Organic selenium-rich yeast, its preparation method, product and application

Abstract

The application relates to organic selenium-rich yeast, a preparation method and products and applications thereof. The organic selenium-rich yeast is prepared by step-by-step expansion culture, fermentation culture, collection of yeast cells and drying, wherein the fermentation culture takes organic starch hydrolysis sugar, organic plant protein enzymolysis liquid and selenium-rich yeast extract as a culture medium. In the organic selenium-rich yeast, the proportion of selenomethionine form selenium in the total selenium weight is greater than 80%, even greater than 90%, the proportion of organic selenium in the total selenium weight is greater than 99%, the total selenium content is 800-2100 ppm, the absorption and utilization rate of the yeast to selenium can reach more than 95%, and the absorption and utilization rate and conversion rate in feeding and food are high. Organic starch and organic plant protein are used as culture medium raw materials, the organic raw material usage is more than 95%, and the organic product certification requirements can be met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fermentation industry, in particular to a kind of organic selenium-rich yeast, its preparation method and product and application. BACKGROUND

[0002] Selenium is an important trace element necessary for human and animal, mainly in the form of selenoenzymes and selenoproteins in living organisms. It has been reported in published literature that selenium has the functions of antioxidant, immune regulation, free radical scavenging, gene expression regulation, etc. in living organisms. Selenium can protect the myocardium, prevent and treat Keshan disease, Kashin-Beck disease, liver disease and various cancers, activate pancreatic islet to assist in the treatment of diabetes, and lack of selenium is significantly related to the occurrence and development of cardiovascular diseases such as Keshan disease, coronary heart disease, atherosclerosis, hypertension and cardiomyopathy. In animal breeding, adding organic selenium to the daily diet of sows can promote the development of embryos in the early stages of pregnancy and improve the reproductive performance of sows and boars.

[0003] Due to the health functions of selenium-rich yeast, selenium-rich yeast is approved for use in food nutrition enhancers, feed additives and other purposes. Currently, there are two main production technologies for selenium-rich yeast: the first one is chelation, in which a certain amount of selenate or selenite is chelated with yeast cell emulsion at low temperature, and then dried to obtain the product. The second one is fermentation, in which yeast strains are cultured in a culture medium with sugar or starch or molasses as carbon source and ammonia water, ammonium sulfate, ammonium carbonate or urea as nitrogen source, and inorganic selenium is converted to yeast selenium by the growth and absorption of yeast.

[0004] Chinese patent CN107058208A discloses a production process of selenium-rich yeast powder, which comprises the following steps: preparation of culture medium, slant strain culture, primary liquid seed culture, secondary liquid seed culture, seed culture in a fermentation tank, fermentation culture in a fermentation tank, separation, drying, crushing and packaging. The selenium-rich yeast powder prepared by the process has a high selenium content, with a selenium content of 1200 mg / kg, in which the organic selenium content accounts for 92.8% of the total selenium, and the selenium-methionine form accounts for 44.5% of the total selenium.

[0005] CN102181371B discloses a yeast and a method for producing selenium-rich yeast using the yeast, in which a specific yeast strain is selected, and an organic nitrogen source containing amino nitrogen is supplemented every 5-10 hours during the addition of inorganic selenium salt aqueous solution; the inorganic selenium salt aqueous solution is selenate aqueous solution, selenite aqueous solution or a mixture of selenate and selenite aqueous solution; and the organic nitrogen source containing amino nitrogen is one or more of peptone, yeast extract, plant protein and amino acid. The selenium-rich yeast prepared by the method has selenium-methionine form accounting for 55-70% of the total selenium. SUMMARY

[0006] The technical problems solved by the present application: the organic selenium content in the selenium-rich yeast prepared by the fermentation method in the prior art is low, the selenium absorption rate is low, and the fermentation medium contains a large amount of inorganic selenium, inorganic nitrogen and inorganic phosphorus, which does not meet the requirements of organic product certification.

[0007] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide an organic selenium-rich yeast; the second purpose of the present application is to provide a preparation method of the above-mentioned organic selenium-rich yeast; the third purpose of the present application is to provide an organic selenium-rich yeast product prepared from the above-mentioned organic selenium-rich yeast; and the fourth purpose of the present application is to provide the application of the above-mentioned organic selenium-rich yeast or organic selenium-rich yeast product in feed additives and food nutrition enhancers.

[0008] The technical scheme of the present application:

[0009] The present application provides an organic selenium-rich yeast, wherein the organic selenium accounts for more than 99% of the total selenium weight, and the selenomethionine form selenium accounts for more than 80% of the total selenium weight.

[0010] Preferably, the selenomethionine form selenium accounts for more than 90% of the total selenium weight.

[0011] Preferably, the total selenium in each kg of organic selenium-rich yeast is 800-2100 mg, and preferably, the selenium absorption rate of the yeast is more than 95%.

