The Scoville Scale

Which is hotter: a Serrano pepper or a Jalapeno?

Let's take this question to Science.

Believe it or not, there is a scale to measure specifically the relative amount of "spicy heat" in a chili pepper -- or scientifically, the amount of capsaicin (cap-SAY-sin) in a given sample.  Capsaicin is the chemical that creates the burning associated with the spiciness or hotness of a chili pepper.

Side note: if you do ever get capsaicin in your eyes or nose or wherever -- it is a hydrophobic compound -- which means it will not wash-off with water very well.  The best way to rid yourself of the burn asap is to use some type of oil -- which will remove any capsaicin which has not already been absorbed by your skin.  Milk or sugar-water are also better than water alone.

The Scoville Scale is the tool used to rate the hotness and, usually, a helpful resource if you want to know which pepper is more or less hot than another.  Just incase you were curious -- the measurements are made by incrementally adding the sample of a dried pepper (or even more specifically, a capsaicin extract of the dried sample) to simple sugar water until the spice or hotness is detected by a panel of judges.  Yep, just human people.  

Here's a helpful cheat sheet:

So, going back to our original question -- it is most likely that the Serrano pepper is hotter -- but there is a chance that the difference could be very small.  In this case, it may likely depend from pepper-to-pepper.

Another indicator of spice or heat is the coloring of the pepper.  Peppers are red (or purple, or brown, or not-green) when fully ripe.  A green pepper is simply a pepper that was picked prematurely for one reason or another.  The riper or darker the pepper, the hotter, spicier and/or sweeter it will be.  That's why green peppers cost less.  So, as I have personally learned, a red Jalapeno is very much hotter than a green one -- and I have no idea why anyone would prefer a green Bell to a red one.

Seriously.

You can ripen your prematurely picked green pepper by putting it in a paper bag or wrapping it in newspaper -- although it may take a week or two -- and will not be as delicious as if it was ripened on the plant.

Besides being hot and spicy -- fresh peppers are also very, very, very rich in Vitamin C (a water-soluble antioxidant).  Fresh peppers have way more Vitamin C than citrus fruit!  Green peppers having about 2x as much, red as much as 3x, and some chilis up to 3.5x!

Peppers are also rich in alpha & beta-carotenes (which are then converted into Vitamin A) and lutein (protects eyes and skin from sun damage) -- as well as minerals like potassium (maintains body's water balance), magnesium (proper functioning of muscles and nerves), iron (plays role in carrying oxygen to all of body's cells), and manganese (proper thyroid function).

Whew -- and as a disclaimer -- all of these vitamins and minerals and enzymes found in fresh fruits and vegetables do a lot more than just the things I note in the parentheses.  I like to just highlight a few general example-functions when I drop them so perhaps they will become more familiar over time.

On a final note, when you're selecting peppers at the store you mainly want to ensure that the vegetable is firm and without blemishes.  Moisture leads to rot -- so keep them dry and refrigerated!

Thanks Petey for the question!