Chewing gum is a type of confectionery which is designed to be chewed, not swallowed. Traditionally, it was made of chicle, a natural latex product, although for reasons of economy and quality many modern chewing gums use petroleum-based polymers instead of chicle. Chicle is nonetheless still the base of choice for some "upscale" gum brands, as well as some regional markets, such as in Japan.
Composition and manufacture
The chewing gum is made of a "gum base" with added flavoring and sometimes food coloring . The exact composition of gum bases is usually a trade secret, but common ingredients can be latexes (eg. leche, caspi, sorva, nispero, tunu, jelutong, or chicle, which is still commercially produced), paraffin wax or beeswax, polyethylene, polyvinyl acetate, stearic acid, and various natural gums.
Old gum bases were based on latexes, vegetable gums like chicle, spruce gum, or mastic gum. Alternative choices were waxes, eg. paraffin wax and beeswax. Researchers at the University of Illinois at Urbana and at Wm. Wrigley Jr. Company are studying the possibility of making gum base with biodegradable zein (corn protein).
The approximate manufacturing methods are fairly constant between brands. The gum base is melted at a temperature of about 115°C (240°F), until it has the viscosity of thick maple syrup, and filtered through a fine mesh screen. Then it is further refined by separating dissolved particulars in a centrifuge, and further filtered. Clear base, still hot and melted, is then put into mixing vats. Other ingredients that may be added include: powdered sugar, whose amount and grain size determines the brittleness of the result, corn syrup and/or glucose which serve as humectants, coat the sugar particles and stabilize their suspension, and keep the gum flexible, various softeners, food colorings, flavorings, preservatives and other additives.
The homogenized mixture is then poured onto cooling belts, and cooled with cold air. Extrusion, optionally rolling and cutting, and other mechanical shaping operations follow. The chunks of gum are then put aside to set for 24 to 48 hours.
Coated chewing gums then undergo other operations. The chunks are wrapped with optional undercoating for better binding with outer layers and then immersed into liquid sugar. The pellets are then colored and coated with a suitable glazing agent, usually a wax.
Non-coated varieties are covered in sweetened marble dust to prevent the wrapper from sticking to the product.