The following excerpt taken from the Food Safety and Inspection Service, United States Department of Agriculture.

Spoilage bacteria are microorganisms too small to be seen without a microscope that cause food to deteriorate and develop unpleasant odors, tastes, and textures. These one-celled microorganisms can cause fruits and vegetables to get mushy or slimy, or meat to develop a bad odor.

Most people would not choose to eat spoiled food. However, if they did, they probably would not get sick.

Pathogenic bacteria cause illness. They grow rapidly in the "Danger Zone" – the temperatures between 40 and 140 °F – and do not generally affect the taste, smell, or appearance of food. Food that is left too long at unsafe temperatures could be dangerous to eat, but smell and look just fine. E. coli O157:H7, Campylobacter, and Salmonella are examples of pathogenic bacteria.

There are different spoilage bacteria and each reproduces at specific temperatures. Some can grow at the low temperatures in the refrigerator or freezer. Others grow well at room temperature and in the "Danger Zone." Bacteria will grow anywhere they have access to nutrients and water.

Under the correct conditions, spoilage bacteria reproduce rapidly and the populations can grow very large. In some cases, they can double their numbers in as little as 20 minutes. The large number of microorganisms and their waste products cause the objectionable changes in odor, taste, and texture.

In a large piece of meat the outside surface serves as a natural barrier preventing access to bacteria. Every time we create a new surface cut with a knife we create an opening for bacteria to enter the meat from the outside and start spoiling it. The more cuts, the more spoils of meat and that is the reason why ground meat has the shortest shelf life. Duties like cutting meat, grinding, mixing or stuffing all increase meat temperature and should be performed in the kitchen at the lowest possible temperatures as fast as possible. Otherwise we create conditions for the growth of bacteria and that will decrease the shelf life of the product.

When you answer the telephone and leave ground meat on the kitchen table for 3 hours it will not matter much, as long as you only make one or two pounds of sausage. It will be consummed in a day or two and there will not be enough time for the meat to go bad. But if you buy a 50 lbs box of pork butts to make different sausages for your family at Christmas, now it is a different matter. You can not eat all that meat in a day or two. Some of it will hang in the kitchen, some will be in a refrigerator, a good half will go into the freezer. It is in your own interest to have those sausages last as long as possible and now all those low temperatures and good manufacturing techniques will come into play.

Let’s follow the scenario of a box with 50 lbs of pork butts. There are 10 butts in a box and each of them has a little shoulder blade that we have to

remove what will take us a few minutes. We are going to keep all pork butts in the refrigerator, remove one butt only, cut out the bone, remove the skin, separate fat, dice the butt into 2" cubes and put this ready to cure or grind meat back into the refrigerator. All this work may take us 10 minutes and this is how we should process each of the butts. The total time will be about 2 hours and imagine leaving the box for so long at the room temperature. As you know the meat once it gets warmer, it becomes mushy and soft and is not easy to cut. This makes another reason to work with each piece only for a few minutes.

Now we have to grind the previously diced meat and we only take from the refrigerator a few pounds of meat at the time. After grinding the first batch, we place the ground meat back in the refrigerator and start grinding the next portion. When meat gets warmer the knife of the grinder struggles to make clean cuts and the fat smears a lot. As before--in and out of the refrigerator-- a few pounds at the time. We are assuming a typical hand cranked home grinder, if you own a commercial unit depending on a model it will grind from 5 to 50 lbs of meat per minute.

Most likely you will make two or three different types of sausages and your meat will be kept in separate containers. Mix meat with spices one container at the time as each type of sausage will require different spices. You will probably add a cup or two of water to mix meat better and facilitate stuffing and of course the water should be cold. The traditional stuffing procedure using a hand cranked grinder with a stuffing tube attachement is a very slow two man operation. Take from the refrigerator only a part of the mixed meat, stuff it into a casing, then take some more.

Let’s assume that you have decided to smoke one whole pork butt and you need to cure it by the wet cure method. Make one gallon of sufficient strength brine one day earlier and place it in a refrigerator. The butt will have to remain in this curing solution for up to ten days and of course it must be kept at refrigerator temperatures. If you have no space in a refrigerator keep the meat in an insulated foam box or a food cooler but add some "blue ice" packs from time to time and check the temperature of the solution with a thermometer. Adding ordinary ice makes little sense as you will be diluting the solution, then you will have to add more salt, use a brine tester again, all kinds of unnecessary work that might make you an unhappy person.

If you live in a tropical climate without air conditioning, try to process meat in the evening and work with a small portion of meat at one time. This is an ongoing battle and the bacteria will not surrender unless you deep freeze the meat. But you can keep them in check and prolong the life of your product.

Other factors which influence your product quality and can eliminate the danger of any food poisoning are the 4 C’s of Food Hygiene: