More on coffee

The post on coffee caused a few questions.

But Bo, if caffeine is alkaline, then how come everybody tells me to avoid coffee because it's too acidic for my tender tummy? And wutup widat acid reflux? Huh?

Although caffeine is an alkaloid, and that's the molecule that sits on your nerve ending keeping the synapse firing making you jittery, and so is of chief interest in coffee as a pharmacologic substance, chemically, there's more to coffee than just caffeine.

But first, here's a picture of caffeine molecules sitting on nerve synaptic terminal buttons, keeping the communication between nerve endings firing until the body dispels the unnatural introduced intruders. 

Coffee beans contain other compounds including several acids. Once coffee hits your stomach, your stomach acids gets into the act working to break it down, and this is what causes problems for many people, especially when ingested on an otherwise empty stomach.

The PH of coffee is slightly acid, very nearly neutral. The perceived acidity of coffee is considered by coffee lovers as (+), but extremes of acidity, which is perceived as bitterness, is a definite (-). This perception of acidity is the result of proton donation of acids to receptors on the human tongue.

A coffee researcher named Blank found that typical medium roast coffee consisted of

.30% citric acid
.22 % malic
.13% lactic
.07 pyruvic
.27% acetic

At very light roasts, Blank found that the total concentration of these acids was around 1.58 % while dark roasts these acids were as low as .71% Let's look at these acids. The pictures are boring, just a bunch of repeated letters connected with lines.

Citric acid is a weak unstable acid that can readily accept and donate three protons. It's a molecule of clumps of carbon atoms surrounded with oxygen atoms associated with hydrogen atoms to varying degrees as it cycles through its various forms interacting with water and other elements.

Malic acid is an intermediate in the citric acid cycle. It's dicarboxylic written as -COOH, or -CO₂H, also a proton donor.

Lactic acid, more carbon (3), hydrogen(6) and oxygen(3) atoms.

Pyruvate is the result of aerobic metabolism of glucose. One molecule of glucose = two molecules of pyruvate. As expected, more carbon, hydrogen and oxygen atoms but this time, in its various permutations, associated with one atom of nitrogen.

Acetic acid is what gives vinegar its sour taste. Guess the atoms. Go on, guess. Yay! You win!

So, what you have here chemically, is a whole bunch of carbon hydrogen and oxygen atoms in various configurations giving acidic characteristics to your coffee. It's doing a number on your stomach, along with other things, like acting as antioxidants. This is combined then, with the alkaline nature of caffeine, which is doing the number on your nerves. So you're getting hit in the stomach, and in the nerves in opposite directions.