Wine aficionados know that a well-harmonized wine enhances the flavors of all the foods they consume, while a poorly harmonized wine does the opposite. And some foods can, in turn, influence the flavors of a wine. Is there a better accompaniment to your favorite cheeses and / or cured meats than a good bottle of Bordeaux or a California Cabernet? A team of French scientists has specifically explored the role of interactions between tannins in wine and the fat molecules known as lipids in food to better understand what is happening at the molecular level with these complementary pairs, according to a recent article published in the Journal of Agricultural and Food Chemistry.
Obviously, the taste of wine is highly subjective to the individual; we all have different combinations of flavor receptors that influence how we perceive flavors. But some characteristics are quantifiable: bitterness, sweetness, acidity and the body (or weight) of a wine. This is the basis for the art and science of combining wines in most sophisticated restaurants. The tannins in wine are polyphenolic compounds responsible for much of the bitterness and astringency of a particular wine; they are derived from the skins and stems of grapes, or as a result of aging in oak barrels. Tannins combine well with proteins and fats, which compensates for their astringency and bitterness. That is why wines with a heavier tannic component (such as Cabernet Sauvignon or Barolo) go so well with cheeses and cold cuts.
The degree of residual sugar – how much sugar remains after fermentation – determines the sweetness of a wine. Very dry wines have almost no residual sugar, while very sweet dessert wines, such as Sauternes or tokays, have high residual sugars. Sweeter wines go well with spicy dishes, for example, because sugar contrasts with the heat of the food. Acidity is a measure of how acid a particular wine is, and there are three primary acids in wines. Malic acid imparts a kind of green apple flavor; lactic acid confers a milky component; and tartaric acid will give the wine additional bitter flavors. More acidic wines combine with fatty, oily, rich or salty foods, because the acids will neutralize these qualities on the palate.
Finally, the amount of alcohol influences the amount of body (or weight) that the wine has and gives a feeling of warmth on the palate. The higher the alcohol content (and the more tannins are present), the greater the perception of heat. Conventional wisdom has long held that white wines go well with fish or poultry, while reds go with heavier meats. But the reality is more complex. There are heavier and richer white wines (like chardonnay) and lighter red wines (like Beaujolais). It is the weight, or body, of the wine that must be considered when making this combination.
French scientists have focused their research on tannins, particularly on how these compounds affect the size and stability of fat globules (lipids) in an emulsion – a common model used in experimental food studies. Then, they created their own emulsions in the laboratory with olive oil, water and a phospholipid emulsifier and added a grape tannin called catechin. Next, the researchers analyzed the emulsions with a variety of techniques, including optical microscopy, electron microscopy and nuclear magnetic resonance spectroscopy, as well as measuring the size of the droplets with static light scattering. The analysis showed that the presence of grape tannins caused the formation of larger drops of oil.
Come on lipid
Next, the researchers performed a sensory evaluation, recruiting a group of male and female students from the engineering department of the University of Technology in Bordeaux in Périgueux, France. Participants were trained for a period of two weeks, learning to classify aqueous solutions of different concentrations (citric acids, caffeine, potassium sulfate and aluminum) and to recognize common wine aromas, especially those related to oils and tannins (most notably the overall flavor intensity, acidity, fruity, herbaceous, dried fruit, bitterness, astringency and persistence of taste). The group sniffed five isolated flavors chosen randomly out of 24 possible and learned to identify them.
Participants were asked to taste various tannin solutions either alone or after swallowing a spoonful of rapeseed, grape or olive oil. The results showed that the oils reduced the astringency of the compound, mainly olive oil, which the participants reported to make the tannins more fruity. French researchers concluded from all this that tannins interact with oil droplets in the mouth, making these oils less likely to bind to saliva proteins, which causes the astringent taste.
“Dietary oils are able to decrease the astringency induced by vegetable tannins,” wrote the authors. “These findings confirm the mutual affinity between tannins and lipids, as well as components of … fatty foods. Therefore, the tannin-lipid interaction must now be considered by oenologists to find the best association between too much astringent red wine and fatty foods such as like cheese, meat, cold cuts or desserts, for example. “
DOI: Journal of Agricultural and Food Chemistry, 2021. 10.1021 / acs.jafc.0c06589 (About DOIs).