In general, the method for the determination of water-insoluble ash in foods is based on the principle of extracting the ash with hot water, then filtering and burning through the ashless filter paper and finally weighing the amount of water-insoluble ash.

In these analysis studies, 20 ml of boiling purified water is put into the container containing the ash and waited for half an hour. The solution in the vessel is then passed through the ashless filter paper. The flask and filter paper are washed five or six times with hot water. When the amount of filtrate to be obtained is 60 ml, washing is stopped. If alkalinity is to be determined in water-soluble ash after the test, this filtrate is stored.

The ash collected in the filter paper is placed in the same test vessel together with the filter paper and placed in the oven. The oven temperature is set to 500-550 again and waited until the filter paper is completely burned. The test vessel is then allowed to cool to room temperature and weighed again.

Within the scope of physical analysis, determination of the amount of ash insoluble in water is carried out in authorized laboratories. During these studies, the standards published by national and international organizations are followed. At the same time, globally accepted test methods are followed. When determining the amount of ash soluble in water, the following standards are observed:

• TS 1565 Tea - Determination of water-soluble ash and water-insoluble ash
• ISO 1576 Tea - Determination of water-soluble ash and water-soluble ash

The quality and taste of tea is determined by quality control studies. Water insoluble ash analysis carried out in laboratories is also important in this respect. In this sense, technological developments affect the food sector positively. On the other hand, the awareness of consumers and being more sensitive about health issues increases the importance of food quality control studies.