As mentioned above, ash is the inorganic residue remaining after the water and organic
matter have been removed by heating in the presence of oxidizing agents, which provides a
measure of the total amount of minerals within a food. Analytical techniques for providing
information about the total mineral content are based on the fact that the minerals (the analyte)
can be distinguished from all the other components (the matrix) within a food in some
measurable way. The most widely used methods are based on the fact that minerals are not
destroyed by heating, and that they have a low volatility compared to other food
components. The three main types of analytical procedure used to determine the ash content of
foods are based on this principle: dry ashing, wet ashing and low temperature plasma dry ashing.
The method chosen for a particular analysis depends on the reason for carrying out the analysis,
the type of food analyzed and the equipment available. Ashing may also be used as the first step
in preparing samples for analysis of specific minerals, by atomic spectroscopy or the various
traditional methods described below. Ash contents of fresh foods rarely exceed 5%, although
some processed foods can have ash contents as high as 12%, e.g., dried beef.
As mentioned above, ash is the inorganic residue remaining after the water and organicmatter have been removed by heating in the presence of oxidizing agents, which provides ameasure of the total amount of minerals within a food. Analytical techniques for providinginformation about the total mineral content are based on the fact that the minerals (the analyte)can be distinguished from all the other components (the matrix) within a food in somemeasurable way. The most widely used methods are based on the fact that minerals are notdestroyed by heating, and that they have a low volatility compared to other foodcomponents. The three main types of analytical procedure used to determine the ash content offoods are based on this principle: dry ashing, wet ashing and low temperature plasma dry ashing.The method chosen for a particular analysis depends on the reason for carrying out the analysis,the type of food analyzed and the equipment available. Ashing may also be used as the first stepin preparing samples for analysis of specific minerals, by atomic spectroscopy or the varioustraditional methods described below. Ash contents of fresh foods rarely exceed 5%, althoughsome processed foods can have ash contents as high as 12%, e.g., dried beef.
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