Submitted by Stuart on Thu, 2007-09-27 08:37.

Additions

Amelioration (Water Addition)
Amelioration is when water is added to a must in an effort to dilute the concentration of grape sugars. High sugar levels bring the potentials of high alcohol levels and fermentations that have difficulty completing to full dryness. High sugar levels are more common in areas like California, where sunshine is plentiful, grapes easily mature to full ripeness, and winemaking trends have shifted toward longer hang times for the fruit before harvesting.

Although there is a concern about dilution of the wine, it is important to note that most of the high sugar level in very ripe grapes is due to dehydration and adding water back merely restores the balance that was in the grapes.

Enzyme Addition
To achieve extraction in fermentation requires contact between the fermenting juice and the skins that tend to float to the top. The more contact, the greater the extraction level (think about a teabag in a cup of water). In small lot winemaking, especially with thick-skinned varietals as Cabernet Sauvignon, it can be difficult to get enough mechanical mixing to maximize extraction. Color or tannin extraction enzymes can be added during fermentation to help break down skins for more extraction without being too aggressive with the fermenting must (note that this is an especially good idea if the seeds are still a little green and tannic).

Lafase HE enhances gentle extraction of softer tannins and flavors from the cell wall of mature grapes. Low anthocyanase activity helps promote color stability. Lafase HE has little effect on seed tannins. Use can help reduce the amount of pump overs required during fermentation, helping to avoid over-extraction or extraction of vegetal characters.

Malolactic Bacteria
Malolactic fermentation, also referred to as secondary fermentation, uses bacteria to transform muscular malic acids (think green apple) into smoother tasting lactic acids (think milk). The process reduces the wine’s acid content and helps create a creamier textural quality in the mouth. With the exception of very light styles, like Beaujolais Nouveau or Dolcetto, all red wines undergo malolacticfermentation.

Secondary conversion for white wines depends on the region, varietal and style the winemaker wants to create. Lighter grapes, like Riesling, which feature crisp acidity and explosive aromatics, usually avoid malolactic fermentation so that the grape's natural vibrancy isn't lost. However, depending on the desired wine style, larger bodied varietals, like Chardonnay and Viognier, may go though at least some degree of secondary fermentation to add complexity and smoother textural qualities.

Nutrient Addition
To ensure a healthy fermentation, nutrients can be combined with yeast immediately prior to inoculation or added directly to the must. The additions provide yeast with micro-nutrients and prevent nitrogen deficiencies. Low levels of available nitrogen can lead to a sluggish or stuck fermentation.

• Go Ferm- Yeast strains are commonly packaged in a dry state and need to be re-hydrated with warm water to become active. Go-Ferm is a micro-nutrient added during the re-hydration. It is combined with the yeast prior to inoculation so that the nutrients are not consumed by competing wild yeast strains present in the must.

• Diammonium Phosphate or DAP, contains fermentable nitrogen for the development of healthy new yeast cells.

• Fermaid K is a yeast nutrient that supplies ammonia salts (DAP), free amino acids, sterols, unsaturated fatty acids, key nutrients (magnesium sulfate, thiamin, folic acid, niacin, biotin, calcium pantothenate) and inactive yeast. Fermaid K is usually used in conjunction with a yeast rehydration nutrient (such as GoFerm) to assure proper nutrition of the cultured yeast throughout the entire fermentation cycle.

• Yeast Hulls- The addition of yeast hulls has been shown to increase the number of viable yeast cells. In sluggish fermentations, yeast hulls assist by absorbing toxins such as decanoic and hexanoic acids and esters. Yeast hulls are highly beneficial in oxygen deficient juices and wines as they contribute sterols and unsaturated fatty acids. Together with adequate nitrogen, yeast hulls can help promote cell growth and increase fermentation kinetics.

Sulfur Dioxide
SO₂ is commonly used during the winemaking process as a tool to prevent bacterial spoilage and oxidation.

Sulfur adjustments are typically made during key periods when the grapes or wine are at greatest risk for corruption. For red wine, SO₂ is first added after the destemming/crushingprocess. During this initial stage, concentration levels of between 20 to 50 mg/L are used to inhibit bacterial growth and prevent wild yeast strains from starting fermentation. Because white wines rarely go through the destemming and crushing process, they have SO₂ added immediately after the grapes are pressed.

Aromatic white varietals, such as Sauvignon Blanc or Viognier, require the antioxidant effect of SO₂ to maintain the complex bouquet associated with the grape varietals. However, the protective qualities of SO₂ may prevent any bitter and astringent phenolics from oxidizing out from the wine. Depending on the style of Chardonnay being made, different levels of SO₂ are sometimes used by winemakers. At higher levels, SO₂ is used to produce fresh, lighter styled Chardonnays. With lower levels of SO_2, fruit characteristics take a backseat to more complex aromatics and nutty tones. However, because the wine isn't protected from oxidation, the color takes on a brownish quality.

SO₂ is also added just after malolactic fermentation and is maintained at a level (e.g., 25 parts per million) throughout the life of the wine. SO₂ levels that are too high can increase bitterness while bleaching color from a wine. Without SO₂, wines would typically oxidize and/or be attacked by microbes. Note that organically labeled wines do not use SO₂ and tend to not age more than a year or two.

Tannin Addition
Tannins are phenolic compounds present in skins and seeds of grapes. They are responsible for tactile sensations and are perceived as a drying sensation on the mouth and insides of the cheeks. The winemaker works to create a balance of fruit and textural components while minimizing the tannic elements associated with bitterness. Tannin levels vary widely by varietal (Pinot Noir has relatively little tannin, while Cabernet Sauvignon has a lot) and are influenced by the climate in which the grapes are grown.

Grapes grown in cool climates typically feature more muscular tannins, while warm climate grapes tend to have softer tannins that favor earlier drinking. Near the end of the growing cycle, grape tannins can soften – this is highly desirable in cool/mountain climate fruit, but may make warm/valley climate fruit a little too soft. If tannins are too soft, a wine can benefit from a tannin adjustment. Tannins can be added from whole cluster inclusion or adding enological tannins that have been created from grape skins. Note that while oak barrels also add tannin, they tend to impart a “drying” tannin that will stick out unless balanced with enough grape tannin.

• VR Supra is composed of proanthocyanic and ellagic tannins formulated for red wine fermentation. During the first few days of extraction, indigenous tannins can bind with proteins and precipitate out. This can create an unbalanced tannin to anthocyanin ratio. Adding VR Supra at the beginning of fermentation protects indigenous tannins allowing them to remain in the wine. The indigenous tannins bind with anthocyanins to create more color stability.

• Tannin Galalcool is derived from the gall nut of oak trees. It was specifically developed for addition to white wines because it is colorless. Tannin Galalcool is recommended for use on grapes that have Botrytis, other molds or rot. It inhibits oxidation and protects the must against browning. It may also help stabilize proteins in varietals such as Sauvignon Blanc which are protein rich. This tannin may be used in aging red wines when very subtle changes are desired.