Q. Antimicrobial Barriers -  proliferation of microorganisms?

The first barrier is the integument: a physical barrier to protect the food, e.g., the shell on eggs, the skin on poultry, the shell on nuts and the rind or skin on fruits and vegetables, or these may be surrounded by natural wax. It is usually composed of macromolecules relatively resistant to degradation and provides an inhospitable environment for microorganisms either with a low water activity or nutrients deficiency or antimicrobial compounds e.g. short chain fatty acids on animal skin, essential oils on plant surfaces etc. This physical protection to the food may not only help in its preservation but may also determine the kind, rate and course of spoilage. Layers of fat over meat may protect that part of the flesh, or scales may protect the outer part of the fish.