CN104450803A - A kind of method of producing gallic acid - Google Patents

Abstract

The invention discloses a method for producing gallic acid. In the method, the gallnut slag produced after preparing tannic acid or gallic acid is dried and pulverized to prepare an acid-producing medium, directly sterilized by high-pressure steam, and inoculated with Aspergillus niger for liquid fermentation to obtain gallic acid. By adopting the method of the invention, the residual tannic acid in gallnut slag can be fully utilized to realize waste utilization, and at the same time, the industrial added value of gallnut is improved.

Description

A kind of method of producing gallic acid

technical field

The invention belongs to the field of biotechnology, and in particular relates to a method for producing gallic acid by using the remaining Galla slag after preparing tannic acid.

Background technique

At present, the production process of gallic acid mainly uses gallnut as raw material, adopts chemical hydrolysis method, that is, gallnut is leached with hot water, and the residue is filtered out, and the gallic acid obtained is hydrolyzed with acid and alkali to obtain gallic acid. Gallic acid can also be prepared by directly carrying out alkaline hydrolysis of gallnuts, such as CN200810143946.8 "Gallic Acid Production Technology by Beihua One-step Method", the obtained gallate is then separated, decolorized, refined and dried to obtain finished gallic acid. The production method uses a large amount of acid and alkali, which is likely to cause large discharge of three wastes and pollute the environment. Another example is CN201010165152.9 "A Method for Preparing Gallic Acid", CN201310557351.8 "A Method for Preparing Gallic Acid Using Fermentation Separation Coupling Technology Using Gallic Tannin as a Raw Material" to prepare tannase and prepare gallic acid in two It is carried out in a container, and the pH of the fermentation broth is adjusted by NaOH solution. Although the disadvantages of strong ammonia flavor, easy volatilization, and easy pollution of the environment have been eliminated, there are disadvantages such as cumbersome preparation of medium and long fermentation time. Moreover, gallnuts were used as raw materials in the previous production methods. After gallic acid was prepared by acid-base hydrolysis or fermentation, the gallnut residue produced was often not effectively utilized, and was directly discarded as waste, causing great environmental pollution. .

The purpose of the present invention is to provide a kind of method that can make full use of gallnut processing by-product to produce gallic acid. The remaining Galla slag after extracting tannic acid or gallic acid is used as raw material, carbon source, nitrogen source and inorganic salt are added as acid-producing medium, after high-pressure steam sterilization, Aspergillus niger is inoculated for acid-producing fermentation, and the obtained fermentation liquid is filtered, Degumming, concentration, crystallization and other processes to obtain gallic acid. The purpose of this invention is to provide a kind of method that can make full use of Galla galla slag to produce gallic acid. The gallic acid remaining after the preparation of tannic acid or gallic acid is used as a reaction raw material to produce gallic acid through microbial fermentation, and the enzyme production and acid production are carried out in the same container. The method can not only effectively utilize gallnut slag, realize waste utilization, but also increase the industrial added value of gallnut.

Contents of the invention

The present invention aims to overcome the deficiencies of the prior art, uses Galla slag as a raw material, prepares gallic acid by whole-cell catalysis, and provides a method for producing gallic acid.

In order to achieve the above object, the technical solution provided by the present invention is: 

The described method for producing gallic acid comprises the steps:

(1) drying and pulverizing the galla slag produced after the preparation of tannic acid or gallic acid to obtain galla slag powder;

(2) Add galla slag powder to the acid-producing medium, adjust the initial pH value to 4-6, and obtain the gallic slag powder acid-producing medium, which is sterilized for use; each liter of the gallic slag powder acid-producing medium contains Components by weight as follows: 0.8-1.2g NH ₄ NO ₃ , 3-7g MgSO ₄ , 0.3-0.7g ZnSO ₄ , 45-55g gallnut slag powder, 8-12g glucose, and the balance is water;

(3) Inoculate Aspergillus niger into the gallic slag powder acid production medium, and ferment for 24-48 hours at 24-37°C, with a rotation speed of 140-160r/min, preferably 150r/min, and a pH of 3-5;

(4) centrifuging after fermentation to obtain a gallic acid fermentation supernatant, and adjusting the pH of the gallic acid fermentation supernatant to acidic;

(5) adding activated carbon to the gallic acid fermentation supernatant for degumming, and filtering after degumming to obtain the filtrate;

(6) Concentrating and crystallizing the filtrate to obtain gallic acid.

Step (6) adopts conventional methods in this field.

Preferably, the gallnut residue powder acid production medium contains the following components by weight per liter: 1g NH ₄ NO ₃ , 5g MgSO ₄ , 0.5g ZnSO ₄ , 50g gallnut residue powder, 10g glucose, and the balance is water.

Wherein, during step (3) fermentation, the pH is adjusted to be 3-5 by 1 mol/liter of NaOH. The degumming in step (5) is to add 5-8 g of activated carbon to each liter of gallic acid fermentation broth supernatant, degumming at 70°C-80°C for 30-60 minutes, and then filter to obtain a filtrate.

Since the tannic acid contained in the gallnut dregs produced after the extraction of tannic acid from the gallnuts has been greatly reduced, the gallnut residues can be directly used as raw materials for microbial fermentation. During the fermentation process, the residual tannic acid in galla slag can not only serve as an inducer for microbial synthesis of tannase, but also directly participate in the catalyzed reaction of tannase as a reaction substrate, converting tannic acid into gallic acid, thereby realizing the production of tannin. Enzymes and acid production go hand in hand. By adopting the method of the invention, the residual tannic acid in gallnut slag can be fully utilized to realize waste utilization, and at the same time, the industrial added value of gallnut is improved.

