1. Linnea Johnson & Justin Alexander
THE CHEMISTRY OF FOOD
PACKAGING OF FOOD
PRODUCTS

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Justin Alexander
Linnea Johnson
Food Chemistry 447
Dr. Stone
April 13, 2015
The Chemistry of Food Packaging of Food Products
Food packaging is the first line of defense for the food products that we use on a daily
basis, and even less frequently. As Brunazzi, et al. stated, “The advent of packaging in the
modern food industry has caused fundamental transformations with concern to the
relationship between people and foods. As a result, food packaging has progressively been
turned into an essential element for the sale and the consumption of the food product”. Nearly
every type of food and drink today is contained in some sort of package; even “fresh” apples
are covered with a thin wax to prevent the oxidation of the skin prior to being consumed.
There are many different types of food packaging containers; paper, cardboard, plastics,
aluminum, and glass just to name a few. It is amazing how many different types of foods are
packaged in this modern day and age. Items that are packaged can range from the fresh fish at
the grocery store is packaged right in front of the consumer by the butcher, to fresh fruit is
packaged to keep it from being bruised, to the frozen ice cream found in the frozen section.
There are so many reasons for packaging use on a daily bases that a majority of consumers
don’t even think about. In the graph below, it is apparent that plastics (rigid and flexible) are
the most widely used type of container in the food industry, followed closely by paper and
cardboard types of containers.

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When packaging a food item there are a multitude of
options to consider. When you know what type of product is
being packaged, you need to take into account whether or not it
meant to be frozen or fresh, how long of a shelf life it needs to
have before being purchased and used by the consumer, and last but not least, the cost of the
package from production to shipping to storage. A few other things to consider are how far the
food item is traveling, how to prevent oxidation if rancidity is of concern, and how the package
will interact with the food product. With all these in mind, the producer can start to get an idea
of what package is best suited for their food product. As an example, if the food item is
perishable and needs to be kept in aerobic conditions, the preferred package is a rigid plastic
with holes punched throughout the container, or in the covering film, that will allow
respiration. The rigid plastic is often chosen in order to protect the perishable food product
from damage during transportation and handling.
A large reason that food packaging chemistry is of utmost importance is because the
food products we rely on can be highly reactive with the environment they are created,
shipped, and stored in. This environment can include moisture content and thermal leaps, both
of which can have a large impact on the olfactory characteristics of the food item. A large
number of food product are being packaged because certain foods may be oxidized easily, and
that leads to the need to be packaged in something impenetrable to the environment. With
fresh product packaging, the concern is not impenetrability; it’s how much environmental
exposure the product needs to stay shelf-stable and how to choose the proper package to
accommodate that. The second reason food products are packaged is for protection against

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crashes. Food products are shipped all over the country, and even the world, and they need
protection for the long travel. Shipping also brings into concern how long the product will take
to arrive at its destination, and how to choose the package that will account for that transit for
the product’s shelf life. During transportation, food products may be mishandled, and if not in
the correct package, the food product may be susceptible to damage. The shipping package
also needs to prevent microbial spreading, organoleptic modification, colorimetric variations, as
well as remain preventative of oxidative reactions. The strength of the package is vital, because
if it breaks, the risk of rodents and insects consuming the product exponentially increases, as
well as microorganism contamination from the environment and the intruders themselves. As
equally as important are safety and hygiene. Both of these aspects are very important in food
storage because the absence of microbial contamination and harmful or toxic chemicals is
highly required by the majority consumers of packaged foods. All of these reasons to package
go hand-in-hand because they are all key elements in the prevention of spoilage and health.
Packaging of the product is highly concerned with the protection and preservation of
food products. Protection is the “defense of the packaged product and the whole food product
from external attack” (Brunazzi, et al. 2014). The external factors that the package must protect
the product from are powders, ultraviolet rays, compression, vibration, moisture and many
other equally important influences. The external factors can be split into two categories:
external physical agents and external chemical agents. External physical agents are the
ultraviolet rays, powders, crashes, and thermal leaps. External chemical agents are
environmental moisture, and toxic or harmful substances. Many would not consider oxygen as
a chemical agent, but it is very much so because it can cause an oxidation reaction, and that can

