Preservatives and pH
Part of the Food Chemistry and the Lab section of Coddy's Chemistry journey. Lesson 15 of 27.
Most bacteria cannot grow in acid. Vinegar (ethanoic acid) and lactic acid preserve food.
Lactic acid, the acid of yogurt: a hydroxyl group and a carboxyl group
A brine of pH 3 or lower keeps most bacteria away. pH = −log[H₃O⁺]: lower pH, more acidic.
Preservatives like sodium benzoate work best in acidic drinks.
Challenge
A jar of pickles is kept in a brine with [H₃O⁺] = . Work out the pH of the brine and say whether it is acidic, neutral or basic.
Try it yourself
Acids and basesWork out the solution
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.