Monosodium glutamate and preparation method thereof

文档序号:1837075 发布日期:2021-11-16 浏览:25次 中文

阅读说明:本技术 一种味精及其制备方法 (Monosodium glutamate and preparation method thereof ) 是由 冯文清 林琳 苏丽敏 伍钧 刘志坚 黄东江 王景林 陈思杰 白耀龙 赵伟恩 李建 于 2021-08-03 设计创作,主要内容包括:本发明涉及食品加工技术领域,公开了一种味精及其制备方法。该方法包括以下步骤:(1)在晶种存在下,将味精母液进行结晶处理,得到饱和度为30-32波美的第一溶液;所述结晶处理的方法包括:每间隔60-100min向所述味精母液中加入0.05-0.2L水,加水次数为3-8次;(2)将所述第一溶液进行分离,得到第一分离液和固体物料,将所述固体物料进行干燥处理。采用本发明的方法能够获得晶体质量优异且收率高的味精产品。(The invention relates to the technical field of food processing, and discloses monosodium glutamate and a preparation method thereof. The method comprises the following steps: (1) crystallizing the monosodium glutamate mother liquor in the presence of a seed crystal to obtain a first solution with the saturation of 30-32 Baume; the method for crystallization treatment comprises the following steps: adding 0.05-0.2L of water into the monosodium glutamate mother liquor every 60-100min, wherein the water adding frequency is 3-8 times; (2) and separating the first solution to obtain a first separation liquid and a solid material, and drying the solid material. The method can obtain the monosodium glutamate product with excellent crystal quality and high yield.)

1. A method for producing monosodium glutamate, comprising the steps of:

(1) crystallizing the monosodium glutamate mother liquor in the presence of a seed crystal to obtain a first solution with the saturation of 30-32 Baume; the method for crystallization treatment comprises the following steps: adding 0.05-0.2L of water into 1L of the monosodium glutamate mother liquor at intervals of 60-100min, wherein the water adding frequency is 3-8 times;

(2) separating the first solution to obtain a first separation liquid and a solid material, and drying the solid material;

wherein the light transmittance of the monosodium glutamate mother liquor is not less than 95%, and the pH value is 6-7.5;

based on the total weight of the monosodium glutamate mother liquor, the monosodium glutamate mother liquor contains 40-50 wt% of sodium glutamate, 0.02-0.08 wt% of chloride ions, 0.00015-0.0003 wt% of iron ions, 0.02-0.08 wt% of sulfate and 45-65 wt% of water.

2. The method according to claim 1, wherein, in the step (1), the crystallization treatment method comprises: adding 0.05-0.15L of water into 1L of the monosodium glutamate mother liquor at intervals of 80-100min, wherein the water adding frequency is 4-6 times.

3. The process according to claim 1 or 2, wherein in step (1), the seeds have an average particle size of 30-50 mesh, preferably 30-40 mesh;

preferably, in the step (1), the dosage of the seed crystal is 50-60g relative to 1L of the monosodium glutamate mother liquor.

4. The process according to any one of claims 1 to 3, wherein, in step (1), the crystallization treatment is carried out under stirring conditions, the conditions of the crystallization treatment comprising at least: the stirring speed is 15-45rpm, the temperature is 65-72 ℃, the vacuum degree is-0.07 MPa to-0.09 MPa, and the time is 1-3 h.

5. The method according to any one of claims 1 to 4, wherein in step (2), the conditions of the separation process comprise at least: the temperature is 45-55 ℃, the pressure is 0.5-0.7MPa, the rotating speed is 900-1100rpm, and the time is 1-5 min.

6. The method according to any one of claims 1 to 5, wherein the preparation method of monosodium glutamate mother liquor comprises the following steps:

(I) mixing glutamic acid and sodium carbonate in the presence of water to obtain a neutralized solution containing 30-55 wt% of sodium glutamate;

(II) in the presence of a filter aid, mixing the neutralization solution with activated carbon to perform first decolorization, and then performing pressure filtration on the obtained neutralization decolorized solution to obtain a white crystal solution containing sodium glutamate;

(III) adding the white crystal liquid at a ratio of 2.5m3/h-3m3The flow rate/h is passed through an exchange column containing a combination of anionic resins for a second decolorization.

