraacetate to the sodium dodecyl sulfate to the sodium citrate is 1-5: 1-3: 1-4: 1-3.
The dosage of the composite medium accounts for 10-20 wt% of the mass of the thallus dregs; adding water into the mixture of the bacterial slag and the composite medium, preparing the bacterial slag and the composite medium into an aqueous solution, and uniformly mixing, wherein the total mass concentration of the bacterial slag and the composite medium in the aqueous solution is 10-50 wt%.
The step of pretreating the thallus dregs is to treat the thallus dregs for 30 to 50min at the temperature of between 20 and 30 ℃.
The filtration and separation step after the thallus residue pretreatment is centrifugal filtration, and the centrifugal rotating speed is 1000-1200 rpm.
In the step (3), the step of saccharifying while fermenting specifically comprises: after the pre-saccharification is finished, adding yeast extract into the fermentation liquid, adding ammonia water solution into the fermentation liquid to adjust the pH of the fermentation liquid to be 6.0 +/-0.1, adding lactobacillus liquid accounting for 6-12% of the total volume of the fermentation liquid when the temperature of the fermentation liquid reaches 50 +/-2 ℃, and adding the OD of the lactobacillus liquid620When the value reaches 9.5-12, introducing sterile air into the fermentation tank, and keeping the temperature for continuous fermentation; OD of the liquid to be fermented620When the value reaches 10, adjusting the pH value of the fermentation liquid to 5.5 +/-0.1, and continuously adding 50-100U/g of saccharifying enzyme into each gram of total sugar in the liquefied sugar liquid to perform synchronous saccharification and fermentation.
In the step (1), the filtering and separating step adopts a plate-and-frame filter press for filtering, the feeding pressure of the plate-and-frame is controlled to be 0.4-0.45Mp, and the compression pressure of the plate-and-frame is controlled to be 18-20 Mpa.
In the step (5), the inoculation amount of the thermophilic lactobacillus is 10%, the temperature of the solid state fermentation step is 30-35 ℃ for fermentation for 45-48h, and the temperature of the drum drying step is 90 ℃.
In the step (2), in the pre-saccharification step, the adding amount of the saccharifying enzyme is calculated according to the addition of 400-600U/g of total sugar per gram in the liquefied sugar solution, and the pre-saccharification treatment is carried out by controlling the fermentation liquor at 50-70 ℃ and pH4.5 +/-0.1.
And (4) drying the insoluble impurities obtained by separation and preparing the desulfurizer.
The method for producing lactic acid and co-producing protein feed by circular fermentation is based on the existing lactic acid production process of simultaneous saccharification and fermentation, realizes the circular utilization of thalli by combining the pretreatment method of lactic acid fermentation thalli residues, and can realize the multi-circular fermentation by using a single batch of strains. According to the pretreatment method of the lactic acid fermentation bacteria residues, ammonium sulfate, disodium ethylene diamine tetraacetate, sodium dodecyl sulfate and sodium citrate are used as composite media, the fermented bacteria residues are pretreated, and the fermented bacteria residues contain bacteria, unconsumed nutrition and other metal ions which influence early fermentation, such as calcium and the like. The data show that after the thalli residues are pretreated, the efficiency of fermenting lactic acid is not reduced, and the thalli residues carry residual nutrient substances in fermentation liquor, so that the saccharic acid conversion rate in subsequent circulation is improved, and the maximum benefit of lactic acid fermentation production is realized. The separated metal ions are mainly calcium ions and can be used as a desulfurizing agent of a thermal power plant after being dried. In addition, the invention adopts a centrifugal separation method to rapidly separate the thalli, the separated thalli is used as a nutrient nitrogen source to return to the fermentation process for recycling, the use amount of nutrient substances in the fermentation culture medium is reduced, the problem of fermentation waste residue outlet is solved, the consumption of raw and auxiliary materials is reduced, the composite medium can be recycled, and the resource recycling is realized.
In addition, the method for producing lactic acid and coproducing protein feed by circulating fermentation introduces an automatic plate-and-frame filtration technology to quickly separate corn starch residues in the sugar production process; meanwhile, the separated corn starch residue is subjected to solid state fermentation to co-produce protein feed, so that the amino acid content can be obviously improved, and all components in the starch residue are digested and absorbed by animals to prepare the corn protein feed with high added value.
