@Philpots has covered this, but refrigeration and freezing only serve to slow down the growth of microbes - not kill them (vaccines containing live viruses and bacteria are often stored at low temperatures for that very reason). Often liquid nitrogen is used and that is at minus 196 degrees Celsius. Refrigeration slows down the growth less and so food can still spoil at that temperature (around 4 to 8oC). The other factor is that bacteria and fungi produce toxins and, although the toxins themselves cannot reproduce, they will still be present after cooling or freezing - so how fresh the food is and how it was stored BEFORE we purchase it is a consideration (in that the amount of pathogens and/or toxins present will already be set). Then we have to consider enzymes within the food - they are naturally there within a live animal but upon death of the animal they still have a continuing effect upon the food. Cooling/freezing will also slow down their actions but they continue to have an effect on the nature, and so texture and taste, of the food. Some of this is true for plants - for example, ergot of Rye ( ) can cause gangrene and convulsions! It is even thought that the Bubonic Plague was exacerbated in people affected by ergotism. So RYE has a lot to answer for!