Jung Han. Innovations in Food Packaging
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Innovations in Food Packaging
M anufactu rer/paten t
holder/trade name
Freshness indicators
AVL Medical Instruments
Biodetect Corporation
VTT Biotechnology
Aromascan
Visual Spoilage Indicator Company
Cox Technologies (Fresh Tag)
Sealed Air Ltd. (TufflexGS)
Time—temperature indicators
Lifelines Technology Inc. (Fresh-Check)
Trigon Smartpak Ltd. (Smartpak)
3M Packaging Systems Division
(MonitorMark)
I Point AB (I Point)
Oxygen indicators
Mitsubishi Gas Chemical Co., Ltd.
(Ageless Eye)
Toppan Printing Co., Ltd. (Fertilizer)
Togagosei Chemical Industry Co., Ltd.
(Vitalon)
Finetec Co., Ltd. (Sanso-Cut)
Pathogen indicators
Food Sentinel System (Sira
Technologies)
Toxin Guard (Toxin Alert)
^s^and contammation indicator ^tems for food packages
Compound detected
CO2,
NH4, amines, H2S
e.g.
Acetic
acid,
lactic
acid,
acetaldehyde, ammonia, amines
H2S
Volatile compounds
CO2
Volatile amines
CO2
Time-temperature
Time-temperature
Time-temperature
Time-temperature
02
02
Various microbial toxins
Various pathogens
Lawrence Berkeley National Laboratory E. coli 0157 enterotoxin
Principle of the indicator
Color change of
CO2,
NH4 and amine-sensitive
dyes,
formation of color of heavy-metal
sulfides (H2S)
Visually detectable color change of
a
pH-dye
(e.g.,
phenol red, cresol red)
Color change of myoglobin
Miniaturized electronic component
with electrical properties affected by volatile
compound associated with spoilage
Color change
Color change of
a
food dye
Color change
Color change due to chemical polymerization
Physical diffusion of
a
chemical solute causing a
color change
A lipid substrate indicator becomes hydrolyzed,
causes a pH change and consequently a permanent
color change
Color change
Color change
Color change
Color change
Barcode detector comprising a toxin printed
onto a substrate and indicator color irreversibly
bound to the toxin; in the presence of toxin the
barcode is illegible
Formation of
a
colored pattern when a target
analyte is first bound to labeled antibody and
subsequently to capture antibody
Color change of polydiacetylene-based polymer
Intelligent packaging to provide protection against theft,
counterfeiting, and tampering
Although theft and counterfeiting are not
too
common in the food industry, they
do
pose
a huge economical burden in other industries. Electronic Article Surveillance (EAS) is
used to deter the theft of high-priced goods, and leads the technology in electronic
tagging systems. Tampering is another global issue, and therefore more sophisticated
Intelligent packaging 151
anti-tampering devices or packages with responsive technology are necessary to con-
trol and minimize these problems.
Andrew Scully, of Food
Science
Australia of CSIRO (New South
Wales,
Australia),
has invented a technology for flexible packaging that creates a large-diameter color
change on the surface of the package after tampering. Even a pinhole can be detected
with the highly visible mark, so as to alert customers about potential damage to the
contents of the package (Brody, 2002a). Irreversible thermochromic materials can
provide a closure which "bruises" during any attempts to tamper, thus alerting the
customer before the goods are purchased (Ahvenainen, 2003).
The main purposes in lowering
the
risks of tampering are
first
to eliminate tampering,
and secondly to locate the already tampered products on the shelf by integrated iden-
tification. Aluminum and plastic closures can help customers identify if the package
has been opened. The tamper-proof band will split when the package is opened, which
provides tamper evidence for consumers. Alcoa CSI of Germany has invented the spe-
cial
cap
that
has
"skirts"
which curl under
the
bottom edge of the
closure.
The segments
of the tamper-evident ring
("skirt")
rupture when the container is opened (Jansen and
Schelhove, 1999). Furthermore, ITW Envopak has produced the rectangular bolt seal
that cannot be rotated. The bright coating on the bolt functions to increase the visibil-
ity of bottle seals and prevent counterfeiting (Jansen and Schelhove, 1999).
Holograms, thermochromic inks, tear labels and tapes, micro-tags, and diffraction
devices
are used to
deter counterfeiting. They can be incorporated
into
films,
transfer foils,
tear
tapes,
and
labels.
Holograms cannot be duplicated by copiers, scanners, or printers.
Their visual effects cannot be reconstructed or simulated (Daniel, 2000). Tamper-evi-
dence labels
or tapes
are invisible before tampering
occurs,
but change their color perma-
nently and leave behind a
"STOP"
message when the package is opened (Fault, 1995).
