Kosher Foods are divided into three main categories: Meat, Dairy and Pareve.
Kosher meat is ranked the most sensitive item and the details for kosher meat are numerous. In general for meat to be kosher it must first be a kosher animal requiring both signs as dictated in the bible. they must have split hooves and chew its cud. this restricts it basically to cows, goats, sheep, deer, and giraffe. other details of kosher is in the method of slaughtering where strict care is taken in regards to the sharpness of the special slaughtering knife cutting the trachea and esophagus to drain the blood of the animal the fastest. Aside from the production the supervision is of the highest standard requiring constant supervision
Chalav Stam – Generally all milk coming from a kosher animal is kosher. Milk coming from a non-kosher animal is not kosher. In the United States cows milk predominantly does not need supervision because there are such strict laws of the FDAA regarding the mixing of other milk in product.
Chav Yisroel – The predominant law is that all milk needs to be supervised based on the possibility that non-kosher milk will be mixed with cows milk. although not likely in this country but in other countries where the law is not so strict it is treated as a highly sensitive item.
Cheeses are a very sensitive item and require Kosher supervision. The reason being that in order to make hard cheese a rennet enzyme needs to be inserted in the milk. this rennet comes from the stomach of a cow and it must be kosher verified before inserting. even though these days many rennet’s are synthetically made Jewish law still requires and Kosher supervisor to administer the enzyme at production
In regards to other milk products since many manufacturers include other ingredients such as mono-diglycerides which could come from non-kosher sources so kosher certification is required. Yogurt plants and ice cream manufactures put gelatin in their product so in general these types of products need kosher certification
The word pareve or parve meats simply neither meat or dairy. Such items include eggs, fish, grains, fruits and vegetables. There is a strict prohibition on mixing meat and dairy together. cheeseburgers are out of the question. Any products that contain milk and meat together are considered not-kosher of the strictest order. Parve products are items that can be eaten together with either milk or meat.
The list of birds that are forbidden by Torah law are many. A simple rule that many say are any birds that are non-predatory and scavengers. these include birds such as eagle hawk owl and vulture. basically what is left are chickens, ducks, geese, quail, turkeys and pigeons.
Two signs are required for a fish to be kosher. fins and scales. anything without fins and scales including all shell fish lobster, crab, crawfish and catfish are not kosher.
There are five separate prohibitions in the Torah against eating bugs. If the insect is a flying one there is an additional prohibition making a total of six. the application of this prohibition is found in the consumption of certain vegetables. So strict supervision is required when it comes to green leafy vegetables and many fruits such as strawberries, raspberries, blackberries. the vegetables or fruit must be washed and checked for insects prior to consumption
Wine and derivatives of grapes are also a highly sensitive item in kosher food production. Raisins, on the other hand, are not a sensitive item since there is no juice in them. There are many reasons for this prohibition. Mostly having to do with tradition of using wine used in holy rituals and practices and the strictest distancing of idol worship.
For one week of the year Jewish law dictates that all leaven must not be consumed or owned. Leaven is when water will come in contact with a grain for a period of 18 minutes or more. This law is held in the strictest form in that even a derivative of any of the five grains is prohibited. these five grains are wheat, barley, spelt, oats and rye. The Jewish people do eat a grain product on Passover. Its called matzah. Matzah is bread that was fully baked within the 18 minutes from when it came into contact with water. If a grain product is not matzah, then it is called chometz which is loosely translated as leaven. Derivatives of leaven could be anything with grain alcohol in it. even if machinery had come in contact with it it would render any food product that was produced on the same machinery not kosher for Passover.