St Thomas Aquinas had some
views on this question.I don’t think that is a very useful angle to approach this. If we hold that crackers are “not bread” in the common sense of the word, we must then explain why hosts qualify as bread and not crackers in the common senses of the words. I don’t have any good explanation; I think that hosts are more cracker than bread. Therefore, I contend that crackers are bread for our purposes.
Next we must assess what disqualifies bread/crackers from being valid matter. St Thomas addressed the mixing of other ingredients specifically with regard to other grains, but I think his view would also apply to other impurities and ingredients. There is certainly much more wheat than all the other ingredients in most crackers, so that’s not helpful in disqualifying things.
Thomas also said “such corruption of the bread that the species of bread is lost, as when the continuity of its parts is destroyed, and the taste, color, and other accidents are changed.” Strictly speaking, he’s only addressing something that is no longer bread at all, but I think we can apply this approach more liberally to disqualify as valid matter cheese bread and garlic bread. While it may not be as noticeably different from a plain wheat cracker as the
Xplosive Pizza flavor, I lean toward the idea that even the regular flavor of Goldfish differs enough from plain wheat that it is invalid matter.
Another factor is the yellow-orange color. Thomas thinks color is an essential part of the species of bread - in this day and age I happen to disagree. If a few drops of food coloring accidentally got mixed into the recipe for hosts, I think it would still be valid matter even if it had a bluish hue.
Anyway, my bottom line is that unsalted saltines or similarly basic crackers do qualify as valid matter; goldfish and other flavorful snacks probably don’t qualify, and that the priest didn’t intend to consecrate anything under the pew even if it was valid matter.At larger masses, such as some papal masses, the quantity of bread and wine may be greater than can be fit on the altar (at least without undignified stacking). At such events, I think they usually manage to keep the chalices on the altar, but there are sometimes large containers of hosts standing beside the altar, or being held by clerics adjacent to the altar. The important thing is that the priest celebrant intends to consecrate those particular hosts, but not the spare hosts behind the wall six feet away.