Nature is a lead player in the production of quality wine, yet nature is not always as cooperative as she might be when harvest time comes around. Preservation of quality, in fruit and throughout the winemaking process, can be a major challenge for vignerons in both good vintages and those with less ideal conditions. Fortunately, nowadays there are a host of techniques and technologies available to aid wine producers in meeting the challenges of preserving and enhancing quality.
In seasons when fruit ripeness is compromised or fruit colour is sub-optimal, Flash Détente extraction enhances wine colour, removes green, unripe flavour characters, improves wine structure and texture and accelerates production time. An evolution of thermovinification for red wines, in flash détente, de-stemmed grapes are heated to 80-85 ᵒC then immediately pumped into a vacuum chamber where flash vaporisation of water inside the vacuoles of the grapes skins, causes them to explode, releasing all the pigments contained within, while avoiding the jammy characteristics of thermovinified wines.
The complete release of colour precursors replaces traditional maceration. Flashed wines have on average, 30% more colour and improved structure. Further, the flash vapor carries away undesirable grape volatiles, including vegetal methoxy-pyrazine. The minimised skin contact resulting from Flash Détente helps to eliminate laccase from botrytis and other unwanted characteristics. And more, experience shows a lift of around two Brix after flash-détente.
In white wine production, speedy clarification of juice helps to preserve pristine fruit flavours and to eliminate unwanted characters. With Juice Flotation, suspended solids adhere to micro-bubbles of food grade nitrogen, creating a flocculate. The clarified juice is then simply pumped out from underneath the flocculate and the remaining solids can be further filtered for additional juice recovery.
Similarly, juice can be clarified by Centrifuge, where solids are spun-out, often with the efficiency to process entire tanks of juice or wine, including the lees, ejecting solids at such a concentration (~ 95% v/v) that no further product recovery is necessary by lees filter or RDV.
With Rotary Drum Vacuum (RDV) filtration, juice and wine can be recovered from lees that would otherwise be discarded. As much as 80 percent of juice from lees that was once dumped down the drain can now be kept – all adding to yield per tonne of grapes harvested.
Modern membrane technologies, such as Reverse Osmosis and Ultrafiltration can be utilised to selectively remove undesired compounds based on molecular weight, while desirable compounds are retained in the wine.
Reverse Osmosis is used to ‘surgically’ remove a low-molecular-weight constituent of the wine with minimal changes in the rest of the wine’s composition. For example, RO can be employed to reduce excess alcohol, remove volatile acidity, remove Brettanomyces taint, remove water from must or to increase wine concentration.
Ultrafiltration is superior to other techniques used to address browning, tannin removal or minimizing botrytis character. Fining agents indiscriminately remove valuable phenolics, resulting in loss of aroma, mouth-feel and varietal character. Use of these agents also results in higher volume losses due to the lees they create. In contrast, ultrafiltration minimizes losses while producing valuable by-products for use in other wines.
The results of both reverse osmosis and ultrafiltration can be effectively demonstrated using a small, five litre sample of the wine or juice to be treated and a suitcase sized, benchtop micro-laboratory.
Vintech Pacific, New Zealand’s leading provider of technology to the wine industry, rigorously research, test and invest in specialised new technology and equipment, to provide a range of the latest process innovations as mobile services, to the winery door, across New Zealand’s wine regions. Equipment is delivered, set-up on-site, operated then cleaned-down and removed by a skilled and experienced Wine Technician.
Contact Vintech Pacific
Phone: 06 863 0028
Mobile: 021 783 236