24th of Adar, 5770
According to the Ashkenazi custom any food (we are talking today about industrial food products) to be consumed during Pesach has to be prepared or manufactured under special rabbinical supervision for Pesach.
The Sephardic tradition, however, holds that foods which do not contain any Chametz ingredient in their basic composition are permitted during Pesach, provided that they were bought before Pesach begins.
Regarding food additives, if the additive is present in the final product in a proportion smaller than 1.6% of the total product and that food was elaborated before Pesach, that food is permitted during Pesach even if eventually that additive would be considered Chametz (eno choze veneor)
Moreover, any food with no Chametz ingredient in its composition will be allowed, even if it could have been processed in machinery previously used for Chametz, and that eventual "cross contamination" (Noten Taam barNoten taam) with Chametz would not render a food as Chametz if that food was elaborated before Pesach.
That is why all the products that are allowed to use in Pesach without special Hashgacha must be purchased before Pesach.
Some examples: regular tea, pure sugar, regular salt, fresh fish, fresh meat and poultry, fresh milk, fresh fruits, and fresh vegetables, 100% pure saffron and many other products, when we know for sure that no Chametz ingredients were used in them.
PS: B'H soon we will publish a list of other products which do not contain Chametz and therefore are permitted even without a special Pesach supervision.