Microbes in Milk

We examine the number of microorganisms in different types of milk using resazurin indicator. Samples of pasteurised milk, UHT milk and powdered milk are left in the open for three days before resazurin indicator is added and the samples are heated in a water bath. The colour change in each type of milk is examined to determine the different amounts of bacteria present. Biology - Cells And DNA - Learning Points. Microorganisms can spoil food. Milk can be treated in different ways to help preserve it against spoilage by bacteria. Methods such as salting, pickling and freezing can be used to help preserve food. Some microorganisms can be used to help produce foods such as yoghurt, cheese and bread. A Twig Experiment Film. Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.