7. The method according to claim 6, wherein in the step (I), the glutamic acid, the sodium carbonate and the water are used in a mass ratio of 1: 0.2-0.8: 1-5, preferably 1: 0.3-0.5: 2-4.

8. The process according to claim 6 or 7, wherein in step (II), the conditions of the first decolorization are at least satisfied: the stirring speed is 90-120rpm, the temperature is 60-70 ℃, and the time is 45-90 min.

9. The method according to any one of claims 6 to 8, wherein, in the step (III), the anion resin composition comprises a first resin, a second resin and a third resin which are sequentially packed in terms of a liquid-phase stream flow direction, and a packing volume ratio of the first resin, the second resin and the third resin is 1: 1-5: 1-5, preferably 1: 1-3: 1-3.

10. Monosodium glutamate obtainable by the process according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of food processing, in particular to monosodium glutamate and a preparation method thereof.

Background

The monosodium glutamate industry is one of the main industries of the fermentation industry in China, and the monosodium glutamate produced in China is gradually increased along with the social development. The production of monosodium glutamate usually uses rice, starch and molasses as main raw materials, and adopts the processes of saccharification, fermentation and the like to separate and extract glutamic acid, and then the monosodium glutamate product is obtained by refining.

For the production of monosodium glutamate, strict process control must be carried out to ensure the quality of monosodium glutamate. From the perspective of a refining plant, the great influence on the quality of the flavor is probably caused by two aspects, namely the purity of the feed liquid and the treatment of the mother liquid. In the traditional process, the impurity content of the monosodium glutamate is greatly increased and the viscosity is increased due to repeated and cyclic decolorization and crystallization in the refining and crystallization process of the monosodium glutamate, and the monosodium glutamate is used for producing the monosodium glutamate, so that the crystal growth speed is reduced, the crystallization period is prolonged, and the quality of monosodium glutamate crystals is influenced. Therefore, it is necessary to develop a production process for obtaining monosodium glutamate with good crystal quality.

Disclosure of Invention

The invention aims to overcome the defect that the quality and the yield of monosodium glutamate crystals in the prior art cannot be considered at the same time.

In order to achieve the above object, the present invention provides, in a first aspect, a method for preparing monosodium glutamate, comprising the steps of:

(1) crystallizing the monosodium glutamate mother liquor in the presence of a seed crystal to obtain a first solution with the saturation of 30-32 Baume; the method for crystallization treatment comprises the following steps: adding 0.05-0.2L of water into 1L of the monosodium glutamate mother liquor at intervals of 60-100min, wherein the water adding frequency is 3-8 times;

(2) separating the first solution to obtain a first separation liquid and a solid material, and drying the solid material;

wherein the light transmittance of the monosodium glutamate mother liquor is not less than 95%, and the pH value is 6-7.5;

based on the total weight of the monosodium glutamate mother liquor, the monosodium glutamate mother liquor contains 40-50 wt% of sodium glutamate, 0.02-0.08 wt% of chloride ions, 0.00015-0.0003 wt% of iron ions, 0.02-0.08 wt% of sulfate and 45-65 wt% of water.

In a second aspect, the present invention provides a monosodium glutamate produced by the method of the first aspect.

The monosodium glutamate prepared by the method of the invention not only can obtain a monosodium glutamate product with full particles and uniform crystal form, but also can improve the yield of monosodium glutamate crystals.

Drawings

FIG. 1 is a diagram of a monosodium glutamate crystal prepared in example 1 of the present invention;

FIG. 2 is a diagram of a monosodium glutamate crystal prepared in example 2 of the present invention;

FIG. 3 is a diagram of a monosodium glutamate crystal prepared by example 7 of the present invention;

FIG. 4 is a schematic diagram of monosodium glutamate crystals prepared in comparative example 1.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

In the present invention, unless otherwise stated, the pressures are gauge pressures.

In the present invention, the seed crystal is monosodium glutamate crystal without reverse explanation.