[0012] Preferably, the above-mentioned organic selenium-rich yeast is obtained by fermentation culture of the yeast strain Saccharomyces cerevisiaed. The strain was deposited in the China Center for Type Culture Collection (CCTCC) on August 1, 2016, with the deposit number CCTCC NO: M2016418, and the strain has been recorded in the patent publication CN108220175A.

[0013] Preferably, the above-mentioned organic selenium-rich yeast is obtained by fermentation culture of the yeast strain Saccharomyces cerevisiaed with organic starch hydrolysis sugar, organic plant protein enzymatic hydrolysate and selenium-rich yeast extract as the culture medium.

[0014] The present application provides a preparation method of the above-mentioned organic selenium-rich yeast, which comprises step-by-step expansion culture of the yeast strain, fermentation culture, collection of the yeast cells and drying to obtain, wherein the fermentation culture is carried out with organic starch hydrolysis sugar, organic plant protein enzymatic hydrolysate and selenium-rich yeast extract as the culture medium.

[0015] Preferably, the pH during the fermentation culture is 5.0-7.0, and preferably, the fermentation temperature is 25-35℃.

[0016] Preferably, the organic starch hydrolysis sugar is prepared by enzymatic hydrolysis of organic starch by amylase and glucoamylase, preferably, the organic starch is one or more of organic corn starch, organic wheat starch, organic cassava starch and organic rice starch, further preferably, the amylase is thermophilic amylase and / or pullulanase.

[0017] Preferably, the pH during the amylase enzymatic hydrolysis is 5.6-5.8, and the amylase is used in an amount of 1-2‰ based on the weight of the organic starch.

[0018] Preferably, the pH during the glucoamylase enzymatic hydrolysis is 4.2-4.4, and the glucoamylase is used in an amount of 1-2‰ based on the weight of the organic starch, further preferably, the glucoamylase enzymatic hydrolysis time is 15-20 hours.

[0019] Preferably, the total sugar content in the organic starch hydrolysis sugar is 26-31% based on 100% of the weight of the organic starch hydrolysis sugar.

[0020] Preferably, the organic plant protein enzymatic hydrolysis liquid is prepared by enzymatic hydrolysis of organic plant protein by protease, preferably, the organic plant protein is one or more of organic soybean meal powder, organic corn protein, organic soybean protein and organic rice protein, further preferably, the protease is one or more of papain, bromelain, trypsin, alkaline protease, flavor protease, acid protease and neutral protease, more further preferably, the protease has an enzymatic activity of greater than 5000u / g.

[0021] Preferably, the protease enzymatic hydrolysis includes two enzymatic hydrolysis.

[0022] Preferably, the first protease enzymatic hydrolysis has a pH of 6.0-6.5, a hydrolysis temperature of 53-57℃, and the protease is used in an amount of 1-3‰ based on the weight of the organic plant protein, further preferably, the enzymatic hydrolysis time is 2-5 hours.

[0023] Preferably, the second protease enzymatic hydrolysis has a pH of 6.0-6.5, a hydrolysis temperature of 50-54℃, and the protease is used in an amount of 6-8‰ based on the weight of the organic plant protein, further preferably, the enzymatic hydrolysis time is 10-15 hours.

[0024] Preferably, the amino acid nitrogen content in the organic plant protein enzymatic hydrolysis liquid is >0.3% based on 100% of the weight of the organic plant protein enzymatic hydrolysis liquid.

[0025] Preferably, the selenium content in the selenium-rich yeast extract is greater than 2000 ppm, preferably greater than 4000 ppm, based on 100% of the dry weight of the selenium-rich yeast extract, and preferably, the total nitrogen content in the selenium-rich yeast extract is greater than 6%, and further preferably, the amino acid nitrogen content in the selenium-rich yeast extract is greater than 3.5%.

[0026] Preferably, the organic starch is used in an amount of 30-40%, the organic plant protein is used in an amount of 55-65%, and the selenium-rich yeast extract is used in an amount of 2.4-4.2%, based on the weight of the medium raw materials, and preferably, the sum of the amounts of the organic starch and the organic plant protein is greater than 95%.

[0027] The present application also provides an organic selenium-rich yeast product prepared from the organic selenium-rich yeast or the organic selenium-rich yeast prepared by the above method. The organic selenium-rich yeast product can be an organic selenium-rich yeast hydrolysate or an organic selenium-rich yeast extract, which is obtained by autolysis, enzymatic hydrolysis, separation and purification of the organic selenium-rich yeast.

[0028] The present application also provides the use of the above organic selenium-rich yeast or the organic selenium-rich yeast prepared by the above method or the above organic selenium-rich yeast product in feed additives or food nutrition enhancers.

[0029] The present application has the following advantages:

[0030] (1) The present application uses organic starch hydrolysis sugar, organic plant protein enzymatic hydrolysate and selenium-rich yeast extract as the culture medium, and the selenium-rich yeast prepared thereby has greater than 80%, even greater than 90%, of the total selenium in the form of selenomethionine, greater than 99% of the total selenium in the form of organic selenium, a total selenium content of 800-2100 ppm, and a selenium absorption and utilization rate of the yeast of greater than 95%, which has a high absorption and utilization rate and conversion rate when applied to feeding and food.

