OK, this is not a feminist article at all, but it does involve another Skepchick favorite: wine. The Pshhhh I am speaking about cleansing is your palate. Recently, I read an article in Current Biology about palate cleansing and it didn’t leave me satisfied. Their study gave a slightly vague reason about why wine goes with cheese and peanut butter goes with jelly. Their conclusion was right on, but there is an underlying chemical phenomena the article didn’t mention.
In this study they determined that a mild astringent, such as wine or tea, alternated with eating a fatty food, such as a cheeseburger or steak, creates the sensation of a meal. This makes perfect sense. They also claimed that water did not produce the same sensation. This also makes perfect sense. Biologists like to blame this on enzymes, which is completely true. But being a chemist, I wanted to examine this at the molecular level.
Perhaps it was the repetitive (but not defined) ‘astringent‘ terminology that I didn’t like. This word reminds of a teenage acne solution, but I went to the ever trusty wikipedia for an applicable solution. Astringency was defined as the puckery mouthfeel caused by tannins. So what is a tannin? Tannins are acids, which you can see from the structure below. All of those OH (hydroxyl) groups are acidic. There are a bunch. If you are a fan of wine (which I am), you often hear people refer to tannins, which is simply one of the acidic components of wine. Tannins also exist in other familiar food and drink items such as tea, coffee, berries, and nuts.
Let’s look at the other component of the equation: fat. Fats consist of molecules named tryglycerides, which are not acidic. They are composed of hydrocarbon chains with just a few ‘acidic-esque’ functional groups. Perhaps you have heard of fatty acids. In these, there are significantly less acidic components compared to a tannin. The only acidic elements here are the hydrogen atoms that neighbor oxygen atoms. There are way less of them compared to tannic acid pictured above. Hence, fats are considered to be more basic.
So this astringent/fatty stimuli affect is simply combining an acid and base that neutralizes your mouth. The astringent takes away the fatty feeling left in your mouth after a bite of meat. Palate cleansing – Voila! Also, water is a neutral substance, which is why the same sensation isn’t achieved upon guzzling H2O after a fatty bite.
Many of our foods go together like this such as salad dressing (oil & vinegar) or salsa with guacamole. Meats are marinated with an acidic base. You drink coke with a hot dog. Beer with chicken wings. One of my favorites is a reuben sandwich: sauerkraut balances the swiss, the pickle balances the Russian dressing and corned beef.
This reaction happens in most things you eat. What is your favorite acid/base oral reaction? Do you have a favorite palate cleanser?