As previously mentioned, a first aspect of the present invention provides a process for producing monosodium glutamate, comprising the steps of:

(1) crystallizing the monosodium glutamate mother liquor in the presence of a seed crystal to obtain a first solution with the saturation of 30-32 Baume; the method for crystallization treatment comprises the following steps: adding 0.05-0.2L of water into 1L of the monosodium glutamate mother liquor at intervals of 60-100min, wherein the water adding frequency is 3-8 times;

(2) separating the first solution to obtain a first separation liquid and a solid material, and drying the solid material;

wherein the light transmittance of the monosodium glutamate mother liquor is not less than 95%, and the pH value is 6-7.5;

based on the total weight of the monosodium glutamate mother liquor, the monosodium glutamate mother liquor contains 40-50 wt% of sodium glutamate, 0.02-0.08 wt% of chloride ions, 0.00015-0.0003 wt% of iron ions, 0.02-0.08 wt% of sulfate and 45-65 wt% of water.

In the invention, under the condition of not carrying out reverse explanation, in the crystallization treatment process, timing is started at the moment of finishing seed crystal feeding, first water adding is carried out after an interval of 60-100min, timing is restarted at the moment of finishing first water adding, second water adding is carried out after an interval of 60-100min, and the time of subsequent water adding is analogized.

Preferably, in the step (1), the method of crystallization treatment includes: adding 0.05-0.15L of water into 1L of the monosodium glutamate mother liquor at intervals of 80-100min, wherein the water adding frequency is 4-6 times. The inventor finds that in the preferable condition, the prepared monosodium glutamate crystal has more full particles, more uniform crystal form and higher yield.

Preferably, the monosodium glutamate mother liquor contains 45-50 wt% of sodium glutamate, 0.02-0.05 wt% of chloride ions, 0.00015-0.0002 wt% of iron ions, 0.02-0.06 wt% of sulfate and 48-60 wt% of water based on the total weight of the monosodium glutamate mother liquor.

Preferably, in step (1), the average particle size of the seed crystals is 30 to 50 mesh, more preferably 30 to 40 mesh.

Preferably, in the step (1), the dosage of the seed crystal is 50-60g relative to 1L of the monosodium glutamate mother liquor.

Preferably, in step (1), the crystallization treatment is performed under stirring conditions, and the conditions of the crystallization treatment at least include: the stirring speed is 15-45rpm, the temperature is 65-72 ℃, the vacuum degree is-0.07 MPa to-0.09 MPa, and the time is 1-3 h.

In the present invention, the time of the crystallization process is counted from the moment the last water addition is completed, that is, the time of the crystallization process does not include the time consumed in the interval water addition process.

Preferably, in step (2), the conditions of the separation process include at least: the temperature is 45-55 ℃, the pressure is 0.5-0.7MPa, the rotating speed is 900-1100rpm, and the time is 1-5 min.

Preferably, in step (2), the conditions of the drying treatment include at least: the temperature is 70-90 deg.C, and the time is 1-5 min.

According to a particularly preferred embodiment, the preparation method of the monosodium glutamate mother liquor comprises the following steps:

(I) mixing glutamic acid and sodium carbonate in the presence of water to obtain a neutralized solution containing 30-55 wt% of sodium glutamate;

(II) in the presence of a filter aid, mixing the neutralization solution with activated carbon to perform first decolorization, and then performing pressure filtration on the obtained neutralization decolorized solution to obtain a white crystal solution containing sodium glutamate;

(III) adding the white crystal liquid at a ratio of 2.5m3/h-3m3The flow rate/h is passed through an exchange column containing a combination of anionic resins for a second decolorization.

Preferably, in step (I), the glutamic acid, the sodium carbonate and the water are used in a mass ratio of 1: 0.2-0.8: 1-5, more preferably 1: 0.3-0.5: 2-4.

Preferably, in step (I), the mixing conditions at least satisfy: stirring speed is 90-150rpm, temperature is 60-80 deg.C, and time is 40-70 min. More preferably, in step (I), the mixing conditions at least satisfy: the stirring speed is 100-120rpm, the pH value is 6.5-7.4, the temperature is 60-80 ℃, and the time is 50-90 min.

Preferably, in step (II), the activated carbon is activated carbon powder with an average particle size of 250-300 μm.

Preferably, in step (II), the filter aid is he south river perlite # 3 or yuba pluvialis perlite # 3.