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In order that the present disclosure may be more readily and clearly understood, the following detailed description of the present disclosure is provided in connection with specific embodiments thereof and the accompanying drawings, in which,
FIG. 1 is a process flow chart of the invention for producing lactic acid and co-producing protein feed by circulating fermentation.
Detailed Description
Example 1
The method for producing lactic acid and co-producing protein feed by circulating fermentation comprises the following steps:
(1) preparing raw materials: removing impurities from corns, crushing, mixing slurry, and spraying and liquefying to obtain corn slurry, wherein the corn slurry is filtered and subjected to solid-liquid separation by using a plate-and-frame filter press, the plate-and-frame feeding pressure is controlled to be 0.4Mp, the plate-and-frame compression pressure is controlled to be 18Mpa, and after filtering and separating, liquefied sugar liquor and corn starch residues with DE (dextrose equivalent) values of 22% are obtained, and the total sugar content in the liquefied sugar liquor is 120 g/L;
(2) pre-saccharification: the pre-saccharification temperature is 59 ℃, and the liquefied sugar solution is added into a sterilized fermentation tank for pre-saccharification; adding hydrochloric acid with the mass fraction of 3% to adjust the pH of the liquefied sugar solution to 4.5 +/-0.1, adding 400U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar solution, introducing sterile air into a fermentation tank, keeping the pressure in the tank at 0.2Mpa, and pre-saccharifying for 4 hours to obtain fermentation liquid; DX value in the obtained fermentation feed liquid is 88%;
(3) saccharifying while fermenting: adding yeast extract into the fermentation liquid after pre-saccharification, adding 30 wt% ammonia water solution into the fermentation liquid to maintain pH of the fermentation liquid at 5.9, adding lactobacillus liquid with 6% of total volume of the fermentation liquid when the temperature of the fermentation liquid is reduced to 48 deg.C, and adjusting OD of the lactobacillus liquid620Keeping the value at 10 deg.C, introducing sterile air into the fermenter, and detecting OD of the fermentation liquid620Value of feed liquid to be fermentedOD620When the value is increased to 10, adjusting the pH value of the fermentation liquid to 5.5, adding 100U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar liquid, detecting that the lactic acid bacteria do not produce acid after fermenting for 46 hours, and finishing the fermentation;
(4) filtering the obtained fermentation liquid, performing solid-liquid separation to obtain solid bacteria residue and lactic acid liquid, weighing the obtained solid bacteria residue, adding a composite medium (in the embodiment, the composite medium comprises ammonium sulfate, disodium ethylenediamine tetraacetate, sodium dodecyl sulfate and sodium citrate in a mass ratio of 1: 3: 1: 3) accounting for 10 wt% of the weight of the bacteria residue for pretreatment, adding water into a mixture of the bacteria residue and the composite medium, preparing the bacteria residue and the composite medium into an aqueous solution, uniformly mixing, allowing the total mass concentration of the bacteria residue and the composite medium in the aqueous solution to be 20 wt%, standing at the temperature of 20 ℃ for 50min, performing centrifugal filtration on the treated bacteria solution at the rotation speed of 1000-1200rpm, and performing solid-liquid separation again to respectively obtain soluble nutrient substances and insoluble impurities;
the soluble nutrient substances are used for being circulated to a fermentation tank for the next circulation of fermentation, and the obtained impurities can be used for preparing a desulfurizer after being dried and crushed;
evaporating and concentrating the lactic acid liquid obtained after solid-liquid separation to obtain a concentrated solution containing lactic acid, detecting that the content of residual total sugar in the fermented concentrated solution is 0.4%, the content of residual reducing sugar is 0.15%, and the sugar-acid conversion rate reaches 95.3%;
(5) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus according to the inoculation amount of 10%, performing solid state fermentation for 48 hours at the temperature of 30 ℃, performing rotary drum drying on corn starch protein slurry obtained by fermentation at the temperature of 90 ℃, and crushing to obtain protein feed; according to GB/T18246-.
