WINETECH Technical Yearbook 2021

the processed wine is the next stage of the process. A dual combination filter is used to ensure continuous filtration by cleaning one filter, while the other one is used for filtration. Up to 95% of the bitartrate crystals can be recovered. Before wine can be stabilised by K-Stop, it must be heat stable and filtered to NTU level of one to two. Padovan’s Ambra equipment is a new version of ion exchange, which is one of the present tartrate stabilisation methods. The potassium and calcium ions are removed from the wine and replaced by a hydrogen ion from the resin. As a result the precipitation of excess tartrate is prevented. The hydrogen ion, which is however released in the wine, causes an increase in the titratable acid concentration and subsequent decrease in the pH of the wine. Cellars therefore may opt to process some of the unstable wine and blend it with unprocessed wine to a level below the instability of the wine. The acid increase and pH decrease can also not be corrected by anion exchange, because that will also remove other acids from the wine. Ambra is

consequently rather recommended to lower the pH of juices originating from warmer regions to a more acceptable level in order to make more balanced wines. Oenodia’s STARS XF mobile equipment uses electrodialysis for the tartrate stabilisation of wines. Wine is passed through two types of membranes, which are arranged in pairs. An electric current flows over the membranes. This removes bitartrate anions, potassium and calcium cations from the wine, which prevents the precipitation of excess tartrates in the wine. The liquid waste, which contains the removed anions and cations, can be a problem. Oenodia has therefore created a reverse osmosis system in the latest equipment to solve the problem. Della Toffola initiated a project based on reverse osmosis membranes. Its greatest advantage is time and energy savings, as well as better water management. The flow rate of the process is 4 000 to 4 500 litres per hour for 22 hours daily. The system consists of two sets of reverse osmosis membranes, which function in series. The

unprocessed unstable wine is transferred to the first membrane set and its retentate is transferred to the second membrane set to obtain a more concentrated product, which is then transferred to a concentration tank. Tartrate crystallisation will take place as a result of the concentration. Filtration from the concentration tank recovers the crystals, and the mixing of different retentates and permeates will result in a stable wine. The equipment is self-maintaining and has a low water and energy use. The flow rate of the equipment is however decreased by sweetened wines and the process is thus not recommended for wines with a residual sugar concentration higher than 50 to 60 grams/litre. The method is however also suitable for red wines, since cooling is not applicable and colour losses are limited. Cleaning processes are simple seeing that a CIP (“Cleaning in place”) system is built in. A complete cleaning cycle lasts 3.5 hours. Della Toffola’s DTX equipment is an ion exchange system where potassium ions are selectively removed, which increases the titratable acid concentration and decreases the pH. Capacities of 2 000 to 10 000 litres

per hour are available and 600 to 2 800 litres water are required for regeneration. If it is used for juice, the sulphur dioxide addition is decreased as result of the pH decrease. Colour will also be stabilised and a smooth malolactic fermentation (MLF) is ensured. If it is used for wine, the wine need not to be filtered before the process and tartrate stability will be obtained. Wine with a higher titratable acid concentration and lower pH with all the resulting advantages will also be obtained (Carey, 2020). Although these three processes are inno - vative equipment, the principles that are applied have already been used in the past. Cellars must consequently think thorough- ly which process(es) and/or additives are used for tartrate stabilisation. The legality and cost thereof are determining factors, which need to be considered. REFERENCE Carey, R., 2020. New ways to stabilize tartrates in wine. Wine Business Monthly , August 2020: 34-39.

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