Re: What are the pH levels in the stomach during a titration of saliva & food?

The pH of the stomach may go as low as 1.0. This is a very acidic level. 
Because the pH scale is a logarithmic scale, the pH of the stomach is 
hundreds or thousands or millions of times stronger than typical cellular 
fluids which are generally close to 7.0 (the neutral level on the pH 
scale.)  When food comes into the stomach, the pH may rise to levels in the 
3.0 to 4.0 level due to the buffering capacity of proteins.

The stomach secretes hydrochloric acid (HCl). This strong acid can directly 
degrade proteins and it also creates conditions in the stomach that 
encourage the formation of the ionic form of iron that can be absorbed. The 
enzymes that the stomach lining secretes are specially "designed" so that 
they work best in a strongly acid solution.

Sometimes the protective ability of the stomach lining breaks down and the 
acid eats a hole into the stomach or duodenum. These are gastric or 
duodenal ulcers, respectively. They are treated with drugs that inhibit the 
stomach's production of acid.

After the food enters the duodenum, bicarbonate ions are secreted to 
neutralize and alkalinize the food mixture. The pH of the small intestine 
is in the 8.0 area.

Solutions at a pH of 1.0 are strong enough to burn through fabrics, injure 
eyes or irritate skin. Be careful if you are trying to replicate stomach 
conditions. Wear eye protection and wash your hands if you come into 
contact with the solutions. Have a plan for eye irrigation and transport to 
an emergency room if an accident occurs.

Hope this helps,
David Winsemius, MD