Citric Acid
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.
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 milk
yes
Hydrochloric acid makes vomit sour.
I have never noticed a sour taste in my dairy foods. You are possibly letting it get over date.
Lemonade or vinegar are examples of foods that have a sour taste.
lemon, lime, vinegar, sour sweets, unripened fruit,
the citric acid makes it sour
sour powder I think
acids