When organic contents of a material are burnt down, the left behind is ash. It is the inorganic content present in any material. If any material is heated to its burning point in presence of oxidizing agents, only ash is left behind. To assess the quality of a material, it is very important to assess the presence of inorganic components. There are different processes defined to measure the ash content in the food products, and they are;
· Wet ashing
· Dry ashing
· Low-temperature ashing
The test method is selected based on the application of the material, requirements of the sample, specifications of the sample. These test processes also help in analysing the minerals present, as they can be easily differentiated.
In the food industry, to ascertain the quality of food, different tests are performed. Nowadays, ash testing is catching up the trend as it tells a lot about the quality. Minerals present in the material can also be assessed with this test. According to the regulatory authorities, the presence of ash up to 5% is acceptable, more than this helps in determining the age of the food.
How to Prepare Samples?
To perform the ash test, preparing the sample is a crucial part. The food sample has to be in powdered form. Any moisture content present is dried first and it would lead to sprinkling during heating. Fatty food samples leave moisture when dried which prevents spattering. Another major problem is contamination of sample due to surroundings or due to the container used for holding the sample. The weight of the sample has to be in-between 1 to 10 gms.
· Dry Ashing – In this process, a muffle furnace is used to burn down the sample. The temperature of the chamber is maintained to approx. 600°C. At this temperature, the water evaporates from the sample and rest of the contents burnt down. During this process, most of the minerals get changed into phosphates, sulphates and oxides. Due to the presence of some volatile materials in the sample, the test results might outcome inaccurate. This is why other testing methods are preferred when materials like lead mercury and iron are present in the sample.
By leveraging the advancement in the technology, smart analytical instruments are introduced in the market that does not require processing of sample before testing. They are equipped with decision-making circuits to dry out the moisture first and then change it into ash for analysis, using very high-temperature range.
· Wet Ashing – This technique of determining ash content in a food sample is comparatively faster than other techniques. The time period may range from 10 minutes to few hours. In this process, the temperature range is set at 350°C.
The difference in weight before and after the test is the percentage of ash content.
MASH = Mass of the ash sample,
MDRY = Refers to the mass of the dried sample.
MWET = Refers to the mass of the wet sample.
· Low-temperature plasma ashing – This process is quite complicated in comparison to other processes. The sample is placed inside the glass chamber. This chamber is turned on using a vacuum pump. To oxidise the organic component present in the sample, a small amount of oxygen is inserted into the chamber. Due to the high temperature, the moisture evaporates. The chamber then creates a low temperature to not affect the volatile materials present in the sample.
Presto is the leading manufacturer and supplier of the testing instruments in India and across borders. For performing ash test of different test materials, multiple models of Muffle furnace are offered. All these models work on different temperature ranges and thus can be chosen as per industrial requirements.