Ash (gravimetric, calculated from minerals, alkalinity of ash)

Ash is sum of substances, which remain after ashing of evaporation residue, whereby main elements are alkaline metals and alkaline earth metals (e.g. potassium, calcium, magnesium, sodium) and non-metal phosphorus. Trace elements like manganese, zinc, copper and iron are represented too. Ash content of products can be determined gravimetric or can be calculated through the analysis of cations and anions. In addition to determining ash content, Alkalinity of ash can also be determined as parameter.

Ash content into wine lie normally between 1,3 and 3,5 mg/l and is strongly influenced by water balance of vine. All relevant substances are absorbed during grape ripeness through the soil, whereby minerals are the biggest part of ash. Because of the link between ash and content of minerals and trace elements, it is possible to assess quality of wine with this parameter.

The relation between ash and quality of product leads to legal regulations for minimum ash content for example for vinegar, therefor the analysis of ash is also important for assessment of product specifications.

Gravimetric

Gravimetric analysis of ash is based on incineration of wine extracts until complete combustion of carbon at 500 to 550 °C. Content of ash is expressed in g/l.

Calculated from minerals

The principle of the method is based on the calculation of ash content from the sum of different minerals and salts. For the calculation, we need: phosphate content of wine, expressed as K3PO4, rest content of potassium as well as content of sodium, magnesium and calcium were expressed as carbonate. The sum of these values describes the ash content.

Alkalinity of ash

The alkalinity of the ash is defined as the sum of cations, other than the ammonium ion, combined with the organic acids in the wine. The alkalinity of ash will be expressed in milliequivalents per litre or in grams per litre of potassium carbonate.