10 Food Irradiation _detection SCL Strasbourg

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Centre de Ressources TechnologiquesInstitut Technique Agro-Industriel

Applications multi-sectorielles des techniques d’ionisationEtudes et assistance technique pour l’industrie agro-alimentaireLyophilisation pour les bio-industries

AAéérialrial

Colloque Compléments alimentairesIllkirch le 14 octobre 2011

Dalal AOUDÉ- WERNER

Applied Research

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Training

Expert Advice

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Aérial’s activities

Radiation processing

Food Processing

Freeze -Drying

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1400m2 - Parc d’innovation - Illkirch

A specific equipment :

Pilot Freeze-Dryers

Experimental electron beam irradiation plant

5 Laboratories

� Microbiology (L2 and L3)

� BioChemistry

� Sensory Analysis

�Detection of irradiated food

� Dosimetry

�Experimental Freeze-Drying Laboratory

Our facilities

Not to confuse irradiation and activation !

� Submit a product of ionizing radiation

� Remove electrons from atoms of matter

� Appearance of highly reactive radicals

Irradiation

Irradiation dose

Absorbed dose is the mean energy imparted to a

quantity of matter divided by the mass of that matter

i.e. energy per unit mass

Unit: J kg-1

Special name: gray (Gy) 1Gy = 1 J kg-1

How is irradiation performed ?

Two types of radiation :

� Electromagnetic radiation

� γ Rays

� X Rays

� Corpuscular radiation

� Electron beam

γγ, electrons, X Rays, electrons, X Rays

Radiation actions on chemical systems or

biological organisms

IRRADIATION Ionisation

9

Free

radicals

Chemical

ReactionsBiological

Reactions

Direct effect of irradiation

Indirect effect of irradiationH3O++ •OH /•H + •OH /

H2O + •H

Parameters impacting µo radiosensitivity

Nature and state of the microorganism

�Gram- bacteria are globaly more radio sensitive than the Gram+ bacteria

�Vegetative cells are more radio sensitive than spores

�Bacteria are more radio sensitive in growth ϕ than in stationnary ϕ

10

Media and water availibility

� Deep freezing or deshydratation increases µo radioresistance

� The higher the water activity aw, the higher the radiation sensitivity

�µo radioresistance is lower under oxygen

102

101

100

10-1

10-2

10-3

La notion de dose reflète la quantité d'énergie absorbée par l'unité de masse du produit traité

La dose s'exprime en Gray (symbole Gy)

1 Gy = 1 joule/kg

Destruction de virus Stérilisation Destruction d'enzymes Réticulation Greffage sur polymères Vulcanisation de caoutchouc

Traitement des eaux et de déchets Pasteurisation Aseptisation

Elimination de parasites dans les produits carnés Désinsectisa- tion

Mutation des végétaux Inhibition de germinationStimulation

de la croissance des végétaux

Suivant les doses appliquées - de 0,001 à 100 kGy - l'ionisation génère des effets extrêmement variés qui vont de la stimulation de croissance à la stérilisation

(kGy)

Applications of radiation processing

In France (official)

4,383 t of irradiated food Products in 2003

3,004 t of irradiated food Products in 2006

2,139 t of irradiated food Products in 2007

12

Food submitted to irradiation

In EU (official)

17,164 t of irradiated food Products in 2003

15,058 t of irradiated food Products in 2006

8,154 t of irradiated food Products in 2007

Source : journal officiel de l’Union Européenne

�European legislation L66/16 (1999)L66/16 (1999)

�� Control of labeling

� Respect for freedom of consumer choice

Detection of irradiated food

20021996

EN 1784 (HCV)

EN 1785 (2-ACB)

EN 1786 (RPE os)

EN 1787 (RPE cellulose)

EN 1788 (TL silicates)

EN 13708 (RPE sucre)

EN 13751 (PSL)

EN 13783 (DEFT-APC)

EN 13784 (comète)

Detection of irradiated Food

� EN 1788:2001, Foodstuffs - Thermoluminescence detection of irradiated food

from which silicate materials can be isolated

� EN 13751:2002, Detection of irradiated food by pulsed photostimulated

Luminescence-Screening method

Physical MethodsThermoluminescence & Photostimulated Luminescence

� Basis: release by heating (TL) or pulsed infra-red light (PSL) of trapped energy

in dry crystalline materials.

