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Keeping kosher is a Jewish religious observance going back thousands of years. Read on to find out more about these sacred dietary rules, and how they have adapted to modern food production.
What kosher means
Kosher foods are those that are considered fit for consumption under Jewish dietary law, or kashrut. These laws are taken from the Torah, primarily the books of Leviticus and Deuteronomy, and outline which foods are permitted (kosher), and how they should be prepared, as well as which foods are forbidden (trief). To outsiders, kashrut may seem like a particularly strict set of food safety rules, but for many Jews, keeping kosher goes beyond practical motives, and is an important way of showing obedience to God.
Kosher rules are extremely complex, and some Jews observe only some of them, or none at all. Modern food production methods can make life difficult for those who are strict in their observance, as many products contain multiple ingredients whose nature and preparation method is near-impossible to guess.
Kosher food is divided into three categories:
Meat, or fleishig, includes any kosher meat or poultry, as well as products derived from them, like broth.
Dairy, or milchig, includes milk-derived products such as milk, cheese, butter and yoghurt.
Pareve refers to all other kosher foods, including fish, eggs, and plant-based foods.
Food combinations
Even if a food is classed as kosher, there are certain foods that should never be eaten together. Any food that is classed as meat (fleishig) should never be eaten at the same meal as a food classed as dairy (milchig). You should also wait a set amount of time after eating meat before you eat dairy. This varies according to different customs and can be anywhere from 1 to 6 hours.
To properly prepare kosher food, you should keep separate sets of utensils and equipment, one set for the preparation of meat, and one for the preparation of dairy. These utensils should be kept apart from one another, and washed in separate sinks, if possible.
Food from the pareve category can be eaten with either meat or dairy according to most traditions, although the matter is still debated, and there are various exceptions. For example, if a pareve ingredient is prepared using your meat utensils, it is reclassified as meat, and cannot be eaten with dairy. Similarly, if you use your dairy utensils, the pareve ingredient cannot be eaten with meat.
Fish is classed as pareve, but this too must not be eaten or prepared with meat. In this case there is no need to wait a set amount of time between eating one and the other, but it is customary to cleanse your palate by having a drink or eating some bread.
Meat
For the meat of an animal to be considered kosher, it must meet both of the following requirements:
It must have cloven hooves - this refers to animals that have a split down the middle of their hooves. Horse meat is not considered kosher, because horse’s hooves are in one piece rather than two halves.
It must be a ruminant - a ruminant is an animal that chews cud, a semi-digested ball of food that is brought back up from the stomach to be chewed again. Pigs are perhaps the most famously non-kosher animal, and this is because, despite their cloven hooves, they do not chew cud.
Examples of kosher animals include cows, sheep, goats and deer. All of these animals have cloven hooves and chew cud.
For meat to be considered kosher, it must be taken from the forequarters of a kosher animal and prepared in a specific way, from the slaughterhouse to your plate. The animal must be slaughtered by a trained kosher slaughterer, or shochet, and its internal organs carefully inspected for any abnormalities that could render it non-kosher.
Certain blood vessels and nerves are considered non-kosher, and it is also forbidden to consume any blood. The non-kosher parts are cut away, and all blood is drained from the meat by broiling or using large salt crystals, known as kosher salt, to draw the blood out of the meat.
Poultry
When it comes to kosher poultry, the Torah does not give a set of criteria by which kosher birds can be identified, instead giving a list of birds that are non-kosher. Due to translation issues, it is difficult to identify all of the forbidden birds on the list, but it is generally agreed that birds of prey, scavengers and seabirds are non-kosher, while chicken, turkey, duck and goose are usually considered kosher. As a part of the meat (fleishig) category, poultry should be slaughtered, inspected and prepared in the same way as other meats.
Fish
According to the Torah, fish must have both scales and fins in order to be considered kosher. This means that shellfish are not kosher. Fish is classed as pareve, and does not require any special preparation. As discussed above, it should not be eaten or prepared with meat. This includes using any food item where fish is an ingredient, such as fish sauce or Worcestershire sauce.
Milk, eggs and oil
Dairy products such as milk, cheese, butter and yoghurt are permitted if they meet certain criteria. They must be made using the milk of a kosher animal, and all the equipment and other ingredients used to make them must be kosher too. Due to the law against mixing meat and dairy, dairy products should not contain any meat products, which means no animal rennet in your cheese, for example.
Eggs should also come from a kosher bird, or, in the case of caviar, a kosher fish. They must not have any traces of blood on them, which means that each egg must be inspected individually. Once laid, an egg is considered pareve, but if it is found inside an animal after slaughtering, it is considered to be a part of the animal, and is therefore classed as meat.
Although vegetable or nut oils are made using pareve ingredients, they may not always be kosher due to manufacturing procedures. Some oils may contain animal additives such as digestive enzymes, which are impossible to verify as kosher without seeing the animal they were taken from. Others may have been manufactured using equipment previously used for non-kosher ingredients, so even oil that has been certified vegetarian may not be kosher. As with any manufactured foodstuff, it is best to look for kosher-certified products if you want to be sure.
Fruit and vegetables
All fresh fruit and vegetables are considered kosher, but if they have been processed in any way - including canned or frozen produce - you should look for kosher certification to confirm they haven’t been processed using non-kosher equipment and don’t contain non-kosher additives.
One thing you do need to look out for with fresh fruit and vegetables is possible insect infestations. Any insect that is visible to the naked eye is non-kosher, so it is important to inspect produce very carefully, under a bright light, especially vegetables that are particularly susceptible to infestation like artichokes, asparagus, brussels sprouts, cauliflower, and leafy vegetables.
Certification
Certain foods carry a stamp to say they are kosher certified. This means that they are approved by a rabbinic agency, and have been thoroughly checked by qualified individuals to ensure all ingredients are kosher, and none of the equipment used during production has been in contact with non-kosher ingredients. It also ensures there are no forbidden combinations, such as meat and dairy.
For meat products, kosher certification confirms that the animal has been correctly slaughtered by a schochet, it’s organs declared free of non-kosher defects, and any forbidden portions have been cut away.
For more information on kosher food take a look at our guide to 7 basic rules of kosher food.
