Nitrates  and  nitrites:  These are  added  as  preservatives  to  particularly meat products like ham, bacon and pickled meat. They are especially effective against bacteria  like Clostridium botulinum  and  Staphylococcus aureus  which have  a long history of causing lethal  food poisoning. Its preservative action is mainly due to the formation of nitric acid and other oxides of nitrogen and their action increases with decreasing pH value. Nitrates are more effective when they  are used in  combination with common  salt. The  presence  of nitrites  imparts  the characteristic pink color to meat apart from protecting its  flavor. It also delays the  development of off-flavors during storage. Note,  nitrates and nitrites are,  -however, not permitted  to be  added  to  any  infant  food.