How many people have ever taken the time to think about what is really happening to food when it is fried? We know that the result is a hot, delicious, golden-brown, crispy product, but what happens during frying?
Frying is probably the most dynamic food process of all. Food is immersed in hot oil and comes out as a totally different product. The frying process is considered a dehydration operation. Moisture is removed from the food being fried, whether that food is a French fry, potato chip or piece of chicken. The simplest system is the potato chip. A potato slice is more than 95% water. It goes into the fryer and out comes a chip that has almost no water at all, hence the crispy texture and the long shelf life. In products, such as French fries and chicken, the result is a product with a crispy surface and a moist interior. In a restaurant, these items will be consumed immediately whereas products produced in food processing facilities will be flash frozen for future cooking either in ovens or fryers.
The dehydration process that occurs with the food while in the fryer is very dynamic. When the food is plunged into the oil, the water in the food evaporates as steam into the hot oil. Water in the food moves towards the surface to replace what is being removed. What initially occurs is that the moisture flowing from the food pushes the oil away from the food. If this continues, the fried food will come out light colored and appear undercooked (below, left). As oil breaks down, surfactants in the oil contact the surface of the food causing the browning reactions needed to produce that desirable golden-brown color and enhancing moisture removal from the food. You may have observed in your own restaurants or kitchens that food fried in brand new oil is often very light in color. It is for this reason that doughnut fryers will often add a little old oil to a fryer to ensure that hey get the color their customers expect. If the oil is badly abused, the surfactants can cause the oil to be in constant contact with the food. This causes surface hardening and a rush of oil from the interior to the surface. The result is that the center of the food may become hollow (below, right). This can also occur with the coating on chicken or other products. These are not what the operator wants to sell. So, maintaining oil quality is an essential tool for ensuring proper control of dehydration (frying) of food, to ensure that your customers are happy. Filtercorp’s SUPERSORB pads will help you achieve this goal. Learn more about the Carbon SuperSorb pads here: http://filtercorp.com/supersorb/