Separators and decanters can be used at several points in the production of grape juice:

Juicing the grape mash Clarifying the freshly extracted juice Polishing the stabilised juice treated with enzymes or clarified by means of fining agents Retentate clarification in conjunction with ultrafiltration Tartrate separation

The mash enzyme treatment before phase separation increases the yield and degree of clarification of the juice. The juice is then depectinised, dearomatised and preconcentrated, and the semi-concentrate is then polished by means of ultrafiltration. In the retentate cycle of the ultrafiltration section, a separator continuously removes coarse particles; this increases the flux rate and degree of clarification. In order to prevent the subsequent precipitation of tartrate, the contact method is used in conjunction with the Westfalia Separator separating method.

The process for making red grape juice is modified in order to extract the valuable phenolic substances, e.g. colour pigments, and tannin from the cells of the grape skin. For this purpose, the mash is normally heated; with types which are particularly rich in pectin, e.g. the Concord grape, enzymes are also added (hot Concord process).

Depending on the temperatures involved, the phases can be separated by means of a decanter either immediately or after a defined dwell time. If the product enters the decanter directly from the heating equipment, the grape juice can be made in a continuous process.

In comparison with the conventional process, decanters provide considerable advantages in terms of quality and economy in the process of making juice from the Concord grape:

Much higher colour quality Better sensory quality Savings in terms of filter aids

Decanters are also an alternative to conventional pressing technology for processing grapes. Grapes are still more significant in terms of wine production than for juice production (in volume terms). The comparison system is the tank press. In terms of yield and sensory quality, the decanter is fully comparable with this system. Only minor increases in phenolic compounds during the separating process indicate that the decanter is a gentle technology. Pips are not damaged. This can be demonstrated analytically by means of HPLC technology. The most important phenolic compounds, such as epicatechin-3-O gallate, gallic acid, catechin or epicatechin are extracted from the grapes by the decanter to a lesser extent than the tank press. All other press technologies feature much higher values as a result of intensive mash processing.