A week ago I harvested an orange Bell pepper from my garden. It was still halfway green, so I put it on our kitchen counter to ripen. When I finally cut it open for a salad after a week of ripening, it had a horrible ammonia smell, unlike anything I've ever experienced from a vegetable. Visually, there was nothing wrong with it, but the smell was a clear sign that something was rotten.
What can cause an ammonia smell from a pepper?
I'd agree with mfg that ammonia smell is highly uncommon (sure, the smell of rotting stuff is puke-worthy, but not close to ammonia) for a bell pepper plant.
The primary way in which ammonia is released into the atmosphere naturally is by putrefaction of living matter. Anything that contains proteins or amino acids (contains an -NH2 bond), when broken down, releases ammonia (NH3). Although wikipedia lists proteins as being 0.86% by weight of a bell pepper, it is possible that your variety (or this particular one) had an excess.
So, combined with other coincidental factors such as infection of the plant, lack of proper air circulation once outside the plant, anaerobic microbes, etc., it is possible that ammonia was actually produced, although the chances are slim.
I don't frequently have peppers from the garden sit around more than 3-4 days. The time sitting on the counter may have been sufficient for that particular pepper to go bad. Unless the plant appears to be producing rotted produce, I would chalk this one up to a statistical anomaly / too much time on the counter. That said, ammonia is an odd smell to get from a rotting pepper; though not uncommon with other foods (e.g. mushrooms).
I don't know if too much nitrogen might be to blame for the ammonia smell (i.e. there is nitrogen in ammonia, thus ammonia smell is from too much nitrogen; but that's an inversion of a logical fallacy). Still, it seems to be the likeliest first step in a more detailed diagnosis if the plant continues to produce fruit that smell like ammonia when they ripen. Are you sure ripenening color was appropriate to the cultivar of the pepper? If you picked it too young the resultant bitterness, then ripening could have forced some odd, under-ripe flavors.
Were you having any sinus issues when this occurred? Do you suffer from post nasal drip, acid reflux? Or, did you have independent confirmation of the ammonia smell? Sorry for the health questions, but I'm curious and trying to approach this from a different angle. If you have independent confirmation, nevermind; but if you suffer from these things occasionally, there may have been something that caused a flare up and resulted in these things stimulating an ammonia-y experience.
