Chewing gum
Chewing gum is a soft, cohesive substance designed to be chewed without being swallowed. Modern chewing gum is composed of gum base, sweeteners, softeners/plasticizers, flavors, colors, and, typically, a hard or powdered polyol coating. Its texture is reminiscent of rubber because of the physical-chemical properties of its polymer, plasticizer, and resin components, which contribute to its elastic-plastic, sticky, chewy characteristics.
History
The cultural tradition of chewing gum seems to have developed through a convergent evolution process, as traces of this habit have arisen separately in many early civilizations. Each early precursor to chewing gum was derived from natural growths local to the region and was chewed purely out of the instinctual desire to masticate. Early chewers did not necessarily desire to derive nutritional benefits from their chewable substances but at times sought taste stimuli and teeth cleaning or breath-freshening capabilities.Chewing gum in many forms has existed since the Neolithic period. 5,000-year-old chewing gum made from birch bark tar, with tooth imprints, has been found in Kierikki in Finland. The tar from which the gums were made is believed to have antiseptic properties and other medicinal benefits. It is chemically similar to petroleum tar and is in this way different from most other early gum. The Mayans and Aztecs were the first to exploit the positive properties of gum; they used chicle, a natural tree gum, as a base for making a gum-like substance and to stick objects together in everyday use. Forms of chewing gum were also chewed in Ancient Greece. The Ancient Greeks chewed mastic gum, made from the resin of the mastic tree. Mastic gum, like birch bark tar, has antiseptic properties and is believed to have been used to maintain oral health. Both chicle and mastic are tree resins. Many other cultures have chewed gum-like substances made from plants, grasses, and resins.
| Ancient civilization | Chewing gum precursor |
| Ancient Greece | Mastic |
| Ancient Maya | Chicle |
| Ancient Horn of Africa and Yemen | Khat |
| Chinese | Ginseng plant roots |
| Inuit | Blubber |
| Native Americans | Sugar pine and spruce sap |
| South Americans | Coca leaves |
| South Asia | Betel nuts |
| Tropical West Africa | Kola nuts |
| United States | Tobacco leaves |
Although chewing gum can be traced back to civilizations worldwide, the modernization and commercialization of this product mainly took place in the United States. The American Indians chewed resin made from the sap of spruce trees. The New England settlers picked up this practice, and in 1848, John B. Curtis developed and sold the first commercial chewing gum called The State of Maine Pure Spruce Gum. In this way, the industrializing West, having forgotten about tree gums, rediscovered chewing gum through the First Americans. Around 1850 a gum made from paraffin wax, a petroleum product, was developed and soon exceeded the spruce gum in popularity. To sweeten these early gums, the chewer would often make use of a plate of powdered sugar, which they would repeatedly dip the gum in to maintain sweetness. William F. Semple, a dentist from Mount Vernon, Ohio, filed an early patent on chewing gum, patent number 98,304, on 28 December 1869. Semple's gum was intended to clean the teeth and strengthen the chewer's jaw. It was not a sweet treat; ingredients included chalk and powdered licorice root. Charcoal was also suggested as a "suitable" ingredient in the patent.
The first flavored chewing gum was created in the 1860s by John Colgan, a Louisville, Kentucky, pharmacist. Colgan mixed with powdered sugar the aromatic flavoring tolu, a powder obtained from an extract of the balsam tree, creating small sticks of flavored chewing gum he named "Taffy Tolu". Colgan also led the way in the manufacturing and packaging of chicle-based chewing gum, derived from Manilkara chicle, a tropical evergreen tree. He licensed a patent for automatically cutting chips of chewing gum from larger sticks: US 966,160 "Chewing Gum Chip Forming Machine" 2 August 1910 and a patent for automatically cutting wrappers for sticks of chewing gum: US 913,352 "Web-cutting attachment for wrapping-machines" 23 February 1909 from Louisville, Kentucky, inventor James Henry Brady, an employee of the Colgan Gum Company.
Modern chewing gum was first developed in the 1860s when chicle was brought from Mexico by the former president, General Antonio Lopez de Santa Anna, to New York, where he gave it to Thomas Adams for use as a rubber substitute. Chicle did not succeed as a replacement for rubber, but as a gum cut into strips and marketed as Adams New York Chewing Gum in 1871. Black Jack, which is flavored with licorice, Chiclets, and Wrigley's Spearmint Gum were early popular gums that quickly dominated the market and are all still around today. Chewing gum gained worldwide popularity through American GIs in WWII, who were supplied chewing gum as a ration and traded it with locals. Synthetic gums were first introduced to the U.S. after chicle no longer satisfied the needs of making good chewing gum. By the 1960s, US manufacturers had switched to butadiene-based synthetic rubber, as it was cheaper to manufacture. In the United States, chewing gum experienced a decline in popularity in the early 21st century, as it lost its association with counterculture and teenage rebelliousness. Others blamed smartphones reducing impulse purchases at the checkout.
