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