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Antimicrobial Agents

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. Read more about Antimicrobial Agents

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Dangers of Oxidation in Table Wines

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. Read more about Dangers of Oxidation in Table Wines

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Lactic Acid Bacteria and Wine Spoilage

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. Read more about Lactic Acid Bacteria and Wine Spoilage

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Preparing Standard Sodium Hydroxide Solution*

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. Read more about Preparing Standard Sodium Hydroxide Solution*

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Titratable Acidity

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. Read more about Titratable Acidity

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Wine Yeast

It is often said that a "wine is made in the vineyard" or "you can't make a silk purse out of a sow's ear." These comments emphasize the point that good quality fruit is needed for good quality wine. Although the importance of quality grapes in making superior wine cannot be denied, it is equally important to realize that it is one of the critical components but not the only component necessary to make good wine. There are many other factors that are vital to wine quality, otherwise, how can one explain poor quality wine from high quality grapes? Read more about Wine Yeast

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Racking

When a fermentation ceases, the suspended particles settle rapidly and form a sediment. The sediment, referred to as lees, usually consists of macerated grape tissue, dead yeast cells and yeast autolysis products. The young wine is separated from the lees by transferring the wine to another container, leaving the lees behind. This process is called racking.  Read more about Racking

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Yeast Autolysis

The term autolysis literally means 'self-destruction'. It represents self-degradation of the cellular constituents of a cell by its own enzymes following the death of the cell. In the process of autolysis, the medium (wine) is enriched by the compounds released as a result of the degradation of intracellular constituents. These yeast constituents have an important influence on the sensory properties and biological stability of wine.  Read more about Yeast Autolysis

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Yeast Autolysis*

The term autolysis literally means 'self-destruction'. It represents self-degradation of the cellular constituents of a cell by its own enzymes following the death of the cell. In the process of autolysis, the medium (wine) is enriched by the compounds released as a result of the degradation of intracellular constituents. These yeast constituents have an important influence on the sensory properties and biological stability of wine.  Read more about Yeast Autolysis*

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