Question

A food engineer stated that the milk sample he analyzed in the laboratory was “FRESH MILK” in terms of acidity; reported that the concentration of non-sodium hydroxide base used in the experiment was 4 times higher than normal, and the sample analysis amount was used at the standard value.According to this information, how many microliters of base did most people use in the analysis?

Answer 1

The biological, biochemical and physical changes in the milk is usually dependent on the pH. The pH change might be due to the following reasons

• Ionization of components
• Binding of protons
• Dispersion of salts and proteins between the phases

The acid-base equilibrium of the milk, whey or curd is a main parameter for control of the processing of cheese.

Determination of milk acidity by titration

Titration is usually done with the base Sodium hydroxide, and hence the common name, “Soda Test”. Sodium hydroxide used for the titration is ninth molar (0.111 M), since the number of millilitres of 0.111 M NaOH solution used to titrate 10ml of the milk to the end-point of phenolphthalein (pink) can be used to express 'the equivalent percentage of lactic acid' in the milk

1.0 ml of 0.111 M NaOH = 0.1% lactic acid in the sample