Bubble gum (or bubblegum) is a type of
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 tex ...
, designed to be inflated out of the mouth as a
bubble.
Composition
In modern chewing gum, if natural rubber such as
chicle
Chicle () is a natural gum traditionally used in making chewing gum and other products. It is collected from several species of Mesoamerican trees in the genus '' Manilkara'', including '' M. zapota'', '' M. chicle'', '' M. staminodella'', and ...
is used, it must pass several purity and cleanliness tests. However, most modern types of chewing gum use
synthetic gum-based materials. These materials allow for longer lasting flavor, a softer texture, and a reduction in
tackiness.
Mechanical properties
As a sort of
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 tex ...
consisting of long-chain
polysaccharides
Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long-chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wat ...
, bubblegum can typically exhibit linear and nonlinear viscoelastic behaviors. Therefore, the distinct deformations under chewing can be affected by
shear rate,
shear strain, and
shear stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross secti ...
applied through teeth.
Based on these, it is helpful to characterize the intrinsic rheological properties of chewing gums for future improvement and optimization of commercial products’ texture and
chewiness.
The linear
viscoelastic
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both Viscosity, viscous and Elasticity (physics), elastic characteristics when undergoing deformation (engineering), deformation. Viscous mate ...
(LVE) property can be probed on pre-shaped gum cuds through a small isothermal strain deformation (i.e., below
yield strain) under small amplitude oscillatory shear (SAOS).
Here the critical
yield strain is defined as the modulus deviating about 10% from its initial value. Under it, gum cuds show
elastic deformation that follows power-law behavior as a critical gel in the linear regime; otherwise, exhibiting nonlinear responses with increasing shear stress (plasticity). Normally, this yield strain is less than 1%.
Regarding
plastic deformation, the nonlinear
viscoelasticity
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like water, resist both shear flow and strain lin ...
can be explored through shear creep experiments (relaxation time) and the start-up of steady shear stress-controlled uniaxial/biaxial extension. The former demonstrates that fractional recovery, defined as the ratio between measured strain after deformation and recovered strain without adding
shear stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross secti ...
, for chewing gums under moderate
shear stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross secti ...
(~ 1000 Pa) is between 25% and 40%.
This relatively high fractional recovery (the ability to recover its previous shape) is consistent with providing a satisfying sensory feel. On the contrary, bubble gums only show fractional recovery lower than 15%. Therefore, bubble gums can withstand more substantial stresses before break-up than normal
chewing gums. This distinction is mainly due to its on-purpose design, which allows it to form and maintain large, stable bubbles when blown up through sizeable shear stress on the tongue.
The stretching experiment shows gum cuds owning
strain hardening
Work hardening, also known as strain hardening, is the process by which a material's load-bearing capacity (strength) increases during plastic (permanent) deformation. This characteristic is what sets ductile materials apart from brittle materi ...
during uniaxial extension. In particular, the LVE regime is absent with applying a constant Hencky strain rate, like the plastic flow in polycrystals or polymers. Moreover, different values of Hencky strain rates can lead to either extensional
viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for e ...
plateaus before sagging (macroscopic failure) or necking (strain hardening) following a low/high
strain rate. Typically, the strain softening at a low
strain rate manifests the disintegration of brittle networks within gums. In contrast, the nonuniform deformation of polymers and crystallization induced by strain explain the
strain hardening
Work hardening, also known as strain hardening, is the process by which a material's load-bearing capacity (strength) increases during plastic (permanent) deformation. This characteristic is what sets ductile materials apart from brittle materi ...
behavior at a high
strain rate.
History

In 1928,
Walter Diemer
Walter E. Diemer (January 8, 1905 – January 8, 1998) was an American accountant who, in 1928, invented bubble gum.
Life
Born and raised in Philadelphia, Pennsylvania, Diemer was working as an accountant at Fleer in 1926 when the company ...
