Ether-insoluble impurities are one of the important parameters that determine the quality and quality of olive oil. During the production of olive oil, total impurities other than the volatile substances that are insoluble in petroleum ether and which are left into the oil as a result of incomplete processes or poor production are called insoluble substances or insoluble impurities. These materials are generally substances such as sand and soil, oxidized fatty acids, nitrogenous substances, mineral substances and carbohydrates. The oil may also contain resin or a portion of calcium or alkali soaps.

Turkish Food Codex Communiqué on Methods of Analysis of Olive Oil and Pirina Oil (Communiqué no: 2014 / 2014) was published by the Ministry of Food, Agriculture and Livestock in 53. This communiqué was issued to determine the analysis methods for official controls for olive oil and pomace oils. Many analysis methods are explained in the annexes of the Communiqué.

According to the aforementioned communiqué, the insoluble impurity ratio must be at most 0,1 percent in natural olive oils. If this ratio is exceeded in the analyzed oil, the oil is considered non-standard. According to the Communiqué, if the result is high, factors affecting the production or storage conditions of olive oil should be checked, then the production and storage conditions of the sampled oil should be checked and, if necessary, olive oil should be filtered.

In the authorized laboratories, insoluble impurities in animal and vegetable fats and oils are determined within the scope of chemical tests. The standard used in these studies is as follows:

• TS EN ISO 663 Animal and vegetable fats and oils - Determination of insoluble impurity content

This international standard describes the method for the determination of peroxide value in animal and vegetable fats and oils by iodometric method. The peroxide value is the measurement of the amount of oxygen chemically bound to animal or vegetable oils.