Stomach Acid and Antacid

We use the enzyme pepsin and hydrochloric acid to simulate the conditions within the stomach in two boiling tubes. Cooked egg whites are ground and added to two boiling tubes of hydrochloric acid, but one is mixed with a crushed antacid tablet first. We see how the antacid neutralises the hydrochloric acid and prevents the egg from breaking down. Then pH paper is used to see how the acidity of the mixtures changes. Biology - Human Body- Learning Points. Food needs to be digested before it can be absorbed into the bloodstream. Digestive enzymes act to chemically break down food molecules, such as proteins. Pepsin is a protease enzyme. Protease enzymes break down proteins into amino acid. Pepsin has an optimum pH of 3, which is created by the hydrochloric acid secreted by the stomach. People sometimes take antacids to neutralise their gastric acids (also known as stomach acids) and alleviate problems such as indigestion. A Twig Experiment Film. Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.