Issur ve-Heter and Kashrut
Principles
Kashrut law rests on the categories of issur (forbidden) and heter (permitted). Know the simanei behemah (split hooves and chewing cud) and simanei dagim (fins and scales). Understand basar b'chalav, treifah, neveilah, and shechitah requirements.
Mixtures (ta'arovot)
Master bitul (nullification): batel b'shishim for most forbidden foods, batel b'mashehu for certain categories, and bitul b'rov for mixtures of the same type. Know nat bar nat and ta'am k'ikar.
Supervision
Understand hashgachah (kosher certification), ne'emanut (reliability), and chazakah (presumption of status). Know the rules of bishul akum, pat akum, and stam yeinam.
Traps
- Applying bitul b'shishim to a case requiring bitul b'mashehu (e.g., a whole insect).
- Confusing bishul akum (which applies to certain cooked foods) with general non-Jewish cooking.
- Ignoring the difference between a forbidden food that is batel and one that is not.
Worked example
A drop of milk falls into a pot of chicken soup. Since milk and chicken are both forbidden to mix, the milk is batel b'shishim if the soup is at least 60 times the volume of the drop. If the drop is a whole piece of cheese, bitul does not apply because it is a davar she'yesh lo matirin or a whole entity.