Can I prevent hot pepper sauce losing heat? I regularly make a few different condiments with hot peppers:


Pico de Gallo (tomato, onion, jalapeño, cilantro, lime, salt)
Pepper Sauce consisting of habanero, garlic, lime, culantro, salt
Variation on above using dry roasted chile de arbol in stead of the habanero


In every case I've noticed a significant decline in heat after the first day, then a slow and steady decline as time goes on The taste immediately after preparation can border on unbearably hot, while on the proceeding days it can become almost what I would call mild.

Why does this happen and can anything be done about it?  I'm wondering if it's possible that any of the ingredients I use are having a chemical reaction with the capsaicin causing the loss in heat.  Or is it storage related?  Or is this simply something that cannot be avoided once you cut and grind the peppers?

UPDATE:

For the record I think this is fairly reproducible:


Get the hottest peppers you can imagine.
Grind them up with some water, salt and lime juice.
Taste and experience the hopefully insane level of heat.
Refrigerate &amp; taste again in a few days. Notice how it's not as hot as before?
The heat of your condiments isn't actually being lost. The condiments are marrying, meaning the heat becomes more homogenously distributed through the condiment. This means you don't have bits and pieces that have as high a spike in heat than the rest of the salsa, and therefore the condiment is more evenly hot (thought apparently cooler to the taster) throughout.

Pepper or chile sauces use vinegar and oil to retain and even accent their perceived heat. Neither actually increases it though. Vinegar helps clean the palate like strawberries for champagne, or ginger for sushi. It cleans the tongue so the heat can get to it better. Oil helps hold the heat to the tonque and other mouth parts making it seem hotter because it doesn't wash away as easily. 

Keep in mind though that pico de gallo is really meant to be made and served fresh. You don't want to give it time to macerate and marry. You want to bite into and taste the individual components of this condiment. Leaving Pico to sit overnight in my opinion really turns it more into a chuncky but watery Salsa.