Chemistry of Food

Packaging of Food

Products

By Linnea Johnson and Justin Alexander

Decisions, Decisions, Decisions

Paper

Cardboard

Rigid Plastics

Flexible Plastics

Biologically

Synthesized Plastics

Glass

Aluminum

Tin

Stainless Steel

Wax

Ceramics

Wood

Tetra Paks

Market Share of Packaging Materials

Choosing a Packaging Type

Cost

Storage size

Frozen

Fresh

Shelf-stability

Expansion after

storage

Recyclability

Effects on the product

Shape

What food product is

being packaged

Where the food

product will end up

Chemistry of Food Packaging

Allows us to determine what type of packaging will prevent food

products and drink products from environmental harm.

Organoleptic properties through exposure to air and light.

Harmful pathogens such as Escherichia coli and Salmonella spp.

Food packaging can also be a source of harm to foods and the

consumer.

Some food packages can leach harmful compounds into foods and drinks.

Chemical structure can also determine what type of package is best

suited for recycling, composting, or enzymatic decomposition.

Food Packaging Features

1) Reactivity of the food

product to the

environmental

moisture and thermal

leaps

2) Protection against

crashes

3) Safety and hygiene

Preservation and Protection

Protection

Defense of the packaged

product and the whole

food product from

external attack

Powders

UV rays

Thermal leaps

Moisture

Crashes

Compression

Vibrations

Preservation

Against microbial agents

Degrading microorganisms

Pathogenic bacteria

Correlated degraded

chemical reactions

Plastics

Plastics have a 37%

market share of food

packaging materials.

Includes both ridged

and flexible plastics

Used widely by many

manufacturers to store

multiple types of food.

Fresh

Frozen

Shelf-stable

Refrigerated

Classifications of Plastics

Rigid and semi-rigid containers

Flexible Food Packaging

Polycoupled Food Packaging

Plastic components for plastic and hybrid packages.

Polystyrene

Mainly known as

“Styrofoam”.

Can be easily molded to

fit almost any shape.

Used widely as a tray for

wrapping fish, meats,

cheeses, etc.

Can leach di(2-

ethylhexyl)adipate (DEHA)

into foods.

DEHA is known to cause

cancer in the liver (in vivo

mice trials).

Bisphenol A (BPA)

Used to produce

polycarbonate plastics,

epoxy resin for cans, toys,

and microwave

containers.

Heat coupled with acidic

or basic foods hydrolyzes

the ester bonds holding

the BPA molecules

together, allowing them to

leach into foods.

Polyethylene Terephthalate (PET)

PET bottles are known for their ability to prevent oxidation of

the liquids contained within.

They are highly resistant to the sorption of aroma compounds.

Tests have been done to compare the sorption of aroma

compounds comparing PET bottles to bag-in-box (BIB) multilayer

flexible plastics and another study comparing PET bottles to

linear low density polyethylene (LLDPE) and polycarbonate (PC)

films.

Bioplastics

Bioplastics obtain their carbon from renewable sources.

“Biodegradable polymers are polymers that are capable of

undergoing decomposition into CO2, CH4, H2O, inorganic

compounds or biomass through predominantly the

enzymatic action of microorganisms.” (Peelman, et al,

2013)

Bioplastics can also be compostable.

Polylactic Acid (PLA)

Lactic acid can be obtained on the basis of renewable starch

containing resources by fermentation, or by chemical synthesis of

non-renewable resources.

Sources can be from starch-rich products such as corn and wheat.

Starch is converted to glucose and then subsequently fermented into

lactic acid, and from there into L-lactide.

Also known as polylactide, it is capable of decomposing at higher

rates than petroleum-based counterparts.

Polyesteracetal (PEA)

1,3-dioxolan-4-one (DOX) can be obtained by combing natural gas with wood/cellulose, producing methanol. With the addition of water, carbon monoxide, and formaldehyde, you will achieve the product DOX.

Synthesized by combining L-lactide and DOX.

Degrade in salt solutions easier and at a higher rate than PLA.

Degradation does produce 85 mg formaldehyde, but at a strength that is equivalent to 9 pears.

Polyhydroxyalkanoates (PHA)

“The polyhydroxyalkanoates (PHA) family are biodegradable

thermoplastic polymers, produced by a wide range of microorganisms.