And (3) circularly fermenting to produce lactic acid according to the conditions of the steps (1) to (5), wherein the strains in the step (3) are all the strains which are circularly returned to the fermentation tank after being pretreated in the previous circulating step (4), continuously fermenting for 5 cycles, detecting the condition of residual sugar in the lactic acid fermentation liquor after the fermentation of each cycle is finished, and calculating the sugar-acid conversion rate.
In this example, after 5 cycles of fermentation treatment under the above conditions, the sugar-acid conversion rates in the 2-4 cycles were 95.5%, 95.8%, 96.1%, and 96.8%, respectively. Therefore, the method for producing the lactic acid and the protein feed through the circulating fermentation has the advantages that the multi-circulating fermentation can be realized by using a single batch of strains, the efficiency of fermenting the lactic acid is not reduced after the bacterial residues are pretreated, and the saccharic acid conversion rate in the subsequent circulation is improved due to the fact that residual nutrient substances in the fermentation liquor are carried.
In addition, the method for producing lactic acid and coproducing protein feed by circulating fermentation introduces an automatic plate-and-frame filtration technology to quickly separate corn starch residues in the sugar production process; meanwhile, the separated corn starch residue is subjected to solid state fermentation to co-produce protein feed, so that the amino acid content can be obviously improved, and all components in the starch residue are digested and absorbed by animals to prepare the corn protein feed with high added value.
Example 2
The method for producing lactic acid and co-producing protein feed by circulating fermentation comprises the following steps:
(1) preparing raw materials: removing impurities from corns, crushing, mixing slurry, and spraying and liquefying to obtain corn slurry, wherein the corn slurry is filtered and subjected to solid-liquid separation by using a plate-and-frame filter press, the plate-and-frame feeding pressure is controlled to be 0.45Mp, the plate-and-frame compression pressure is controlled to be 20Mpa, and after filtering and separating, liquefied sugar liquor and corn starch residues with the DE value of 28% are obtained, and the total sugar content in the liquefied sugar liquor is 180 g/L;
(2) pre-saccharification: controlling the pre-saccharification temperature to be 70 ℃, and adding the liquefied sugar liquid into a sterilized fermentation tank for pre-saccharification; adding 2% by mass of sulfuric acid to adjust the pH of the liquefied sugar solution to 4.4, adding 400U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar solution, introducing sterile air into a fermentation tank, keeping the pressure in the tank at 0.1MPa, and pre-saccharifying for 6 hours to obtain a fermentation solution; DX value in the obtained fermentation feed liquid is 89%;
(3) saccharifying while fermenting: adding yeast extract into the fermentation liquid after pre-saccharification, adding ammonia water solution with mass fraction of 20% into the fermentation liquid to maintain pH of the fermentation liquid at 6.0, adding lactobacillus liquid with 10% of total volume of the fermentation liquid when the temperature of the fermentation liquid is reduced to 50 deg.C, and adjusting OD of the lactobacillus liquid620The value is 12, the temperature in the fermentation tank is kept at 50 ℃, sterile air is introduced into the fermentation tank, and the OD of the fermentation liquid is detected620Value, OD of feed liquid to be fermented620When the value is increased to 10, adjusting the pH value of the fermentation liquid to 5.4, continuously adding saccharifying enzyme, adding 100U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar liquid, after fermenting for 47 hours, detecting that the lactic acid bacteria do not produce acid, and ending the fermentation at this moment;
(4) filtering the obtained fermentation liquid, carrying out solid-liquid separation to obtain solid bacteria residue and lactic acid liquid, weighing the obtained solid bacteria residue, adding a composite medium (comprising ammonium sulfate, disodium ethylene diamine tetraacetate, sodium dodecyl sulfate and sodium citrate in a mass ratio of 5: 1: 4: 1) accounting for 15 wt% of the weight of the bacteria residue for pretreatment, adding water into a mixture of the bacteria residue and the composite medium, preparing the bacteria residue and the composite medium into an aqueous solution, uniformly mixing, keeping the total mass concentration of the bacteria residue and the composite medium in the aqueous solution at 15 wt%, standing at the temperature of 30 ℃ for 30min, carrying out centrifugal filtration on the treated bacteria solution at the rotation speed of 1000 plus 1200rpm, and carrying out solid-liquid separation again to respectively obtain soluble nutrient substances and insoluble impurities;
the soluble nutrient substances are used for being circulated to a fermentation tank for the next circulation of fermentation, and the obtained impurities can be used for preparing a desulfurizer after being dried and crushed;
evaporating and concentrating the lactic acid liquid obtained after solid-liquid separation to obtain a concentrated solution containing lactic acid, detecting that the content of residual total sugar in the fermented concentrated solution is 0.4%, the content of residual reducing sugar is 0.15%, and the sugar-acid conversion rate reaches 95.3%;
(5) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus according to the inoculation amount of 10%, performing solid state fermentation for 45 hours at the temperature of 35 ℃, performing rotary drum drying on corn starch protein slurry obtained by fermentation at the temperature of 90 ℃, and crushing to obtain protein feed; according to GB/T18246-.
