AOAC 925.41 Acids (Volatile) in Fats and Fats (Reichert-Meissl and Polenske Values) Titrimetric Method

The AOAC 925.41 standard, developed by the Official Society of Analytical Chemists (AOAC), describes the requirements for acids in oils and fats, and defines a titrimetric test method.

Some oils are extremely unstable during storage. It undergoes physical and chemical changes by accumulating on primary and secondary oxidation compounds. The generally used but highly empirical Reichert-Meissl and Polenske values, determined in advanced laboratories, are considered a measure of soluble and insoluble essential fatty acids, respectively, in vegetable oils.

Oil oxidation is a series of undesirable chemical reactions involving oxygen that degrade the quality of an oil. Oxidation produces oily rancidity that eventually accompanies tastes and odors. All oil is in a state of oxidation, it cannot be completely stopped, but there are ways to reduce it. Therefore, attempts should be made to reduce oxidation at every stage of oil production. Oxidation is not a single reaction, but a complex series of reactions. When oil is oxidized, it produces a cascade of degradation products, starting with primary oxidation products (peroxides, free fatty acids), then secondary products (carbonyls, aldehydes), and finally tertiary products.

The Reichert Meissl and Polenske values ​​are a measure of the shorter chain of fatty acids found in some oils, particularly milk fat, coconut and palm kernel oils. The Reichert Meissl and Polenske values ​​allow to distinguish between butter and butter substitutes made from vegetable oils.

The Reichert Meissl number is the number of milliliters of 5 N alkali (such as potassium hydroxide) required to neutralize the volatile water-soluble fatty acids in a 0.1 gram oil sample. The Reichert Meissl test determines the amount of butyric and caproic acids that are readily soluble in water and caprylic and capric acids that are sparingly soluble. The Polenske number is the number of milliliters of 5 N alkaline required to neutralize the volatile, water-insoluble fatty acids present in a 0,1 gram sample.

Within the scope of the AOAC 925.41 standard, with its trained and expert staff and advanced technological equipment, our organization has given numerous test, measurement, analysis and evaluation studies for businesses in various sectors. It also provides titrimetric testing services for acids (volatile) in oils and fats (Reichert-Meissl and Polenske values).