The polymer is produced in the microbial cells through a fermentation

process and then harvested by using solvents such as chloroform,

methylene chloride or propylene chloride.” (Peelman, et al. 2013)

New vs. Recycled

There is an increasing desire

for renewable resources as well

as reusable resources.

Recycled products are

becoming increasingly more

common in the packaging

industry.

Their increased relevance in

the packaging industry is due to

the fact that more and more

consumers are becoming aware

of their “footprint” during their

lifetime.

PET Bottles

A study was conducted using virgin glass bottles, virgin PET bottles, and recycled PET bottles (respectively in table below) concerning the aging of wine.

Esters, alcohols, and acids were tested at times of 0, 5, 9, and 12 months.

0 Months 5 Months 9 Months 12 Months

Esters 15.0+/-0.5

mg/L for all

• 13.4

• 22.8

• 22.6

• 26.6

• 26.9

• 26.9

• 26.4

• 24.1

• 21.9

Alcohols 96.6+/-2.4

mg/L for all

• 96.1

• 68.7

• 74.5

• 66.1

• 64.0

• 64.2

• 52.5

• 50.7

• 55.0

Acids 8.3+/-0.2

mg/L for all

• 4.8

• 7.8

• 8.2

• 8.1

• 8.1

• 8.1

• 7.8

• 7.8

• 6.7

PET Bottles

Pros

Bioplastics

Capable of a “green birth” – they don’t require fossil fuels to

produce.

Bioplastics are capable of degradation by enzymatic action and

have a shorter biodegradable timeline (typically).

Plastics

BPA has a wide range of uses; from food packaging to toys to water

pipes.

Polystyrene is capable of being molded into a plethora of different

shapes, allowing its use as a container in the food packaging

industry to be nearly unlimited.

Plastics Cons

BPA has been associated with moderate estrogenic

activity and can influence reproduction.

BPA has also been associated with disruption of

thyroid hormones, proliferation of prostate

cancer cells, and blocking testosterone

production.

Polystyrene has shown that it releases DEHA into

foods, potentially causing liver cancer.

Bioplactic Cons

Bioplastics

Brittleness (due to high glass transition and melting temperatures),

stiffness, poor impact resistance, difficult heat stability, high water vapor

and oxygen permeability, and thermal instability are finally also factors

limiting the application of PHA films as food packaging (Peelman, et al).

PLA isn’t confirmed to biodegrade at a faster rate compared to its fossil

fuel-based counterparts. It is recommended that PLA go through industrial

composting with the addition of enzymes.

“Because of the hydrophilic nature of starch and cellulose, packaging

materials based on these materials have a low water vapor barrier, which

causes a limited long-term stability and poor mechanical properties

(sensitive to moisture content). Other drawbacks are bad processability,

brittleness and vulnerability to degradation”

Costs are greater for bioplastics due to lack of availability and lack of land

for use in production.

Conclusions

When choosing a food packaging container, it is

vital to choose the right one.

Some containers may leach harmful chemicals

into your product.

Consumers are becoming more conscious of

recyclable materials, increasing the demand for

biodegradable and reusable containers.

Questions?

[Insert amusing photo of celebrity here]

References Dombre, C., Rigou, P., Wirth, J., & Chalier, P. (2014). Aromatic Evolution of

Wine Packed in Virgin and Recycled PET Bottles. Food Chemistry, (176), 376-

387.

Fasano, E., Bono-Blay, F., Cirillo, T., Montuori, P., & Lacorte, S. (2012).

Migration of phthalates, alkylphenols, bisphenol A and di(2-ethylhexyl)adipate

from food packaging. Food Control, 27(1), 132-138.

Martin, R., Camargo, L., & Miller, S. (2014). Marine-degradable polylactic

acid. Green Chemistry, 16(4), 128-141

Muncke, J. (2012, October 5). Food Packaging Materials. Retrieved April 7,

2015, from http://www.foodpackagingforum.org/food-packaging-

health/food-packaging-materials

Peelman, N., Ragaert, P., Meulenaer, B., Adons, D., Peeters, R., Cardon, L.,

Van Impef, F., Devlieghere, F. (2013). Application of bioplastics for food

packaging. Trends in Food Science & Technology, 128-141.