Dr. Carien Coetzee
30 May 2023
There is a growing interest in the wine industry in the production of partially or totally dealcoholized wine. The reasons for the trend include general health concerns, religious reasons, import excises, and stricter driving laws related to alcohol consumption. Dealcoholized wine can be produced using physical dealcoholization methods. The Spinning Cone Column vacuum distillation equipment and the Reverse Osmosis system (see blog post) are the most utilized systems in the industry. In this blog post, the principles of the Spinning Cone Column will be briefly explained.
Spinning Cone Column
The Spinning Cone Column (SCC) is a distillation device with established commercial applications for the separation of volatile components from liquids and slurries. Common industry applications include the alcohol adjustment of wines and recovery of volatile flavours from various food and beverage streams, including coffee, tea, citrus products and other fruits and vegetables.
The Spinning Cone Column is an efficient and versatile winemaking tool and specific applications have been developed, giving the winemaker control over both flavour and alcohol levels in the final product. In addition, the same technology can be used to recover flavour from grape juice, desulphite grape juice, remove unwanted flavours and recover useful flavours and alcohol from waste streams.
Wineries apply the Spinning Cone Column technique to reduce ethanol content by one or two alcoholic degrees in order to obtain more balanced wines. However, new consumption habits and alcohol safety laws have induced the wine industry to produce new products using non-alcoholic or low-alcohol wines.
Spinning Cone Column for the dealcoholization of wine
A Spinning Cone Column consists of a rotating vertical shaft and vertically packed cones. The cones alternate between rotating cones and stationary cones. The cones spin the wine into thin liquid films in a vacuum environment. The thin film of liquid flows down the stationary cone and drains into the base of the rotating cone where it moves upwards and outward on the surface of the rotating cone, again as a thin film, by the action of centrifugal force. A vapour rises off the thin film of wine, carrying the volatiles (which may include ethanol) up the column (counter-current to the flow of the liquid).
A graphical demonstration of the process can be viewed here:
The lowering of alcohol in finished wines using the Spinning Cone Column method involves a two-stage process1.
Stage 1: Remove aroma
The wine is passed through the Spinning Cone Column in the first stage at a low vacuum pressure (0.04 atm) and temperature (around 28°C) to recover the ultra-light vapour component consisting of the delicate volatile wine aromas. This component is condensed and saved for later to be recombined with the wine once the alcohol is removed. The wine is now dearomatized (but still contains alcohol).
Stage 2: Remove alcohol
In the second stage, the dearomatized wine is treated at a slightly higher vacuum pressure and temperature of around 38°C. This is done to remove the alcohol. The wine is now dearomatized (stage 1) and dealcoholized (stage 2).
Stage 3: Reconstitution
The recovered and saved wine aroma (captured and condensed during stage 1) can now be added back into the dearomatized and dealcoholized wine (obtained after stage 2) to obtain a dealcoholized wine which should, theoretically, resemble the original wine minus the ethanol. However, studies have shown that significant aromatic losses can take place (especially during stage 2)2 depending on the methodology used1. The optimum operating conditions will be defined by the raw wine flow rate and the aromatic extraction percentage that optimize the aromatic richness of the corresponding dealcoholized wine.
The low residence time and relatively low operating temperature of the Spinning Cone Column help to reduce the impact of heat on the wine aroma compounds3,4, however, studies5,6 have shown that heat treatment processes significantly affect the aroma, flavour, and taste of the nonalcoholic wines, even when operated at moderate temperatures or during the use of strip streams.
(1) Ma, T.-Z.; Eudes Sam, F.; Zhang, B. Low-Alcohol and Nonalcoholic Wines: Production Methods, Compositional Changes, and Aroma Improvement. In Recent Advances in Grapes and Wine Production – New Perspectives for Quality Improvement; IntechOpen, 2023. https://doi.org/10.5772/intechopen.105594.
(2) Börjesson, J.; Karlsson, H. O. E.; Trägårdh, G. Pervaporation of a Model Apple Juice Aroma Solution: Comparison of Membrane Performance. J Memb Sci 1996, 119 (2), 229–239. https://doi.org/10.1016/0376-7388(96)00123-8.
(3) SCHAFER, T.; HEINTZ, A.; CRESPO, J. Sorption of Aroma Compounds in Poly(Octylmethylsiloxane) (POMS). J Memb Sci 2005, 254 (1–2), 259–265. https://doi.org/10.1016/j.memsci.2004.12.047.
(4) Trifunovic, O. The Influence of Permeant Properties on the Sorption Step in Hydrophobic Pervaporation. J Memb Sci 2003, 216 (1–2), 207–216. https://doi.org/10.1016/S0376-7388(03)00072-3.
(5) Kujawski, W. Application of Pervaporation and Vapor Permeation in the Environmental Protection. Pol. J. Environ. Stud. 2000, 9 (1), 13–26.
(6) Montgomery. D.C. Design and Analysis of Experiments; John Wiley & Sons: New York, 1997; pp 200–201.
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