[0031] (2) The present application uses organic starch as the starch hydrolysis sugar raw material and organic plant protein as the protein enzymatic hydrolysate raw material, and the amount of the organic raw materials is greater than 95%, and no inorganic phosphorus source, inorganic nitrogen source or metal trace elements are added, which meets the requirements of organic product certification and meets the requirements of organic feeding and organic food. DETAILED DESCRIPTION

[0032] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0033] The present application provides an organic selenium-rich yeast, which has greater than 99% of the total selenium in the form of organic selenium and greater than 80% of the total selenium in the form of selenomethionine.

[0034] In a preferred embodiment of the present application, the selenium form of selenomethionine accounts for more than 90% of the total selenium weight.

[0035] In a preferred embodiment of the present application, the total selenium content in the organic selenium-rich yeast is 800-2100 mg per kg, preferably, the selenium absorption rate of the yeast is more than 95%.

[0036] In a preferred embodiment of the present application, the organic selenium-rich yeast is obtained by fermentation culture of the yeast strain Saccharomyces cerevisiaed.

[0037] In a preferred embodiment of the present application, the organic selenium-rich yeast is obtained by fermentation culture of the yeast strain Saccharomyces cerevisiaed using organic starch hydrolysis sugar, organic plant protein enzymatic hydrolysate and selenium-rich yeast extract as the culture medium.

[0038] The present application also provides a preparation method of the organic selenium-rich yeast, comprising step-by-step expansion culture of the yeast strain, fermentation culture, collection of the yeast cells and drying to obtain, wherein the fermentation culture uses organic starch hydrolysis sugar, organic plant protein enzymatic hydrolysate and selenium-rich yeast extract as the culture medium.

[0039] By using organic starch hydrolysis sugar as the carbon source, organic plant protein enzymatic hydrolysate as the nitrogen source and phosphorus source, and selenium-rich yeast extract as the selenium source, vitamins and metal trace elements source, and also providing part of the nitrogen source and phosphorus source, and the organic plant protein enzymatic hydrolysate and selenium-rich yeast extract both contain amino acids, which can promote the selenium absorption and utilization capacity of the yeast, and the selenium-rich yeast extract also contains vitamins and metal trace elements, which can improve the nutrition of the yeast, so that the organic selenium-rich yeast obtained has more than 99% of the total selenium weight as organic selenium, more than 80% of the total selenium weight as selenomethionine form of selenium, even more than 90%, the total selenium content in the organic selenium-rich yeast is 800-2100 mg per kg, the selenium absorption and utilization rate of the yeast is more than 95%, the nutrition is balanced and rich, and the digestion and absorption are easy.

[0040] In a preferred embodiment of the present application, the fermentation culture is carried out at pH=5.0-7.0, preferably, the fermentation temperature is 25-35°C. The pH range is mainly considered to be a relatively good acidic environment for the yeast, which promotes the maturation of the yeast and facilitates the end of fermentation; the fermentation temperature is controlled in the above range mainly considering the growth and reproduction of the yeast, and this temperature range is the optimal growth temperature.

[0041] In a preferred embodiment of the present application, the organic starch hydrolysis sugar is prepared by sequentially subjecting organic starch to amylase and glucoamylase enzymolysis, preferably, the organic starch is one or more of organic corn starch, organic wheat starch, organic cassava starch and organic rice starch, further preferably, the amylase is one or more of thermophilic amylase and / or pullulanase.

[0042] Specifically, the organic starch hydrolysis sugar is prepared as follows: organic starch is slurried with water, the specific gravity is controlled to be about 15.5-17, and the pH is adjusted to be 5.6-5.8; after the slurry is prepared, 1-2‰ (based on the weight of the organic starch) amylase is added and stirred uniformly, and high-temperature liquefaction is performed at 105-115℃; then after being kept at 95℃ for 1 hour, the temperature is lowered to 60℃, the pH is adjusted to 4.2-4.4 to inactivate the enzyme; 1-2‰ (based on the weight of the organic starch) glucoamylase is added and mixed uniformly, and saccharification is performed at 60℃ for 15-20 hours, then diatomite is added, and the supernatant is collected by plate and frame filtration to obtain the organic starch hydrolysis sugar.

[0043] In a preferred embodiment of the present application, the total sugar content in the organic starch hydrolysis sugar is 26-31% based on 100% of the weight of the organic starch hydrolysis sugar.

