​How Long Is Mayonnaise Good for After Opening?

Homemade Mayonnaise
You make homemade mayo from fresh items. These include raw eggs, oil, and lemon juice or vinegar. It does not contain store-bought preservatives. So, it goes bad much faster.
You must put homemade mayo in the fridge right away. It is good to eat for about three to five days. Always check it for changes. If it looks strange, smells sour, or turns watery, throw it out. Because it uses raw eggs, it can have salmonella. Do not keep it longer than five days.
Store-Bought Mayonnaise
Store-bought mayo lasts longer. Companies use pasteurized eggs. This process kills bad bacteria. They also add preservatives. These ingredients fight spoilage and keep quality high.
After you open it, you must refrigerate it. Keep the lid on tight. It will usually stay good for two to three months after its "best by" date. Always read the label for specific advice.
Remember this rule: if mayo sits out for more than two hours, do not eat it. If the room is very hot, over 90°F, throw it away after one hour. Bacteria grow fast in warmth. Putting it back in the fridge does not make it safe again.

You can keep an unopened jar in a cool, dark pantry. It will stay good for one to two months past the "best by" date. If your pantry is warm, refrigerate it instead. This keeps its flavor and texture better.
The "best by" date is about quality, not safety. But once you open the jar, you must put it in the refrigerator. Never leave an open jar on the counter.

How to Tell If Mayonnaise Has Gone Bad?

You can easily see if mayo is bad. First, look at it. Good mayo is smooth, creamy, and light in color. If you see any mold, throw the entire jar away. Mold grows deep roots you cannot see.
Next, smell it. Fresh mayo has a light, tangy smell. A strong sour or nasty odor means it is spoiled. Finally, feel its texture. If it is lumpy, watery, or will not mix when stirred, it has gone bad.

People often ask：People often ask：does mayo need to be refrigerated？ An unopened jar does not. But once you open it, you must refrigerate it.
Always close the lid tightly after use. This blocks air and moisture. Do not dip a dirty spoon into the jar. This can put bacteria inside. It is best to use a clean utensil every time.
Keep the jar in the main part of the fridge. The door is too warm because it opens often. The constant temperature change makes spoilage happen faster. A cold, sealed jar stays fresh longest.

Can You Eat Expired Mayonnaise?

You should not eat expired mayo. The "best by" date shows when quality may drop. After that, the preservatives work less well. This lets bacteria grow more easily.
If it is only a few days past the date and was always cold, you can check it. But if it is weeks old or was left out, do not risk it. Buying a new jar is cheaper than getting sick.
If you are not sure if it is safe, the best choice is to throw it away.

You might feel nauseated, vomit, have diarrhea, or get stomach cramps. A fever is also possible. Most healthy adults feel better in a few days. But it is more serious for young children, the elderly, or sick people.
Very bad cases can cause dehydration. If you have a high fever, bloody stool, or feel very weak, see a doctor immediately.

How to Make Homemade Mayonnaise When It Expires？

If your store-bought mayo is gone, you can make your own. You need a few simple things: one pasteurized egg (it is safer), one cup of neutral oil, one tablespoon of lemon juice, 1/4 teaspoon of salt, and a little sugar if you want.
Put the egg in a blender. Blend it for ten seconds. Then, slowly add the oil while the blender is on. Keep pouring until the mix gets thick and creamy. This takes about one or two minutes.
Stop the blender. Add the lemon juice, salt, and sugar. Stir everything together. Taste it and add more seasoning if you like. Put your mayo in a clean jar. Close the lid and put it in the fridge. It will stay fresh for three to five days. Only make what you will use soon.