HNU 146 Lecture Notes - Lecture 7: Food Industry, Powdered Milk, Food Preservation
Document Summary
Quick review: see handout that is titled factors to control when dehydrating. Water activity: definition of water activity: free unbound water. Surface area: increase in surface area means a decrease in time it takes for dehy- dration. Uniform pieces - the point of drying is that we want to get heat to the center of the food. If the pieces are smaller and more uniform, that helps with the dehydra- tion of the food. Foods that are high in salt and sugars end up with case hardening when they are heated up too quickly. The mois- ture leaves the food through pores, but it leaves the salts and sugars behind, which actually blocks the pores and creates a hardening on the food. The sugars and salts clog the pores (creates a hardening) Airflow: when you incorporate air into the process you dry something quicker. analogy: blow dryer, uses air to dry hair. Enzymatic browning: enzymes need to have a substrate.