[0044] In a preferred embodiment of the present application, the organic plant protein enzymolysis liquid is prepared by subjecting organic plant protein to protease enzymolysis, preferably, the organic plant protein is one or more of organic soybean meal powder, organic corn protein, organic soybean protein and organic rice protein, further preferably, the protease is one or more of papain, bromelain, trypsin, alkaline protease, flavor protease, acid protease and neutral protease, and more further preferably, the protease has an enzyme activity of greater than 5000u / g. The protease can be used for one-time enzymolysis, two-time enzymolysis or more-time enzymolysis, as long as the content of amino acid nitrogen in the final enzymolysis liquid is greater than 0.3%, which meets the requirements, and the selection of the enzymolysis mode depends on the enzymolysis effect and production cost of different enzymes.

[0045] Specifically, the organic plant protein enzymolysis liquid is prepared as follows: organic plant protein is weighed, water is added according to the ratio of 1:5 of the organic plant protein to water, and the mixture is stirred uniformly, heated to 53-57℃, and the pH is adjusted to 6.0-6.5 by using sodium carbonate; 1-3‰ (based on the weight of the organic plant protein) protease is added, and enzymolysis is performed for 2-5 hours; then 6-8‰ (based on the weight of the organic plant protein) protease is added, the temperature is raised to 50-54℃, and the pH is 6.0-6.5; enzymolysis is performed for 10-15 hours; after the enzymolysis is completed, the pH is adjusted to 4.5-5.0, the temperature is raised to 90℃ to inactivate the enzyme for 1.5 hours, and then the temperature is lowered to 50℃; perlite is added and mixed uniformly, the supernatant is collected by plate and frame filtration to obtain the liquid organic plant protein enzymolysis liquid.

[0046] In a preferred embodiment of the present application, the content of amino acid nitrogen in the organic plant protein enzymatic hydrolysate is >0.3% based on 100% of the weight of the organic plant protein enzymatic hydrolysate.

[0047] In a preferred embodiment of the present application, the content of selenium in the selenium-rich yeast extract is greater than 2000 ppm based on 100% of the weight of the dry matter of the selenium-rich yeast extract, preferably the content of selenium in the selenium-rich yeast extract is greater than 4000 ppm, preferably the content of total nitrogen in the selenium-rich yeast extract is >6%, and further preferably the content of amino acid nitrogen in the selenium-rich yeast extract is >3.5%.

[0048] In a preferred embodiment of the present application, the amount of organic starch in the medium raw material is 30-40%, the amount of organic plant protein is 55-65%, and the amount of selenium-rich yeast extract is 2.4-4.2% based on the weight of the medium raw material, and preferably the sum of the amounts of the organic starch and the organic plant protein is >95%. When the weight is specifically calculated, the weight of the medium raw material is the sum of the weights of the organic starch, the organic plant protein, the selenium-rich yeast extract, and the protease, amylase, and glucoamylase used for enzymolysis.

[0049] The present application also provides an organic selenium-rich yeast product prepared from the organic selenium-rich yeast or the organic selenium-rich yeast prepared by the above preparation method. The organic selenium-rich yeast product is an organic selenium-rich yeast hydrolysate or an organic selenium-rich yeast extract, which is obtained by autolysis, enzymolysis, separation, and purification of the organic selenium-rich yeast.

[0050] The present application also provides the use of the above organic selenium-rich yeast or the organic selenium-rich yeast prepared by the above preparation method or the above organic selenium-rich yeast product in a feed additive or a food nutrition enhancer.

[0051] The beneficial effects of the present application will be further illustrated by specific examples.

[0052] In the present application, the detection methods of various indexes are as follows:

[0053] (1) Determination of total nitrogen

[0054] The Kjeldahl method in 6.4 of the national standard GB / T 23530-2009 is adopted: take a sample (equivalent to 30-440 mg of total nitrogen), under the action of 5 g of mixed catalyst a (potassium sulfate and sewage copper sulfate mixed at a ratio of 97:3) and 2.5 g of catalyst b (selenium powder and potassium sulfate mixed at a ratio of 0.1:100), add 20 mL of concentrated sulfuric acid for digestion; then perform distillation, and absorb the product ammonia with boric acid; then titrate with 0.1 mol / L hydrochloric acid, read the data, and calculate the content of total nitrogen.

[0055] (2) Determination of amino acid nitrogen

[0056] The amino acid nitrogen detection method described in 6.5 of the national standard GB / T 23530-2009 is adopted: 5g of sample is taken, diluted, and then titrated with 0.5mol / L sodium hydroxide solution to pH 8.2 and kept for 1min. 10mL of 36% formaldehyde solution is slowly added to react with the non-dissociated amino in neutral amino acid to generate monomethylol and dimethylol induced bodies, and the reaction is quantitatively complete. At this time, the released hydrogen ions are titrated with the above sodium hydroxide solution, and the content of amino acid nitrogen is calculated according to the consumption of the lye.

[0057] (3) Determination of total selenium content

[0058] In the present application, the total selenium content refers to the first method of hydride atomic fluorescence spectrometry in GB5009.93-2017.

