Method for preparing seed medium for fermenting citric acid, medium for fermenting citric acid and citric acid from whole starch

A technology for fermenting citric acid and whole starch, which is applied in the field of fermenting citric acid and citric acid, and can solve the problems of unstable quality, high residual sugar and long fermentation time.

Active Publication Date: 2020-12-15
COFCO BIOTECHNOLOGY CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, the current method for producing citric acid by fermentation is long on the one hand, and the quality is unstable. On the other hand, the fermentation time is long. Time is also difficult to effectively reduce the residual sugar

Method used

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  • Method for preparing seed medium for fermenting citric acid, medium for fermenting citric acid and citric acid from whole starch

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preparation example Construction

[0033]The preparation method of the starch slurry can adopt various conventional methods known to those skilled in the art, for example, mixing starch with water to obtain a starch slurry, and prepare a starch slurry with a starch concentration of 15-35% by weight.

[0034]According to the present invention, in step (2), the addition amount of the added nitrogen source can be changed within a wide range, as long as it can meet the requirements of the fermentation strain for the nitrogen source. In general, the added amount of the nitrogen source can be 0.01-0.2% by weight, preferably 0.05-0.1% by weight, based on the nitrogen element. The types of the supplementary nitrogen source are well known to those skilled in the art. For example, the supplementary nitrogen source may be one or more of urea, ammonium sulfate, ammonium nitrate, and corn steep liquor.

[0035]More preferably, the nitrogen source is corn steep liquor. In this preferred case, the pH value of the starch liquefaction solu...

Embodiment 1

[0066]This example is used to illustrate the preparation method of citric acid provided by the present invention

[0067]1) Sizing: Sizing with water and whole corn starch to obtain a starch slurry, and the amount of water added is such that the slurry concentration of the starch slurry is 20% by weight.

[0068]2) Enzymatic hydrolysis: mix the starch slurry obtained in step (1) with amylase (Novozymes, α-amylase, this amylase in the embodiments of the present invention) at 50°C to obtain a mixture (relatively The amount of amylase is 15 enzyme activity units per gram of dry starch, and the mixture is sprayed with steam at 240°C in an ejector (the weight ratio of steam to the mixture is 0.04:1), and the contact time is For 3 seconds, the temperature of the mixture after contact with steam was 100°C, the pH value was adjusted to 5.3, and the temperature was maintained for 70 minutes.

[0069]3) Flash vaporization: flash vaporize the above-mentioned mixture after contact with steam (vacuum deg...

Embodiment 2

[0075]This example is used to illustrate the preparation method of citric acid provided by the present invention

[0076]1) Sizing: Sizing with water and corn starch to obtain a starch slurry, and the amount of water added is such that the slurry concentration of the starch slurry is 15% by weight.

[0077]2) Enzymatic hydrolysis: mix the starch slurry obtained in step (1) with amylase (Novozymes, α-amylase, this amylase in the embodiments of the present invention) at 50°C to obtain a mixture (relatively The amount of amylase is 10 enzyme activity units per gram of dry starch, and the mixture is sprayed with steam at 230°C in an ejector (the weight ratio of steam to the mixture is 0.04:1), and the contact time is For 3 seconds, the temperature of the mixture after contact with the steam was 91°C, the pH value was adjusted to 5.4, and the temperature was maintained for 60 minutes.

[0078]3) Flash vaporization: flash vaporize the above-mentioned mixture after contact with steam (vacuum degree...

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Abstract

The invention relates to the field of citric acid production, and discloses methods for preparing a seed medium for fermenting citric acid, a medium for fermenting citric acid and citric acid by wholestarch. Whole starch slurry and amylase are mixed and are in contact with steam at pH5.2-6, a temperature after the contact is 90-105 DEG C and is kept for 60-90 minutes; and then a nitrogen source is added, the pH is adjusted to 4.5-6.5, and the mixture is optionally saccharified to obtain the seed medium. The unsaccharified seed medium is mixed with a saccharifying enzyme, the pH is adjusted to3.8-4.5 and the unsaccharified seed medium is saccharified at 60-63 DEG C for 5-20 h; and the pH of the saccharified seed medium is adjusted to 3.8-4.5 to obtain the fermentation medium. A fermentation strain is cultured in the seed medium; and seed liquid is obtained and cultured in the fermentation medium for fermentation to obtain the citric acid. The methods improve nutrient composition of the seed medium. Seeds grow fast and is stable in quality. The fermentation cycle is shortened, the acidity of the end point and the citric acid conversion rate are increased, and the residual sugar rate of the end point is reduced.

Description

Technical field[0001]The present invention relates to the field of citric acid production by fermentation, in particular to a method for preparing seed culture medium for fermenting citric acid, culture medium for fermenting citric acid and citric acid from whole starch.Background technique[0002]At present, the citric acid industry mainly uses corn flour as a raw material to ferment to produce citric acid, or use corn flour to combine with starchy raw materials such as wheat and sweet potatoes to ferment to produce citric acid. The current technical solution is mainly the following operation steps. Firstly, the corn meal is liquefied to form a liquefied liquid, and 5-15% is selected for cultivating Aspergillus niger seeds; secondly, 70-90% of the corn liquefied liquid is selected for press filtration, and the press filter liquid is used as the citric acid fermentation Main carbon source; again choose 5-15% corn liquefied liquid as the fermentation substrate medium to supplement the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C12P7/48C12N1/14C12R1/685
Inventor 佟毅张德国李久仁周勇卢宗梅俞建良熊结青杨儒文朱继成郭世堂王强
Owner COFCO BIOTECHNOLOGY CO LTD
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