Introduction Homemade bread fresh out of the oven has a unique taste that for many of us is among our treasured memories. All too soon, subtle chemical changes produce markedly inferior, stale bread. The duration of choice flavor can be prolonged by keeping the bread in a refrigerator, and greatly extended by storage in a freezer. But eventually the breakdown of complex molecules converts the best bread into undesirable food. The degradation of organic material is a familiar experience.
Organic molecules are high energy configurations of carbon, hydrogen, and oxygen atoms.
These configurations may also contain nitrogen and a small proportion of other elements such as sodium, phosphorous, sulfur, potassium, calcium, and iron. The atoms in these molecules tend to reorganize into arrangements that have a lower energy, and eventually break down into water, carbon dioxide, and relatively simple compounds of carbon and the other elements. The DNA sequences there are more broken up than are those from the skin. The rate of DNA degradation is critically dependent on the chemical environment. At such a relatively infinitesimal concentration level, there would still be sufficient DNA molecules to be detectable by sensitive modern techniques.