White wine agents

Fining is a winemaking technique used to enhance sensory or clarity properties of the wines. Common fining agents used with North Coast white wines are bentonite (a clay), casein (milk protein), gelatin (animal protein),... 

Comparison of Wheat Gluten and Other Fining Agents for White Wine... 

Marchal, R., Marchal-Delahaut, L., Michels, R, Parmentier, M., Lallement, A., Jeandet, P. (2002c). Wheat gluten used as clarifying agent of musts and white wines. Am. J. Fnol. Vitic., 53, 308-314. 

The hydroferrocyanic derivatives prodnced are in colloidal form. Their floccnlation in wine is accelerated by adding a protein fining agent. Fnr-thermore, precipitation of ferric ferrocyanide at least partially eliminates proteins (Vogt, 1931). This may be advantageous in white wines susceptible to protein turbidity. The precipitation of proteins is not due to the ferrocyanide itself, but rather to an insoluble ferric complex. Indeed, when potassium ferrocyanide is added to a wine containing no iron, no protein turbidity is observed. 

As bentonite flocculates in wine, with a behavior analogous to that of protein fining agents, experiments have been made in using it to clarify wine. In fact, its effectiveness in clarification depends on the type of bentonite and the composition of the wine. The only wines that may be properly clarified are reds or whites with low concentrations of polysaccharides and other protective colloids (Section 9.4.1), as these inhibit the flocculation and settling of the bentonite particles. In some winegrowing areas, bentonite is well suited to clarifying dry white wines, but elsewhere white wines may be more turbid after bentonite treatment than before. 

The presence of indole or an indole derivative in a food is not always desirable. Some white wines develop an off-flavor described as ...floor polish like... within a few months of storage [33]. The chemical responsible for this unpleasant flavor was identified as 2-aminoacetophenone 16 in 1993 [34]. Reported in a series of papers over the next 10 years, researchers traced the ultimate source of this agent to indole-3-acetic acid 15 that was present in the grapes before harvesting Indole-3-acetic acid itself is derived from another indole L-tryptophan. The proposed mechanism for this transformation is shown in Scheme 14 [35]. 

Four of the 12 flavouring agents in this current group (Nos 1771,1772,1774 and 1777) have been reported to occur naturally in foods. They have been detected in white wine, spinach, potatoes, sweet potatoes, yams, kale, brown rice, brown rice germ, brown rice sprouts, barley, barley sprouts, beans, bean sprouts, corn, oatmeal, squash, carrot, onion, chestnut, apple, shiitake mushrooms, green laver, lactobacilli and broccoli (Cutillo et al., 2003 Oh et al., 2003 Anon., 2004). No quantitative data on the natural levels in food were available, and therefore consumption ratios (the ratios of their consumption from natural food sources to their use as flavouring agents) were not calculated. 

Clarification of fruit juices Chitosan at low concentrations was found to be effective. Clarification of white wines The industrial tests showed that in most cases, an equivalent or even greater technological effect was obtained with chitin-glncan in comparison to common fining agents. 

As noted previously, lysozyme complexes with and is partially inactivated by red wine phenolics and bentonite. In red wines, utilization may have an indirect sensory impact on palate structure similar to that of proteinaceous fining agents. In white wines, potential protein instability may result from its utilization. Thus, treated wines should be evaluated and treated with bentonite as appropriate. As of this writing, lysozyme is in the process of approval for winemaking purposes. 

For this reason, some American wineries have adopted the use of products that increase surface tension. This process reduces foam formation and stability. Two anti-foaming agents are gaining popularity dimethyl polysiloxane and a mixture of oleic acid mono- and diglyceride. They are used at a concentration of less than 10 mg/1 and do not leave a residue in wine, especially after filtration. Due to their efficiency, red wine tanks can be filled to 75-80% capacity and white wine tanks to 85-90%. These products are not toxic. The Office International de la Vigne et du Vin recommends the exclusive use of the mixture of oleic acid mono-and diglyceride. 

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