Pellicle is a general term referring to a thin film of tissue, protein or other component that serves as a coating or protective layer to a particular surface or object. Pellicles are nonliving organisms and sometimes encapsulate objects for better protection. Depending on where the term is used, there are many different functions and specific definitions of the term.
Dental pellicle pertains to the protein film enveloping the tooth enamel. Also called "enamel pellicle" or "salivary acquired pellicle," it is considered as tooth's skin and protects teeth from acids. The exact composition of dental pellicles is still not known, although protein is thought to be their main component. Presence of dental pellicles enables bacteria like Streptococcus mutans to thrive in the teeth; hence the development of plaque. To resolve this, dental pellicles are removed through abrasion.
In gastronomy, pellicles give smoky flavor in meat, poultry or fish. The thin protein coating serves as a protective layer of the meat after marinating or curing. In effect, when the food is smoked, flavors and moisture get trapped inside the meat and the smoky flavor sticks to the skin. For instance, smoked salmon can be dry without having a pellicle before it gets into a smoker.
Pellicle mirror pertains to the very thin and lightweight translucent mirror used in a single-lens reflex (SLR) camera to split the light beams into two beams of reduced intensity. Canon, through its Pellix camera, first used this innovation back in 1965. By splitting the beams, different camera effects can be achieved by varying combinations of shutter speed and film exposure. Because the film is ultra thin, the usual reflections created by typical glass beam splitters are also avoided.
In life sciences, pellicles are thin protein layers that protect cell membranes and allow organisms like paramecia and ciliates to maintain their shapes. The thin layers of translucent membranes also facilitate movement. Stiff pellicles in protists are also quite flexible, enabling them to go inside tight spaces. Among Euglenids, protein pellicles allow organisms to slide against one another, which in turn allows for the organisms' writhing motion.