Why do foods spoil?
To understand why these temperatures are considered optimal it helps to know what it is that causes foods to spoil. Foods change markedly if they suffer a chemical or physical change. Chemical changes include ripening, maturing or oxidising, also known as becoming rancid. Physical changes include: • Mechanical stress – particularly poor packaging and handling. • Cooling – particularly freezing or changes in phase. • Heating – particularly cooking and migration of moisture. Microbial micro-organisms, also known as bacteria and moulds, spoil food by eating the cell structure. In the process they increase in number. Some micro-organisms are bad not only because they spoil the sensory and nutritional value of food but also because they can be poisonous. While most pathogenic micro-organisms can be easily killed by thorough cooking, some produce toxins that are not destroyed by cooking. Many foods are eaten raw and some of these can be risky. Some bacteria can cause food poisoning and other