[0059] (4) Determination of organic selenium content

[0060] About 1g of sample is weighed, with a precision of 0.0001g, and placed in a 50mL volumetric flask. About 25mL of water is added, and the sample is ultrasonically dissolved for 10min to fully dissolve the sample. Add water to the mark and shake well. The solution after constant volume is placed in a centrifuge at 5000r / min for 10min. 10.0mL of centrifugal supernatant is taken in a 15mL centrifuge tube, 2.0mL of hydrochloric acid and 1.0mL of potassium ferricyanide solution are added, and the mixture is mixed and measured. At the same time, a blank test is performed. The inorganic selenium content is determined according to the first method of hydride atomic fluorescence spectrometry in GB5009.93-2017, and then the total selenium content obtained in (3) is subtracted from the inorganic selenium content to obtain the organic selenium content, which is calculated according to the following formula,

[0061] ω1=X2 / X*100%

[0062] ω1——organic selenium percentage content

[0063] X2——organic selenium content, unit: mg / kg;

[0064] X——total selenium content, unit: mg / kg.

[0065] (5) Determination of selenomethionine content

[0066] Accurately weigh 50 mg (accurate to 0.1 mg) of the sample into a glass container, add 2.5 mL of TRIS buffer solution (accurately weigh 18.17 g of tris-hydroxymethyl aminomethane, dissolve in 900 mL of water, adjust the pH to 7.60-7.70 with hydrochloric acid, and make up to 1 L), place the glass container in a constant temperature water bath at 90℃ for 10 min, and then take it out and cool to room temperature. Add 2.5 mL of protease, seal the glass container, and place it in a water bath shaker at 37℃ and 150 rpm for enzymolysis for 40-48 hours. Take it out and transfer it to a 100 mL volumetric flask and make up to the volume. Detect and calculate the content of selenomethionine by liquid chromatography-tandem mass spectrometry, and calculate the weight percentage of selenomethionine selenium in total selenium according to the following formula:

[0067] ω2 = 0.4026 * X3 / X * 100%

[0068] ω2 - weight percentage of selenomethionine selenium in total selenium

[0069] X - total selenium content, in mg / kg;

[0070] X3 - selenomethionine content, in mg / kg.

[0071] (6) Selenium absorption rate of yeast

[0072] Selenium absorption rate of yeast % = yield of organic selenium-rich yeast * total selenium content of yeast / (amount of selenium-rich yeast extract * total selenium content of selenium-rich yeast extract) * 100%

[0073] The raw materials and equipment sources used in the examples and comparative examples of the present application are shown in Table 1.

[0074] Table 1 Raw materials and equipment sources used in the examples and comparative examples of the present application

[0075]

[0076]

[0077] Example 1

[0078] (I) Preparation of organic starch hydrolysis sugar

[0079] Weigh 3000 kg of organic corn starch, dissolve it in a dissolving tank, add water to make a slurry, control the Baume degree to about 17, and adjust the pH to 5.8; after the slurry is prepared, add 6 kg of high-temperature amylase, stir and mix evenly, and spray at 105℃ for high-temperature liquefaction; after keeping at 95℃ for 1 hour, cool to 60℃, adjust the pH to 4.2 to inactivate the enzyme; then add 6 kg of saccharifying enzyme and mix evenly, saccharify at 60℃ for 15 hours; add diatomite and mix evenly, and pass through a plate and frame filter to obtain 10.2 cubic meters of organic starch hydrolysis sugar with a total sugar content of 31.1%.

[0080] (II) Preparation of organic plant protein enzymatic hydrolysate

[0081] Take 5000 kg of organic soybean meal powder, add water to make up to 25 cubic meters, and mix thoroughly; heat to 55°C, adjust pH to 6.2 with sodium carbonate, add 15 kg of papain, and enzymatically hydrolyze for 3 hours; then add 40 kg of flavor protease, control the temperature at 52°C, and the pH at 6.0-6.5. Enzymatically hydrolyze for 12 hours; after the enzymatic hydrolysis is completed, adjust the pH to 4.5, heat to 90°C to inactivate the enzyme for 1.5 hours, and then cool to 50°C; add perlite and mix evenly, collect the supernatant by plate and frame filtration, and obtain 22 cubic meters of organic plant protein enzymatic hydrolysate, with an amino acid nitrogen content of 0.38%.

[0082] (III) Preparation of selenium-rich yeast extract

[0083] Take 300 kg of selenium-rich yeast extract (total selenium content of 2530 ppm), and dissolve according to the mass ratio of selenium-rich yeast extract: water = 1:10 to obtain a selenium-rich yeast extract solution.

