Food Chem Paper

Linnea Johnson & Justin Alexander

THE CHEMISTRY OF FOOD PACKAGING OF FOOD

PRODUCTS

Alexander & Johnson 1

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.


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


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


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


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


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


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


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


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


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.


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.

Food Chem Paper

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