Quality
Titratable Acidity Calculator — Lactic Acid % in Milk
Free online titratable acidity calculator for milk using 0.1N NaOH titration method. Calculate lactic acid percentage per IS 1479 standard.
Formula
(naohVolume * 0.009) / sampleVolume * 100
naohVolume
NaOH Volume Used (mL)
sampleVolume
Milk Sample Volume (mL)
Worked Example
1
Given:
naohVolume = 1.6
sampleVolume = 10
2
Apply the formula:
(naohVolume * 0.009) / sampleVolume * 100
3
Result:0.144 % lactic acid
What is Titratable Acidity?
Titratable acidity (TA) measures the total acid content of milk, expressed as % lactic acid. It reflects both the original acidity (due to phosphates, citrates, and CO₂ in fresh milk) and the developed acidity (lactic acid produced by bacterial fermentation).
This test is one of the most important routine quality tests at dairy receiving docks.
Formula
Titratable Acidity (%) = (Volume of NaOH × 0.009 × 100) / Volume of Milk Sample
Where:
- Volume of NaOH = mL of 0.1N NaOH used to reach endpoint
- 0.009 = equivalent weight of lactic acid per mL of 0.1N NaOH
- Volume of sample = typically 10 mL
Test Procedure (IS 1479)
- Pipette 10 mL of well-mixed milk into a white porcelain tile or beaker
- Add 2–3 drops of 1% phenolphthalein indicator
- Titrate with 0.1N NaOH from a burette
- Stop when a permanent faint pink color persists for 30 seconds
- Record volume of NaOH used
- Calculate % lactic acid using the formula above
Acidity Standards for Milk
| Milk Type | Maximum Acidity | Decision |
|---|---|---|
| Fresh Milk | ≤ 0.14% | Accept |
| Borderline | 0.14 – 0.16% | Test further |
| Sour Milk | > 0.16% | Reject |
Standards per IS 1479 and FSSAI guidelines
Typical Values
- Fresh cow milk: 0.13–0.14% lactic acid
- Buffalo milk: 0.13–0.15% lactic acid
- Milk at 37°C (soured): Can exceed 0.20% within 8 hours