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Packaging materials have traditionally been chosen to avoid unwanted
interactions with food.
Food packaging exists to make our lives easier. We need packaging to
protect foods from the outside environment, for convenience and to
communicate information to consumers about the food inside the package.
Migration of packaging materials components into the product, absorption
of product components into the packaging material, high permeability to
moisture, vapors and gases, as well as to light, are undesired in most of the
common packaging systems, such as metal cans, glass bottles and jars and
most plastic and composite packages.
New packaging systems are called active, smart or intelligent
“Active packaging includes components of packaging systems
that are capable of scavenging oxygen; absorbing carbon
dioxide/ releasing carbon dioxide, moisture, ethylene and
maintaining temperature control and/or compensating for
Active or smart packaging is designed to….
To correct deficiencies that exist in passive packaging
To deliberately interact with the product and respond to changes.
Product quality, safety and preservation
Oxygen and ethylene scavengers, ethanol emitters, carbon dioxide generators and
Anti-microbial surfaces and time-temperature integrators
Optimum conditions to which a food is exposed, while passive packaging is used as
an effort to minimize the deleterious effects of a limited number of external variables
such oxygen, water and light
Selected examples of active packaging systems
System mechanisms food
Iron based, Metal/acid
Nylon MXD6, Metal (e.g.
Bread, cakes, cooked rice,
biscuits, pizza, pasta,
cheese, cured meats and
fish, coffee, snack foods,
dried foods and beverages
Iron oxide/calcium hydroxide
scavengers/emitters Ferrous carbonate/metal halide
Calcium oxide/activated charcoal
Coffee, fresh meats and
nuts and other snack food
products and sponge cakes
Fruit, vegetables and other
Spice and herb extracts
Vitamin E antioxidant
Chlorine dioxide/sulphur dioxide
Cereals, meats, fish, bread,
cheese, snack foods, fruit
Pizza crusts, cakes, bread,
biscuits, fish and bakery
Activated clays and minerals
Fish, meats, poultry, snack
foods, cereals, dried foods,
sandwiches, fruit and
Cellulose triacetate, Acetylated paper
Citric acid, Ferrous salt/ascorbate
Fruit juices, fried snack
foods, fish, cereals, poultry,
dairy products and fruit
Non-woven plastics, Double-walled
containers, Hydrofluorocarbon gas
nitrate/water, Calcium chloride/water
Super corroding alloys/salt water
Ready meals, meats, fish,
poultry and beverages
A scavenger in chemistry is a chemical substance added to a mixture in order to
remove or inactivate impurities or unwanted reaction products
Oxygen scavengers (also referred to as oxygen absorbers) -- food product
quality by decreasing food metabolism, reducing oxidative rancidity, inhibiting
undesirable oxidation of labile pigments and vitamins, controlling enzymic
discoloration and inhibiting the growth of aerobic microorganisms.
Small sachets or self adhesive labels that are placed inside modified
atmosphere packs to help extend product life (notably cooked meats) and help
improve product appearance.
The reduction of oxygen inhibits aerobic organisms, especially mold, and
prevents oxidative rancidity.
Table : Selected oxygen scavenger systems
Easily oxidizable --- remove O2 by means of a chemical reaction
In sachets made of a material highly permeable to air but it can also be
included in bottle closures or in the plastic film matrix
Use of scavengers led to faster reduction and to lower levels of residual
oxygen, as compared to nitrogen flushing.
These chemical systems often react with water supplied by the food to
produce a reactive hydrated metallic reducing agent that scavenges oxygen
within the food package and irreversibly converts it to a stable oxide.
The most common substances used are iron powder and ascorbic acid.
O2 scavenger several requirements:- Be safe and not produce toxic substances or odors
- Be handled easily
- Be compact in size and absorb a large amount of oxygen
- Have an appropriate rate of oxygen absorption, and
- Be economic.
The scavengers may be of self-reaction type or moisture dependent
The oxidation mechanism of
iron powder can be expressed as follows:
Scavengers also differ in the reaction speed: from immediate action (0.5 to 1
day) to slow action (4 to 6 days); on the application :: particularly the
moisture content of the food; and on the function :: i.e., oxygen scavenging
only or dual function, such as absorbing or generating carbon dioxide,
besides removing the oxygen.
oxygen scavengers --- capable of reducing oxygen levels to less than 0.01%
which is much lower that the typical 0.3–3.0% residual oxygen levels
achievable by modified atmosphere packaging (MAP).
