Making fruit wines can be economically rewarding. A certain segment of the population enjoys these wines. A winemaker can produce high quality fruit wines as a specialty product and benefit from this existing niche in the marketplace.
Food is essential for survival. Since the beginning, people have been interested in preserving food for later consumption. Overtime, many methods of food preservation have been tried. These include heating, freezing, drying, fermenting, and adding chemical preservatives. In recent years, the use of chemical preservatives has increased. This is due to the developments in marketing and distribution of the food we consume and also because of the large variety of foods offered for consumption.
Missouri vintners produce some of the finest white table wines from French hybrid cultivars. Vignoles, Seyval, Vidal, and Cayuga White are the leading grape varieties used in premium white wine production. In 1992, Missouri wines received 240 awards in 17 wine competitions. Over 55 percent of these awards were given to white wines. Premium white wines are, therefore, very important to the growth of Missouri's wine industry. One of the quality features of these white wines is the presence of typical varietal character. Maintaining this quality attribute is crucial to the production of premium white table wines in Missouri.
Lactic acid bacteria (LAB) are responsible for many fermented foods such as sauerkraut, pickles and yogurt. They have also been isolated from wines at various states of vinification. In wines they are responsible for malolactic fermentation (MLF) which can be beneficial in some cases and undesirable in others. Besides conducting MLF, these bacteria under certain conditions can also cause undesirable changes in wine flavor which renders the wine undrinkable. Many species of LAB do not conduct MLF and their growth in wine can cause some serious wine spoilage.
Maturation and aging can be considered as a group of reactions and series of changes that occur in wine during storage and lead to wine improvement. Boulton et al (1996) suggested that wine aging should not be viewed as single procedure and single event but rather a family of changes. They further suggested a distinction between the term maturation and aging. Term maturation used for the changes during bulk storage and aging used for the changes during bottle storage. The key difference is that during bulk storage a wine is likely to be exposed to air where as in bottled it is stored in essentially anaerobic conditions. For the purpose of this presentation when we say oak aging of red wine we also mean oak maturation of red wine.
In a wine laboratory, analyzing wine for TA, VA and S02 involves the use of a sodium hydroxide (NaOH) reagent. Winemakers usually buy sodium hydroxide solution of a known concentration (usually 0.1 Normal). This reagent is relatively unstable and its concentration changes over time. To ensure the accuracy of analytical results it is important to periodically check the concentration (Normality) of sodium hydroxide. If the concentration has changed then it must be readjusted to the original concentration or the new concentration (Normality) value needs to be used in calculations.
Premature cessation of an alcoholic fermentation, commonly known as a stuck fermentation, is a serious winemaking problem. Restarting a stuck fermentation is often difficult and time consuming, but more importantly, it creates a favorable condition for the growth and activity of spoilage microorganisms. There are several factors that are responsible for fermentation problems.
The basic procedure of red wine production is outlined in the diagram. An important point in making red wine is that the fermenting must consists of juice skins and seeds. As a result, the composition of red wine is determined by the constituents extracted from skins and seeds in addition to those present in the juice.
Grapes contain significant amounts of organic acids. The major organic acids in the must are tartaric, malic, and citric. Of these three acids, tartaric and malic acids account for over 90% of the total acid constituents of the juice (Amerine and Joslyn 1950). During ripening, the tartrate and malate content of the fruit decrease. This is accompanied by a steady increase in pH. Due to variation in buffer capacity, there is no direct relationship between titratable acidity and pH. In general, however, higher acid levels in fruit are often associated with lower pH values and vice versa. Thus the acids of the fruit have a significant bearing on pH. They also play a significant role in taste, color, and microbial stability of the juice.
The first step in copper treatment is to experimentally determine the amount of copper needed for the wine treatment. This can be achieved by following the procedure given below.