And (3) circularly fermenting to produce lactic acid according to the conditions of the steps (1) to (5), wherein the strains in the step (3) are all the strains which are circularly returned to the fermentation tank after being pretreated in the previous circulating step (4), continuously fermenting for 5 cycles, detecting the condition of residual sugar in the lactic acid fermentation liquor after the fermentation of each cycle is finished, and calculating the sugar-acid conversion rate.
In this example, after 5 cycles of fermentation treatment under the above conditions, the sugar-acid conversion rates in the 2-4 cycles were 95.6%, 95.9%, 96.2%, and 96.8%, respectively. Therefore, the method for producing the lactic acid and the protein feed through the circulating fermentation has the advantages that the multi-circulating fermentation can be realized by using a single batch of strains, the efficiency of fermenting the lactic acid is not reduced after the bacterial residues are pretreated, and the saccharic acid conversion rate in the subsequent circulation is improved due to the fact that residual nutrient substances in the fermentation liquor are carried. Example 3
The method for producing lactic acid and co-producing protein feed by circulating fermentation comprises the following steps:
(1) preparing raw materials: removing impurities from corns, crushing, mixing slurry, and spraying and liquefying to obtain corn slurry, wherein the corn slurry is filtered and subjected to solid-liquid separation by using a plate-and-frame filter press, the plate-and-frame feeding pressure is controlled to be 0.42Mp, the plate-and-frame compression pressure is controlled to be 19Mpa, and after filtering and separating, liquefied sugar liquor and corn starch residues with the DE value of 25% are obtained, and the total sugar content in the liquefied sugar liquor is 140 g/L;
(2) pre-saccharification: the pre-saccharification temperature is 50 ℃, and the liquefied sugar solution is added into a sterilized fermentation tank for pre-saccharification; adding 1% hydrochloric acid by mass to adjust the pH value of the liquefied sugar solution to 4.6, adding 600U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar solution, introducing sterile air into a fermentation tank, keeping the pressure in the tank at 0.4Mpa, and pre-saccharifying for 3.5 hours to obtain a fermentation solution, wherein the DX value in the fermentation solution is 90%;
(3) saccharifying while fermenting: adding yeast extract into the fermentation liquid after pre-saccharification, adding 30 wt% ammonia water solution into the fermentation liquid to maintain pH of the fermentation liquid at 6.2, adding lactobacillus liquid with 8% of total volume of the fermentation liquid when the temperature of the fermentation liquid is reduced to 52 deg.C, and adjusting OD of the lactobacillus liquid620The value is 9.5, the temperature in the fermentation tank is kept at 52 ℃, sterile air is introduced into the fermentation tank, and the OD of the fermentation liquid is detected620Value, OD of feed liquid to be fermented620When the value is increased to 10, adjusting the pH value of the fermentation liquid to 5.6, adding saccharifying enzyme, wherein the adding amount of saccharifying enzyme is 80U according to the total sugar per gram in the liquefied sugar liquid, detecting that the lactic acid bacteria do not produce acid after fermenting for 45 hours, and ending the fermentation;
(4) filtering the obtained fermentation liquid, carrying out solid-liquid separation to obtain solid bacteria residue and lactic acid liquid, weighing the obtained solid bacteria residue, adding a composite medium (comprising ammonium sulfate, disodium ethylene diamine tetraacetate, sodium dodecyl sulfate and sodium citrate in a mass ratio of 3: 2: 3: 2) accounting for 15 wt% of the weight of the bacteria residue for pretreatment, adding water into a mixture of the bacteria residue and the composite medium, preparing the bacteria residue and the composite medium into an aqueous solution, uniformly mixing, keeping the total mass concentration of the bacteria residue and the composite medium in the aqueous solution at 25 wt%, standing at the temperature of 25 ℃ for 40min, carrying out centrifugal filtration on the treated bacteria solution at the rotation speed of 1000 plus 1200rpm, and carrying out solid-liquid separation again to respectively obtain soluble nutrient substances and insoluble impurities;
