WORLD OF WINE: When it comes to wine, what are tannins?

Tannins are part of the biochemical makeup of living, fruit-producing plants. In high concentrations in under-ripe fruit, they remain unpalatable until a particular level of ripeness takes place.

The fruit is considered most highly edible with a sugar content and acidity level that makes them appealing to the consuming animal. That consuming animal could be anything including an insect, a bird, or one of us.

Tannins are intended by nature to be a defense mechanism to assure species survival, since the peak of ripeness indicates the seeds within are mature enough to germinate and continue life on their own.

Cut open an unripe apple, tomato, or grape. Do the same with a ripe companion of the same species, and note the seed color and taste differences between them. Experienced vintners do this with their grapes to time their harvest as close as possible to what is considered the optimal ripeness to begin the wine-making process.

Some tannin impact gives red wines the structure that aids in taste enjoyment. Strong red tannic wines are blamed for causing headaches for some people. Check the alcohol level, and the residual sugar content. If both are high, they could be the culprits. Wines with an alcohol by volume amount of 12.5 percent and residual sugars below 5 percent might be the answer to solving the headache problem with red tannic wines. Look for red wines with labels that identify as being dry or off dry.

I’ve often referred to grapes being soft pressed upon harvesting, with the juice and grape skin contact monitored by the vintner to get the right level of color and tannin impact in the finished wine.

The soft pressing ruptures the skins to release the juice, but does not fracture the seeds, which would impart a bitter taste to the wine. Cheap red wines typically hard press their grapes, which results in some seed fracture, with the resulting bitterness in the wine masked by the addition of sugar.

Some tannin impact can be ameliorated with decanting before a formal tasting or consumption for a couple of hours to allow mellowing. This is especially true with light red wines that were aged in new oak barrels. Along with decanting, bottle aging at home for about a year will aid in softening the tannin impact.

Ever notice in a wine-tasting session that one of the last wines tasted were ones you most enjoyed? You purchase a couple of bottles to consume at home to find them only just so-so?

The mistake you made was the decision to purchase the wine after your taste buds became fatigued. That’s why sipping water with red wines is important – to keep the taste buds sharp.

If you are tannin sensitive, then go for the lighter tannic wines like merlot or malbec, and stay away from the varietals with typically high tannin content like nebbiolo or cabernet sauvignon.

Ron Smith, a retired NDSU Extension

horticulturist, writes weekly about his love of wine and its history. Readers can reach him at