Kashrut is the body of Jewish law dealing with what foods we can and cannot eat and how those foods must be prepared and eaten on a daily basis. “Kashrut” comes from the Hebrew root word for Kaf-Shin-Reish, which meaning fit, proper or correct. It is the same root as the more commonly known word “kosher,” which describes food that meets these standards. The word “kosher” can also be used to describe ritual objects that are made in accordance with Jewish law and are fit for ritual use.
Contrary to popular misconception, rabbis and other religious figures do not “bless” food and cannot make it magically kosher. There are blessings that observant Jews recite over food before eating it, but these blessings have nothing to how kosher food is made. Food can be kosher without a rabbi or priest ever becoming involved with it: the vegetables from your garden are undoubtedly kosher (as long as they don’t have any bugs, which are not kosher!). However, in our modern world of processed foods, it is difficult to know what ingredients are in your food and how they were prepared, so it is helpful to have a rabbi examine the food and its ingredients and preparation and assure kosher consumers that the food is kosher.
Kosher dietary laws are observed all year round and not just during Pesach (Passover). There are additional dietary restrictions during Pesach, and many foods that are kosher for year-round use are not “kosher for Passover.” A bagel, for example, can be kosher for year-round use but is certainly not kosher for Passover!
This top 10 list focuses on food that are not kosher according to principle laws of Kashrut.
The pig is not kosher because it does not ruminate and chew its cud. With the exception of a case where a Russian Rabbi made pork kosher, this law is universally kept. These laws do not prevent Jews from carrying these animals as pets for other purposes.
All Kosher fish have to have scales and fins. All shellfish do not have the criteria to certify them to be kosher.
Although it chews its cud, it does not have hoofs with clefts. They are thus not clean and walk on their paws; making them un-Kosher.
Jello has gelatin which is a protein in the animal connective tissues. The gelatin, itself, comes from a non-kosher source such as the pig. This law is not universal, as gelatin is not defined in concrete terms. It thus depends on the Rabbi and the source of protein. Most conservative rabbis see it as kosher.
5. Catfish, Sharks, Sturgeon:
These fish do have fins but no scales. As the kosher laws require fish to have both, the three fish are not kosher. This means that black caviar (sturgeon) is not allowed for kosher consumption.