Adjusting pH with Lactic Acid: Calculation vs. Measurement

Calculating the exact percentage of Lactic Acid needed to adjust pH from 5 to 3.5-4 is complex and generally not recommended for practical formulation. This is because the amount required depends heavily on several factors specific to your solution, including:

• The buffering capacity of the initial solution (how well it resists pH change).
• The concentration and type of other ingredients present.
• The initial concentration of the lactic acid solution you are using.
• Temperature.

Therefore, the standard and most reliable method used in practice is to adjust the pH incrementally. You would add a small amount of lactic acid solution to your batch, mix thoroughly, and then measure the pH using a calibrated pH meter. Repeat this process, adding small amounts and measuring, until the desired pH range of 3.5-4 is reached. This method accounts for all the variables in your specific formulation and ensures accurate pH adjustment.