Chewing Gum

Alyssa Fenske

March 8, 2010

CBE 555

Outline

1. Why talk about Chewing Gum?

2. History of Chewing Gum

3. Manufacture & Structure of Gum

4. Sugar-free gum: Market Claims and Health Benefits

5. A News Worthy Story? Vinyl Acetate in Gum

6. Additional Uses and Applications of Gum

7. Myths and Urban legends

Why Chewing Gum?• A lot of people chew gum

– Average person chews 300 sticks per year– About 50% of Americans Chew gum– Over $2.8 billion of gum is sold yearly

• World records involving gum– The world’s largest bubble

• In 1994, Susan Montgomery Williams blew a bubble measuring 58 cm (23 inches) in diameter.

– The world’s longest gum wrapper chain• 8.8 miles (30 Empire State Buildings) made by 1,081,574

Wrigley gum wrappers

Chewing Gum History• Many ancient cultures chewed gum (Greeks

used mastiche tree resin; the Aztecs, chicle; Native Americans, spruce tree resin).

– Archeologists found 5000 year old chewed birch resin in Finland- oldest case of chewing gum

• In the early 1800s the first commercial gum was made with spruce tree resin.

• Around 1850 sugar was added to paraffin wax to make a sweeter gum and succeed spruce gum in the market. However, paraffin was not very chewy.

• Chicle (from the sapodilla tree in Mexico) had been introduced to the US in the 1860s by the Mexican general, Santa Anna.

• In the 1870s Thomas Adams experimented with chicle as a substitute for rubber.

– That experiment failed but he discovered that heating chicle with sugar made a superior gum since it had a smoother texture and held onto flavor better than paraffin wax.

– First flavor produced in a factory was Black Jack

History, Cont.• In 1891, William Wrigley Jr. founded

Wrigley Chewing Gum. By 1910, Wrigley was the largest manufacturer of gum.– In 1915 Wrigley mailed 3 sticks of gum to

everyone listed in the phone books (1.5 million people)

– In the early 1900s, all of the 62,500 street cars and subways in America had a Wrigley logo on them

• After WWII, the chicle gum base was replaced by various synthetic rubbers such as polyvinyl acetate, latex, or polyisobutylene – Glee Gum is the only American producer

of gum made with the authentic original chicle

Manufacture

• Ribbons of gum are cut into stick or pellet patterns

• Gum is conditioned to ensure correct consistency and long shelf-life

• Final steps are additional coating (sweeteners), wrapping, and packaging

1. Prepare Gum Base– Melt at 115°C (viscosity similar to maple syrup)– Purify the base by filtration through a mesh screen

2. Transfer gum base to a mixer and add ingredients– Sugar, flavorings, etc are added in a specific order and

quantity– Mixers are built to hold up to 1 ton of ingredients

3. Extrude the gum into thin ribbons– Powdered sugar or substitute is sprinkled on the gum to

keep it from sticking

Gum Structure

4 main components in most gum– Flavorings– Gum Base & other

softeners (glycerin) – Powdered Sugar– Glucose/corn syrup } Sugar-free gums do not

contain these

50-60%

15-30%

12-20%

1-2%

Gum Base Gum Base is the insoluble part of gum left in

the mouth after chewing Most of the differences between gum brands

are in the gum base. Typically Gum Base contains:

Elastomers to provide elasticity. This was originally provided by chicle, but replaced by synthetic rubber such as latex, polyisobutylene, or styrene-butadiene (10-20%)

Resins to give cohesion and strength. Examples are glycerol esters and polyvinyl acetate (10-35%)

Plasticizers such as paraffin wax, fats, vegetable oils, and other softening agents (10-40%)

Fillers to add texture such as calcium carbonate or talc (5-30%)

Emulsifiers to keep the gum moist, anti-oxidants to help preserve the gum, and colors

polyisobutylene

Styrene butadiene

How much gum base is in gum?

Chemistry of different flavorings require gum base modifications– Non-acidic flavorings use calcium carbonate as a filler– Acidic flavorings use talc as a filler because calcium carbonate

would react and form a gas

Differences in the Gum Base

Gum base (15-30% of Gum)

Bubble Gum (contains higher MW elastomers)

Sugar-free Gum (Contains Xylitol, Sorbitol, Aspartame)

25-30%15-20%

Example of the Effects Flavorings have on Gum Base

• Problem: Flavorings that contain a lot of fat (Chocolate, caramel, fudge, English Toffee) affect gum quality– Cocoa butter (25-40 wt% of chocolate) caused the gum to be so

soft that it would dissolve in the mouth– Increasing the elastomers content in the gum base would be too

expensive and would create an unfavorable chewing texture

• Solution: It was found that mixing the fatty flavors with other ingredients that were already in the gum base created the soft gum– Keep the filler to less than 10% – Keep the “gum base matrix disrupting materials” to less than