[0084] (III) Preparation of selenium-rich yeast extract

[0085] Take the preserved Saccharomyces cerevisiae FX-2 (preservation number CCTCC NO: M2016418) and activate it on YPD medium, incubate at 30°C for 48 hours, and store it in a 4°C refrigerator for future use; use the obtained strain to expand in a triangular flask and a caries bottle to a 10 cubic meter seed tank, and use the prepared seed to inoculate a 50 cubic meter fermentation tank by differential pressure method, adjust the pH to 5.0 with sodium carbonate and citric acid, and add the organic starch hydrolysis sugar prepared in step (I) at a flow rate of 100-1000 L per hour during the fermentation process, add the organic plant protein enzymatic hydrolysate prepared in step (II) at a flow rate of 200-2000 L per hour during the fermentation process, and add the selenium-rich yeast extract solution prepared in step (III) at a flow rate of 50-250 L per hour during the fermentation process. Incubate at a fermentation culture temperature of 25°C for 35 hours, and after the fermentation is completed, obtain 35.4 m 3 Fermentation broth, centrifugal separation, concentration, and spray drying, finally obtain 0.88 tons of selenium-rich yeast, with a total selenium content of 835 ppm, an organic selenium proportion of 99.8%, a selenium-methionine form selenium proportion of 90.6% of the total selenium, and a selenium absorption rate of the yeast of 96.8%.

[0086] Example 2

[0087] (I) Preparation of organic starch hydrolysis sugar

[0088] Take 2600 kg of organic corn starch, dissolve in the dissolving tank, add water to adjust the pulp, control the Baume degree to about 15.5, adjust the pH to 5.6; after the pulp is adjusted, add 2.6 kg of pullulanase, mix well, and spray at 115 ℃; after 1 hour of insulation at 95 ℃, cool to 60 ℃, adjust the pH to 4.4 to inactivate the enzyme; then add 2.6 kg of saccharifying enzyme and mix evenly, saccharify at 60 ℃ for 20 hours; add diatomite and mix evenly, pass through plate and frame filter to obtain 9.7 cubic meters of liquid organic starch hydrolysis sugar with a total sugar content of 26.3%.

[0089] (II) Preparation of organic plant protein enzymatic hydrolysate

[0090] Take 5400 kg of organic soybean meal powder, add water to make up to 25 cubic meters, and mix well; heat to 55 ℃, adjust the pH to 6.5 with sodium carbonate, add 5.4 kg of papain, and enzymatically hydrolyze for 5 hours; then add 32.4 kg of flavor protease, control the temperature at 52 ℃, and the pH at 6.0, and enzymatically hydrolyze for 15 hours; after the enzymatic hydrolysis is completed, adjust the pH to 5.0, heat to 90 ℃ to inactivate the enzyme for 1.5 hours, and then cool to 50 ℃; add perlite and mix evenly, pass through plate and frame filter to collect the supernatant to obtain 20 cubic meters of liquid organic plant protein enzymatic hydrolysate with an amino acid nitrogen content of 0.31%.

[0091] (III) Preparation of selenium-rich yeast extract

[0092] Take 350 kg of selenium-rich yeast extract (total selenium content of 4376 ppm), and dissolve according to the mass ratio of selenium-rich yeast extract: water = 1:10 to obtain a selenium-rich yeast extract solution.

[0093] (IV) Preparation of organic selenium-rich yeast

[0094] Take the preserved Saccharomyces cerevisiae FX-2 (preservation number CCTCC NO: M2016418) and activate it on YPD medium, and incubate it at 30 ℃ for 48 h, and store it in a 4 ℃ refrigerator for standby; use the obtained strain to expand in a triangular flask and a caries bottle to 10 cubic meters of seed tank, and use the prepared seed to inoculate a 50 cubic meter fermentation tank by differential pressure method, adjust the pH to 5.0 with sodium carbonate and citric acid, and during the fermentation process, add the organic starch hydrolysis sugar prepared in step (I) at a flow rate of 100-1000 L per hour, add the organic plant protein enzymatic hydrolysate prepared in step (II) at a flow rate of 200-2000 L per hour, and add the selenium-rich yeast extract solution prepared in step (III) at a flow rate of 50-250 L per hour. Incubate at a fermentation culture temperature of 25 ℃ for 40 hours, and after the fermentation is completed, obtain 33.3 cubic meters of organic selenium-rich yeast with a total amino acid nitrogen content of 0.31% and a total selenium content of 4376 ppm. 3The fermentation liquid is centrifuged, concentrated and spray dried to obtain 0.73 tons of organic selenium-rich yeast, the total selenium content of which is 2011 ppm, the organic selenium accounts for 99.5%, the selenium form of selenomethionine accounts for 86.6% of the total selenium, and the selenium absorption rate of the yeast reaches 95.8%.

[0095] Example 3

[0096] (I) Preparation of organic starch hydrolysis sugar

[0097] Take 3300 kg of organic corn starch, dissolve it in a dissolving tank, adjust the slurry with water, control the Baume degree to about 17, and adjust the pH to 5.8; after the slurry is completed, 6.6 kg of high-temperature amylase is added and stirred uniformly, and the liquid is jetted at 105°C for high-temperature liquefaction; after keeping at 95°C for 1 hour, it is cooled to 60°C, the pH is adjusted to 4.2 to inactivate the enzyme; then 6.6 kg of saccharifying enzyme is added and mixed uniformly, and saccharification is carried out at 60°C for 15 hours; siliceous earth is added and mixed uniformly, and plate and frame filtration is carried out to obtain 10.8 cubic meters of organic starch hydrolysis sugar, and the total sugar content is 30.7%.

