Please review the Preliminary Overview of NC Harvest 2011. We plan to provide access to regularly compiled data from hundreds of juice and wine samples submitted to the Enology Services Lab in a confidential and anonymous format for your reference.

Information includes popular NC varieties, as well as average BRIX, pH, acids, VA, Residual Sugar, etc on juice and wine samples submitted from August through early October 2011.

As you will see from the data, the more samples and descriptive information (varietal, vintage, etc) that you send, the more details we can provide and well help you consider your own data in the context of other data collected throughout the state. Eventually we will make this information accessible through our website (http://wine.appstate.edu/) for ease of access along with your own personal data.  Feel free to make suggestions on how this may be made most useful for your own needs.

As we move from harvest to fermentation and cellaring, keep in mind analysis that will help track your wine quality and provide you with early detection of potential faults.  We also encourage you to submit samples for sensory evaluation especially during blending and addition trials and pre-bottling.

See below for descriptions of some vital fermentation analyses. Shipping and sample submission information can be found at our website http://wine.appstate.edu/lab/shipping

Monitoring during Fermentation:

Nitrogen (FAN + NH4) Measuring nitrogen levels prior to fermentation is essential for trouble free ferments. Proper nutrient supplies for yeast ensure less H2S formation and decreased likelihood of stuck fermentations. Looking at both nitrogen sources (ammonia and amino acids) provides a complete picture of how much and what type of nutrients are needed. If nitrogen levels are adequate, having that information can prevent unnecessary nutrient additions, helping to reduce the chance of feeding spoilage microorganisms. Having depleted nitrogen sources post fermentation can aid in wine stability.

Malic Acid Testing for malic acid prior to primary fermentation, along with pH and TA gives a complete picture of acid balance in wine. Malic levels can vary greatly from year to year based on weather conditions and should be taken into consideration when determining final acid levels in wine. Closely monitoring malic acid levels during malic fermentation can help prevent incomplete and/or stuck ML fermentations, and are critical for maintaining wine quality and stability. pH levels can increase during ML fermentations putting wine at risk of spoilage.

Sugar (Glucose + Fructose) Analytical determination of glucose and fructose levels post fermentation verifies wine stability and can be used as a measure of mouth feel and desired wine style. Knowing the sugar levels will aid in filtration decisions. These sugars can be measured together or separately. Looking at specific glucose/fructose levels can help with stuck fermentations.

Volatile Acidity (VA) Volatile acidity is a measure of acetic acid in wine and is an indication of spoilage. High VA can help determine the cause of stuck fermentations; should be monitored post fermentation, post ML and monthly during storage. Increasing VA can be an indicator of potential microbial issues; TTB regulates maximum levels in wine.

Yeast count and viability Can help identify issues during stuck fermentations. A good indicator of yeast health.

SO2 (free and total) Measuring SO2 levels in wine ensures wine stability and prevents spoilage; there are also TTB regulations governing maximum SO2 levels in wine. A decrease in free SO2 during storage can be a leading indicator of potential issues (oxidation and microbial stability). It is important to determine a precise SO2 (free and total) number early on in cellaring.  This will allow you to adjust maintenance levels and track SO2 loss closely during the first month when critical, especially for ML- wines.

-- 
Franya Hutchins
Enology and Viticulture
Appalachian State University
828-262-8158

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http://wine.appstate.edu