the soluble nutrient substances are used for being circulated to a fermentation tank for the next circulation of fermentation, and the obtained impurities can be used for preparing a desulfurizer after being dried and crushed;
evaporating and concentrating the lactic acid liquid obtained after solid-liquid separation to obtain a concentrated solution containing lactic acid, detecting that the content of residual total sugar in the fermented concentrated solution is 0.35%, the content of residual reducing sugar is 0.13%, and the sugar-acid conversion rate reaches 95.6%;
(5) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus according to the inoculation amount of 10%, performing solid state fermentation for 46h at the temperature of 32 ℃, performing rotary drum drying on corn starch protein slurry obtained by fermentation at the temperature of 90 ℃, and crushing to obtain protein feed; according to GB/T18246-.
And (3) circularly fermenting to produce lactic acid according to the conditions of the steps (1) to (5), wherein the strains in the step (3) are all the strains which are circularly returned to the fermentation tank after being pretreated in the previous circulating step (4), continuously fermenting for 5 cycles, detecting the condition of residual sugar in the lactic acid fermentation liquor after the fermentation of each cycle is finished, and calculating the sugar-acid conversion rate.
In this example, after 5 cycles of fermentation treatment under the above conditions, the sugar-acid conversion rates in the 2-4 cycles were 95.8%, 96.0%, 96.2%, and 96.7%, respectively. Therefore, the method for producing the lactic acid and the protein feed through the circulating fermentation has the advantages that the multi-circulating fermentation can be realized by using a single batch of strains, the efficiency of fermenting the lactic acid is not reduced after the bacterial residues are pretreated, and the saccharic acid conversion rate in the subsequent circulation is improved due to the fact that residual nutrient substances in the fermentation liquor are carried. Example 4
The method for producing lactic acid and co-producing protein feed by circulating fermentation comprises the following steps:
(1) preparing raw materials: removing impurities from corns, crushing, mixing slurry, and spraying and liquefying to obtain corn slurry, wherein the corn slurry is filtered and subjected to solid-liquid separation by using a plate-and-frame filter press, the plate-and-frame feeding pressure is controlled to be 0.4Mp, the plate-and-frame compression pressure is controlled to be 20Mpa, and after filtering and separating, liquefied sugar liquor and corn starch residues with the DE value of 28% are obtained, and the total sugar content in the liquefied sugar liquor is 180 g/L;
(2) pre-saccharification: the pre-saccharification temperature is 60 ℃, and the liquefied sugar solution is added into a sterilized fermentation tank for pre-saccharification; adding 1% by mass of sulfuric acid to adjust the pH of the liquefied sugar solution to 4.4, adding 500U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar solution, introducing sterile air into a fermentation tank, keeping the pressure in the tank at 0.05Mpa, and pre-saccharifying for 3 hours to obtain a fermentation solution; DX value in the obtained fermentation feed liquid is 90%;
(3) saccharifying while fermenting: adding yeast extract into the fermentation liquid after pre-saccharification is finished, adding 25 wt% ammonia water solution into the fermentation liquid to maintain the pH of the fermentation liquid at 6.0, adding lactobacillus liquid with 6% of the total volume of the fermentation liquid when the temperature of the fermentation liquid is reduced to 49 ℃ until OD of the lactobacillus liquid620The value is 9.5, the temperature in the fermentation tank is kept at 49 ℃ all the time, sterile air is introduced into the fermentation tank, and the OD of the fermentation liquid is detected620Value, OD of feed liquid to be fermented620When the value is increased to 10, adjusting the pH value of the fermentation liquid to 5.5, continuously adding saccharifying enzyme, adding 50U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar liquid, detecting that the lactic acid bacteria do not produce acid after fermenting for 45.5 hours, and finishing the fermentation;
