Gastric acid
The highest concentration that gastric acid reaches in the stomach is 160 mM in the canaliculi. This is about 3 million times that of arterial blood, but almost exactly isotonic with other bodily fluids. The lowest pH of the secreted acid is 0.8, but the acid is diluted in the stomach lumen to a pH between 1 and 3.
Botulism
Low-acid foods have pH values higher than 4.6. They include red meats, seafood, poultry, milk, 
and all fresh vegetables except for most tomatoes. Most mixtures of low-acid and acid foods also 
have pH values above 4.6 unless their recipes include enough lemon juice, citric acid, or vinegar 
to make them acid foods. Acid foods have a pH of 4.6 or lower. They include fruits, pickles, 
sauerkraut, jams, jellies, marmalades, and fruit butters.