by Loftie Ellis, Hand Perabo & Brett Rightford
Decanter technology can have a huge impact on juice recovery in future, according to results of commercial-scale tests.
Standard practices for the processing of grapes to juice include destemming, crushing, draining, pressing and settling or flotation. The result is always two fractions of juice: higher-quality free-run juice and lesser-quality press juice. New developments in decanter technology allow separation of juice, either directly after removal of the stems, or after some contact time. The juice is recovered without draining and/or pressing and the processing is continuous.
Worldwide, decanters are commonly used on many different products to remove solids from liquids. When the use of the Hiller decanter was first considered for commercial-scale grape processing, the idea was met with great resistance (especially from Germany). Yield and the quality of the juice obtained were the main concerns. After trialling the Hiller decanter for the past five vintages in South Africa, it can be concluded that it has the possibility of making a significant contribution to process optimisation in wineries. This article reports on three of the trials conducted in the past five years.
Materials and methods
The Hiller decanter used in the trials was a small unit, capable of processing 10 tonnes of grapes per hour. The grapes entered the system either destemmed and crushed, or destemmed and uncrushed. Separation of juice and solids happened within minutes. The pomace, mainly grape skins and pips, contained less than 50 ℓ of juice per tonne of grapes.
Trials were performed with Sauvignon Blanc and Chardonnay at Groote Post; Sauvignon Blanc at Boschendal; and Chardonnay and Pinot Noir for the production of Méthode Cap Classique (MCC) sparkling wine at Graham Beck, Robertson.
Analyses performed on both decanter and control juice and the resulting wines included: juice yield, total phenols, pH, titratable acidity (TA), potassium concentration, as well as informal sensory evaluations of the final wines. The analyses were performed by Wine Quality Consultants and Vinlab.