[0098] (II) Preparation of organic plant protein enzymatic hydrolysate

[0099] Take 4700 kg of organic soybean meal powder, add water to make up to 25 cubic meters, and mix thoroughly; heat to 55°C, adjust the pH to 6.2 with sodium carbonate, add 9.4 kg of papain, and enzymatically hydrolyze for 3 hours; then add 23.5 kg of flavor protease, control the temperature at 52°C, and the pH at 6.0-6.5, and enzymatically hydrolyze for 12 hours; after the enzymatic hydrolysis is completed, the pH is adjusted to 4.5, the temperature is raised to 90°C to inactivate the enzyme for 1.5 hours, and then the temperature is lowered to 50°C; add perlite and mix uniformly, collect the supernatant by plate and frame filtration to obtain 21 cubic meters of organic plant protein enzymatic hydrolysate, and the amino acid nitrogen content is 0.34%.

[0100] (III) Preparation of selenium-rich yeast extract

[0101] Take 200 kg of selenium-rich yeast extract (total selenium content is 4376 ppm), and dissolve it according to the mass ratio of selenium-rich yeast extract: water = 1:10 to obtain a selenium-rich yeast extract solution.

[0102] (IV) Preparation of organic selenium-rich yeast

[0103] The preserved Saccharomyces cerevisiae FX-2 (preservation number CCTCC NO: M2016418) is activated on a YPD culture medium, and is incubated at 30°C for 48 hours, and is preserved in a 4°C refrigerator for standby; the obtained strain is expanded in a triangular flask and a carter flask to a 10 cubic meter seed tank, the prepared seed is connected to a 50 cubic meter fermentation tank by a differential pressure method for fermentation, sodium carbonate and citric acid are used to adjust pH = 5.0, in the fermentation process, step (I) is used to prepare organic starch hydrolysis sugar, the flow adding amount is 100-1000 L per hour, in the fermentation process, step (II) is used to prepare organic plant protein enzymolysis liquid, the flow adding amount is 200-2000 L per hour, in the fermentation process, step (III) is used to prepare selenium-rich yeast extract solution, the flow adding amount is 50-250 L per hour. The fermentation culture temperature is 25°C, and the ventilation culture is carried out for 37 hours, after the fermentation is completed, 33.9 m 3 The fermentation liquid is centrifuged, concentrated and spray dried, and finally 0.82 tons of organic selenium-rich yeast is obtained, the total selenium content is 1029 ppm, the organic selenium proportion is 99.7%, the selenium form of selenomethionine accounts for 89.1% of the total selenium, and the selenium absorption rate of the yeast reaches 96.4%.

[0104] Example 4

[0105] Preparation of organic selenium-rich yeast hydrolysate: in a batching tank, the organic selenium-rich yeast prepared in Example 2 is prepared into a 10% (yeast dry matter content) solution, heated to 80°C for heat shock for 50s, and adjusted to pH 5 with citric acid; cooled to 50°C, incubated for 12h, and 2‰ papain is added for enzymolysis reaction for 6h; adjust the pH to 6.8, the temperature to 60°C, and add 3‰ neutral protease for enzymolysis reaction for 6h; adjust the pH to 7, the temperature to 65°C, and add 1‰ alkaline protease for enzymolysis reaction for 10h, after the enzymolysis reaction is completed, the temperature is raised to 90°C for 1h to inactivate the enzyme, and then concentrated to dry matter 35%, and spray dried to obtain the organic selenium-rich yeast hydrolysate product. The total selenium content of the organic selenium-rich yeast hydrolysate product is 1882 ppm, the protein content is 40.2%, the acid-soluble protein content is 33%, the small peptide content is 22%, and the cell wall content is 31%.

[0106] Example 5

[0107] Preparation of the organic selenium-rich yeast extract: the organic selenium-rich yeast prepared in Example 3 was prepared into a 20% (dry matter content of the yeast) solution in a batching tank, heated to 90°C for 30 minutes, cooled to 55°C, adjusted to pH 8.0, added with 2‰ alkaline protease, enzymolysed for 20 hours, then heated to 90°C for 1 hour to inactivate the enzyme, centrifuged at 5000 rpm to remove the cell wall, and the supernatant was collected, concentrated to 37% dry matter, and then spray-dried to obtain the organic selenium-rich yeast extract product. The selenium content of the organic selenium-rich yeast extract product was 1288 ppm, the total nitrogen content was 10.8%, and the amino acid nitrogen content was 3.3%.

