BIOL 261 Chapter : Chapter 36 Study Questions
15 Mar 2019
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Whether food is perishable depends on the amount of water in the food. Cold: slows microbial growth rate and delays spoilage. Freezing allows for longer storage, but isn"t suitable for all foods. Pickling and acidity: ph is an important factor in microbial growth. It uses vinegar (acetic acid) to decrease the ph and increased salt or sugar concentrations to make a hypertonic solution. The hypertonic solution dehydrates the bacteria and kills them. Drying and dehydration: removing the water causes the bacteria to die or at least stop growing. Lyophilization is even a method of culture preservation. This technique removes the water under a vacuum. Heating: heat denatures proteins which in turn kills the bacteria. Used to reduce the bacterial load of a product or to actually sterilize it. Pasteurization is used to reduce the number of organisms especially pathogens in heat sensitive foods like milk. Canning can be used for foods that are effected by boiling temperature.