Preferably, in step (II), the first decolorizing condition is at least satisfied: the stirring speed is 90-120rpm, the temperature is 60-70 ℃, and the time is 45-90 min.

Preferably, in step (II), the conditions of the pressure filtration at least satisfy: the pressure is 1-5MPa, the temperature is 60-70 deg.C, and the time is 45-75 min.

Preferably, in the step (III), the anion resin composition comprises a first resin, a second resin and a third resin which are sequentially filled in a liquid phase stream flow direction, and a filling volume ratio of the first resin, the second resin and the third resin is 1: 1-5: 1-5, more preferably 1: 1-3: 1-3. The inventors have found that in this preferred case a monosodium glutamate product with superior crystal quality and higher yield can be obtained.

According to a particularly preferred embodiment, in the combination of anionic resins, the first resin is Amberlite FPA90Cl resin, dow, usa, the second resin is ela 94 resin, ela 38 resin.

Preferably, in step (III), the second decoloring condition at least satisfies: the temperature is 40-50 ℃.

As mentioned above, the second aspect of the present invention provides a monosodium glutamate produced by the method of the first aspect.

The present invention will be described in detail below by way of examples. In the following examples, various raw materials used are commercially available ones unless otherwise specified.

Glutamic acid: the purity is 98.5 percent and is purchased from Hurenbel northeast Biotechnology Co., Ltd;

sodium carbonate: purchased from Shandong Hai nationality Weifang alkali factory;

filter aid-1: henan perlite No. 3, available from Zhongnan Filter aid, Inc. of Henan province;

filter aid-2: the wine is shengda perlite No. 3, purchased from south China company;

activated carbon-1: the average grain diameter is 300 mu m, and the product is purchased from Fujian litchi chinensis active carbon industry Co., Ltd;

activated carbon-2: the average particle size is 270 mu m, and the product is purchased from Fujian litchi chinensis active carbon industry Co., Ltd;

activated carbon-3: the average grain diameter is 250 mu m, and the product is purchased from Fujian litchi chinensis active carbon industry Co., Ltd;

amberlite FPA90Cl resin: brand FPA90Cl, available from dow company, usa;

LKA94 resin: brand number LKA94, available from eimeria healthcare, bio-medicine, inc;

LKA38 resin: brand number LKA38, available from eimeria healthcare, bio-medicine, inc;

seed crystal-1: the average particle size is 30 meshes, and the grain size is taken from monosodium glutamate refining workshop of Guangzhou Ossa monosodium glutamate food Co., Ltd in 20 months in 5 months in 2020;

seed crystal-2: the average particle size is 40 mesh, and is obtained from monosodium glutamate refining workshop of Guangzhou Oslo monosodium glutamate food Co., Ltd in 04/07/2020;

seed crystal-3: the average particle size is 50 meshes, and the product is obtained from monosodium glutamate refining workshop of Guangzhou Ossa monosodium glutamate food Co., Ltd in 2020, 08 and 16 months;

without going to the contrary, in the following examples:

the light transmittance was measured using a 722-S spectrophotometer instrument.

The content of the sodium glutamate is detected by a polarimeter, and the specific detection method is an polarimeter in GB 5009.43-2016.

The sulfate content, the iron ion content, the chloride ion content and the pH value are all detected by adopting the national standard GB/T8967-2007.

Preparation example 1

The preparation example provides a preparation method of monosodium glutamate mother liquor, which comprises the following steps:

(I) introducing 1000g of glutamic acid and 2230g of water into a neutralization tank with a stirring speed of 110rpm, adding 360g of sodium carbonate for neutralization, controlling the pH value to be 6.5-7.0 in the neutralization process, controlling the neutralization temperature to be 70 ℃, and neutralizing for 90min to obtain a neutralization solution with the sodium glutamate content of 55 wt%;

(II) in the presence of a filter aid-2, mixing the neutralization solution with activated carbon-2 at a stirring speed of 120rpm and a temperature of 70 ℃ for first decolorization for 90min, filtering to obtain a neutralization decolorized solution, and then performing pressure filtration on the obtained neutralization decolorized solution for 75min at a pressure of 4MPa and a temperature of 80 ℃ to obtain a white crystal solution containing sodium glutamate;

(III) sequentially loading Amberlite FPA90Cl resin, LKA94 resin and LKA38 resin on an anion exchange column according to a liquid phase stream flow direction, wherein a loading volume ratio of the Amberlite FPA90Cl resin, the LKA94 resin and the LKA38 resin is 1: 1: 1, then heating the white crystal liquid at the temperature of 50 ℃ for 3m3The flow rate of the second decolorization is carried out by passing through the exchange column containing Amberlite FPA90Cl resin, LKA94 resin and LKA38 resin in sequence at the flow rate of/h, and the monosodium glutamate mother liquor is 1.