Consumer acceptance and legislative issues
General consumer behavior regarding the use of separate non-edible objects such as
sachets and inserts
in the
headspace of food
packages
is one of the primary concerns that
the intelligent packaging industry faces today. Labels and laminated structures are more
easily accepted by consumers, since they are attached to the package (Ohlsson and
Bengtsson, 2002). The food industry is currently studying consumer attitudes, preju-
dices,
fears, and expectations about the quality improvement and assurance of color
indicators. Manufacturers must educate the public about new packaging technologies
in order to increase consumer confidence in the safety of the foods they
purchase.
Table
9.4 outlines some potential problems and solutions in introducing new smart packages.
Current packaging legislation requires that the migration of substances from food-
contact materials is low. The acceptability of smart packaging techniques is consid-
ered
fi*om
a migration point of view. The techniques can be divided into two groups:
1.
Group 1, consisting of external indicators fixed on an outer surface of
a
package,
such as time-temperature indicators
152 Innovations in Food Packaging
Table 9.4 Problems and solutions encountered with introducing new products using intelligent
packaging techniques (adapted from Ahvenainen, 2003)
Problem/fear
Consumer attitude
Doubts about performance
Increased packaging costs
False sense of
security,
ignorance
of date markings
Mishandling and abuse
False complaints and returns of
packs with color indicators
Difficulty of checking every color
indicator at the point of purchase
Solution
Consumer research: education and information
Storage tests before launching; consumer education and
information
Used in high-quality products; marketing tool for increased
quality assurance
Consumer education and information
Active compound incorporated into label or packaging
film;
consumer education and information
Color automatically readable at the point of purchase
Barcode labels: intended for quality assurance for
retailers only
2.
Group 2, consisting of internal indicators intended
to
be placed in the headspace of
a package, such as oxygen and carbon dioxide indicators (Ohlsson and Bengtsson,
2002).
Migration does not occur in Group
1
indicators, since there is no direct contact of the
indicator with the food product. Indicators in Group 2 are not intended to come into
direct contact with the packaged foods. However, they are placed in the free head-
space of
a
package or fixed to the inner surface of
the
lid (de Kruijf
^^
a/., 2002). In
the case of sachets, migration is also a problem, since in practice the system is in
direct contact with
the
food product - especially with moist or fatty foods - and sachet
materials are generally very porous.
Conclusions
Recommendations
In the fiiture, intelligent packages can contain more complex invisible messages.
Some types of intelligent tags can replace the current barcode system, such as
electronic labeling consisting of a chip with ink technology in a printed circuit
(Ahvenainen, 2003). In addition, built-in battery radio frequency identity tags will be
popular in food supplies. It is also expected that in the future all necessary indicators
(time-temperature, leak, freshness etc.) as well as product handling information will
be contained within the same electronic tag. Warnings regarding potential allergens,
the expiry date, and health monitoring tools for diet management (such as calories,
fats and sugars) will also be readily available to consumers through easily readable
devices placed in shopping carts at supermarkets. For
freshness
and pathogen identifica-
tion indicators, more influential metabolite compounds and bacterial quantification
Intelligent packaging 153
will be carried out via advances in biosensors and biotechnologies applied in food
packaging systems.
Increasing marketing efforts will not only contribute to entertainment expansion
but also contribute to enhance brand-packaging recognition via information features
such as sound and image interactivity (Fito et al, 1997). In the future, packages may
talk to consumers. Consumer interactions and error prevention will be improved with
the introduction and enhancement of refrigerator recordings, auto-cooking features on
microwaves, dosage devices for pharmaceutical products, etc. Furthermore, thermo-
chromic materials will be used to produce containers that darken in the sunlight to
protect the product and return to a clear, transparent package under normal lighting.
This can also enhance product visibility, such as for soft drink containers (Berragan,
1996).
Glow-in-the-dark packages using thermosensitive inks will be adopted
to
mon-
itor serving temperatures (Berragan, 1996). Consumers will no longer have to worry
about cooking
times,
since time and temperature sensors installed in
the
packages will
be able to tell if the meal is cooked either by a color change or by a displayed message
(e.g. "cooking is completed") (Anonymous, 1994).
Conclusions
Intelligent packaging
is an
emerging
and
existing area of food technology that can provide
better food preservation and extra convenience benefits for
consumers.
The introduction
of quality and
fi-eshness
indicators (temperature indicators, time-temperature integra-
tors,
and gas-level controls), the increased convenience of product manufacturing and
distribution methods, the smart permeability films, and the theft and counterfeiting
evidence systems maximize the safety and quality of food
products.
