How much Impure Food must be present, in order to communicate impurity: Shabbat 91a, 144b-145a; Eruvin 82b-83a; Pesachim 15b, 33b, 34b, 45b, 49b; Rosh HaShanah 13a; Yoma 80a; Ketuvot 64b; Keritot 13a
The size of "Achilat Peras" ["eating a portion"], a key threshold quantity of food: Eruvin 4a, 82b-83a; Yoma 80b; Keritot 12b
All foods combine to reach the necessary threshold quantity to make their consumer impure: Eruvin 29a
All foods combine to reach the necessary threshold quantity to make other foods impure on contact: Eruvin 29a
Combining food, an egg-sized amount of which is subject to tumat ochlin, with a piece of a dead person, an olive-sized amount of which is subject to tumat meit: Keritot 21a-b
Combining grain, flour and dough to reach the threshold quantity for communication of impurity: Menachot 70b
Combining grains with their shells for the threshold amount, while moist or dry: Menachot 70b
Berries whose outside are impure, crushed in amounts of less than an Egg-Size to avoid making the juice Impure: Pesachim 33b, 34b
If the olives or grapes were of exactly an Egg-Size when they were crushed, releasing juice but reducing the Amount: Shabbat 144b-145a
The threshold amount here is different from the threshold quantities given for other laws of consuming food: Eruvin 4a; Yoma 80a
Whether one contracts impurity if he eats part of the shiur [threshold amount to contract impurity], then immerses in a mikvah, and then eats the rest: Keritot 13a
Keeping someone from using the mikvah after he has consumed less than the shiur of impure food, lest he consume the rest of the shiur after immersing and therefore become impure without knowing it: Keritot 13a
Combining impure food with dough in which it is wrapped, to reach an egg-sized amount: Keritot 21b
Shiur in Time - kdei achilat peras
Whether one contracts impurity if he interrupts during an act of eating impure food, such that the pre-interruption and post-interruption acts of eating do not combine with each other: Keritot 12b-13b
Whether one contracts impurity if he eats continually but it takes him a long time to reach the threshold amount for communicating impurity: Keritot 12b-13a
Combining drinkings of amounts which are less than a reviit, if one drinks them within the time it would take to eat a peras, to communicate impurity: Keritot 13a
Whether one creates pigul with a thought of eating a korban inappropriately, but over a longer time than kdei achilat peras: Zevachim 31b
