we now study the effect of four acids used as food additives: acetic and lactic acids that heterofermentative microorganisms release into the surrounding media during the various processing steps in commercial production of sourdough bread ; citric acid, one of the most common additives used in the food industry, which behaves as a sequestering agent; and monosodium phosphate, an inorganic salt from which a similar acidic behaviour is expected in the dough