Figure 1. Conceptual relationship between Acidity, TA, and pH

1. Why Acidity and TA Are Always Read Together

When evaluating the quality of food and beverage products, Bx, pH, acidity, and TA are the most fundamental and interconnected parameters. Among these, pH reflects the current acid intensity of the solution, TA represents the volume of standard alkali consumed to neutralize the sample, and acidity is the result of converting that titration value into a weight-based percentage using a reference acid such as citric acid.

A practical way to keep these straight: pH is ‘intensity,’ TA is ‘titrant consumed,’ and acidity is ‘the converted compositional value.’ Reading all three together is the most useful approach when assessing flavor balance, changes during storage, raw material variation, and formulation consistency.

Parameter	What It Measures	Practical Significance	Typical Unit
pH	Acid intensity of the current solution	Stability, microbiological and thermal process decisions	pH value
TA	Volume of 0.1N NaOH needed to neutralize 100 mL of sample	Magnitude of acidity and formulation comparison	mL / 100 mL
Acidity (%)	Weight-based acid content converted from titration using a reference acid	Specification management, formulation control, raw material comparison	% as citric acid

Table 1. Comparative roles of pH, TA, and Acidity

2. Definition and Calculation of Acidity (%)

Acidity (%) is derived by using the volume of 0.1N NaOH consumed during neutralization and converting it into a weight-based percentage referenced to citric acid. It is not simply an expression of ‘perceived sourness’ — rather, it is a quantitative measure of the amount of acid components that can be neutralized by alkali.

The most important practical point is that the raw titration volume is not used directly. A factor (F) and a citric acid conversion coefficient are applied to convert the result into a final percentage based on sample weight.

Acidity (%) = [ 0.1N NaOH Volume (mL) × F × 0.0064 / Sample Weight (g) ] × 100 0.0064 represents the fact that 1 mL of 0.1N NaOH is equivalent to 0.0064 g of citric acid.

Figure 2. Acidity (%) calculation flow

3. Definition and Significance of TA

TA (Titratable Acidity) is defined as the volume of 0.1N NaOH (in mL) required to neutralize 100 mL of sample. As a volume-based titration value, TA is a relatively intuitive and easy-to-manage parameter in beverage quality control.

For products such as carbonated beverages — where acidity is low and volume variation is significant — TA-based management can be more practical than weight-based acidity. This makes TA particularly advantageous for low-acidity beverage control.

Basic Definition of TA TA = Volume of 0.1N NaOH (mL) required to neutralize 100 mL of sample Example: A TA of 19.5 means that 19.5 mL of 0.1N NaOH was required to fully neutralize 100 mL of the sample.

Figure 3. Conversion flow from TA to Acidity (%)

4. Measurement Principles and Standard Workflow

The measurement principle involves neutralizing the acidic components in the sample with a standard alkali solution and recording the volume consumed up to the endpoint. When using an indicator, the color change point of phenolphthalein is used as the endpoint. When using a pH meter, the endpoint is typically defined as pH 8.2.

In practice, NaOH standardization, sample homogenization, degassing of carbonated samples, pH meter calibration, and titration rate control all have a significant impact on the reproducibility of results.

Common Sources of Measurement Error Unchecked NaOH factor, insufficient sample degassing or homogenization, inadequate pH meter calibration, over-titration past the endpoint, or delayed endpoint determination.

Figure 4. Schematic of the Acidity · TA measurement setup

Step	Action	Key Points
1	Sample preparation	Homogenize the sample; degas or filter as needed.
2	Instrument setup	Prepare 0.1N NaOH, burette, pH meter or indicator.
3	Standardization check	Confirm NaOH factor and apply it to all calculations.
4	Titration	Add NaOH slowly to the endpoint; record volume consumed.
5	Calculation	Apply the Acidity (%) or TA formula to compute the result.

Table 2. Standard workflow for Acidity · TA measurement

5. Practical Interpretation Points

Even at the same pH, a difference in TA can change the length and structural backbone of the perceived acidity. Conversely, two samples with the same TA can yield different pH values if their buffering capacity or organic acid composition differs. For this reason, reading pH, TA, and acidity together provides the most complete picture of both flavor and shelf stability.

In product development, the balance between Bx and TA has a major influence on overall flavor quality. Raising Bx alone can make sweetness feel heavy; raising TA alone can make acidity feel harsh. The most practical approach is to track all three parameters together as an integrated set.

Figure 5. Interpretation framework for Bx · TA · pH in beverage development

Key Takeaways •  pH = current acid intensity;  TA = titrant consumed;  Acidity (%) = converted compositional value. •  TA is volume-based; Acidity (%) is weight-based. The two can be interconverted by applying specific gravity. •  NaOH factor management and consistent sample condition are the primary determinants of analytical accuracy. •  The most accurate interpretation of flavor and stability always involves reading Bx, pH, and TA together.