(4) filtering the obtained fermentation liquid, carrying out solid-liquid separation to obtain solid bacteria residue and lactic acid liquid, weighing the obtained solid bacteria residue, adding a composite medium (comprising ammonium sulfate, disodium ethylenediamine tetraacetate, sodium dodecyl sulfate and sodium citrate in a mass ratio of 2: 2.5: 2: 2.5) accounting for 15 wt% of the weight of the bacteria residue for pretreatment, adding water into a mixture of the bacteria residue and the composite medium, preparing the bacteria residue and the composite medium into an aqueous solution, uniformly mixing, allowing the total mass concentration of the bacteria residue and the composite medium in the aqueous solution to be 30 wt%, standing at the temperature of 25 ℃ for 40min, carrying out centrifugal filtration on the treated bacteria liquid at the rotation speed of 1000-1200rpm, and carrying out solid-liquid separation again to obtain soluble nutrient substances and insoluble impurities respectively;
the soluble nutrient substances are used for being circulated to a fermentation tank for the next circulation of fermentation, and the obtained impurities can be used for preparing a desulfurizer after being dried and crushed;
evaporating and concentrating the lactic acid liquid obtained after solid-liquid separation to obtain a concentrated solution containing lactic acid, detecting that the content of residual total sugar in the fermented concentrated solution is 0.33%, the content of residual reducing sugar is 0.12%, and the conversion rate of saccharic acid reaches 95.4%;
(5) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus according to the inoculation amount of 10%, performing solid state fermentation for 45 hours at the temperature of 34 ℃, performing rotary drum drying on corn starch protein slurry obtained by fermentation at the temperature of 90 ℃, and crushing to obtain protein feed; according to GB/T18246-.
And (3) circularly fermenting to produce lactic acid according to the conditions of the steps (1) to (5), wherein the strains in the step (3) are all the strains which are circularly returned to the fermentation tank after being pretreated in the previous circulating step (4), continuously fermenting for 5 cycles, detecting the condition of residual sugar in the lactic acid fermentation liquor after the fermentation of each cycle is finished, and calculating the sugar-acid conversion rate.
In this example, after 5 cycles of fermentation treatment under the above conditions, the sugar-acid conversion rates in the 2-4 cycles were 95.8%, 96.2%, 96.6%, and 96.9%, respectively. Therefore, the method for producing the lactic acid and the protein feed through the circulating fermentation has the advantages that the multi-circulating fermentation can be realized by using a single batch of strains, the efficiency of fermenting the lactic acid is not reduced after the bacterial residues are pretreated, and the saccharic acid conversion rate in the subsequent circulation is improved due to the fact that residual nutrient substances in the fermentation liquor are carried. Example 5
The method for producing lactic acid and co-producing protein feed by circulating fermentation comprises the following steps:
(1) preparing raw materials: removing impurities from corns, crushing, mixing slurry, and spraying and liquefying to obtain corn slurry, wherein the corn slurry is filtered and subjected to solid-liquid separation by using a plate-and-frame filter press, the plate-and-frame feeding pressure is controlled to be 0.45Mp, the plate-and-frame compression pressure is controlled to be 18Mpa, and after filtering and separating, liquefied sugar liquor and corn starch residues with DE values of 27% are obtained, and the total sugar content in the liquefied sugar liquor is 175 g/L;
(2) pre-saccharification: the pre-saccharification temperature is 55 ℃, and the liquefied sugar solution is added into a sterilized fermentation tank for pre-saccharification; adding 1% phosphoric acid by mass to adjust the pH value of the liquefied sugar solution to 4.5, adding 500U of saccharifying enzyme according to the total sugar per gram in the liquefied sugar solution, introducing sterile air into a fermentation tank, keeping the pressure in the tank at 0.4Mpa, and pre-saccharifying for 1 hour to obtain a fermentation solution, wherein the DX value in the fermentation solution is 93%;