Preparation example 2

This preparation was carried out in analogy to preparation 1, except that in step (III) the loading volume ratio of said Amberlite FPA90Cl resin, said LKA94 resin and said LKA38 resin was 1: 2: 2.

the remaining steps were the same as in preparation example 1.

To obtain monosodium glutamate mother liquor-2.

Preparation example 3

This preparation was carried out in analogy to preparation 1, except that in step (III) the loading volume ratio of said Amberlite FPA90Cl resin, said LKA94 resin and said LKA38 resin was 1: 4: 4.

to obtain monosodium glutamate mother liquor-3.

The sodium glutamate content, the sulfate content, the iron ion content, the chloride ion content, the light transmittance, the pH value and the yield of the monosodium glutamate mother liquor prepared by the preparation example are detected, and specific detection results are shown in table 1.

Wherein, the calculation formula of the yield is as follows: the content of sodium glutamate in the monosodium glutamate mother liquor is multiplied by the weight of the monosodium glutamate mother liquor/(the dosage of glutamic acid is multiplied by the purity of glutamic acid is multiplied by 1.272) multiplied by 100 percent.

TABLE 1

Example 1

This example provides a method for preparing monosodium glutamate, comprising the steps of:

(1) at 70 ℃, adding 50g of seed crystal-1 and 1L of monosodium glutamate mother liquor-1 into a crystallizing tank (the vacuum degree is-0.07 MPa), continuously stirring at 30rpm, adding 0.05L of water into the monosodium glutamate mother liquor at intervals of 80min, adding the water for 6 times, and continuously crystallizing and concentrating for 2 hours to obtain a first solution with the saturation of 32 Baume;

(2) and (2) introducing the first solution into a centrifuge (with the pressure of 0.6MPa, the rotating speed of 1000rpm and the time of 5min) at 50 ℃ for solid-liquid separation to obtain a first separated liquid and a solid material, and then drying the solid material at 80 ℃ for 2min to obtain monosodium glutamate crystals S1.

Example 2

This example provides a method for preparing monosodium glutamate, comprising the steps of:

(1) adding 60g of seed crystal-2 and 1L of monosodium glutamate mother liquor-1 into a crystallizing tank (the vacuum degree is-0.09 MPa) at 65 ℃, continuously stirring at 20rpm, adding 0.1L of water into the monosodium glutamate mother liquor at intervals of 100min, adding the water for 5 times, and continuously crystallizing and concentrating for 2 hours to obtain a first solution with the saturation of 30 Baume;

(2) and (2) introducing the first solution into a centrifuge (with the pressure of 0.7MPa, the rotating speed of 1100rpm and the time of 3min) at 45 ℃ for solid-liquid separation to obtain a first separated liquid and a solid material, and then drying the solid material at 90 ℃ for 3min to obtain monosodium glutamate crystals S2.

Example 3

This example provides a method for preparing monosodium glutamate, comprising the steps of:

(1) adding 56g of seed crystal-3 and 1L of monosodium glutamate mother liquor-1 into a crystallizing tank (the vacuum degree is-0.08 MPa) at 72 ℃, continuously stirring at 45rpm, adding 0.15L of water into the monosodium glutamate mother liquor every 90min, adding the water for 5 times, and continuously crystallizing and concentrating for 2 hours to obtain a first solution with the saturation of 32 Baume;

(2) and (2) introducing the first solution into a centrifuge (with the pressure of 0.6MPa, the rotating speed of 900rpm and the time of 2min) at the temperature of 55 ℃ for solid-liquid separation to obtain a first separated liquid and a solid material, and then drying the solid material at the temperature of 70 ℃ for 5min to obtain monosodium glutamate crystals S3.

