Potentiometric Determination of the Acid Number of Oils and Fats

In the context of process and quality control, the demand for pH measurements and titrations in non-aqueous media is increasing – primarily in the foodstuff and pharmaceutical sector. In accordance with DIN 19260 the pH value can be defined in aqueous media only, a pH measurement is not possible in non-aqueous solutions from the outset or can only be conducted at substantial equipment and scientific cost. Instead, the acid number can be used for the characterisation of free, organic acids in fats, fatty oils, solvents and tensides [2]. The acid number is one of the lipid values and includes all acidic functions that can be neutralised by potassium hydroxide solution. It specifies the KOH mass in mg that is required for the neutralisation of the acids contained in 1g of the sample to be examined (DIN EN ISO 2114) and can be determined by titration.