45%

Sugar-Free Gum

There is a growing popularity of sugar-free gums– In 2008, over $1 billion sold in the US– Popular brands are Orbit, Trident, Orbit White, Trident

White, Dentyne Ice Typical sugar substitutes are aspartame and

polyols (sugar alcohols) such as xylitol, sorbitol, mannitol, maltitol

Polyols– Xylitol is a natural sugar substitute that is produced

naturally in the body and in foods (fruits and vegetables). Sorbitol can also be found naturally in some berries.

– One popularly marketed benefit of sugar-free gum is that they appear to have a positive effect on caries rates (enamel loss on teeth)

Sorbitol

Xylitol

Comparison of Polyols on Caries Rates

There are many published findings relating xylitol, xylitol/sorbitol, and sorbitol to caries rates.– Some studies showed a statistically significant effect

on oral health caused by polyols.– Other studies were inconclusive regarding the polyols’

effect on caries rates One paper from the American Dental

Association synthesized results from 19 previous studies (1973-2004)– Analysis based on consumption of polyol-containing

gum in school-aged children over a duration of 24-40 months

Polyols Effect on Caries Rates Studies measured the Prevented Fraction (PF) using No

Gum as a control

Conclusions were that chewing gum containing xylitol, xylitol/sorbitol, and sorbital all statistically reduced Caries rates

The Effect of Polyol Substitute on Prevented Fraction

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Xylitol Xylitol/Sorbitol SorbitolPolyol Type

Pre

ven

ted

Fra

ctio

n

Control

PolyolControl

RateCaries

RateCariesRateCariesPF

Head-to-Head Comparison Between the Polyols

• The paper could not rigorously run a direct comparison of the different polyols– Each study analyzed had differences, such as different rates of polyol

consumption, different polyols were studied, etc. – However, a correlation did appear that xylitol has the largest positive

effect on caries rate over the xylitol/sorbitol mix and pure sorbitol.

Overall Prevented Fraction using Random Effects Model

0

10

20

30

40

50

60

70

1Polyol Type

Pre

ven

ted

Fra

ctio

n

Xylitol

Xylitol/Sorbitol

Sorbitol

•A Xylitol/Sorbitol blend (typically 1:3 ratio) is often used in industry because Xylitol is more expensive than Sorbitol

Theory for Xylitol Health Benefits• Some studies show that polyols,

particularly Xylitol, reduce caries rates. – Theory: Xylitol cannot be fermented by

bacteria so it starves the microbes on the surface of the tooth (Streptococcus mutans)

– Sorbitol is slowly metabolized by bacteria so it does not select some bacteria species over others.

– In contrast, sugars feed bacteria and cause pH level to drop, which degrades tooth enamel.

• Chewing gum also increases saliva production that decreases bacteria activity on teeth– Source of contention between different studies because caries

rates can be difficult to pinpoint to one cause (Saliva stimulation vs. Xylitol consumption)

– Also differences in how caries rates are measured can lead to non-conclusive results

Gum in the News: Vinyl Acetate (VA)• In 2008 Canada placed Vinyl Acetate (Acetic acid

ethenyl ester) on the List of Toxic Substances (Schedule 1)

• Vinyl acetate has been shown to cause tumors in rats (International Agency for Research on Cancer).– Nasal tumors developed upon inhalation of vinyl acetate– Stomach cancer developed when water containing high

VA concentrations was consumed • Once in the body, vinyl acetate degrades into

acetaldehyde, a known carcinogen– However, there is no known cause of cancer in humans

from VA

VA and Chewing Gum

• In the non-toxic polymer form, polyvinyl acetate (PVA) is present in the gum base of many brands of chewing gum – PVA is also present in hair spray, latex paints,

glue, etc.

• Concern rose about whether consumer products such as chewing gum were carcinogenic

PVA

VA

It’s a Game of Numbers

• Minimum VA daily consumption in rats to notice health effects:140,000 μg/ kg body weight

• Typical daily intake of VA according to Canadian officials: 1.3 – 3.9 μg/ kg body weight

• Minimum air conc. to cause nasal tumors after continuous exposure for 104 weeks:

2000 mg/m3

• Typical aerosol concentrations for consumer products:

Hair spray: 0.05 mg/m3

White glue: 2.3 mg/m3

Consumption Inhalation Stomach Cancer Nasal Tumors

How much VA is in Gum?