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have adverse effects on some food products. The preservation of the food product is against
microbial agents, such as degrading microorganisms, pathogenic bacteria, and correlated
degraded chemical reactions. With the food product protected, the shelf life is extended, but
without it, the consumer is at risk of becoming ill.
There are four classifications of plastics rigid: semi-rigid, flexible, poly-coupled, and
plastic components for plastic and hybrid packages. Rigid plastic containers range from jars,
trays, bottles, and barrel drums, just to name a few. The rigidity of the plastic container may
strengthen or diminish depending on the composition of the plastic mixture. Semi-rigid plastic
containers are made from different polymeric materials and several additives with the aim to
broaden the range of products that can be placed in the container that is made from that
plastic. This is so that the company can be efficient in their production of plastics. Some semi-
rigid plastics are the to-go containers from takeout restaurants, as well as the containers that
holds the fresh fruits in the produce aisle at the grocery store. Flexible plastics are plastic
components and polymers mixed to obtain or enhance strength, including impenetrability to
vapor or gases. Examples of flexible plastics are heat sealed bags, pouches, flexible films and
plastic films for wrapping. Polycoupled food packaging is the newest designed and redeveloped
of the plastics, and they are plastic films and joints. Polycoupled packages are containers that
are different from flexible containers and plastic components. Tetrahedral systems are plastic
films, aluminum and foils that fall under the polycoupled category. Plastic components for
plastics and hybrid packages are plastic components for a whole range of plastic and hybrid
applications. Such as plastic lacquers, enamels, gaskets, and printing inks for metal containers.
Plastic lids and caps for soda bottles fall under this category as well, along with the plastic seals

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that go inside the cap or lid. An example of that is the seal on the inside of the Snapple cap that
seals the jar airtight. Another application of this type of plastic is the thin layer of plastic that
wraps around a soda bottle as its label. Plastic surrounds us in our everyday lives, and we as
consumers are becoming increasingly aware of their effects on the food product, as well as the
environment.
Polystyrene, a “colorless, hard plastic with limited
flexibility” (Fasano, et al. 2012), is a common type of plastic
used in the food industry. Fasano, et al. also states that “It can
be cast into molds with fine detail and thus it is used in the
packaging of yogurts and many lactic products”. Polystyrene has
many uses within the food packaging industry, such as; cups, dishes to hold meats, fish, fruit,
and cheese. With the addition of plasticizers, polystyrene can be molded into a plethora of
different shapes, allowing its use within the packaging industry to be highly unrestricted. While
polystyrene appears to be a highly desirable plastic to be used, it has been shown that it
releases a compound known as di(2-ethylhexyl)adipate (DEHA) into foods. The reason this is of
concern is because “a study carried out in vivo in mice showed that this compound can produce
cancer in liver” (Fasano, et al. 2012). Aside from the potential health risks, polystyrene film is
also a poor barrier against water vapor and atmospheric gases, as well as its vulnerability to be
strongly attacked by aromatic solvents (Brunazzi, et al. 2014).
Bisphenol A (BPA) “has been used commercially
since 1957 to make hard polycarbonate plastics and
epoxy resins used in food-can linings, cash-register

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receipts, and dental resins” (Snedeker, 2014). BPA is known to extend the shelf-life of many
foods, many of them canned. Despite the extensive uses of BPA, exposure poses multiple
dangers to those who consume it. As Brunazzi, et al. put it, it has been one of the “most
discussed dangers in recent years”. Snedeker states that BPA has been associated “with many
health problems including infertility, weight gain, behavioral changes, early-onset puberty,
prostate and mammary gland cancers, cardiovascular effects, obesity, and diabetes.” BPA can
be leaked into food products and drinks with relative simplicity. If the food is of acidic or basic
pH, and it is coupled with heating, the ester bonds linking BPA molecules can be hydrolyzed,
introducing it to the product.
Polyethylene Terephthalate (PET) is “a plastic
widely used in food packaging, including single-use
water and beverage bottles, and reheatable food trays”
(Snedeker, 2014). PET bottles are widely known for their
anti-oxidation capabilities. Not only do they have anti-oxidation properties, they are also highly
resistant to the sorption of aroma compounds (Dombre, et al. 2014). On the other hand, if a
food source is exposed to PET bottles for extended amounts of time or exposed to heat, it is
possible for the bottles to release antimony. Studies on antimony have shown it to be linked to
blood lipids, peripheral artery disease, and pre-eclampsia.
Polylactic Acid (PLA) is the first of three types of plastics
that we will talk about that are bioplastics. PLA can be obtained
from starch-rich products such as wheat and corn. Once the
starches are broken down into simple sugars, they can be