The iron powder is separated from the food by keeping it in a small, highly
oxygen permeable sachet that is labelled ‘Do not eat’ and includes a diagram
illustrating this warning.
The main advantage of using such oxygen scavengers is that they are
capable of reducing oxygen levels to less than 0.01%
Oxygen scavengers can be used alone or in combination with MAP
Non-metallic scavengers include those that use organic reducing agents such
as ascorbic acid, ascorbate salts or catechol.
Enzymic oxygen scavenger systems using either glucose oxidase or ethanol
Selection of the oxygen scavenger, considerations :The nature of the food, such as size, shape and weight
The moisture content and water activity
The initial (residual) oxygen content in the package head-space
The amount of oxygen dissolved in the product
The maximum allowable oxygen intake to end product shelf-life
The packaging material permeability to oxygen.
EVOH as an oxygen barrier layer for prolonging the shelf-life
plastic packaging systems (containing ethylene-vinyl alcohol copolymer (EVOH)
Table. Properties and types of FreshMax TM and FreshPaxTM O2 scavengers.
Fig . AgelessTM formats available: sachet, pressure-sensitive label and card.
Oxygen scavenger Label
FreshPaxTM and FreshMaxTM
Figure. Crown oxygen scavenger from Darex (W.R.Grace).
• Oxygen scavenging sachets ---- disadvantage ---- accidental ingestion
----hampered their commercial success, particularly in North America and Europe.
of oxygen scavenging adhesive labels (increased
Uses : Sliced cooked and cured meat and poultry products, which are
particularly sensitive to deleterious light and oxygen-induced colour changes
Coffee, pizzas, speciality bakery goods and dried food ingredients (Hirst,
Cakes, breads, biscuits, croissants, fresh pastas, cured fish, tea, powdered
milk, dried egg, spices, herbs, confectionery and snack food. (Day, 2001).
Nuts and many high-oil content, processed
foods have saturated fats which can oxidize,
creating an off-flavor and texture issues.
Maintaining the fresh, out-of-the-oven
consumer appeal and texture can be
during extended shelf life using MultisorbÕs
innovative active packaging technology.
Powders, such as baby formulas and
traditionally relied on unhealthy trans-fats
to maintain shelf life. Active packaging
technology allows formula producers to
maintain a desired shelf life while
eliminating the use of trans-fats.
Organic foods made without preservatives
And ---- loss of flavor, color, moisture and
---extend shelf life and lengthen the
distribution chain of goods without additives
or preservatives, thus maintaining organic
“Reduced Oxygen Packaging” means:
The reduction of the amount of oxygen in a package by removing
oxygen; displacing oxygen and replacing it with another gas or
combination of gases; or otherwise controlling the oxygen content to a
level below that normally found in the surrounding, 21% oxygen
Food for which the hazards of Clostridium botulinum and Listeria
monocytogenes require control in the final packaged form
Ethylene is a plant hormone that accelerates the respiration rate and subsequent
senescence of horticultural products such as fruit, vegetables and flowers. Many of
the effects of ethylene are necessary (e.g. induction of flowering in pineapples and
colour development in citrus fruits, bananas and tomatoes) but in most horticultural
situations it is desirable to remove ethylene or to suppress its effects.
Ethylene is a very reactive compound that can be altered in many ways, such as
chemical cleavage and modification, absorption, adsorption, etc. This creates a
diversity of opportunities for commercial applications for the removal of ethylene
There are a number of ethylene removal technologies available:
– Catalysts. Often based on platinum/alumina, these operate at elevated
temperature (> 200ºC) and catalytically oxidise ethylene to carbon dioxide and
--- Use of photocatalytic oxidation of ethylene using titanium dioxide, which
can occur at room temperature
-- Stoichiometric oxidising agents. Mostly based on potassium permanganate,
which again oxidises ethylene and is itself reduced.
Sorbents: Sorption of the ethylene and are often based on high surface area
materials, including activated carbon, clays and zeolites.