Example 4

This example was carried out in a similar manner to example 1, except that in step (1), the monosodium glutamate mother liquor-1 was replaced with an equal volume of monosodium glutamate mother liquor-2.

The remaining steps were the same as in example 1.

Monosodium glutamate crystals S4 were obtained.

Example 5

This example was carried out in a similar manner to example 1, except that in step (1), the monosodium glutamate mother liquor-1 was replaced with an equal volume of monosodium glutamate mother liquor-3.

The remaining steps were the same as in example 1.

Monosodium glutamate crystals S5 were obtained.

Example 6

This example was carried out in a similar manner to example 1, except that in step (1), 0.05L of water was added to the monosodium glutamate mother liquor at intervals of 80min during the crystallization treatment, and the number of times of water addition was 3.

The remaining steps were the same as in example 1.

Monosodium glutamate crystals S6 were obtained.

Example 7

This example was carried out in a similar manner to example 1, except that in step (1), 0.2L of water was added to the monosodium glutamate mother liquor every 80min during the crystallization treatment, and the number of times of water addition was 6.

The remaining steps were the same as in example 1.

Monosodium glutamate crystals S7 were obtained.

Comparative example 1

This comparative example was carried out in a similar manner to example 1, except that in step (1), 0.3L of water was added to the monosodium glutamate mother liquor every 80min during the crystallization treatment, and the number of times of water addition was 6.

The remaining steps were the same as in example 1.

The monosodium glutamate crystals DS1 were obtained.

Comparative example 2

This comparative example was carried out in a similar manner to example 1, except that in step (1), 0.03L of water was added to the monosodium glutamate mother liquor at intervals of 80min during the crystallization treatment, and the number of times of water addition was 6.

The remaining steps were the same as in example 1.

The monosodium glutamate crystals DS2 were obtained.

Comparative example 3

This comparative example was carried out in a similar manner to example 1, except that in step (1), 0.05L of water was added to the monosodium glutamate mother liquor every 80min during the crystallization treatment, the number of times of water addition was 2.

The remaining steps were the same as in example 1.

The monosodium glutamate crystals DS3 were obtained.

Comparative example 4

This comparative example was carried out in a similar manner to example 1, except that in step (1), 0.05L of water was added to the monosodium glutamate mother liquor at intervals of 80min during the crystallization treatment, and the number of times of water addition was 10.

The remaining steps were the same as in example 1.

The monosodium glutamate crystals DS4 were obtained.

Test example

The properties of the crystalline monosodium glutamate products prepared in the examples and the comparative examples, such as light transmittance, yield and the like, are detected, and specific detection results are shown in table 2.

Wherein, the calculation formula of the yield of the monosodium glutamate product is as follows: the weight of finished monosodium glutamate/(the dosage of glutamic acid is multiplied by the purity of glutamic acid is multiplied by 1.272) multiplied by 100 percent.

TABLE 2

As can be seen from Table 1, the monosodium glutamate mother liquor prepared by the method of the present invention not only has the characteristics of high light transmittance and high yield, but also has less impurities such as sulfate, iron ions, chloride ions, etc.

As can be seen from Table 2, the method of the present invention not only can prepare the monosodium glutamate crystal product with full particles and uniform crystal form, but also can effectively increase the yield of the monosodium glutamate crystal product, wherein the light transmittance of the monosodium glutamate crystal product reaches more than 98%.

The invention exemplarily provides a gourmet powder crystal real object diagram obtained in example 1 of the invention, a gourmet powder crystal real object diagram obtained in example 2, a gourmet powder crystal real object diagram obtained in example 7, and a gourmet powder crystal real object diagram obtained in comparative example 1, which are respectively shown in fig. 1-4.

Wherein, FIG. 1 is a diagram of a monosodium glutamate crystal prepared in example 1 of the present invention; FIG. 2 is a diagram of a monosodium glutamate crystal prepared in example 2 of the present invention; FIG. 3 is a diagram of a monosodium glutamate crystal prepared by example 7 of the present invention; FIG. 4 is a schematic diagram of monosodium glutamate crystals prepared in comparative example 1.

As can be seen from fig. 1 to 4, the monosodium glutamate crystals prepared by the method of the present invention have more excellent quality.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

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