CN1129739A

CN1129739A - Method for producing citric acid from crop stalks

Info

Publication number: CN1129739A
Application number: CN 95103163
Authority: CN
Inventors: 张金生; 李忠兴; 焦旭东; 白汉云; 吴莺音
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-03-31
Filing date: 1995-03-31
Publication date: 1996-08-28

Abstract

The method for producing citric acid with stalk or stem f crops includes such technological steps as breaking to 60-80 meshes, pulping, degradation, press filtering to remove non-chlorine extractives, fermentation by inoculation of bacterial strain, extraction and purification by conventional "calcium salt method", and features full use of rich cellulose and protein the stalk or stem contains to make cellulose be degradated into glucose, releasing starch and protein from stalk or stem by destroying cell walls, and no need of bran in fermentation.

Description

With the straw is the method for raw material to produce citric acid

The present invention relates to a kind of is that raw material replaces the Starch Production methods of citric acid with the crop straw.

In existing technology, generally adopt and utilize the method for starch for raw material to produce citric acid, in addition, also must replenish a large amount of wheat brans in the process of production citric acid and make nitrogenous source.Cause citric acid industry cost height, a lot of medium and small citric acid enterprise is difficult to keep.The method of looking for alternative materials to reduce cost along with the flourishing figure of industry is also varied.For example: " utilizing wheat-flour production methods of citric acid " (CN1072456A) not only cost is low, also can make the byproduct gluten powder simultaneously.But this method also is to utilize grain to make raw material, and cost of material also is higher.Other as " utilize vinasse fermentation extract citric acid " (CN1036406) and " utilizing the acetylene waste residue to extract citric acid " to wait all are the methods of looking for approach solution citric acid raw material for other.But the raw material that need develop also that a kind of potentiality to be exploited is big, aboundresources, cost is low is as the novel method of producing the citric acid raw material.Produce 1000 hundred million tons all kinds of crop straws per year based on having in the world, the reproducible carbohydrate of this enormous amount contains abundant Mierocrystalline cellulose and protein, but only has 1/5 to utilize as feed at present, most of no utility value.

The objective of the invention is to develop a kind of crop straw-of utilizing as straw production methods of citric acid such as air-dry millet, buckwheat, broom corn millet, spring wheat, winter wheat, barley, rice.

Design of the present invention is as follows: pass through EMP Embden Meyerbof Parnas pathway, pyruvic acid carboxylation and tricarboxylic acid cycle formation because citric acid mainly is a glucose, and main composition is Mierocrystalline cellulose and protein and fat, pectin and other a small amount of carbohydrate in the straw.Straw cellulose such as wherein air-dry millet, buckwheat, broom corn millet, spring wheat, winter wheat, barley, rice are respectively 39.91%, 39.73%, 30.22%, 40.91%, 36.30%, 33.77%, 32.56%, contain protein and are respectively 2.75%, 4.30%, 5.21%, 2.83%, 2.46%, 1.6%, 3.24%.Contained Mierocrystalline cellulose adopts by degraded, and the high polymer that β-1.4 glucoside bond is formed is degraded to small molecules β-glucose.Contained protein and starch discharge other branch by destroying cell walls.Its protein can satisfy the needs of citric acid bacterial classification fermentation nitrogen source.

Therefore the method for the present invention's employing is: with straw powder particle diameter to 60-80 order; Sizing mixing then fully discharges its starch and protein, and adds cellulase 20 units/gram, adds hydrochloric acid and transfers pH value; Even the degraded slurries are warming up to 55 ± 2 ℃ of insulations 1 hour then, degradation rate reaches more than 90%, and glucose concn is 8-11%: carry out press filtration then, remove filter residue (nitrogen-free extract), the sugar of this moment is in filtrate, and contained sugar is the glucose polysaccharide; Then filtrate is delivered to fermentor tank, again by 8 ‰ amounts add α-amylase behind total amount 1 ‰ adding β-amylase by degraded back starch this moment, purpose is that the glucose polysaccharide is become monose, filtrate is heated to 115 ℃, be incubated 10 minutes, strain fermentation is inserted in the cooling back, and calcium salt method routinely carries out purifying and makes citric acid.

Concrete technical process is as follows:

Straw pulverizing (60-80 order) → size mixing (is adjusted water and material ratio in Different Crop, add cellulase 20 units/gram) → degraded (add HCL and transfer pH value) → press filtration (throwing away waste residue) → send into fermentor tank (press earlier starch total amount 1 ‰ and add β-glucolases, add α-glucoamylase 8 ‰ by total amount again) → sterilization (about 115) → cooling → fermentation (access bacterial classification) → conventional calcium salts method reparation technology together → citric acid.

