Resin is a hydrocarbon
secretion of many plants, particularly coniferous trees. It is valued for
its chemical properties and associated uses, such as the production of
varnishes, adhesives, and food glazing agents; as an important source of
raw materials for organic synthesis; and as constituents of incense and
perfume. In perfumery such products are often termed "ambered", based on
fossilized resins being the source of the gemstone amber. Resins are also
a material in nail polish. The term also encompasses synthetic substances
of similar properties, as well as shellacs of insects of the superfamily
Coccoidea. Resins have a very long history that is documented in ancient
Greece Theophrastus, ancient Rome Pliny the Elder, and especially as the
forms known as frankincense and myrrh in ancient Egypt. They were highly
prized substances, and required as incense in religious rites. There is no
consensus on why plants secrete resins. However, resins consist primarily
of secondary metabolites or compounds that apparently play no role in the
primary physiology of a plant. While some scientists view resins only as
waste products, their protective benefits to the plant are widely
documented. The toxic resinous compounds may confound a wide range of
herbivores, insects, and pathogens; while the volatile phenolic compounds
may attract benefactors such as parasitoids or predators of the herbivores
that attack the plant.
Natural gums are
polysaccharides of natural origin, capable of causing a large viscosity
increase in solution, even at small concentrations. In the food industry
they are used as thickening agents, gelling agents, emulsifying agents and
stabilizers. In other industries, they are also used as adhesives, binding
agents, crystallization inhibitors, clarifying agents, encapsulating
agents, flocculating agents, swelling agents, foam stabilizers, etc. Most
often these gums are found in the woody elements of plants or in seed
coatings. Natural gums can be classified according to their origin. They
can also be classified as uncharged or ionic polymers (polyelectrolytes). |