Detailed ways

Example 1

The described method for producing gallic acid comprises the steps:

(1) Galla slag pretreatment: dry the galla slag produced in the preparation of tannic acid and gallic acid in the sun, and after drying, crush it with a pulverizer, pass through a 40-mesh sieve after crushing, and obtain galla slag powder;

(2) Preparation of acid-producing medium: Add Galla slag powder to the acid-producing medium, adjust the initial pH value to 4-6, and obtain Gallic slag powder-acid producing medium, sterilize at 121°C for 20 min, and set aside; The gallnut residue powder acid production medium contains the following components by weight: 1g NH ₄ NO ₃ , 5g MgSO ₄ , 0.5g ZnSO ₄ , 50g gallnut residue powder, 10g glucose, and the balance is water;

(3) Fermentation acid production: Inoculate Aspergillus niger into the acid production medium of Galla slag powder, and ferment for 24-48 hours at 24-37°C, with a rotation speed of 140-160r/min, preferably 150r/min, and a pH of 3-5 ;

(4) Centrifuge at 5000 rpm for 10 minutes after the fermentation is completed to obtain the gallic acid fermentation supernatant, and adjust the pH of the gallic acid fermentation supernatant to 2-2.5;

(5) Degumming: Add 5-8g of activated carbon to the supernatant of gallic acid fermentation broth, degumming at 70°C-80°C for 30-60min, and then filter to obtain the filtrate;

(6) Ultrafiltration is performed on the filtrate, preferably an ultrafiltration membrane with a molecular weight cut-off of 5 KDa or less, and the working pressure is 100-300 psi. Ultrafiltration is performed on the supernatant until the volume of the permeate is equal to the total volume of the original supernatant. At 90%, stop the ultrafiltration and collect the permeate;

(7) Concentration:

Choose vacuum degree ≥ 0.03MPa; vapor pressure ≤ 0.3Mpa;

(8) Cooling crystallization:

First cool naturally for 2 hours, then cool to ≤25°C with tap water, the stirring speed is 60r/min, and the crystallization time is 18 hours.

(9) Melting crystal decolorization:

The amount of water for dissolving crystals is 5 times the wet weight of the crude crystals, and the amount of activated carbon is 10% of the wet weight of the crude crystals; decolorization temperature: 85°C-90°C; time: 20min-25min; the amount of washing water is 10 times the amount of activated carbon; The water temperature is greater than 90°C;

(10) Recrystallization:

Natural cooling is used for crystallization, and the crystallization time is greater than 24h.

By adopting this method, the conversion rate of tannic acid in gallnut slag is above 75%, and the purity of gallic acid in the prepared product is above 85%.

Claims (6)

1. produce a method for gallic acid, it is characterized in that, described method comprises the steps:

(1) the Turkey-galls slag preparing Weibull, gallic acid produces is dried, pulverizes, obtain Turkey-galls ground-slag;

(2) added to by Turkey-galls ground-slag in the sour substratum of product, adjustment initial pH value is 4-6, and obtain Turkey-galls ground-slag and produce sour substratum, sterilizing is for subsequent use; Often liter of described Turkey-galls ground-slag produces the component containing, for example lower weight in sour substratum: 0.8-1.2g NH ₄nO ₃, 3-7g MgSO ₄, 0.3-0.7g ZnSO ₄, 45-55g Turkey-galls ground-slag, 8-12g glucose, surplus is water;

(3) aspergillus niger being inoculated into Turkey-galls ground-slag produces in sour substratum, in 24-37 DEG C, rotating speed 140-160r/min, pH be 3-5 condition bottom fermentation 24-48 hours;

(4) centrifugal after fermentation, obtain gallic acid fermented supernatant fluid, gallic acid fermented supernatant fluid pH is adjusted to acidity;

(5) gac is joined in gallic acid fermented supernatant fluid come unstuck, filter after coming unstuck, obtain filtrate;

(6) filtrate is carried out condensing crystal, obtain gallic acid.

2. the method for claim 1, is characterized in that, often liter of described Turkey-galls ground-slag produces the component containing, for example lower weight in sour substratum: 1g NH ₄nO ₃, 5g MgSO ₄, 0.5g ZnSO ₄, 50g Turkey-galls ground-slag, 10g glucose.

3. the method for claim 1, is characterized in that, the NaOH by 1 mol/L during step (3) fermentation regulates pH to be 3-5.

4. the method for claim 1, is characterized in that, coming unstuck described in step (5) is add 5-8g gac often liter of gallic acid fermented liquid supernatant, and come unstuck 30-60min under 70 DEG C of-80 DEG C of conditions, then filters, obtain filtrate.

5. the Turkey-galls ground-slag producing gallic acid produces a sour substratum, it is characterized in that, often liter of described Turkey-galls ground-slag produces the component containing, for example lower weight in sour substratum: 0.8-1.2g NH ₄nO ₃, 3-7g MgSO ₄, 0.3-0.7g ZnSO ₄, 45-55g Turkey-galls ground-slag, 8-12g glucose, surplus is water; PH value is 4-6.

6. substratum as claimed in claim 5, is characterized in that, often liter of described Turkey-galls ground-slag produces the component containing, for example lower weight in sour substratum: 1g NH ₄nO ₃, 5g MgSO ₄, 0.5g ZnSO ₄, 50g Turkey-galls ground-slag, 10g glucose, surplus is water; PH value is 4-6.