food preservation is the process of treating food to preserve the natural characteristic and appearance of food and stop or slow down its spoilage
drying
it is used to reduce the amount of water activity in order to prevent bacterial growth
refrigeration
it slows down the growth and reproduction of microorganisms
freezing
it stops bacterial action temporarily
A frozen product retains its freshness, texture and flavour
freeze-drying or lyophilisation
food is frozen and placed in a strong vacuum
it removes all moisture
smoking
it has a drying effect and raises the salt concentration
salting
the salt draws out moisture and creates an environment inhospitable to bacteria
adding sugar
water is withdrawn
pickling
the additions of acids lowers the pH of foods
pasteurisation
the food is heated to a high enough temperature to kill some bacteria and to disable certain enzymes
biopreservation
it uses beneficial bacteria to enhance the safety of foods