In some cuisines, fish recipes include lemon garnish or a vinegar sauce such as sweet and sour sauce. Why these common culinary techniques might be used in terms of organic chemistry?
Lemon garnish and vinegar sauce are used to provide a "tangy" taste to the food.
The "tang" comes from the acids in the foods.
Citrus fruits like lemons contain citric acid.
The molecule contains three carboxylic acid groups, so we can write its dissociation as
Vinegar is a dilute solution of acetic acid in water.
The hydronium ions cause the taste cells to fire in in a specific manner that gives the characteristic taste sensation.