Controlling sweet wines with FTIR

Mosh Valley
10. Jul, 2018
Dr. Loosen from the Mosel Valley explains how the OenoFoss analyser adds value as a faster and more convenient alternative to testing at an external laboratory.

The Mosel valley in Germany is known for the many high quality fruity wines with a relatively high level of residual sugar. “Around 80% of our wines have residual sugar,” says winemaker Thomas Loosen. “The Riesling produced here on the Mosel has quite high acidity and so it is a tradition here to produce wines with natural sweetness. It was a challenge to get this fixed on the OenoFoss, to analyse these high sugar contents. But it works really well.”

Loosen explains how the rapid analysis with the Fourier Transform Infrared (FTIR) analyser complements the tasting of the first wines in January and February. The wines are tasted and when the first ideas about how to use the wines start to form, for a special cuvee for example, the OenoFoss is used to give a rapid analysis of sugar and acidity level. “We have the instrument by the side of our tasting room and we have the figure within two minutes. Then we can go on with our planning,” says Loosen.

The alcohol level is also useful for bottling and labelling purposes as a faster and more convenient alternative to testing at an external laboratory. This on-the-spot aspect of testing with FTIR also pays off when blending of tanks and barrels is involved by making the winemaking process much faster and more dynamic. Barrels can be tested individually and on-the-fly to check ideas pre- blending. Before, they had to do the blend first and then wait one or two days to get a result.  

Loosen concludes by explaining how the actual cost of testing with FTIR is quite low because once the initial investment is made, winemakers can test and test again at no additional cost.

Dr. Loosen is a world-renowned wine estate in Germany, producing distinctive, highly acclaimed Rieslings from the steep, slate-soil vineyards of the Mosel. 

We interviewed Dr. Loosen from Mosel Valley about the value of an OenoFoss instrument.
The whole interview can be seen in the video, or read it below in our transcription.

Explain to us how you use the OenoFoss at Mosel Valley
Dr. Thomas Loosen: Our specialty here in the Mosel is that we produce a lot of fruity style wines with residual sugar, which is not so common in the wine world. I would say that most of the wines produced all over the world are dry wines, so with no residual sugar but here with us, it's totally different. I would say 80% of our wines have residual sugar and therefore the Reisling produced here in Mosel has quite a high acidity. It is also a tradition here to produce wines with residual natural sweetness and it was a challenge to get the measurements on the OenoFoss to analyse such a high sugar content.


But it works really well. We sent in a lot of samples and did a lot of analysis with our local laboratory and then the adjustment, we did with help from FOSS. We got the machine and it worked from the first day, great. In January and February when we have all the wines on the table for the first time, we taste them all in one row. Then when we have the first wine, we imagine how we can use the wine for a special cuvee or something like this, and then we consider, okay, how high is the sugar content, what is the acidity, what is the alcohol level, and then it's quite easy. We do it in this room. We go over here, put the sample in the OenoFoss and after two minutes, we have the figures and then we can go on with our planning.

What is important for you to control in the wine?

For us, it's quite important to know the acidity, the total acidity and the sweetness of the residual sugar content. What is also quite useful for us is the alcohol level, for printing the labels, which you have to do going forward. If you want to bottle the wine and then label it within the bottling process, you have to order the labels beforehand. Normally here in Germany we have the system with the AP numbers so you have to bring your wine to a laboratory and they do an official AP analysis. The normal way is with this analysis; you go to your printer and print your labels but this you can do only when you have the wine bottle.

What benefits do you see in analysing your wine?
With OenoFoss we can do it when we have the finished wine ready for bottling, we do the analysis and then we see, okay, does the wine have, for example, 8.0 % alcohol? We can order the labels and then three days after, we can start the bottling and the labeling with the right alcohol level on the label. We have a lot of different tanks and barrels. For example, we have a vineyard, which is 4,000 square meters big. Out of these vineyards, we have different tanks or barrels, and each barrel and each tank is a little different, cast from a different yeast or the natural fermentation yeast.


Then if you want to do a blend, for example, a cabernet blend of 3,000 liters, we have three barrels of 1,000 liters and then we can analyse each single barrel. In the old days, we had to do the blend, then bring it to the laboratory, wait one or two days and then get the analysis back. Then if you had another idea, then you'd have to perform the same procedure again. So it took quite a long time to get a final blend together. Therefore with the OenoFoss - it’s perfect. It helps you to make decisions much quicker.


Normally, my wife is using this instrument. She runs the small laboratory here and she's doing the sterile controls of our bottlings, and doing the pre-analysis with OenoFoss. She didn't learn this profession and therefore, she likes this machine which is quite easy to handle. It's always a question of what you want to do with this machine. For us, it fits perfectly for our needs, and what we are looking for. We want to keep the whole laboratory very small and still get an overview about this.


Also, the annual costs are quite low, even the cost of every sample, which you're doing with this machine. There are other existing systems, but with these systems you always have cost per sample. Here, whether you're doing 1,000 samples or 5,000 samples, the cost per sample is always the same. You have the investment and I hope that this machine will stay; this machine will work another 10 years. Then, if you figure out, per year, per sample, then it is very low this investment.


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