Gastric acid network (called canaliculi) from which the hydrochloric acid is secreted into the lumen of the stomach. The pH of gastric acid is 1.5 to 3.5 in the human stomach lumen, the acidity being maintained by the proton pump H/K ATPase. The parietal cell releases bicarbonate into the bloodstream in the process, which causes a temporary rise of pH in the blood, known as an alkaline tide. The highly acidic environment in the stomach lumen causes proteins from food to lose their characteristic folded structure (or denature). This exposes the protein's peptide bonds. The gastric chief cells of the stomach secrete
Microbial food cultures from 1970s—production of first industrial concentrated cultures, frozen or freeze-dried cultures, for the direct inoculation of processed milk, improving the regularity of production processes. Microbial food cultures preserve food through formation of inhibitory metabolites such as organic acid (lactic acid, acetic acid, formic acid, propionic acid), ethanol, bacteriocins, etc., often in combination with decrease of water activity (by drying or use of salt). Further, microbial food cultures help to improve food safety through inhibition of pathogens or removing of toxic compounds. Microbial food cultures also improve the nutritional value and organoleptic quality of the food. The microbial food cultures used