Ice cream is a complex product. Dairy ice cream contains milk fat and non-dairy ice cream contains vegetable fat combined with milk fat. All ice cream will also contain non-fat milk components such as proteins and carbohydrates. Sweeteners, flavourings, emulsifiers and stabilisers are added during processing. Ice cream contains over 50% water from milk or other ingredients and air is incorporated into the product resulting in finely-distributed air cells protected by a layer of fat globules.
The production of ice cream involves mixing the ingredients together, followed by pasteurisation; which reduces the number of non-pathogenic bacteria. After pasteurisation, homogenisation takes place, a process to allow the distribution of fat into as many separate small fat globules as possible. After homogenisation there is a cooling and aging process. The mixture is left to age for 24 hours and during this time all the dry ingredients are hydrated and the fat is crystallised. The product is then frozen in a continuous freezer and air incorporation takes place. When the ice cream leaves the continuous freezer at -5ºC, approximately 50% of the water is frozen. The final process is hardening, which freezes out most of the water at -40ºC.
Each ingredient selected for the production of ice cream has specific functions during production and are chosen specifically for their effect on the final structure and eating quality of the product.