1. qiniyot. As we explained yesterday, the Ashkenazi custom is to refrain from eating rice and any other kind of seeds during Pesaḥ. This is called isur qitniyot (the prohibition of legumes). Now, even though the Ashkenazi custom forbids the consumption of qitniyot during Pesaḥ, qitniyot products could be kept during Pesah at one's home and there is no need to throw them out or sell them (Rabbi Eliezer Melamed, penine halakha, following SH. A. Rama, 453:1). Also, as pointed out by Rabbi Eliezer Melamed, although the Ashkenazi custom is to forbid qitniyot during Pesaḥ, that is only when the qitniyot constitute the majority of that product (more than 50%) but if qitniyot are present in a smaller proportion (corn-syrup, corn-starch, etc), the food is not forbidden (see Mishna Berura 8-9). You can read the book of rabbi Eliezer Melamed, Penine halakha online, here
2. eno hozer vene'or. The Sephardic tradition holds that if a food does not have a Hamets ingredient or by-product in their basic composition, but has a Hamets additive or ingredient in a proportion smaller than 1.6 (or 1/60) of the total product (usually an additive), if that food was elaborated before Pesah, that food is permitted for Pesah. Whereas for the Ashkenazi custom, it does no make a difference if the food was done before or during Pesah: even a minimal amount of Hamets (0.001) renders the whole product non-Kosher for Pesah. There are many practical consequences to this rule. One of them is that for the Ashkenazi custom every product to be consumed during Pesah has to be done exclusively under strict Kosher for Pesah Rabbinical supervision. Thus, in a food factory, the criteria to avoid the presence of Hamets would be, in practical terms, the same as the criteria applied to avoid the presence of an allergen in the food product. Establishing a complete Hamets-free environment to preventing even an accidental Hamets's cross-contamination.
Dedicated to the memory of Ya'aqob Ben Yehuda z"l