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fermented into lactic acid, and then subsequently into L-lactide. L-lactide’s ring is then broken
by chemical procedures into PLA that can be polymerized. What makes PLA desirable is that, by
enzymatic degradation, it can be broken down into compostable products and CO2. Despite the
obvious appeals of PLA, “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” (Peelman, et al. 2013).
Although it is said to be vulnerable to degradation, it hasn’t been proven to degrade at a faster
rate compared to its fossil fuel-based counterparts.
Polyesteracetal (PEA) is a combination of PLA and
a compound known as 1,3-dioxolan-4-one (DOX). DOX is
a relatively simple compound formed by combining
natural gas with wood/cellulose, taking the methanol formed and combining it with water,
carbon monoxide, and formaldehyde (Martin, et al. 2014). While PLA isn’t confirmed to
degrade faster than fossil fuel polycarbonates, PEA, in the presence of a salt solution, breaks
down at a much faster rate. During decomposition, it does produce formaldehyde, but only in
the amount that is equivalent to 9 pears.
Polyhydroxyalkanoates (PHA) are another type of
bioplastic. They are polymers of biodegradable plastics that are
the products of microorganisms. “The polymer is produced in
the microbial cells through a fermentation process and then
harvested by using solvents such as chloroform, methylene

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chloride or propylene chloride.” (Peelman, et al. 2013). The products of the fermentation are
obtained in pellet form, and from that form can be heated and molded into the desired
shape(s).
While bioplastics as a whole don’t appear to have many disadvantages, their increased
degradation rate is one of large concern. Food products must be kept in their environment in
order to stay shelf-stable for the desired amount of time by the food manufacturer. Aside from
degrading, bioplastics are still moderately expensive, and producing them requires a large
amount of land (for enzymatic degradation and processing).
Ultimately, plastics and bioplastics have their own advantages and disadvantages. As a
whole, bioplastics have the large advantage being so environmentally friendly, especially
considering that can are non-fossil fuel consuming, and can be birthed by everyday byproducts
of the world that we live in. Along with that, they are most often capable of being degrading by
enzymatic action with a shorter biodegradable timeline. The drawbacks to bioplastics are that
they are brittle due to the high glass transition and melting temperatures. With the brittleness
comes stiffness, poor impact resistance, poor heat stability, and oxygen permeability to name a
few (Peelman, et al). The bioplastic PLA has not been confirmed to bio-degrade at a more rapid
pace than a fossil fuel-based counterpart. The recommendation is that it must go through
industrial composting with addition of enzymes, which can be costly. “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 process ability, brittleness
and vulnerability to degradation” (Peelman, et al). The final disadvantage to bioplastics is that

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they are costly due to the fact that they require large amounts of land for processing.
Processing includes both creation and bio-degradation.
Some advantages to plastics are that they have a wide range of uses, not just in food
packaging. Plastics are used in water pipes, children’s toys, and light fixtures, just to name a few
examples. Polystyrene is capable of being molded into a plethora of different shapes, allowing
it to be used for many different containers in the food industry. Food packaging plastics are
generally inert to different chemical agents and food compounds. To go along with that, they
are low density, have low to high transparency, excellent aptitudes to heat sealing and thermal
processes, and they are able to be print with and on. Plastics are also relatively inexpensive
because of the plastic polymer’s raw materials. The disadvantages of plastics are that BPA has
been associated with moderate estrogenic activity and has been shown to influence
reproduction. BPA also has been seen to disrupt thyroid hormones, proliferation of prostate
cancer cells, and block testosterone production. Polystyrene has shown signs of releasing DEHA
into foods, potentially causing liver cancer. To step away from the health disadvantages there
are also few production disadvantages, such as bubbling, micro-fractures, and crystallites can
form, making the package fragile and unusable because it is then rendered unsafe. The
technology to produce plastic containers can also be relatively expensive, but have ultimately
been deemed worth the cost because of their widespread use over the previous decades.
When choosing a food packaging container, there are a multitude of characteristics to
consider; the vital points of what is being packaged, where it is going and how long the food
product will be sitting at that location, what package to use and whether or not it will it be

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harmful to the food product, if it is recyclable, and how expensive the production is. With all
these options in mind, almost anyone can properly package nearly any food product.

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References
Brunazzi, G., Parisi, S., & Pereno, A. (2014). The importance of packaging design for the
chemistry of food products. New York, New York: Springer.
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.
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.
Snedeker, S. (2014). Toxicants food and in packaging household plastics: Exposure and health
risks to consumers. Ithaca, New York: Humana Press.