Homemade tuna salad should generally be eaten within three to four days when stored continuously in a refrigerator at 4°C or colder. Keeping a large bowl for an entire week is not recommended, even when it still looks and smells normal.
Ingredients such as mayonnaise, chopped eggs, celery, and onions can affect quality, but the main safety issue is time and temperature. Harmful bacteria may multiply without producing an obvious smell, unusual colour, or visible mould. That means tasting an older salad to decide whether it is safe is risky.
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