[0108] In addition, the organic selenium-rich yeast prepared in Examples 1-3 and the organic selenium-rich yeast product prepared in Examples 4-5 were respectively added to pig feed for fattening pig animal experiments, which showed that the feed had a trend of improving the growth rate of the fattening pigs and reducing the feed-meat ratio, and could significantly improve the meat color during the storage period of fresh meat after slaughter and reduce the drip loss. The organic selenium-rich yeast prepared in Examples 1-3 and the organic selenium-rich yeast product prepared in Examples 4-5 were respectively added to chicken feed, which could improve the production performance of laying hens, increase the egg weight, and also increase the selenium deposition in the eggs.

[0109] In summary, the organic selenium-rich yeast prepared by using the organic starch hydrolysis sugar, the organic plant protein enzymolysis liquid, and the selenium-rich yeast extract as the culture medium has more than 80% or even more than 90% of the selenium in the form of selenomethionine, more than 99% of the selenium in the form of organic selenium, a total selenium content of 800-2100 ppm, and a selenium absorption and utilization rate of the yeast of more than 95%. The application in feeding has a high absorption and utilization rate and conversion rate, can improve the growth rate of the fattening pigs and reduce the feed-meat ratio, and can improve the production performance of the laying hens, increase the egg weight, and also increase the selenium deposition in the eggs. The organic starch is used as the starch hydrolysis sugar raw material, the organic plant protein is used as the protein enzymolysis material raw material, the organic raw material content is more than 95%, and no inorganic phosphorus source, inorganic nitrogen source, and metal trace elements are added, which can meet the requirements of the organic product certification and the requirements of the organic feeding and the organic food.

[0110] The above description is only a preferred embodiment of the present application, and does not limit the present application in any form. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing organic selenium-enriched yeast, characterized in that, The method comprises the following steps: brewing yeast ( Saccharomyces cerevisiaed The FX-2 yeast was cultured in a stepwise manner, fermented, and the yeast cells were collected and dried to obtain the organic selenium-enriched yeast. The fermentation culture used organic starch hydrolysate, organic plant protease hydrolysate, and selenium-enriched yeast extract as a fed-batch culture medium. The organic starch and the organic plant protein are used in an amount of 95% or more in the raw material of the fermentation medium. The organic starch is hydrolyzed to obtain the organic starch hydrolysis sugar by using amylase and saccharifying enzyme. The organic plant protein is enzymolyzed to obtain the organic plant protein enzymolysis liquid by using protease. The selenium content in the selenium-rich yeast extract is greater than 4000 ppm.

2. The production method according to claim 1, wherein, The total nitrogen content in the selenium-rich yeast extract is greater than 6%.

3. The production method according to claim 1, wherein, The pH value is 5.0-7.0 during the fermentation.

4. The production method according to claim 1, wherein The fermentation temperature is 25-35 DEG C.

5. The production method according to claim 3, wherein The organic starch is one or more of organic corn starch, organic wheat starch, organic cassava starch and organic rice starch.

6. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The pH value is 5.6-5.8 during the amylase enzymolysis.

7. The preparation method according to claim 6, characterized in that, The pH value is 4.2-4.4 during the saccharifying enzyme enzymolysis.

8. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The saccharifying enzyme enzymolysis time is 15-20 hours.

9. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The total sugar content in the organic starch hydrolysis sugar is 26-31% based on the weight of the organic starch hydrolysis sugar.

10. The method of claim 1, wherein, The protease enzymatic activity is greater than 5000 u / g.

11. The preparation method according to claim 10, characterized in that, The protease enzymolysis comprises two times of enzymolysis.

12. The method of claim 1, wherein, The pH value is 6.0-6.5 during the first protease enzymolysis.

13. The method of claim 1, wherein the step of forming the first and second layers is performed by a process selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. The temperature is 53-57 DEG C during the first protease enzymolysis.

14. The process according to any one of claims 1 to 13, characterized in that, The first protease is used in an amount of 1-3 ‰ based on the weight of the organic plant protein.

15. The preparation method according to claim 14, characterized in that, The first protease enzymolysis time is 2-5 hours.

16. The preparation method according to claim 15, characterized in that, The pH value is 6.0-6.5 during the second protease enzymolysis.

17. The preparation method according to claim 15, characterized in that, The temperature is 50-54 DEG C during the second protease enzymolysis.

18. The preparation method according to claim 15, characterized in that, The second protease is used in an amount of 6-8 ‰ based on the weight of the organic plant protein.

19. The method of claim 14, wherein, The second protease enzymolysis time is 10-15 hours.

20. The preparation method according to claim 19, characterized in that, The amino acid nitrogen content in the organic plant protein enzymolysis liquid is greater than 0.3% based on the weight of the organic plant protein enzymolysis liquid.

21. The preparation method according to claim 19, characterized in that, The selenium content in the selenium-rich yeast extract is greater than 4000 ppm.

22. The preparation method according to claim 19, characterized in that, The total nitrogen content in the selenium-rich yeast extract is greater than 6%.

23. The method of any one of claims 1-13, wherein, ​ 24. The process of any one of claims 1-13, wherein, ​ 25. The preparation method according to claim 24, characterized in that, ​

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