(3) saccharifying while fermenting: adding yeast extract into the fermentation liquid after pre-saccharification, adding 30 wt% ammonia water solution into the fermentation liquid to maintain pH of the fermentation liquid at 5.9, and adding milk with 6% of total volume of the fermentation liquid when the temperature of the fermentation liquid is reduced to 51 deg.COD of acid bacterium solution and lactic acid bacterium solution620Keeping the temperature in the fermenter at 51 deg.C, introducing sterile air into the fermenter, and detecting OD of the fermentation liquid620Value, OD of feed liquid to be fermented620When the value is increased to 10, adjusting the pH value of the fermentation liquid to 5.6, adding saccharifying enzyme, wherein the adding amount of saccharifying enzyme is 50U according to the total sugar per gram in the liquefied sugar liquid, detecting that the lactic acid bacteria do not produce acid after fermenting for 45 hours, and ending the fermentation;
(4) filtering the obtained fermentation liquid, carrying out solid-liquid separation to obtain solid bacteria slag and lactic acid liquid, weighing the obtained solid bacteria slag, adding a composite medium (comprising ammonium sulfate, ethylene diamine tetraacetic acid disodium salt, sodium dodecyl sulfate and sodium citrate with the mass ratio of 4: 1.5: 3.5: 1.5) accounting for 15 wt% of the weight of the bacteria slag for pretreatment, adding water into a mixture of the bacteria slag and the composite medium, preparing the bacteria slag and the composite medium into an aqueous solution, uniformly mixing, wherein the total mass concentration of the bacteria slag and the composite medium in the aqueous solution is 40 wt%, standing at the temperature of 25 ℃ for 40min, carrying out centrifugal filtration on the treated bacteria liquid at the rotation speed of 1000-1200rpm, and carrying out solid-liquid separation again to respectively obtain soluble nutrient substances and insoluble impurities;
the soluble nutrient substances are used for being circulated to a fermentation tank for the next circulation of fermentation, and the obtained impurities can be used for preparing a desulfurizer after being dried and crushed;
evaporating and concentrating the lactic acid liquid obtained after solid-liquid separation to obtain a concentrated solution containing lactic acid, detecting that the content of residual total sugar in the fermented concentrated solution is 0.30%, the content of residual reducing sugar is 0.10%, and the sugar-acid conversion rate reaches 95.8%;
(5) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus according to the inoculation amount of 10%, performing solid state fermentation for 48 hours at the temperature of 30 ℃, performing rotary drum drying on corn starch protein slurry obtained by fermentation at the temperature of 90 ℃, and crushing to obtain protein feed; according to GB/T18246-.
And (3) circularly fermenting to produce lactic acid according to the conditions of the steps (1) to (5), wherein the strains in the step (3) are all the strains which are circularly returned to the fermentation tank after being pretreated in the previous circulating step (4), continuously fermenting for 5 cycles, detecting the condition of residual sugar in the lactic acid fermentation liquor after the fermentation of each cycle is finished, and calculating the sugar-acid conversion rate.
In this example, after 5 cycles of fermentation treatment under the above conditions, the conversion rates of sugar and acid in the 2 to 4 cycles were 95.9%, 96.2%, 96.4%, and 96.9%, respectively. Therefore, the method for producing the lactic acid and the protein feed through the circulating fermentation has the advantages that the multi-circulating fermentation can be realized by using a single batch of strains, the efficiency of fermenting the lactic acid is not reduced after the bacterial residues are pretreated, and the saccharic acid conversion rate in the subsequent circulation is improved due to the fact that residual nutrient substances in the fermentation liquor are carried.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (5)
1. A method for producing lactic acid and co-producing protein feed by circulating fermentation is characterized by comprising the following steps:
(1) preparing raw materials: removing impurities from corn, pulverizing, mixing, spraying to liquefy to obtain corn slurry, filtering, and separating to obtain liquefied sugar solution and corn starch residue;
(2) pre-saccharification: adding the prepared liquefied sugar liquid into a fermentation tank, and adding saccharifying enzyme for pre-saccharification treatment to obtain fermentation liquid;
(3) after the pre-saccharification is finished, adding yeast extract into the fermentation liquid, inoculating lactobacillus liquid and saccharifying enzyme to perform synchronous saccharification and fermentation, and detecting the yield of lactic acid;