, an accountant for the
Fleer Chewing Gum Company in Philadelphia, was experimenting with new gum recipes. One recipe, based on a formula for a chewing gum called "
Blibber-Blubber", was found to be less sticky than regular chewing gum and stretched more easily. This gum became highly successful and was eventually named by the president of Fleer as
Dubble Bubble because of its stretchy texture.
This remained the dominant brand of bubble gum until after WWII, when
Bazooka bubble gum entered the market.
Until the 1970s, bubble gum still tended to stick to one's face as a bubble popped. At that time, synthetic bubble gum was introduced, which would almost never stick. The first brands in the US to use these new synthetic gum bases were
Hubba Bubba and
Bubble Yum.
Bubble gum got its distinctive pink color because the original recipe Diemer worked on produced a dingy gray colored gum, so he added red dye (diluted to pink), as that was the only dye he had on hand at the time.
Flavors
In taste tests, children tend to prefer
strawberry
The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown Hybrid (biology), hybrid plant cultivated worldwide for its fruit. The genus ''Fragaria'', the strawberries, is in the rose family, Rosaceae. The fruit ...
and
blue raspberry flavors, rejecting more complex flavors, as they say these make them want to swallow the gum rather than continue chewing.
Bubble gum flavor
While there is a bubble gum "flavor" – which various artificial flavorings including
ester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distin ...
s are mixed to obtain – it varies from one company to another. Esters used in synthetic bubble gum flavoring may include
methyl salicylate
Methyl salicylate (oil of wintergreen or wintergreen oil) is an organic compound with the formula C8H8O3. It is the methyl ester of salicylic acid. It is a colorless, viscous liquid with a sweet, fruity odor reminiscent of root beer (in which it ...
,
ethyl butyrate,
benzyl acetate,
amyl acetate or
cinnamic aldehyde.
A natural bubble gum flavoring can be produced by combining
banana
A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large treelike herbaceous flowering plants in the genus '' Musa''. In some countries, cooking bananas are called plantains, distinguishing the ...
,
pineapple
The pineapple (''Ananas comosus'') is a Tropical vegetation, tropical plant with an edible fruit; it is the most economically significant plant in the family Bromeliaceae.
The pineapple is indigenous to South America, where it has been culti ...
,
cinnamon
Cinnamon is a spice obtained from the inner bark of several tree species from the genus ''Cinnamomum''. Cinnamon is used mainly as an aromatic condiment and flavouring additive in a wide variety of cuisines, sweet and savoury dishes, biscuits, b ...
,
cloves, and
wintergreen. Vanilla, cherry, lemon, and orange oil have also been suggested as ingredients.
Records
In 1996,
Susan Montgomery Williams of Fresno, California, set the
Guinness World Record for largest bubble gum bubble ever blown, which was in diameter. However, Chad Fell holds the record for "Largest Hands-free Bubblegum Bubble" at , achieved on 24 April 2004.
Tourism
Bubblegum Alley is a tourist attraction in downtown
San Luis Obispo, California
; ; ; Chumashan languages, Chumash: ''tiłhini'') is a city and county seat of San Luis Obispo County, California, United States. Located on the Central Coast (California), Central Coast of California, San Luis Obispo is roughly halfway betwee ...
, known for its accumulation of used bubble gum on the walls of an
alley
An alley or alleyway is a narrow lane, footpath, path, or passageway, often reserved for pedestrians, which usually runs between, behind, or within buildings in towns and cities. It is also a rear access or service road (back lane), or a path, w ...
.
The
Market Theater Gum Wall is a brick wall covered in used
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 tex ...
, located in an alleyway in Post Alley under
Pike Place Market in
Downtown Seattle.
See also
*
Functional gum
*
Gumball machine
*
Gum base
*
Gum industry
*
Inca Kola
*
List of chewing gum brands
References
{{Reflist
Chewing gum
Bubbles (physics)
Products introduced in 1928
American inventions