Refractometric analysis of fats and oils

The refractive index or butyro value of animal and vegetable fats and oils is a quickly measured, easily generated quality parameter value. Moreover, it helps to differentiate between different fats, such as butter and margarine.

Easily differentiate between fats and oils

Along with carbohydrates and proteins, fats and oils belong to the basic building blocks of human nutrition. There are two groups of oils and fats: vegetable oils extracted from plants or nuts, and animal oils which are found in milk products and meat. Oils which are solid at room temperature are referred to as fats.

The varying composition of different oils and fats allows for them to be characterized by refractive index measurement. These measurements can thus also provide insight as to their quality, as any change in their optimal composition will affect the refractive index and butyro value.

International regulations such as the official method 921.08 "Index of Refraction of Oils and Fats" from the AOAC, ISO 6320:200 "Animal and Vegetable Fats and Oils" demand the measurement of oils and fats either with an Abbe refractometer or with a butyro refractometer.

Abbemat refractometer family from Anton Paar

The determination of the refractive index or butyro reading is a simple, accurate and fast method. 

  • Predefined methods: The Abbemat series from Anton Paar has the predefined methods "butyro fat" (40 °C) and "butyro oils" (20 °C) which directly show the butyro readings and are in compliance with the AOAC.
  • Peltier thermostat: The refractive index is dependent on the temperature of the sample.To ensure precise results the temperature is controlled by the Abbemat's internal Peltier element with a tem-perature stability of 0.002 °C.
  • Measurement accuracy: Depending on the chosen Abbemat a measuring accuracy of 0.0001 nD to 0.00002 nD can be obtained.
  • Data security: Varying degrees of security can be set by the user, which include electronic signature and audit trail (not with Abbemat 200).

The refractometric analysis of fats, oils and essential oils is further specified in the corresponding Application Note.

Learn more about the Abbemat Series

Other relevant instruments

The Abbemat 550 refractometer is ideal for determining the oleic and linoleic acid content in peanut oils and peanut seeds.

Good to know

The refractive index or butyro reading of oils and fats can easily be measured with an Abbemat refractometer.