Just a quick look at the majority of restaurant menus across America confirms that folks in the US love their fried foods. Although these deep fried delicacies will not be written up for magical properties that help folks become healthier, they are still a strong draw for countless folks. The main health concern, though, all boils down to the oil for deep frying in which these foods are cooked.
When it comes to the oil that restaurants and cooks use to prepare deep fried foods, there are two general categories of greases, which are various cooking oils and shortening. The more stable types of oils that are most commonly used in deep fat fryers can last for about one hundred hours of use. This means that the restaurant does not have to be concerned with changing the oil after every use, or even on a daily basis.
More often than not, when it comes to the commercial fryers in restaurants and such, the oil for deep frying is not thrown out and replaced, but instead more oil is simply added to the used oil to fill the fryer. Sometimes this can go on for quite some time without completely replacing the oil, especially if the restaurant uses a deep fat fryer for cooking just one type of food, such as in the instance of preparing French fries.
Nevertheless, some problems arise with the oil when the commercial fryer ends up being used for different foods. There have been many instances where folks have complained that their French fries tasted like fish. This can happen anytime that a food with a strong or distinctive taste is fried in the same deep frying oil that is later used for a more bland food, such as French fries. In these cases, the more bland food will pick up the flavor of the stronger food, which has leached into the oil.
The deep-frying oil may not last for days and days in a busy commercial kitchen and depending on how many large batches of deep fried foods are prepared throughout a day, it might even be required to add more oil to the commercial fryers as the day progresses. For example, if a restaurant cooked fifty large batches of French fries in their commercial deep fryer, about five pounds of cooking oil would be used, since some of the oil is always absorbed into the food, even when it is well-drained.
Shortening is the other type of grease that is typically used for deep-frying, instead of oil. For commercial uses, shortening comes in bricks or tubs and it melts quite quickly when used as deep frying oil. The use of shortening in commercial fryers is very popular because it lasts longer, as much as two to three times longer, than oil. This makes it cheaper for the restaurants because they can get many more batches of fried foods from the same amount of shortening before it needs to be changed.
However, shortening is rather old fashioned in restaurant kitchens nowadays since many patrons inquire more often about the type of oil for deep frying that an establishment uses. Since shortening is considered less healthy, it is just not used as frequently as it used to be. In its place, most commercial kitchens use pure vegetable oil or canola oil, which are considered better choices of deep frying oil by those who are health conscious.