NU FS100 Lecture Notes - Lecture 10: Blanca Enriquez, Evaporated Milk, Food Preservation

• School: University of Alberta
• Department: Nutrition and Food Sciences
• Course: NU FS100
• Professor: Wendy Wismer

Document Summary

Today we will talk about using low temp as a method of food preservation. Freezing: 0 to -18 or lower degrees celsius (most commercial freezers use minus. We are not killing microorganisms in freezing or refrigeration. They are just not in their ideal condition to grow. Mesophilic bacteria will not grow at 4 degrees. Food like milk and meat we know that they are not going to last for forever. Cold ice boxes were first used to keep food at lower temp. It has the ability to evaporate or condense. But now we use more environmentally friendly chemical. When a liquid evaporates, it takes in heat with it. Pipe with liquid goes in and take in the heat and evaporates. The gas is very hot and in pressure. And gas is released outside and losing energy. Then it goes to the expansion device and loses the remaining heat and becomes liquid and the process is repeated again.