Why Reporting Units Should Be Standardized

April 2011
by Patricia Howe
The subject of standardized units must be one of the driest and most tiresome topics in the wine industry. Or so it would seem, until a winery experiences a dramatic and expensive unit-related misunderstanding such as a massive over addition of SO2, refermentation in bottles of “dry” wine or unanticipated spoilage in the barrel room. These situations are extraordinarily common, and repeatedly hearing these stories can produce unit-standardizing activists and advocates.

Analytical results reporting consists of several parts: a numerical value, a unit of concentration and an analyte expression. For example, a common result for titratable acidity is: 6.2 grams per liter expressed as tartaric acid. The numerical value is 6.2, the unit of concentration is grams per liter, and the expression of the constituent analyte is tartaric acid.

In the wine industry we use many and varied units of concentration. The units of concentration used for our most common analytes are not universally standardized and frequently must be converted back and forth; additional misunderstandings occur when only the numeric value of the reported result is remembered.

Confusion related to different analytical reporting units is commonly caused by mathematical misunderstanding. Although converting concentration units is relatively simple (see the table below), standardizing units of concentration would minimize confusions and conversions. Despite the American wine industry’s ongoing initiative to standardize reporting units and coordinate with the rest of the world, there will always be occasions when results are reported with alternate concentration units.

Standardizing the terms of concentration is not about choosing which format is “better.” It is about facilitating communication and understanding between people, businesses, bureaucracies, regulatory agencies and countries, and making better wine.

The greater source of potential quality issues is not the actual units of concentration used: It is a communication problem. Ignorance of the potential for misunderstanding units causes miscommunication when different terms and units are wrongfully compared. Frequently people do not pay attention to the units; they see the numerical value alone. Misunderstandings occur and wine quality suffers when people do not know what units they are using. This yields a common scenario: A winemaker might ask if a malic acid of 0.05 is complete, if a sugar of 0.8 is dry, or if a VA of 0.6 is high, but she has no clue which units of concentration are involved. This winemaker might have a nice dry wine with a reasonable acetic level or a nightmarish stuck fermentation with elevated VA levels.

Perhaps the best reason to standardize reporting units is to make it easier for winemakers to know what units they are using and allow them to communicate these values without being troubled by a critical but forgettable detail.

This lack of universally adopted standardized concentration units is a cognitive problem. If we could remember what units of concentration we were dealing with and the skills regarding decimals, fractions and unit conversion from our school days, this would be a non-issue. I confess to still needing paper, pencil and a moment’s silence to do all but the most basic unit conversions.

If we as an industry are not able to adopt a universal system of concentration units, we must instead get into the habit of remembering and repeating the numerical value, the expressed constituent analyte and the actual units of concentration. Perhaps this is the only way we can reduce the number of times we hear winery horror stories (dry wines that aren’t, additions made at 10 times the desired level, etc.) caused by misunderstandings and miscommunications about units.

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