I recently started making my own Ranch dressing. It tastes great, but last night when I took it out of the fridge I noticed it had a few bubbles at the surface--similar to what you might see with some fed bread starter. It smelled fine, so I ate it anyway! It was about a week old.

Today, I don't feel so good. Should I not have ignored those bubbles? The mayo, sour cream, and milk it was made from are all still just fine, is what confuses me.

Any input would be greatly appreciated!

Ingredients: 1 Cup Sour Cream, 1/2 Cup Mayonnaise, 1/8 teaspoon Ground Pepper, 1/2 teaspoon Garlic Powder, 1/4 teaspoon Onion Powder, 1 teaspoon Parsley, 1/2 teaspoon Dill Leaves, 1/2 cup Whole Milk. No salt.

  • 1
    Other than mayo, sour cream and milk, what ingredients did it contain?
    – Catija
    Nov 7, 2017 at 19:29
  • 1 Cup Sour Cream 1/2 Cup Mayonnaise 1/8 teaspoon Ground Pepper 1/2 teaspoon Garlic Powder 1/4 teaspoon Onion Powder 1 teaspoon Parsley 1/2 teaspoon Dill Leaves 1/2 cup Whole Milk I left out 1/4 teaspoon salt, because I'm trying to control sodium intake. I wonder if that would help preserve it longer though..
    – rastoboy
    Nov 7, 2017 at 23:42
  • Did you use fresh or dried herbs and did you stir gently or vigorously?
    – Stephie
    Nov 8, 2017 at 5:45
  • Dried. Pretty vigorously. Does that matter? Do the bubbles mean it's bad?
    – rastoboy
    Nov 8, 2017 at 15:25
  • 3
    Hard to say for sure, a number of things could cause bubbles to appear. Harmless would be incorporated air being released. Most of the other causes would not be so harmless though, uncontrolled fermenting (not the good kind), bacterial decay, etc. Mayonnaise can be a notorious source of food poisoning. If it is cause 1, you should see a reduction in total volume, while other causes may increase volume, but that is no certainty. I am afraid, I practice, when in doubt, throw it out.
    – dlb
    Nov 8, 2017 at 16:06

1 Answer 1


For some background: On our site, only official, stringent food safety is on topic. Any further considerations are considered not suitable for discussion here.

From the point of view of food safety, the question "is it bad" does not exist. The only difference that can be made is between safe food, for which there is absolutely no doubt that there is nothing wrong with it, and not safe food, which includes anything from "formally not OK even though 99% of people would eat it" to "I see the maggots crawling in it". There are no further distinctions made, and this one distinction is based not on the actual chance of the food making someone sick (which is usually not calculable) but on what one can prove about the food's chance to make someone sick.

Based on this (admittedly very unintuitive point of view), your dressing, your mayo and your milk are all unsafe. I am not entirely sure if the sour cream may fall under some exception. The reasons:

  • all food you prepared, and all food you bought in a hermetically closed container and opened, is considered unsafe after 3-5 days from preparation/opening, unless it falls under a more specific rule. (There could be one for sour cream, since it is fermented). Your food was opened/prepared 7 days ago.
  • also, the moment you notice something which you don't know if it is spoilage or not, you are required to assume it is spoilage, which makes your food unsafe. So, it doesn't matter what these bubbles are - if you don't know for sure they are OK, they are considered not OK, no matter on which day it happened (this precedes the time-based rule).

I know you were probably expecting a different kind of discussion, but it is not something we can provide.

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