On the back of each of our bottles, we print a handy-dandy scale to help our customers choose between the many different levels of sweetness the Riesling grape has to offer. The scale was developed by the International Riesling Foundation or IRF (we were proudly at the table as a founding member) and in great part by the wine critic Dan Berger. The scale is a line divided in four sections of growing sweetness from left to right: Dry, Medium Dry, Medium Sweet and Sweet.
The winemaker uses a simple algorithm to show where each particular Riesling is falling on the scale and can, at their discretion, move the ticker a bit to accommodate for anything that the formula is not taking into account (for example: Alcohol, carbon dioxide and phenolics can change the perception of sweetness of a wine). First, the basic calculation looks at the sugar to acid ratio and then it factors in the pH of the wine. The below chart summarizes the standard calculation.
Below is a summary of the past 6 vintages of where our wines would fall on the IRF scale by calculation alone. We also included a visual of where we actually marked the arrow on the back label based on the factors not included in the calculation. KEY: Red: Dry Riesling, Orange: Riesling, Purple: Sweet Riesling, Yellow: Gewurztraminer, Green: Chenin Blanc):
Here I see that despite what the IRF calculation tells us (upper row of dots), we consistently label a bit on the drier side (label placement is the lower row of dots). I think this is fair because we leave a lot of Carbon Dioxide from fermentation in our wines raising the overall acidity of our wines. We also tend to have a fair amount of phenolics in Washington State, which slightly dries the wines. Both factors are not taken into account by the taste scale calculation.
Another reason for “understating” sugar levels versus the IRF calculation is that over the past few years, the baseline for dryness has changed substantially (perhaps we should discuss this at the International Riesling Foundation meeting). Just a few days ago, I tasted a well-known brand of California Pinot Noir and I was shocked at the amount of Residual Sugar I could taste. I was so curious that I decided to take it to the lab (us winemakers can do that easily) and I found out that this particular wine was 0.6% Residual Sugar (6g/L). That is a lot of sugar for a “dry red.” Usually, you can start tasting sugar at 0.3% and some of our Rieslings (with much higher acidity than Pinot Noir in general) have the same level of Residual Sugar as this Pinot Noir. This is just further proof that everyone in the United States is drinking sweeter wines than they might think.