Shekez Hu Lachem (שֶׁקֶץ הוּא לָכֶם) means «this will be an abomination for you». Halacha, or Jewish law, establishes what is permissible and what should be rejected from a kosher table, starting from the rules listed in the Torah, up to the edicts of the Central Rabbinate.
«Do not feed on the blood of any animal, for the life of every animal resides in its blood, and whoever eats it will be cut off».
(Vayikra, 17:14)
Since blood is prohibited in the kosher diet, before consuming an egg it should be checked for its absence. In fact, it is possible to find red spots, caused by protein clots or by the rupture of blood vessels when the egg detaches from the follicle.
If blood is found in the egg white, simply remove it to make the egg kosher; if it is found in the yolk, the whole egg should be discarded.
Generally, it is considered rarer to find traces of blood in the yolks of white-shelled eggs than pink-shelled ones.
«These you can eat among all the winged animals that walk on all fours: all those that have, above their feet, jointed legs for jumping to the ground. Of these you can eat the following: locusts of all varieties; crickets of every variety; and all varieties of grasshopper. All other winged creatures that have four legs will be an abomination to you».
(Vayikra, 11:21)
Among all insects, only some species of locusts and crickets are listed as kosher in the Torah; however, as it is now impossible to establish which these species are, most communities ban them entirely.
At the center of a long controversy, the historical recipe of the Roman Jewish ghettos for artichokes Alla Giudia, which makes it impossible to ensure the absence of worms hidden among the leaves, was recently banned by the Central Rabbinate.
«Any creature of the water that has fins and scales, that lives in the seas or in the rivers, you may eat. But any creature that does not have fins and scales, whether in the seas or in the rivers, among all living creatures in the water, will be an abomination to you».
(Vayikra, 11:9)
Of all aquatic creatures, the kosher diet allows only fish with fins and scales, thereby excluding not only crustaceans, molluscs, and aquatic mammals, but also eels and catfish.
The role of swordfish, in which the dermis - thickened in adulthood - hides the scales, exposed and visible only in young specimens, remains debated.
«You shall not boil a kid in its mother’s milk».
(Exodus, 23:19. Exodus, 34:26. Deuteronomy, 14:21).