https://doi.org/10.1080/21553769.2015.1033653

You may check this article describing citric acid production by A. niger.

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Article Determination of yield and maintenance coefficients in citri...

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To calculate the yield of citric acid produced in a solid-state fermentation (SSF) experiment, follow these steps:

1. Preparation

1.1 Sample Collection: Collect samples from your SSF experiment at appropriate intervals to measure citric acid concentration.

1.2 Sample Processing: If necessary, process your samples to extract citric acid. This might involve blending, filtering, or other methods depending on the nature of the solid matrix.

2. Measurement of Citric Acid

2.1 Analytical Method: Use an analytical method such as High-Performance Liquid Chromatography (HPLC), spectrophotometry, or titration to measure the concentration of citric acid in your samples.

3. Calculation of Yield

3.1 Determine Citric Acid Concentration: From your analytical measurements, determine the concentration of citric acid in your sample.

3.2 Convert to Total Citric Acid: Calculate the total amount of citric acid produced based on the concentration and volume of the extract. If you measured the concentration in mg/mL and used a specific volume, the total amount is:

Total Citric Acid (mg)=Citric Acid Concentration (mg/mL)×Volume of Extract (mL)

Total Citric Acid (mg)=Citric Acid Concentration (mg/mL)×Volume of Extract (mL)

4. Calculate Yield

4.1 Dry Weight Measurement: Measure the dry weight of the solid substrate used in the fermentation. This is the weight of the substrate after it has been dried to remove moisture.

4.2 Calculate Yield:

Citric Acid Yield: To calculate the yield of citric acid, use the formula:

Yield (g/kg)=Total Citric Acid (g)Dry Weight of Substrate (kg)

Yield (g/kg)= Dry Weight of Substrate (kg)Total Citric Acid (g)

​

Yield as a Percentage: To express the yield as a percentage, use:

Yield (%)=Total Citric Acid (g)Dry Weight of Substrate (g)×100

Yield (%)= Dry Weight of Substrate (g)Total Citric Acid (g)×100

4.3 Example Calculation:

If you measured 0.5 g of citric acid in 100 mL of extract and used 1 kg of dry substrate, then:

Total Citric Acid: 0.5 g

Dry Weight of Substrate: 1 kg

Yield (g/kg)=0.5g

1 kg

=

0.5

 g/kg

Yield (g/kg)=

1 kg

0.5 g

​

=0.5 g/kg

To express as a percentage (assuming you had 500 g of substrate):

Yield (%)

=

0.5

 g

500

 g

×

100

=

0.1

%

Yield (%)=

500 g

0.5 g

​

×100=0.1%

5. Verify and Validate

Reproducibility: Check your results by performing replicate measurements and ensure they are consistent.

Comparison: Compare your yield with literature values or theoretical yields to assess the efficiency of your fermentation process.

By following these steps, you can accurately calculate the yield of citric acid produced in your solid-state fermentation experiment.

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