How is milk powder produced?
Removing almost all the water from the milk by freezing or heating and drying and with powder left, the powder is called milk powder. In the milk markets, milk powder is generally produced by heating. The heating method is divided into three types: a pan method, a roller method, and a spray method. Among them, the spray drying method is the most common, and the quality of the produced milk powder is also good. The spray drying method is taken as an example to describe the dairy production process below.
1. Raw material pre-treat and standardization. Raw milk enters the milk company and immediately inspected, filtered, purified, and standardized so that the ratio of fat and fat-free dry substance in the raw milk is equal to the ratio of fat and fat-free dry substance in the milk powder to be produced, and make sure the milk nutrition is rich.
2. Homogenization and preheating. By homogenizing, the milk forms a uniform dispersion system. The purpose of preheating is to kill the bacteria in the milk, passivate the lipolytic enzyme to extend the shelf life of milk powder. At present, a high-temperature short-time or ultra-high temperature instantaneous sterilization method is generally used. Heat at 80-85 °C for 5-10 minutes and 90-95 °C for 10-15 seconds.
3. Add sugar. In the production of sugar-add milk powder or other dairy products, it is necessary to add sucrose to the ingredients. Generally, the sugar content in the milk powder is below 20%. There are many ways to add sugar: one is to add sugar during preheating; the second is to add sterilized syrup to concentrated milk; the third is to add sucrose powder before packaging. Generally, the sweetened milk powder produced by the dissolution sugar addition method is better than the sugared milk powder.
4. Concentrate. Before the raw milk spray drying, vacuum concentration is required. Remove 70-80% of the water in the milk. Vacuum concentration is a very important technology for dairy industry that can greatly reduce the amount of water evaporation during spray drying, thereby saving energy, increasing evaporation efficiency and drying equipment production capacity. It plays a role in improving the physical and chemical properties of milk powder particles and improving the preservation of milk powder and retaining the milk nutritional facts.
5. Dry. The principle of spray drying is that under the action of high pressure or high-speed centrifugal force, the concentrated milk is sprayed into the drying chamber through the atomizer, and when it has contact with the hot air that is blown, the moisture instantaneously evaporates, and the milk powder is dried into particles. In this way, the milk powder is produced at a high drying speed, the milk powder has good dispersibility, and the degree of automation is high.
6. Cooling, storage, and packaging. The temperature of the milk powder just produced should be about 60 °C and should be cooled to normal temperature for packaging and storage.