Demand for chewing gum also declined during the COVID-19 pandemic, as people were less concerned about bad breath and impulse purchases also declined. U.S. sales of gum fell about 30 percent, and while demand was back up to the pre-pandemic level in 2023 in dollar terms, this was the result of inflation as the average price of a pack increased $1.01 from 2018 to $2.71 in 2023. Globally, sales were down 10 percent from 2018.
Ingredient composition
Gum base composition is considered proprietary information known by select individuals within each gum-manufacturing company. Information about the other components of chewing gum are more accessible to the public and they are listed in Table 2.'Table 2: Common ingredients in the formulation of modern chewing gum'''''
Gum base
is made of polymers, plasticizers, and resins. Polymers, including elastomers, are responsible for the stretchy and sticky nature of chewing gum. Plasticizers improve flexibility and reduce brittleness, contributing to the plastic and elastic nature of gum. The interactions of plasticizers within gum base are governed by solubility parameters, molecular weight, and chemical structure. Resins compose the hydrophobic portion of the gum base, responsible for its chewiness. Although the exact ingredients and proportions used in each brand's gum base are trade secrets within the gum industry, Table 3 lists all of the natural and synthetic gum base components approved for use in the United States, demonstrating some examples of key gum base components.Table 3: Gum base ingredients approved for use by the U.S. Food and Drug Administration
| Natural ingredients | Synthetic ingredients |
| Sapotaceae Chicle Chiquibul Crown gum Gutta hang kang Massaranduba balata Massaranduba chocolate Nispero Rosidinha Venezuelan chicle | Butadiene-styrene rubber Isobutylene-isoprene copolymer Paraffin Petroleum wax Petroleum wax synthetic Polyethylene Polyisobutylene Polyvinyl acetate |
| Apocynaceae Jelutong Leche caspi Pendare Perillo | Butadiene-styrene rubber Isobutylene-isoprene copolymer Paraffin Petroleum wax Petroleum wax synthetic Polyethylene Polyisobutylene Polyvinyl acetate |
| Moraceae Leche de vaca Niger gutta Tunu | Butadiene-styrene rubber Isobutylene-isoprene copolymer Paraffin Petroleum wax Petroleum wax synthetic Polyethylene Polyisobutylene Polyvinyl acetate |
| Euphorbiaceae Chilte Natural rubber | Butadiene-styrene rubber Isobutylene-isoprene copolymer Paraffin Petroleum wax Petroleum wax synthetic Polyethylene Polyisobutylene Polyvinyl acetate |
Manufacturing process
First, gum base is previously prepared through a melting and straining or filtering process. The formulation for gum base is proprietary information known to few individuals within each gum-producing company. Next, other ingredients such as nutritive and non-nutritive sweeteners and flavors are added to the gum base until the warm mixture thickens like dough. The gum base mixture is heated during this mixing process to increase the entropy of the polymers to achieve a more uniform dispersion of ingredients. Then, extrusion technology is implemented to smooth, form, and shape the gum. Next, the gum goes through a shaping process that is determined by gum type and consumer demand. For example, cut and wrap pieces are severed straight out of the extruder using a vertical cutter. Sheeting is a technique often used for stick, slab and tab gums. Next, gum is either conditioned by being sprinkled with a powdered polyol or coated via the application of subsequent layers of coating using temperature controlled coating basins before it is sent to packaging.Product varieties
Chewing gum can come in a variety of formats ranging from 1.4 to 6.9 grams per piece, and products can be differentiated by the consumers' intent to form bubbles or the sugar/sugarless dichotomy.Chewing gum typically comes in three formats: tablets, coated pellets, and sticks/ slabs. Bubble gum typically come in three formats as well: tablets, hollow balls, and cubes or chunks. Stick, slab, and tab gums typically come in packs of about five to 17 sticks or more, and their medium size allows for softer texture. Pellet gums, or dragée gums, are pillow shaped pieces that are almost always coated. Packaging of pellet gums can vary from boxes to bottles to blister packs. The coating of pellet gum allows for the opportunity for multiple flavor sensations, since coating is done in a layering process and different flavor attributes can be added to various layers. Cube or chunk gums, which are typically intended for bubble blowing, are called cut and wrap gums as they are typically severed from continuous strands of extruded gum and packaged directly.