Determination of ash content
Principle
The ash content is a measure of the total amount of minerals present within a food, whereas
the mineral content is a measure of the amount of specific inorganic components present within a
food, such as Ca, Na, K and Cl. Thus, ash content refers to the total mineral residue left after
incineration of organic matter. It has no nutritional significance per se, but the value for ash is a
useful check in summing up the proximate composition of food and a measure of its mineral
content. It is expressed as g ash per 100 g sample. Determination of the ash and mineral content
of foods is important for a number of reasons:
Nutritional labeling. The concentration and type of minerals present must often be
stipulated on the label of a food.
Quality. The quality of many foods depends on the concentration and type of minerals
they contain, including their taste, appearance, texture and stability.
Microbiological stability. High mineral contents are sometimes used to retard the growth
of certain microorganisms.
Nutrition. Some minerals are essential to a healthy diet (e.g., calcium, phosphorous,
potassium and sodium) whereas others can be toxic (e.g., lead, mercury, cadmium and
aluminum).
Processing. It is often important to know the mineral content of foods during processing
because this affects the physicochemical properties of foods.