Thus, intelligent
packaging systems will improve the product quality, enhance the safety and security
of
foods,
and consequently decrease the number of retailer and consumer complaints.
Disclaimer
Commercial products and manufacturers'
names
listed in this article
are not the
only ones
that have been commercialized and developed in the world. The authors are not related
to any of the commercial products/manufacturers that are referenced in this article.
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Introduction to
modified atmosphere
packaging
John D.
Floras
and
Konstantinos
L Matsos
Introduction 159
Historical developments 159
Principles of MAP 161
MAP techniques 162
Advantages and disadvantages of MAP 163
Effect ofMAP on shelf life 164
Effect of MAP on micro-organisms - safety issues 168
Effect of MAP on nutritional quality 169
Combination of MAP with other technologies 169
References 171
Introduction
Modified atmosphere packaging (MAP) is an integral part of the food industry. In this
chapter, an historical perspective and the principles of
the
technology are presented.
Examples of product applications are given, and the effects of MAP on product shelf
life,
safety and nutritional value are briefly discussed. Finally, several possible combi-
nations of MAP with other processing methods are explored.
Historical developments
"Controlled atmosphere" and "modified atmosphere" are terms implying the addition or
removal of
gases
firom
storage rooms, transportation containers or packages in order
to manipulate the levels of gases such as oxygen, carbon dioxide, nitrogen, ethylene
etc.,
and achieve an atmospheric composition different
to
that of normal air around the
food (Floros,
1990).
Although "controlled" and "modified" are often used interchange-
ably, they don't have the same meaning. In the case of controlled atmosphere, the gas
Innovations in Food Packaging
ISBN:
0-12-311632-5
Copyright © 2005 Elsevier Ltd
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160 Innovations in Food Packaging
composition around the product (usually in storage rooms or transportation contain-
ers) is continuously monitored and controlled. Modified atmosphere indicates that the
composition of the storage atmosphere is not closely controlled.
Controlled/modified atmosphere is a relatively old
process.
Based on ancient writ-
ings,
certain forms of modified atmosphere storage were used in China, Greece, and
other early
civilizations.
According to some such
reports,
fruits were sealed in clay con-
tainers together with fresh leaves and grass. The high respiration rates of leaves and
grass,
combined with that of the fhiit, quickly modified
the
atmosphere in
the
container,
creating an environment high in carbon dioxide and low in oxygen, which helped retard
fruit ripening.
However, it was not until 1820 that the effect of atmosphere on fruit ripening was
studied (Floros,
1990).
About 100 years later, the effect of carbon dioxide and oxygen
concentration on the germination and growth of fruit-rotting fungi at various temper-
atures was investigated (Brown, 1922). Similarly, in the 1930s a number of research
studies were published regarding the effect of carbon dioxide and storage temperature
on the inhibition of microbial growth on meat surfaces and the resulting extended
product shelf life (Ooraikul and Stiles, 1991).
Despite the mounting scientific evidence for the potential of modified atmospheres
in food preservation, the technique evolved very slowly and its commercialization was
very limited. A few cases of controlled atmosphere storage of fruits and vegetables
existed, and only some degree of atmosphere modification was used in the bulk trans-
portation of beef and beef carcasses (Inns, 1987; Ooraikul and Stiles, 1991). The first
significant trials of retail size modified atmosphere packaging took place in the late
1950s, with vacuum-packed meat, fish and coffee (Inns, 1987). The interest in gas
preservation techniques increased dramatically in the 1970s and 1980s, and commer-
cial applications of MAP have steadily increased since then.
This success has been the result of several factors. Consumer trends toward more
natural, fresh-like and minimally processed foods became popular. Preservatives
came under attack and their
use
became increasingly restricted. As a result, the indus-
try was in need of alternative preservation methods. At the same time, the cost of raw
food products, labour, and energy increased, which negatively affected many tradi-
tional preservation techniques such as canning and freezing. Moreover, advances in
material science allowed the development of many new packaging films with various
physical properties. In addition, a wide range of sophisticated packaging equipments
was developed to take advantage of the improved machinability and properties of the
new films. They allowed inexpensive and easy MAP of foods in small and convenient
retail units. Consequently, many MAP studies were conducted (Ooraikul and Stiles,
1991) and a large number of commercial applications were introduced.
At the same time, consumers were looking for convenient food products due
to their busy lifestyles. Health concerns resulted in an elevated interest in the quality
rather than the quantity of food. The demand for "fresh" and "natural" products
without the addition of
"dangerous"
chemicals increased dramatically. MAP seemed
to be the ideal method of preservation of many foods, because it could extend
the shelf life of the product significantly, without affecting its "fresh" or fresh-like
characteristics. Nowadays, MAP has become an integral part of the food industry.
