Lemons, lime, and other unripe citrus fruit
They will eat certain sour foods, but don't really prefer them. They have been known to eat moderately sour foods, such as yogurt, without a problem, but will not eat lemons or other citrus. They generally stay away from sour drinks.
Sour tasting foods are usually acidic. The sour taste in foods comes from acids such as citric acid, malic acid, or acetic acid that stimulate taste receptors on our tongue and trigger a sour sensation.
Some foods that are sour are lemons, grapes, and tamarind. Some types of oranges and some melon can also have a sour taste to them.
sour milk
yes
I have never noticed a sour taste in my dairy foods. You are possibly letting it get over date.
Citric Acid
Lemonade or vinegar are examples of foods that have a sour taste.
lemon, lime, vinegar, sour sweets, unripened fruit,
acids
When you taste sour while consuming certain foods or beverages, it is because they contain acids that stimulate taste receptors on your tongue, sending signals to your brain that interpret the sensation as sour.
Some foods include yogurt, cheese, and sour cream