I made homemade mayonnaise last weekend with fresh eggs and oil, but I'm not sure how many days it'll last in the fridge before it goes bad. Is there any trick to make it last longer, or is it just not recommended to store it?
I've left it for up to a week and it worked fine, but that's because I keep my fridge at a constant temperature; if yours fluctuates a lot, you're better off not risking it beyond 3 or 4 days. The raw egg is what limits it, so if you want it to last longer, make it with pasteurized egg or cook the egg outright.
Don't keep it for more than three or four days because it has raw egg in it and the risk of botulism or salmonella increases over time, especially if your fridge temperature fluctuates. The best thing is to make small batches right before you use it, or if you want it to last longer, pasteurize the egg first by heating it to about 63 degrees for a while (even though it'll lose a bit of its edge). If you notice a weird smell or color changes, throw it out without thinking twice.
Botulism actually isn't that likely with homemade mayo because the acid from the lemon or vinegar you use lowers the pH and botulism doesn't like that environment, but you're right that raw egg is still a risk. What nobody mentioned is that it really depends on how you store it: if you leave it in an open container or one that breathes, it gets contaminated faster than if you put it in an airtight one. I'd say with a tight lid and a stable fridge you can easily make it to five or six days, but if you notice it looks off, smells different, or has a dull color, don't use it; it's better to make it fresh when you need it instead of keeping it around for weeks.
Log into answer.