(4) filtering the obtained fermentation liquid, pretreating the obtained solid thallus dregs with a composite medium, and filtering and separating the pretreated thallus dregs to obtain soluble nutrient substances and insoluble impurities; meanwhile, the soluble nutrient substances obtained after filtration and separation are circulated to a fermentation tank for the next circulation of fermentation;
the composite medium comprises ammonium sulfate, ethylene diamine tetraacetic acid disodium salt, sodium dodecyl sulfate and sodium citrate;
(5) inoculating the corn starch residue separated in the step (1) into lactobacillus thermophilus for solid state fermentation, drying the corn starch protein slurry obtained by fermentation in a rotary drum, and crushing to obtain protein feed; the inoculation amount of the thermophilic lactobacillus is 10 percent, the temperature of the solid state fermentation step is 30-35 ℃ for fermentation for 45-48h, and the temperature of the rotary drum drying step is 90 ℃;
in the composite medium, the mass ratio of the ammonium sulfate to the disodium ethylene diamine tetraacetate to the sodium dodecyl sulfate to the sodium citrate is 1-5: 1-3: 1-4: 1-3;
the dosage of the composite medium accounts for 10-20 wt% of the mass of the thallus dregs; adding water into the mixture of the thallus dregs and the composite medium, preparing the thallus dregs and the composite medium into an aqueous solution, and uniformly mixing, wherein the total mass concentration of the thallus dregs and the composite medium in the aqueous solution is 10-50 wt%;
the step of pretreating the thallus dregs is to treat the thallus dregs for 30 to 50min at the temperature of between 20 and 30 ℃;
the filtration and separation step after the thallus residue pretreatment is centrifugal filtration, and the centrifugal rotating speed is 1000-1200 rpm.
2. Method for producing lactic acid and co-producing protein feed by cyclic fermentation according to claim 1The method is characterized in that in the step (3), the step of saccharifying while fermenting specifically comprises the following steps: after the pre-saccharification is finished, adding yeast extract into the fermentation liquid, adding ammonia water solution into the fermentation liquid to adjust the pH of the fermentation liquid to be 6.0 +/-0.1, adding lactobacillus liquid accounting for 6-12% of the total volume of the fermentation liquid when the temperature of the fermentation liquid reaches 50 +/-2 ℃, and adding the OD of the lactobacillus liquid620When the value reaches 9.5-12, introducing sterile air into the fermentation tank, and keeping the temperature for continuous fermentation; OD of the liquid to be fermented620When the value reaches 10, adjusting the pH value of the fermentation liquid to 5.5 +/-0.1, and continuously adding 50-100U/g of saccharifying enzyme into each gram of total sugar in the liquefied sugar liquid to perform synchronous saccharification and fermentation.
3. The method for producing lactic acid and coproducing protein feed by circulating fermentation according to claim 1, wherein in the step (1), the filtration and separation step is implemented by adopting a plate-and-frame filter press, the feeding pressure of the plate-and-frame is controlled to be 0.4-0.45Mp, and the compression pressure of the plate-and-frame is controlled to be 18-20 Mpa.
4. The method for producing lactic acid and coproducing protein feed by cyclic fermentation as set forth in claim 1, wherein in the step (2), the saccharifying enzyme is added in an amount of 600U/g per gram of total sugar in the liquefied sugar solution, and the pre-saccharifying treatment is performed by controlling the fermentation broth at 50-70 ℃ and pH4.5 ± 0.1.
5. The method for producing lactic acid and coproducing protein feed by circulating fermentation as claimed in claim 1, wherein the step (4) further comprises the steps of drying the separated insoluble impurities and preparing a desulfurizing agent.
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| CN101134976A (en) * | 2006-08-29 | 2008-03-05 | 武汉天惠生物工程有限公司 | Method for producing validamycin by circulating fermentation |
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| CN1130627A (en) * | 1995-11-24 | 1996-09-11 | 中原制药厂 | Process for preparing sodium (or potassium) L-ascorbate |
| CN101134976A (en) * | 2006-08-29 | 2008-03-05 | 武汉天惠生物工程有限公司 | Method for producing validamycin by circulating fermentation |
| CN103275875A (en) * | 2013-04-23 | 2013-09-04 | 马伟超 | Trichoderma koningii, and compound microbial agent composition and application thereof |
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