Fining Wines
(book excerpts)In winemaking, fining is the process where a fining agent is added to the wine to remove proteins capable of haze formation; to soften or reduce its astringency and/ or bitterness; to remove oxidizable and non-oxidizable compounds which can affect color; and remove offflavors and aromas. Besides having a clarifying effect and a change in the polyphenolic structure of wines it improves the stability of coloring matter by eliminating particles likely to precipitate later in bottle. Fining also helps reduce the microbial load of the wine. The need for fining can vary based on grape composition related to the vineyard site, seasonal conditions, and management practices. Fining agents are usually classified as processing aids rather than additives since they are not expected to stay in the wine. The interaction between fining agents with wine compounds can be in the form of a chemical bond, absorption and adsorption, or electrostatic interaction. A chemical bond formation will bind to the compound in question and normally precipitate. Absorption and adsorption carry no electric charge and captures the compounds upon its structure. Electrostatic interactions involve the fining agent and the compound having opposite charges, attracting the larger molecules which combine with the fining agent and settle out. The aggregates are generally sufficiently large to precipitate quickly. If not, removal can be achieved by filtration or centrifugation. In some cases, two and even three fining agents are used simultaneously to remove or reduce the concentration of one or more undesirable constituents. In most, if not all cases of fining, the solute concentration is merely lowered to a point at which it remains below a solubility condition (in a stability test) or a taste threshold (in a sensory test), and at such a concentration it is acceptable. From an organoleptic standpoint, fining leads to either positive or negative changes. According to the type and quantity of fining agent used, it may make a wine softer and more elegant or, on the contrary, thinner and less attractive. To minimize the influence of complexing agents and colloidal substances on potassium bitartrate precipitation, the wine should be clarified by fining before undergoing tartrate stabilization. Organic compounds used as fining agents are generally animal based, a possible cause of concern to vegans. Although fining is a useful technique to master, it is an indicator that there may be a problem in your vineyard or winemaking.
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Topics Within This Chapter:
- Fining Wine for Clarification
- Protein Hazes
- Potassium Bitartrate
- Phenolic Polymers
- Polysaccharides
- Microbial Hazes
- Fining Agents
- Bentonite
- Silica Gel
- Protein Stability Tests
- Heat Tests
- Chemical Tests
- Fining Wine for Astringency and Bitterness
- Casein
- Preparation of Stock Solution
- Wine Treatment
- Egg Whites
- Preparation of Stock Solution
- Wine Treatment
- Gelatin
- Preparation of Stock Solution
- Wine Treatment
- Isinglass
- Preparation of Stock Solution
- Wine Treatment
- Polyvinylpolypyrrolidone
- Preparation of Stock Solution
- Wine Treatment
- Fining Wine for Color, Off-Flavors, and Off-Aromas
- Activated Carbon
- Casein
- Copper Sulfate
- Polyvinylpolypyrrolidone
- Wine Fining Practices
- Fining Trials
- Methods in Adding Fining Agents
- Order of Addition with Fining Agents
- Co-Fining
- Monitoring
- Fining Agents
