Today we harvested the last 10 rows of the Cabernet Frank and did help adding the yeast to the bins with Cabernet Frank that were harvested about 5 days earlier. Yeast will convert the grape sugars into ethanol (alcohol) and CO2 (carbon dioxide) and heat is given off in the process. The chemical formula is:

C6H12O6 + yeast --> 2 C2H5OH + CO2

In the US, sugars in the grapes are measured in degrees Brix. In order to estimate the final ethanol level in the finished wine, the simple rule of thumb is to divide the Brix reading by two. Meaning grapes harvested at 24 Brix will yield a wine with potential alcohol of 12 percent.

Fermentation is difficult to initiate if the grape must (juice) is cooler than 57 F (14 C) and difficult to control at temperatures higher than 95 F (35 C). The conversion of sugar into alcohol speeds up as the temperature increases; however, at very high temperatures, the yeast will stop working and die.

It is ironic that yeast produces a substance (ethanol) that is toxic to them. The faster the yeast work, the quicker they tire and the more vulnerable they become to the alcohol they are producing. Therefore, warmer fermentations produce wines of lower total alcohol.

Red Wine Production:

As opposed to other wine types, the main distinction in Red Wine Production is that the skins are allowed to macerate in the must for some period of time. This is what gives red wine its color, tannins, and allows the best to age for many years. The steps are as follows:

1 - Crushing

2 - Sulfur addition: it can be added at this time to prevent microbial spoilage, unwanted wild yeast fermentation, oxidation and browning. Less sulfur is needed for red wine than white wine due to the antimicrobial nature of tannins.

3 - Acidification/Chaptalization: If necessary, acid or sugar is added to the must to achieve balance in the finished wine.

4 - Maceration: Maceration and Fermentation usually occur at the same time. Color, tannin and flavor components are extracted from the skins of the gape. In fact, a wine style can be determined by when the juice is separated from the skins. Maceration periods run from 2 - 5 days, 5 - 10 days and longer - and the length of time spent on the skins directly correlates to the wine’s drinkability upon release.

5 - Fermentation: a red wine fermentation runs between 60 and 95 F. The hotter the fermentation the higher the level of extraction, but cap management is crucial.

6 - Malolactic Fermentation:

7 - Extended Maceration:

8 - Pressing:

9 - Clarification: before, during or after the aging process, wines may be clarified by a series of rackings, finings, or filtrations.

10 - Aging/Blending: Most red wines spend some time in barrels. Barrels provide three functions. They soften tannins by polymerization, clarify the wine and adding a subtle oak character to the wine.

11 - Bottling:

12 - Bottle Aging: allows for the development of a complex array of aromas known as the bouquet. Cool cellar/storage conditions (50 - 60 F) allow the bouquet to develop slowly. The finished melange of smells is incredibly multifaceted and complex. Warmer cellar/storage conditions yield a bottle bouquet much quicker, but the overall aroma profile will be simpler and more one-dimensional.

Carbonic Maceration - also known as whole-berry fermentation, takes place when whole grape clusters are placed in a anaerobic (oxygen-free) environment in order to change their metabolism so that they break down the grape sugars to create alcohol without the intervention of yeast. This is an enzymatic fermentation and it runs hot (85 - 95F) and long (1 to 3 weeks). Most Beaujolais Nouveau is crafted through carbonic maceration. Wines that undergo this process are lower in alcohol, tannins and pigment than wines that undergo traditional alcoholic fermentations.