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Transcript of CITRIC ACID
How to synthesis citric acid??
It can be synthesized by using Aspergillus niger strain.
What you need??
A culture of Aspergillus niger
METABOLIC PATHWAYS OF SYNTHESIS OF CITRIC ACID
Citric acid is a weak organic acid that is an important intermediate in the Krebs cycle.
It breaks down glucose to citric acid and carbon dioxide with the presence of oxygen.
Due to its branching structure of white septate hypha
It the capabilities to utilize varieties of substrates
Why Aspergillus Niger?
The process starts with the glycolysis of glucose. In this stage, glucose is splitted into two 3-carbon molecule known as pyruvate @pyruvic acid. As pyruvic acid enter the mitochondrion, carbon is removed, forming carbon dioxide,CO2, and electrons are removed, changing the NAD+ to NADH. Co-enzyme A joins the 2-carbon molecule, forming Acetyl-CoA. Acetyl-CoA then adds the 2 carbon acetyl group to a 4-carbon compound, forming the citric acid.
However, the citric acids need to be extracted. Below are few stages where the extraction process took place.
A. Cell growth in each phases
Log of growth with time
lnxt = lnxo +μt
Cube root of growth linear with time
〖xt^(1/3) =〖xo^(1/3)+kc t
Linear with time
Where xt=biomass concentration of time, t
μ=specific growth rate
B. Product formation
It is related to the growth rate
rp = (a.rx )+(b.x)
Where x=biomass concentration
rx=rate of biomass accumulation
Rate of product formation is proportional to the rate at which the cells entered the maturation state,
Where (t-t_m )=rate of biomass growth at time,t
Primarily, the production of citric acid starts with the reaction of sugar and Aspergillus niger as shown below
Addition of sulphuric acid
(C6H507)2.Ca3.4H2O + 3H2SO4
Calcium nitrate sulphuric acid citric acid
calcium sulphate water
Sugar citric acid carbon dioxide
Addition of calcium hydroxide
2C6H807 + 3Ca(OH)2 (C6H507)2.〖Ca3.4H2O+2H2O
The solution is then centrifuged at 3000rev/min for 10minutes then dried overnight at room temperature to get a crystallized product of citric acid.
However, there is a problem in this equation as the k is not constant. It kept increasing. So we resolve the problem by assuming that there were at least two different types of cells within the mycelium and both have different productivity. This equation is modified and become
rpt=k1 rx (t-tm )+k2 x(t-tm)
K1=growth associated constant
K2= non growth associated constant
a weak organic acid
important intermediate in Krebs Cycle
Breaks down glucose
With the presence of Oxygen
Citric Acid + CO2
All living things
For chemical-processed food
METHOD OF PRODUCTION
Mostly by using Aspergillus niger
by utilizing starchy and sugar substrate
It can be found in citrus fruits such as grapefruits, orange, lemon and etc as well as in all living things.
Citric acid has been widely used as an antioxidant and as an artificial flavouring in chemical-processed food. It is usually produced by Aspergillus niger by utilizing starchy and sugar substrate.
Add sugar into Aspergillus niger
Fungus will recycle sugar into citric acid and carbon dioxide
Filter and extract the citric acid by adding calcium hydroxide
Calcium hydroxide react with acid to form salt that is calcium nitrate that will precipitate.
Scoop the salt and add sulphuric acid into it
Crystallized precipitate will form but you do not need it.. you will only require the liquid solution which is the pure citric acid.
Citric acid calcium hydroxide calcium nitrate water
The reactor selected in the production of citric acid is batch reactor as shown in the schematic diagram below
A bioreactor is a vessel in which an organism is cultivated and grown in
control manner to form byproduct.
consist of ;
• agitation system which will mix the organism completely
• control panel which regulates pumps cooling water , pump air supply and acid/base supply
• sensors-check medium temperature, medium aeration and medium pH value
• There is steam supply to the system
• Thermal jacket
• Tedium air supply and cooling water
supply to control the temperature in the reactor
selection of reactor
It is a strirred fermenter
Size of bioreactor
For laboratories scale 2-100litre
Sources of sugar &pH plays a major role in Citric Acid production
It used strain Aspergillus niger
For industrial scale up to 100m3