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I haven't attempted homemade mayonnaise yet, but reading about how long can it be kept for consumption I found many recipes talk about requiring to keep the prepared mayonnaise for a period at room temperature (actually 20-22 Celsius is cited, what happens if it's a few degrees higher?) first because the acidity from the vinegar works better at killing salmonella when the temperature is above that of refrigeration. Here is a previous SE answer for reference.

So, my main question is whether using just-pasteurized whole eggs negates the necessity of this step?

Another question is whether the general direction I found for vinegar ratio—20ml per egg yolk; 40ml per egg white; 60ml per whole egg—is not too broad? If that aspect is even important with pasteurized eggs, I read an egg+vinegar pH of 4.1 or less is required, but the eggs themselves can have a variety of weights and possibly pH variations.

And finally, if the mayonnaise was properly made, with pasteurized eggs in a sterilized container, is it still only safe to consume for a week or so in refrigeration?

Thanks.

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The main question was answered in the first reference cited in the answer you linked (The fate of Salmonella enteritidis PT4 in home-made mayonnaise prepared with citric acid).

To maintain mayonnaise Salmonella free, the pH should be 4·1 or less and the product should be held at 18–20 °C for at least 72 h unless pasteurized eggs are used (Smittle 1977)

(emphasis added)

If an egg is properly pasteurized, virtually all Salmonella is destroyed. The USDA considers pasteurized eggs safe to eat raw:

in-shell pasteurized eggs may be used safely without cooking.

Shell Eggs from Farm to Table - USDA

Do note that you still need to be careful about properly handling and storing pasteurized eggs, as there is still some risk of introducing other harmful bacteria.

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  • Yeah, perhaps the overall wording didn't seem clear enough to me (and the cited temperature range is a bit different across the report, perhaps due to it citing earlier studies). So using pasteurized eggs should it actually be preferable to place the mayonnaise in refrigeration right away? And the acidity level could be disregarded (so one may add to taste but not under strict consideration of killing non-existent bacteria)?
    – TLSO
    Jun 23 at 22:29
  • @TLSO, personally, I would think you're right about those other points (that you can refrigerate right away and not worry about the pH), but, it's possible that the vinegar might also kill other bacteria (maybe in the oil, or in the mixing bowl). The linked studies don't appear to consider this, so there's likely no definitive ruling, but it's possible that you'd get some benefit from leaving a low pH mixture out of the fridge, even with pasteurized eggs.
    – Juhasz
    Jun 23 at 23:41
  • Well, oil itself shouldn't have bacteria in it (or at least it doesn't promote bacterial growth, but perhaps viable spores could be found). I did read about garlic (which is often added as a spice to mayonnaise) that it is often contaminated with botulinum spores and these can survive boiling temperatures for hours, and in oxygen-deprived environments (such as oil submersion, perhaps mayonnaise if not acidic enough?) it can start growing and producing toxins. So it could be indeed that aiming for a ph around 4.0 could help mitigate these other things.
    – TLSO
    Jun 24 at 0:49
  • Although I wonder if the amount of oil shouldn't also be regulated. Oil itself doesn't have an acidity rating, but won't the potency of the egg-vinegar acidity diminish with increasing oil ratios? And that still gets us back to the question, for how long can a refrigerated homemade mayonnaise stay edible? The cited study mentions "All mayonnaise samples stored at 22 °C were spoiled by moulds in 6–10 d, while no visible moulds were observed after 1 month when they were stored at 5 °C", but no visible molding isn't necessarily good enough.
    – TLSO
    Jun 24 at 0:57
  • Just to update, I tried making this today using 1 whole extra large egg, 60ml of vinegar as adviced somewhere else, 1 cup of oil and some seasoning. It is way too sour and not thick enough, more like a salad dressing. I think the 60ml recommendation was in a different scientific review, so perhaps that's correct health wise for whole egg mayonnaise, but it's not great tasting and not thick enough without some additives. Perhaps that's another reason why using only egg yolks works better, as the white is somewhat alkaline and calls for a greater ratio of vinegar to reach <4.1 pH.
    – TLSO
    Jun 24 at 11:29

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