Why do salsas mold so easily?

We stock both red and green Mexican style salsas. I buy what I consider good brands, open a can or jar and immediately repackage unused quantities in clean jars and place in the refrigerator. But often within a week I find that there is mold on top of the contents. Brand doesn’t seem to matter, although I find that Pace doesn’t mold, which is almost more frightening than those that do. So, my question is why are salsas so prone to mold when spaghetti sauces and other bottled sauces do seem to be? What am I missing?


Intriguing question. I buy commercial salsas too (mostly Desert Pepper and store brand). After opening, I refrigerate them in the original jar. I wonder what would happen if you did not transfer the opened salsa to a different jar? Experiment worthy?


Mold is everywhere, whether you see it or not. If you see mold on top of a sauce, jam, jelly, that means that the whole container is permeated with it. If the mold appears on your salsa more quickly than with other sauces, that must mean that there is more mold present when you bought it. When mold appears on top of something, it should be discarded. The only exception is cheese, when the mold is–usually–the mold that cured the cheese in the first place. In this case it only has to be scraped off.

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@pilgrim & @tomatotomato

  1. Salsas: Probably the vegetable bits in salsas are fermenting. They usually contain pieces of green and red peppers, onion, garlic, spices … and sometimes courgette (zucchine) or aubergine (eggplant), carrot and celery.

  2. Also do check your expiration date (caduca) …

  3. I have never changed jars of tomato sauces; I make my own … however, I do know that tomato sauce usually does not ferment as easily as “salsas” for Mexican for example. Many are over-loaded with additives, preservatives and sugar – sugar ferments …


I wonder if adding a little extra acid like lemon or lime juice will help.

I’d pay a premium for small jars.

Are your jars that clean as you believe? You need to sterilize them if you want them to be really clean.

Also, is there cheese in your fridge? I find when my cheeses are not store in air tight container, all types of food in the fridge tend to mold faster.


I assume those you bought were commercial brands and not traiteur ones…

You mean salsas are not loaded with additives and preservatives?

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This happens to me. Helpful to know I’m not the only one.

So much good thought to consider! Thanks much.

My confufflement is because nothing else in my refrigerator seems to acquire mold. I have wondered if it is because they are so free of additives, including sugar. I am talking about decent ethnic brands like La Victoria and Herdez and also some uber-expensive Hatch products.
I do buy as small a container as possible until I hit that tipping point where it is cheaper to buy large and toss excess rather than the smaller container.
I am wondering if there is such a low acid content in salsas compared to other sauces and condiments, so @Respectfully_Declined 's suggestion of adding acid is very reasonable.
All suggestions happily considered. To be continued…


I am thinking it’s because the discrete pieces in the salsa are fine bits, and thus more prone to biodegradation. One thing in my experience that helps is to take a small spatula, and scrape the neck of the jar back in to the bulk of the salsa, or alternatively, discard it. I also sometimes wipe the underside of the lid off with a paper towel. I’ve had success doing those two things.

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Thanks. But cleaning jar neck and lid are SOP.

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I notice you mention bottles and cans. Do you notice if this is also true for the salsas in the refrigerator section? When I buy salsa, that’s what I get, and they don’t seem to mold any faster than an opened tomato product, which in my house can be within a week or ten days.

OTOH, the place we usually get tacos from includes little table spoon size plastic cups of a blended salsa, and if I leave it out overnight the top puffs out and even explodes! It seems to ferment quickly, but I don’t see mold.

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I keep my salsas in the freezer.

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I have never bought jarred Salsas …

I am inclined to believe the majority do have preservatives and additives … However, ecological or biological do not …

That would be indicated on the labels.

A popular refrigerator brand around here.

I stumbled on this from The Kitchen, which says it stumbled on the info on Still Tasty.

Jarred/canned salsas and refrigerated/home made ones are two different animals. We make our own fresh salsa, just enough for the meal. The commercial canned product I use for enchiladas, but there is usually more than I want to use, ergo into the fridge. Also for fast Mexican style salad dressings: a splat in Mayo, etc.
Most of the refrigerated salsas do contain sodium benzoate or similar preservative. The canned sauces, like Herdez, just basic recipe ingredients.

I’d question that assumption! While that mould has a natural head start, it could be anything. And if you see two visually different moulds fighting a trench-warfare battle over the surface of your cheese, then do the maths – at least one of them is a blow-in! :smiley:

But contrariwise, I’d very much argue against the ‘throw out the whole container’ policy. Or at least, personally blithely ignore it. Jams and jellies are after all pretty much designed for the whole purpose of spoilage-resistance – everything likes sugar, but everything dies from too much of it, one way or another. But certainly it’s deeper than visual.

And indeed, “is everywhere” is a pretty good summary. If you ever see it in your kitchen, you’re probably eating significant amounts of it without there being visible fruiting bodies!


I’ve never seen either term on a label for anything, so I’m assuming there’s a language or jurisdictional difference here. (Or my life is even more sheltered than I realized!) Products could be labelled “organic” or “biodynamic”, and still have added preservatives.

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I definitely think so, yes! Mould spores really are everywhere, including inside one’s immaculately clean stored jars. Unless you wash and boiler-sterilise them and instantly use them. So rejarring food is giving the spores an inch, and they’ll merrily take a mile.

Conversely of course rejarring into a small container will reduce oxidisation of the food itself, and give microbes less, well, oxygen! So there may be a swings and roundabouts aspects, depending on the foodstuff, and on the ambient conditions.