I make a sweet hot sauce which contains red pepper, green pepper, onion and vinegar. I had some spoil on me that were not refrigerated. I was wondering if there was a preservative that I could use so that my sauce does not need to be refrigerated.
Vinegar is typically a perservative. Also, looking at Rooster sauce bottle, they use potassium sorbate and sodium bisulfite to inhibit growth.
What's probably happening is something is fermenting in your room temp sauce. I've had bottled catsup ferment and become carbonated when left out of the fridge.
Cooking the peppers may also kill off some molds. However, fermentation is not a bad thing. Simply a different process to preserve the sauce. And add another dimension.
Be sure to ferment with a vapor lock. Any toy balloon will do.
In general, hot sauces are preserved using acid (like vinegar), salt, and/or fermentation. Acid and salt both retard the growth of bacteria, and fermentation tends to create acids, for the same effect from a different direction.
How was it spoiling - going bad tasting, or growing mould? And how were you storing it?
For storage, I would be careful to sterilize your storage container with boiling water before filling, and fill with piping hot sauce, so it starts out in a sterile condition, and use a bottle that has a small opening, to prevent contaminants from getting into it (think Tabasco bottle).
More acid and salt will help the preservation. I think that too much sugar in a hot sauce can cause mould to grow as well, even with a low pH - you might want to check out canning forums for advice.
If it's fermenting with good bacteria in a controlled fashion, you can get a nice result. If it's just going bad, you won't.
Here's a link to McIlhenny's Tabasco Sauce process:
I'm sure that they aren't giving away all their trade secrets, but there's only three ingredients and no preservatives. I've seen plenty a bottle sitting out in slow diners that probably have been there for months. Maybe they use a lot of vinegar to pepper ratio.
Just asking, why do you not want it in the fridge? What makes it sweet? And by green peppers, you mean chiles, right?