Ethylene Blocking Technologies
1-Methylcyclopropene (1-MCP). 1-MCP is the most widely used
commercial volatile ethylene inhibitor, which blocks ethylene binding
Silver thiosulfate (STS). The use of this material is largely restricted to
cut flowers and it is sold commercially under the trade name Chrysal
Aminoethoxyvinylglycine (AVG). This material is sold commercially as
ReTain® and acts as a plant growth regulator by blocking the production
of ethylene in the plant tissue
Table : Selected ethylene scavenger systems
Potassium permanganate-based scavengers:KMnO4 are available in sachets for packages or blankets for storage
chambers--- not incorporated into food
Immobilized in-- inert substrate such as alumina or silica gel-- 4 – 6%.
The performance and useful life of the scavengers depend on the substrate
surface area and the content in permanganate.
Potassium permanganate oxidises ethylene to acetate and ethanol and in the
process changes colour from purple to brown, and hence indicates its
remaining ethylene scavenging capacity
Ethylene Control, Inc. (USA) ---scavenging capacities: 5g, 9g and 28g,
respectively --- boxes up to 10 lb, 30 lb and 50 lb of produce (one single
sachet per box is considered enough for protection).
Air Repair from DeltaTrak, Inc. -- alumina beads impregnated with
potassium permanganate --- packets of 5g and 8g for boxes, tubes of 5 in.
for display cases and small coolers and 20 in tubes for walk-in coolers, as
well as blankets and bulk beads available by the pound.
Figure. Sachet of ethylene scavenger from
Ethylene Control, Inc.
Activated carbon-based scavengers
Ethylene can be removed by a system using various metal catalysts on
activated carbon. This type of scavenger is more popular in Japan.
Examples:-- SendoMate from Mitsubishi, which is based on a palladium catalyst
-- Hatofresh System from Honshu Paper, which is based on activated
impregnated with bromine-type inorganic chemicals
-- Neupalon from Sekisui Jushi (Japan)
Activated earth-based scavengers
--Finely dispersed clay embedded in polyethylene films or bags that are used for
fresh produce----clays, pumice, zeolites, coral, ceramics, sand, etc.
-- Adsorb the ethylene, they also open pores within the plastic layer---ethylene
will diffuse much more rapidly through open pore spaces within the plastic than
through the plastic itself, it should be expected that ethylene will diffuse out of
these bags faster than through pure polyethylene bags.
Commercial examples: Orega bag (Korea), Evert-Fresh Bags made of oya
clay dispersed within polyethylene film matrix (USA), FH from Thermo Co., and
Dual-action ethylene scavenger and moisture absorber ( Japan, Sekisui Jushi
--- Neupalon™ sachets --- activated carbon, a metal catalyst and silica gel and are
capable of scavenging ethylene as well as acting as a moisture absorber
--- Equilibrium modified atmosphere is likely to develop within these bags
compared with common polyethylene bags, especially if the produce has a high
[Improve produce shelf life and reduce headspace ethylene independently of any
ethylene absorption or adsorption]
Carbon dioxide generators and absorbers
Carbon dioxide generators --- packaging for fresh produce where an increased
concentration of CO2, combined with decreased O2 concentration, reduces the
respiration rate thus increasing the product shelf-life
-- Emitters is in the packaging of meat products where a high level of CO 2 may
inhibit microbial growth.
--Commercial solutions commonly used are the incorporation of a one-way valve
and more recently, the inclusion of a CO 2 absorbing sachet.
Removal of CO2 is needed, as in the case of
roasted ground coffee. Substantial quantities of CO2 are released on grinding
coffee, which must be removed from the package to avoid pressure build up
and bursting, in the case of flexible pouches.
A mixture of calcium oxide and activated charcoal -- coffee pouches to
scavenge carbon dioxide but dual-action oxygen and carbon dioxide
scavenger sachets and labels are more common and are commercially used
for canned and foil pouched coffees in Japan and the USA (Day, 2003;
Dual-action sachets and labels typically contain iron powder for scavenging
oxygen and calcium hydroxide, which scavenges carbon dioxide when it is
converted to calcium carbonate under sufficiently high humidity conditions
Examples of generators or emitters include: Ageless G, Toppan C and
Vitalon GMA, although most of the carbon- and earth-activated based
ethylene absorbers also claim carbon dioxide absorption capacity.
Ageless G is a self-working type, based on ascorbic acid oxidation
mechanism, and absorbs oxygen and generates an equal volume of CO 2.
Examples of absorbers include Ageless
E, which also functions as oxygen
It is based on powdered iron and calcium hydroxide