+ All Categories
Home > Food > Oxygen scavenger,ethylene and other scavengers

Oxygen scavenger,ethylene and other scavengers

Date post: 16-Apr-2017
Category:
Upload: swapnil-prashant-gautam
View: 116 times
Download: 0 times
Share this document with a friend
21
OXYGEN SCAVENGER,ETHYLENE AND OTHER SCAVENGERS 0 3 / 1 4 / 2 0 2 2 1 Prepared by:SWAPNIL PRASHANT GAUTAM M.TECH (FOOD) 2 YEAR 15/PFT/007
Transcript

05/03/2023

1

OXYGEN SCAVENGER,ETHYLENE AND OTHER SCAVENGERS

Prepared by:SWAPNIL PRASHANT GAUTAMM.TECH (FOOD) 2 YEAR

15/PFT/007

2WHAT 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.

3WHY 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.

Oxygen Scavengers

presence of oxygen in food packages

-accelerates the spoilage of many foods.-cause off-flavour development-colour change-nutrient loss-microbial attack

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

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.

7

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

9

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 of foods

plastic packaging systems (containing ethylene-vinyl alcohol copolymer (EVOH)

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.

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

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

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.

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

Carbon dioxide generators and absorbers

PrinciplesCarbon 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.

Carbon Dioxide Generating System

High level of CO2 (10-80%) inhibits surface microbial growth and extends shelf life

EXAMPLES1. ferrous carbonate 2. mixture of ascorbic acid and sodium

bicarbonate

Fresh meat, poultry, fish, cheeses and strawberries

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

R

R

R

end

21

THANK YOU


Recommended