• Amount of VA in a 2 gram stick of gum containing PVA in the gum base:

1μg

• Number of sticks of gum that need to be chewed per day by a 75 kg person to reach cancer-causing levels:

10,500,000

• Assuming a mouth volume of about 100 cm3, the maximum VA conc. in the nasal passage from 1 stick of gum:

10 mg/m3

• Number of sticks of gum that need to be chewed continuously to cause nasal tumors:

200

Consumption Inhalation Stomach Cancer Nasal Tumors

Conclusion about VA and Gum

• The amount of VA in gum is very small– There is no evidence to suggest carcinogenic

health effects from chewing gum

Applications Gum in the military

– Caffeinated gum (100 mg, ≈ equivalent of 1 cup of coffee)– Looking into adding antibacterial components to replace conventional oral

hygiene Nicotine

– Nicotine absorbed through the mouth– Varying strength; gum containing 2 mg of nicotine are common

Memory Aid– Theory that chewing stimulates hypothalamus to keep us alert

Stomach and Digestive aid– Stimulates saliva flow up to 10-fold to neutralize acid via hydrogen carbonate– Spearmint oils also act as additional digestive aid and anti-flatulent

Working on biodegradable gum using corn protein called zein (byproduct of ethanol production)– Gum hardens instead of being sticking; completely degraded after 2 weeks– Help prevent gum from sticking to asphalt

Also gum is available that has Green tea and ginseng added to it

Myths and Urban Legends1. Swallowing gum Takes 7 years to pass

through the digestive tract– False. The gum base is insoluble but it passes

through the system at the normal rate2. Peanut butter is useful for removing gum from

hair• True. The oils in peanut butter are hydrophobic,

just like the gum base. The gum and the oils prefer to stick to each other than hair protein. The gum becomes less sticky and can be removed from the hair.

• Salad oils and mayonnaise also work.

+ =

References1. Mint Industry Research Council. http://usmintindustry.org/Portals/1/Hist2.pdf

2. “Chewing Gum.” Burkes, Rachelle. Chemical & Engineering News. Volume 85, No 32. p. 36. August 6, 2007 p. 36 http://pubs.acs.org/cen/whatstuff/85/8532sci2.html

3. “Chewing Gum.” June 2005. http://www.bbc.co.uk/dna/h2g2/A172342 .

4. “Chewing Gum.” http://en.wikipedia.org/wiki/Chewing_gum

5. “How Gum is Made.” http://www.wrigley.com/global/about-us/how-gum-is-made.aspx

6. “Gum Base.” http://en.wikipedia.org/wiki/Gum_base

7. “Chewing Gum Products.” Phillips, D, et. al. Chicago, IL. http://www.faqs.org/patents/app/20090202673#ixzz0fM7ZOF5s

8. http://www.bwcliffordcandy.com/sugarfreechewinggumstatistics.aspx

9. “The impact of polyol-containing chewing gums on dental caries” Jadad, A, Deshpande, A. The Journal of American Dental Association. 2008. Vol 139. pp 1602-1614

10. “The Effects of Xylitol-containing Chewing Gums on Dental Plaque.” Scheie. A, et al. Journal of Dental Research. July 1998. pp 1542-1547.

11. “Xylitol – Sugar Substitutes, Chewing Gum, and Dental Caries.” Br Dent J. Medline. January 1998.

12. “Vinyl acetate toxic? Just chew on the facts.” Schwarcz, Joe. Montreal Gazette. May 24, 2008. http://www.canada.com/montrealgazette/news/books/story.html?id=c44590c2-3ab9-470e-92ec-81f6c1d2151a

13. “How does Peanut Butter Remove Gum from Hair?” Brown, Richard. eHow. http://www.ehow.com/how-does_4603606_peanut-butter-remove-gum-hair.html

Effect of Xylitol Load on Caries Rates

• The study also compared the xylitol load (total xylitol consumed during a study) on the Prevented Fraction– General trend is that as xylitol consumption

increased, the preventive fraction increased

Gum in the News

• Dangerous weight loss caused by Sorbitol– In high concentrations, sorbitol is a laxative that is not absorbed

well in the small intestine but causes water to be drawn into the large intestine

• In 2008 two patients checked into hospital in Britain for excessive diarrhea and weight loss (up to 20% of body weight)

• Study of their eating habits showed that they were eating 20-30g of Sorbitol per day from gum and other candy. They were eating about 20 sticks of gum a day (1.25g Sorbitol per stick)

• Sorbitol intake was discontinued and symptoms went away.