This document discusses various types of scavengers used in food packaging, including oxygen scavengers, ethylene scavengers, and carbon dioxide scavengers. It defines scavengers as chemicals that remove or inactivate impurities or unwanted reaction products. It describes how oxygen scavengers work to reduce oxygen levels in packages to prevent food deterioration. Common oxygen scavengers use oxidation of iron or ferrous salts. It also discusses ethylene scavengers that remove the plant hormone ethylene from produce packaging to slow ripening. Carbon dioxide scavengers and generators are also outlined that control CO2 levels to inhibit microbial growth and extend shelf life of foods.

1. SCAVENGER,ETHYLE
NE AND OTHER
SCAVENGERS
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Prepared by:SWAPNIL PRASHANT GAUTAM
M.TECH (FOOD) 2 YEAR
15/PFT/007

2. WHAT IS SCAVENGER?
 A scavenger in chemistry is a chemical substance added to a mixture in
order to remove or inactivate impurities or unwanted reaction products.
What is oxygen scavenger?
 Oxygen scavengers are added to enclosed packaging to help
remove or decrease the level of oxygen in the package.
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3. WHY OXYGEN SCAVENGER
 The residual oxygen in a food package is main cause for food
deterioration.
 Oxygen is the main cause for food deterioration due to oxygen of
fats ,oils and growth of aerobic m.o
 Oxygen is well known to accelerate processes leading to
discolouration, change in texture,rancidity,off flavor,off odour.
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4. Oxygen Scavengers
 presence of oxygen in food packages
-accelerates the spoilage of many foods.
-cause off-flavour development
-colour change
-nutrient loss
-microbial attack

5. Mechanisms of action of Oxygen Scavengers
 a.) Oxidation of iron and iron salts
 oxidation of iron and ferrous salts (provided in the
packet) that react with water provided by food to
produce a reaction that moisturizes the iron metal in
the product packaging and irreversibly converts it to a
stable oxide.
 The iron powder is contained within small oxygen
permeable bags that prevent contact with food.
4Fe (OH)2 + O2 + 2H2O→4Fe(OH)3

6. TYPES
 OXYGEN SCAVENGERS
 materials incorporated into package structures that chemically
combine with, and thus effectively remove, oxygen from the inner
package environment
eg:- ferrous compounds, catechol, ascorbic acid and its
analogues, ligands, oxidative enzymes such as glucose
oxidase, unsaturated hydrocarbons and polyamides
 OXYGEN INTERCEPTORS
 blocks the adverse effect of oxygen in the air on the food, before
the oxygen can enter the food.

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8.  OXYGEN ABSORBERS
 absorbers remove oxygen by physically trapping the
oxygen and not through chemical reaction
 ANTIOXIDANTS
 compounds that react with lipid or peroxide radicals
or, in light, with singlet oxygen, and that are
themselves oxidized to generate what are generally
innocuous nontoxic compounds
 BHA—butylated hydroxyanisole
 BHT—butylated hydroxytoluene
 PG—propyl gallate

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10. 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.

11. EVOH as an oxygen barrier layer for prolonging the shelf-life
of foods
plastic packaging systems (containing ethylene-vinyl alcohol copolymer (EVOH)

12. ADVANTAGES
 prevent oxidation phenomena: rancidification of fats
and oils and consequent emergence of off-odours
and off-flavours, loss or change of colours
characteristic of food, loss of oxygen-sensitive
nutrients
 prevent the growth of aerobic microorganisms.
 reduce or eliminate the need for preservatives and
antioxidants
 slow down metabolism of food.

13. Principles
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.
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.
Ethylene scavengers

14. •apples, bananas, mangos, tomatoes, onions, carrots.

16. Ethylene Blocking Technologies
 1-Methylcyclopropene (1-MCP). 1-MCP is the most widely used
commercial volatile ethylene inhibitor, which blocks ethylene binding
sites.
 Silver thiosulfate (STS). The use of this material is largely restricted to
cut flowers and it is sold commercially under the trade name Chrysal
AVB®.
 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.

17. Examples
 activated alumina, vermiculite, and silica gel that have
been impregnated with potassium permanganate
(KMnO4).
 Activated charcoal alone or after impregnation with
bromine.
 bentonite, Kieselguhr, and crystalline aluminosilicates, e.g.,
zeolites, have been reported capable of adsorbing ethylene

18. Carbon dioxide generators and absorbers
Principles
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 CO2 may
inhibit microbial growth.
--Commercial solutions commonly used are the incorporation of a one-way valve
and more recently, the inclusion of a CO2 absorbing sachet.

19. Carbon Dioxide Generating System
 High level of CO2 (10-80%) inhibits surface
microbial growth and extends shelf life
 EXAMPLES
1. ferrous carbonate
2. mixture of ascorbic acid and sodium
bicarbonate
 Fresh meat, poultry, fish, cheeses and
strawberries

20. Commercial examples
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 CO2. Examples of absorbers include Ageless E,
which also functions as oxygen scavenger.It is based on
powdered iron and calcium hydroxide
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21. THANK YOU
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