Fining
Fining is an oenological practice used to clarify and stabilise wine by removing suspended particles and undesirable compounds through the addition of specific substances known as fining agents. These agents bind with targeted components in the wine, forming aggregates that can be removed by settling, racking or filtration, thereby improving visual clarity and, in some cases, sensory balance.[1]
Purpose of fining
The primary objective of fining is to enhance wine clarity by removing colloids, proteins, phenolic compounds or other unstable constituents that may cause haze, sediment or flavour imbalance. In addition to visual improvement, fining may reduce bitterness, astringency or oxidative instability, depending on the agent used and the wine style.[2]
Fining is distinct from filtration, though the two processes are often used together as part of a broader clarification and stabilisation strategy.
Mechanism of action
Fining agents function through physicochemical interactions, typically involving electrostatic attraction between the agent and oppositely charged wine components. Once bound, the resulting complexes increase in size and mass, allowing them to precipitate out of solution under gravity or to be removed mechanically.[3]
Because these interactions are not entirely selective, fining inevitably removes some desirable compounds along with the intended targets.
Common fining agents
A wide range of fining agents is authorised for use in winemaking, each with specific affinities and applications:
- Protein-based agents such as egg white (albumin), gelatin and casein are commonly used to reduce excess phenolics and soften tannin structure, particularly in red wines.[4]
- Clay-based agents, most notably bentonite, are widely used to remove heat-unstable proteins in white and rosé wines, improving protein stability.[5]
- Synthetic or mineral agents such as PVPP and silica sol may be employed to target specific phenolic compounds or to assist settling.
- Plant-based and alternative agents have gained importance in response to allergen concerns and vegan certification requirements.
All authorised agents are regulated at international and national levels.[6]
Timing and application
Fining may be carried out at various stages of winemaking, including during fermentation, after fermentation or prior to bottling. Bench trials are considered essential to determine the appropriate agent, dosage and contact time for a given wine, as over-fining can strip aroma, flavour and texture.[7]
Once fining is complete, wines are typically racked or filtered to remove the precipitated material.
Sensory and qualitative considerations
While fining can improve balance and stability, it also carries the risk of diminishing varietal character and mouthfeel. Winemakers must therefore weigh technical necessity against stylistic intent, particularly for wines intended to express terroir or minimal intervention philosophies.[8]
As a result, some producers choose to minimise or avoid fining, accepting a degree of natural haze or sediment.
Regulatory and allergen aspects
Certain fining agents, especially those derived from animal products, are subject to allergen labelling requirements in many jurisdictions. This has contributed to increased use of alternative fining materials and to the rise of unfined wines in some markets.[9]
See also
References
- ↑ Jancis Robinson, Oxford Companion to Wine, Oxford University Press, 17 Sept. 2015. ISBN 9780198705383.
- ↑ PhD Jackson, Ronald S., Wine Science: Principles and Applications, Academic Press Inc, 14 April 2020. ISBN 9780128161180.
- ↑ Ribéreau-Gayon et al., Handbook of Enology, Vol. 2, Wiley, 2006, ISBN 978-0470010396.
- ↑ Roger B. Boulton, Vernon L. Singleton, Linda F. Bisson, Ralph E. Kunkee, & 1 more, Principles and Practices of Winemaking, Springer, 31 Oct. 1998. ISBN 9780834212701.
- ↑ Andrew L. Waterhouse, Understanding Wine Chemistry, Wiley, 19 Aug. 2016. ISBN 9781118627808.
- ↑ OIV, “Authorised fining agents”.
- ↑ AWRI, “Fining trials and impacts”.
- ↑ UC Davis, “Wine clarification and fining”.
- ↑ OIV, “Authorised fining agents”.