Introduction to modified atmosphere packaging 161
particularly the fresh produce industry, and it is more important than freezing and
canning combined.
Principles of MAP
The objectives of MAP are to extend the shelf life of food products and to prevent (or
at least retard) any undesirable changes in the wholesomeness, safety, sensory char-
acteristics, and nutritive value of
foods.
MAP achieves the above objectives based on
three principles:
1.
It reduces undesirable physiological, chemical/biochemical and physical changes
in foods
2.
It controls microbial growth
3.
Just like any other packaging technique, it prevents product contamination.
The three main gases used in MAP are nitrogen (N2), oxygen (O2), and carbon diox-
ide
(CO2).
At sea level, the approximate composition of atmospheric air is
78.1%
N2,
20.9%
O2,
and
0.03%)
CO2.
The role and
the
importance of each gas in
MAP
are related
to its
properties.
Nitrogen is an inert and tasteless gas, without any antimicrobial activ-
ity. It is not very soluble in water, and it is primarily used to displace oxygen and pre-
vent package collapse. Oxygen inhibits the growth of anaerobic micro-organisms, but
promotes the growth of aerobic
microbes.
Additionally, oxygen is responsible for sev-
eral undesirable reactions in foods, including oxidation and rancidity of fats and oils;
rapid ripening and senescence of fruits and vegetables; staling of bakery products;
color
changes;
and spoilage due to microbial growth. Due to oxygen's negative effects
on the preservation of the food quality, it is generally avoided in the MAP of many
products. However,
its
presence in small quantities is at
times
necessary for some prod-
ucts.
For example, a minimum oxygen concentration is required by many fruits and
vegetables in order to sustain their basic process of aerobic respiration. In other cases,
such as red
meats,
high oxygen concentration is used to initiate "bloom" and preserve
the bright red color of
fresh
meats. Finally, carbon dioxide is soluble in both water and
lipids,
and its solubility increases with decreasing temperatures. The dissolution of
CO2 in the product can result in package collapse. Carbon dioxide has a bacteriostatic
effect, and it slows down
the
respiration of many
products.
All three gases are common
and readily available, safe, economical, and are not considered to be chemical addi-
tives.
However, the optimum level of each gas for each food product must be deter-
mined and used in order to maximize the positive and minimize the negative effects.
In some cases, additional gases are used in combination with the above mentioned
gases.
For example, carbon monoxide (CO) is sometimes added to inhibit microbial
growth. However, CO is toxic to humans, and its application is limited. Similarly, sul-
fur dioxide (SO2) may be used to prevent oxidative browning and to control the
growth of bacteria and molds. Ethanol has also been used to enhance the firmness of
tomatoes, improve flavor, and reduce fixngal activity, and argon has been used to
reduce microbial growth.
162 Innovations in Food Packaging
MAP techniques
The atmosphere inside a package can be modified by either passive or active means
(Floros, 1990). In the first case, the rate of change and the
final
gas composition in the
package depend largely on both the packaged product and the permeability of the
packaging material. It is well known that most foods come from living entities and
continue to live after harvesting. Fruits and vegetables, for example, consume the
oxygen of the surrounding environment and release carbon dioxide via the respiration
process. Similarly, the natural microflora of many products also consume oxygen.
Besides the biochemical and physiological processes that utilize the available gases,
oxidative reactions also take place during the storage period of foods, resulting in a
reduced oxygen concentration over time.
If
the
above phenomena occur in a sealed package, impermeable or permeable to
gases,
the gas composition inside the package will change. If the container is imper-
meable to gases (e.g.
glass
jars,
rigid metal cans, barrier plastic
films),
the rate of gas
production and/or consumption will dictate the gas composition at any
time.
However,
if
the
container is permeable to gases (e.g. flexible non-barrier plastic package), the
gas exchange with the environment will also take place through the package (Figure
10.1).
As
a
result, the gas composition inside the package will be
fiirther
modified and
the final gas composition will be different in the two containers.
The main disadvantage of
the
passive atmosphere modification method is that the
desired atmosphere is achieved very slowly (Figure
10.2a).
This can sometimes result
in uncontrolled levels of oxygen, carbon dioxide or ethylene, with a detrimental effect
on the quality of the product. Active modification of the atmosphere can provide a
Figure 10J Gas exchange between a product and its surrounding atmosphere in a permeable package.
Figure 10,2 Graphical illustration of (a) passive and (b) active atmosphere modification.