In manufacturing processed because the different contained protein of crop straw and the content difference of β-1.4 glucoside bond polymkeric substance, so straw powder slurry concentration difference, generally between 18-40%.Owing to contain the needs that more competent protein is enough to satisfy required nitrogenous source when fermenting in the straw, need not add wheat bran more simultaneously.Contain nitrogen-free extract in the straw, be contained in the waste residue and can remove by press filtration.

The present invention utilizes the very cheap crop straw of aboundresources price to replace starch and other grain to make raw material to produce citric acid, and the cost of making citric acid is reduced greatly.Products obtained therefrom meets GB-88 standard, its fermentation index, transformation efficiency, extraction yield all reach or part to surpass starch be every index of raw material to produce citric acid, the cycle is at 52.3h, average acid production rate 10.73%, average conversion is 95.4%, average fermentation index 1.83kg/h.m ³, replenish nitrogenous source owing to when fermentation, need not add a large amount of wheat brans simultaneously, thereby greatly reduce cost.Remarkable economic efficiency is arranged, and for citric acid industry has brought vigor and vitality, is a quantum jump of fermentation industry raw materials for production, also is a leap that develops the straw resource in a large number.

Below in conjunction with embodiment the present invention is illustrated:

Embodiment 1 (air-dry Semen setariae straw pole):

With air-dry Semen setariae straw pole be crushed to 60-80 orders → concentration of sizing mixing reach about 30% → by straw total amount 20 units/gram add cellulase → add hydrochloric acid transfer pH value between 4.5-5.5 → 55 ± 2 ℃ of insulations that heat up made it degraded in 1 hour, degradation rate 90%, glucose concn 11%, protein content 0.6% → press filtration, elimination waste residue (nitrogen-free extract discards) → filtrate is sent into fermentor tank, add β-glucoamylase by degraded back starch total amount 1 ‰, add α-glucoamylase enzyme liquefaction by 8 ‰ of total amount then, about saccharification post-heating to 115 ℃, be incubated 10 minutes → cooling and feeding sterile air, inserting strain fermentation → inoculum size when temperature is controlled 37 ± 1 ℃ is every ml substratum 4 * 10 ⁶Individual spore, fermentation condition: air quantity is 1: 0.08,37 ± 1 ℃ of temperature, tank pressure 0.1MPa, fermentation → calcium salt method gets citric acid through the neutralization → affination → acidolysis → acid → purification of decolouring → wash → concentrated → Crystallization Separation routinely then stopping below 0.5% for 110 ± 5 rev/mins of fermentor tank rotating speeds, residual sugar.

Embodiment 2 (with buckwheat straw system citric acid):

Air-dry buckwheat straw is crushed to 60-80 orders → concentration of sizing mixing reaches about 18% → press 20 units/gram of straw total amount, add complex cellulase → add HCL transfer pH value between 4.5-5 → heat up 55 ± 2 ℃, be incubated 1 hour and make it degraded, degradation rate is more than 90%, glucose concn 8%, protein content 0.6% → press filtration, filter residue discards → and filtrate sends into fermentor tank, add starch, make starch concentration 5%, add β-amylase by 1 ‰ of starch total amount, 8 ‰ add α-amylase, liquefaction, be warming up to after the saccharification about 115 ℃, be incubated 10 minutes → cooling and feeding sterile air, 37 ± 1 ℃ of air themperature, insert strain fermentation, inoculum size, fermentation condition and purification condition are with embodiment 1.

The concentration of glucose and fermentation need suitable nitrogenous source after all should considering to degrade in the embodiment of other straws, controlled according to different crops straw powder slurry concentration, also according to the material ratios of the different decision of the content straw powder slurry of contained protein of different crops straw and β-1.4 glucoside bond polymkeric substance.

Claims

1, is the method for raw material to produce citric acid with the straw, it is characterized in that the used raw material of above-mentioned production citric acid is a crop straw, comprise the straw of air-dry millet, buckwheat, broom corn millet, spring wheat, winter wheat, barley, rice and other crop.

2, according to claim 1 is the method for raw material to produce citric acid with the straw, it is characterized in that the concrete steps that adopted are:

20 units/gram that crop straw is crushed to 60-80 orders → size mixing (adjusting water and material ratio in Different Crop) → press straw total amount add cellulase → addings HCL transfer PH between 4.5-5 → 55 ± 2 ℃ of intensifications, be incubated 1 hour and make it degraded, degradation rate more than 90% → carry out press filtration, remove the waste residue that contains nitrogen-free extract → sacchariferous filtrate is delivered in the fermentor tank, add behind β-amylase again by 8 ‰ amounts by 1 ‰ of starch total amount and add α-amylase → filtrate is heated to 115 ℃ of insulations 10 minutes → cooling feed the calcium salt method extraction citric acid of sterile air → access strain fermentation → routinely.