A lot of people seem to get confused by the instructions on how to prepare frozen foods. The conditions for food poisoning often occur at this stage of food preparation. Frozen food fall into three main categories, which are:
Breaded raw food, raw marinated or seasoned meat and fish
Pre cooked food
The first category, raw food, includes all those types of food which have been frozen in their pre-cooked and raw state. This includes meat, fish, poultry, vegetables, mushrooms, doughs, fruits and fruit juices.
The second category, breaded raw food, includes meat, poultry, fish, vegetables, mushrooms and anything else which has been prepared for cooking but not cooked. This type of food may have been dipped in egg, flour or any other type of industrial grade bread crumb adhesive, breaded and then frozen
The third category, pre-cooked food, includes everything which has been fully cooked, meaning that prior to freezing, it is completely cooked and ready to eat and then frozen. This may include breaded poultry pieces, szitzels, cordon bleu, chicken kiev, stir fried dishes, oven dinners or any other type of food dish except for liver. Liver should never be re-frozen or frozen after cooking.
In the first category it is absolutely imperative to thaw all meat and poultry in refrigerated conditions until the meat is thawed. Never thaw any type of meat in water and it is not advisable to thaw in a microwave oven, in my own opinion. The reason for this is because it will take the meat a particularly long time to thaw and areas inside the meat which thaw first will not heat up sufficiently to prevent bacterial development because the frozen center keeps the thawed meat at a moderate temperature which is optimal for bacterial development for extended periods of time. Therefore, the risk of food contamination is particularly high.
Vegetables fruits and fish may be cooked in their frozen state. However, it is advisable to cut the fish into small portions to ensure that the fish is cooked through within a few minutes. Large pieces of fish such as whole salmon should be thawed thoroughly before cooking.
The second category presents a wider range of possibilities for food contamination. There are several reasons for this. If we were to take raw breaded foods and attempt to cook them in the oven, we would provide bacteria with conditions that are ideal for their growth because the center of the piece of meat would take a long time to thaw and the area surrounding the frozen center would remain at a suitable temperature for bacterial growth for a considerable period of time. In addition, the center of the piece of food may remain uncooked. If there is some of the meat left raw or semi-raw bacteria will develop. Conditions like these are perfect for bacterial development.
Pre marinated or spiced foods are particularly problematic for three main reasons. The first is because the product has been left unfrozen for an relatively long period of time in comparison to whole frozen chickens, for example, which are frozen as soon as they have been fully processed.
Secondly, the meat has been handled and exposed to potentially contaminating environmental conditions. Thirdly, it has had substances added which may contain bacteria. To thaw such materials in heated conditions or an attempt to cook them in their frozen state will provide bacteria with all the conditions that they need to multiply. All such materials must be either deep fried in oil or in the case of marinated and spiced meats, must be thawed in refrigerated conditions and then stir fried on a very hot surface in small quantities. Cooking the meat completely within a couple of minutes will curb the bacterial potential for development.
When food has been completely cooked at the time of the manufacturing process as explained in the third category, one can heat it up in the oven or deep fry it. However, if you do choose to oven cook such foods do make sure that the pieces of food are not too large. Hamburger size would be as large as I would attempt to cook in this way. If you are re-heating something like a pre-cooked pot roast or a pot of goulash, for instance, it is absolutely vital to thaw it thoroughly first in refrigerated conditions. Never pre-suppose that food is free of bacteria just because it has been pre cooked. The key to preventing this type of food poisoning is to plan your meals well enough in advance. Forgetfulness, procrastination and refusing to abide by the manufacturer's instructions all present situations where dangerous mistakes can easily be made.
All of these principles, if preformed correctly, ensure a correct food hygiene regime and prevent people from falling ill due to mistakes made in the preparation of food.