David’s article as prepared for the Duluth News Tribune for the article which ran on 4/15/2015:
The Key Components of Wine, Part III: Sugar
A few years ago I was canal boating through France and stopped our boat before going through a tunnel. The canal pierced straight through the most amazing little hill. The hill wasn’t very tall or very wide and it was a bit out of place – it was the only hill in a relatively flat valley. But this little hill, called Malpas, had a medieval drainage tunnel, dug by monks in the 1200’s to convert a nearby swamp into farmland, a canal for barges dug in 1679, and a modern train tunnel bored through in 1800’s, all passing through it at different elevations. To cap it off, the road that ran along the hill’s spine was the ancient Via Domita used by everyone from Hannibal and his elephants to Julius Caesar to Napoleon. All of this was on and through the sturdy little Malpas hill. I insisted we stop the boat and go have a proper look.
It was as you imagine. A tiny little hill with holes bored through, most of which were hidden from view except for the one we were going to transit on our boat. The road on top was mostly paved, but rutted, old, narrow and dusty. Hardly a road worthy of Rome’s great legions. We wandered around a bit and noticed that a field not far from the hill was being harvested. Curious, we walked over to watch the farmers work the vineyard. We were enthusiastically greeted by the Frenchmen. They insisted we ride the mechanical harvester, they ripped bunches of ripe grapes from the vines and encouraged us to form a pouch from our outstretched shirts and loaded them with bunches of ripe berries. We were happy to oblige, and when I asked which grape variety they were sharing they proudly said, “cabernet sauvignon.”
We were ecstatic. This is why I travel. For moments like these. Where stopping to look at a small hill turns into a cultural exchange. And as we loped back down to our boat with our load of fresh cabernet sauvignon we greedily ate handfuls of sweet, juicy berries full of concentrated flavor. The sweetness of the fruit surprised me. Every glass of cabernet sauvignon I’ve ever tasted, as a wine, had never been sweet. It had been dry, sometimes so dry it feels like all the slippery is stripped from my mouth. Yet here I was, tasting the most amazingly sweet delicious fruit.
Grapes typically contain 15 to 25 percent sugar at harvest. To be more precise, grapes contain roughly equal amounts of two sugars: glucose and fructose. Both of these are simple sugar molecules that yeast can break down during fermentation and under the right conditions convert the sugars into ethanol.
Allowed to ferment to completion the yeast will eat all the sugar and the wine will be considered dry. The residual sugar level will be around 0.5 percent and no one will notice any sweetness. At 1 percent about half of the tasters will detect the sugar. This would be called off-dry. Wines made specifically sweet like most German rieslings would be considered medium sweet or sweet. Dessert wines have 10 to 25 percent residual sugar and are considered very sweet.
Sweetness is important because it can balance a high level of acid, making the wine both stable for aging and delicious. On the flip side, sweetness can be used to cover up faults as most people are predisposed to enjoy sweet tastes. But sweet doesn’t compliment savory food, it coats the mouth with sweet flavor and it doesn’t cleanse the mouth when eating fats. The reverse, dry wines, compliment savory foods, they strip fats from the mouth and they lift the palate, refreshing the senses for another delectable bite. That is why wines are made dry and why dessert wines are served last.
Next week we will discover tannin and its important roll in red wine.
David Devere is a certified specialist of wine. He teaches wine classes mainly in the Duluth, MN area. Contact him at firstname.lastname@example.org.