Reducing wine movements during production
Clarification is a major reason for moving juice and wine between tanks at wineries – either racking off lees after a period of static settling or passing juice/wine through a centrifuge or filter. Each movement requires a destination tank for the clarified product and uses labour, water and cleaning chemicals, as well as creating wastewater that needs to be managed. Furthermore, significant quantities of juice/wine can be ‘tied up’ in lees and are commonly subject to significant quality downgrades when processed by rotary drum vacuum filtration (RDVF).
This project is investigating the possibility of ‘reverse racking’ as a new way to achieve clarification with fewer tank transfers. In this process the small quantity of lees in tanks is removed from underneath the clear juice or wine so that the bulk of the liquid may remain in the same tank. In an idealised configuration, the lees would be clarified concurrently back into the top of the same tank using an RDVF alternative that does not result in any quality degradation.
Laboratory studies of lees removal
Following collection and analysis of a range of lees samples during vintage 2014, the principal task has been the construction of a laboratory apparatus to study tank configurations that might allow for the removal of lees without the clear juice or wine channelling through it. The apparatus that has been constructed allows for different tank bottom designs to be fitted (e.g. 5° back to front sloped wine tank, 55° sloped cone beer tank) and for lees to be pumped out at controlled speeds. The apparatus also has heating, cooling and inert gas services. Experiments using this apparatus to assess a range of wine process lees samples in conjunction with different tank fittings are ongoing.