: The main ingredient in vinegar is ethanoic acid / acetic acid. Its chemical symbol is CH₃COOH . It is a weak organic acid , so it dissolves in small amounts in aqueous solution. 100% pure ethanoic acid has a snowy white shape at 16.7 C. Hence it is called glacial acetic acid. It is available as a liquid and is soluble in water in any proportion ; This is because it can form effective hydrogen bonds with water molecules. Its boiling point is 118 C. Vinegar contains 4-10% ethanoic acid. Vinegar is a natural food preservative. Its use in food preservation is very common. The reason is that since it is a mild acid, taking it with food does not increase the acidity but maintains the balance of food and body pH . As it is an acidic solution, it lowers the pH value of the preserved food solution (below 5 to 4 ). As a result, microorganisms, especially bacteria, do not have a favorable environment for growth and reproduction. Vinegar contains 5% ethanoic acid, which has a pH of about 2.4 which is sufficient to kill bacteria. However, applying salt with vinegar makes food preservation more effective. This is because when salt is added, excess water comes out of the food. This is not likely to reduce the concentration of vinegar. Since it dissolves in aqueous solution , it easily mixes with food water, maintaining a balanced concentration everywhere, building resistance against microorganisms. Since its boiling point is higher than that of water ( 118 ° C) , it does not have a chance to evaporate during application of heat during food processing. As it is readily available and has no side effects, anyone can process and preserve food with vinegar and eat it all year round. If it is necessary to reduce the pH value of any food preservation , it can be done easily by increasing the amount of acid in the solution. Generally , the higher the pH value of food items, the higher the acid value of vinegar. Fruits , vegetables , fish , meat can be processed and preserved with the help of vinegar . So the role of vinegar in food preservation is immense.