The dietary laws in Judaism, as explained in the Torah (the five books of Moses) are rules allowing and disallowing certain kinds of food. Nowadays, with food additives, it is difficult to know what is kosher (clean) and what is treif (dirty). Below is a list of the UNKOSHER food additives:

E120 E422 E432 E433 E434 E435 E436
E470 E471 E274(a) E472(b) E472(c) E472(e) E473
E474 E475 E476 E477
E481 E382 E483
E491 E492 E493 E494 E495
E542 E570 E572


There are also products which do not have EEC serial numbers, but which are still unkosher:
Edible Fat/Oil, Fish Oil
Gelatine, Glycerides, Polysorbates, Stearates, Diacetin, Triacetin
Casein, Caseinates
Wine Vinegar, Wine/Brandy
Shortening, Rennet

Of the above, Wine Vinegar, Wine and Brandy are unkosher because of regulations controlling the production and harvesting of wine, and not because they may contain animal products (although it has been said that some wine presses are greased with animal fat).