I heard something about this on the apprentice but it was to do with a chicken. As a chicken is slaughtered it is blessed by a holy man. maybe it's the same.

(http://www.koshercertification.org.uk/) Rabbis inspect and certify food under numerous regulations -- see the link above

A couple of principles, first: 1. Meat ____a. Must come from a Kosher Animal that both chews its cud and has split hooves. Sometimes Deer and Buffalo are included. ____b. Animal must be hoisted and slaughtered by a qualified, trained, religious person, using a very sharp knife and one stroke against the trachea and neck artery. Blood must be drained. ____c. Carcass has to be inspected (esp. lungs) for adhesions and other defects. The hindquarter is usually discarded and sold to non-kosher butchers, because the Sciatic Nerve renders that part forbidden to Jews. ____d. The cut pieces of meat must be soaked and salted to remove all blood. 2. General ____a. Meat and Dairy products must never be mixed together. A Kosher-Pareve label certifies that the product is "neutral," and can be used with either meat or dairy meals. Non-Jews rely on the label for dairy-free content. ____b. All Seafood must have fins and scales. No Shrimp, Lobster. Seafood should not be an ingredient in meat products. ____c. All products must have Kosher ingredients. Each is checked by the Certifying Authority. Gelatin may be made from non-Kosher bones; Carmine coloring comes from non-Kosher beetles; seaweed or other vegetables may be infested with insects or other animal organisms, etc. Naturally, there's more and complex. The Kosher Certifying Authorities maintain high standards, because a lot of religious people rely on them. That's it in a Kosher Nutshell.

Kosher essentially means clean, but there are a long list of rules that need to be followed for food to be considered kosher. Scavenger animals are not kosher. Only animals with split hooves, chew their cud and are healthy can be used for kosher. Fish must have scales. Fowl must be herbivores. Eggs must be unfertilized. A masgiakh is paid to supervise that the food is in fact being prepared according to Jewish cleanliness rules. He certifies that the food is in fact clean and proper for human consumption. That the animal was slaughtered as humanely as possible and accordance to Jewish law and that the animal was healthy and was well treated.

Processed foods need to be supervised to make sure that no non-kosher ingredients* are included in the food. This supervision includes seeing that the kosher products are not produced on the same production line as non-kosher products. A representative from the supervising facility will visit factories sporadically to ensure that the kosher procedures are followed. He will then renew the kosher "licence on those products for the next few months until his next inspection. * Non kosher ingredients could be: Meat/milk mixtures, gelatin, meat products that are not from kosher animals or birds that have been ritually slaughtered, vegetables that are known to have insect infestation and need to be cleaned before use.