Question

the example of acid used in food flavouring and preservative

Answer 1

Since many bacteria are unable to grow in an acidic environment, citric acid is often added to jams, jellies, candy, canned foods, and even meat products as a preservative. Because citric acid can be made in a powder form, it can also be used in dry foods when a sour flavor is desired.

Answer 2

acetic acid is the answer.