� Suitable materials: silicate minerals and soils; absorbed or sands

� Equipment: TL or PSL

Physical MethodsThermoluminescence & Photostimulated Luminescence

Physical Methods - TLuminescence

Measurement of the energy released

Translation in signal

Irradiation

Excieted

Metastable

Fundamental

(1) irradiation →minerals electrons absorb a part of

energy, and are placed in excited state,

(2) emission of a photon → electrons are

maintained during a long-term in a metastable state,

(3) TL (heating) → the metastable electron is

replaced in an excited state,

(4) return at the fundamental state →release of

energy in the form of luminous photons.

State

Physical Methods – TLAnalytical protocol

Mineral silicates Extraction

TL measurement

� Thermoluminescence measurement →Glow1

� Irradiation at 1kGy

� Thermoluminescence measurement → Glow 2

� Extraction of minerals silicates :

(sample+water+ ultra-sound treatment)

� Separation by centrifugation

� Purification by density (Add sodium

polytungstate )

� Drying of minerals silicate

70°C

6°C/S

400°C

Luminescence 1

Standardization curve

Luminescence 1

Physical Methods – TL

ratio of luminescence (T°interval / 150°C - 250°C •R < 0,1 : Non irradiated

•R > 0,1 : Irradiated

Luminescence 2 Luminescence 2

Physical Methods – PSL Luminescence

Same basis as the TL, except that the release of trapped energy is

done by optical stimulation (pulsed infra-red light)

Physical Methods-

Electron Spin Resonance (ESR)

� EN 1786:1996 Foodstuffs - Detection of irradiated food containing bone -

Method by ESR spectroscopy

� EN 1787: 2000 Foodstuffs - Detection of irradiated food containing cellulose by

ESR spectroscopy

� EN 13708: 2000 Foodstuffs - Detection of irradiated food containing sugar by

ESR spectroscopy

Dry part of food (cellulose, hydroxyapatite, crystalline sugar ...)

Physical Methods - ESR

Basis: Free radical or paramagmetic species trapped in dry, rigid matrices.

Suitable materials: bone; shell, seeds,…

Equipment: ESR

Specifications: A unique, stable signal after irradiation with reasonable dose

dependence

� Manual excision of the dry or hard part of food� Additional drying (acetone, diethyl ether, vacuum oven ...)� Recording

Physical Methods – ESRAnalytical Protocole

Remouve flesh Take the central part of bone

Remouve marrow Put into acetone Dry in oven 3h at 50°C

Physical Methods – ESR

Bones

Signal of non irradiated bone Signal of irradiated bone at 1kGy

Pistachio shells, control

Pistachio shells, irradiated at 4kGy Strawberry achenes, irradiated at 3.5 kGy

Strawberry achenes, control

Physical Methods - ESRCellulose : Fruit achenes, Pip fruit, ……

Poivron non irradié Poivron irradié à 1 kGy

27

Dried mango control

Dried mango irradiated at 3 kGy

Dried fig control

Dried fig irradiated at 3 kGy

Physical Methods – ESR

28

Raisin sec non irradié Raisin sec irradié à 1 kGy

A B

�� Dried fruitDried fruit

�� ChocolatChocolat

0,33 0,335 0,34 0,345 0,35 0,355Tesla

Physical Methods - ESR

Chemical Methods

EN 1784:1996 Foodstuffs - Detection of irradiated food containing

fat - Gas chromatography of hydrocarbons

EN 1785:1996 Foodstuffs - Detection of irradiated food containing

fat - Gas chromatographic analysis of 2-alkylcyclobutanones

� Suitable materials: lipids and fatty acids

� Suitable foods: product containing lipids

� Equipment: fat extraction technology, fluorisil chromatography, GC or GC-MS

� Advantages: common equipment for food laboratories.

� Disadvantages: requires knowledge of unirradiated lipid composition.

Chemical Methods

Triglycéride

H2C

HC O C O R1

R2COOH2C

O CO n-2-CH3(CH2)

Chemical Methods

Triglycéride

3

H2CO

HC O

C

C O

CH2

CH

R1

R2COOH2C

O CHCH(CH2)n-5

2

2 ( CH3CH2

)n-5CH2CH2CH3

( ) CH3CH2 n-5CH2 CH

Irradiation

2-Alkylcyclobutanone

( CH3

CH2)n-5

CHO CH2C

CH2

(c) (a)

(b)

(c)

(a)

(b)

C, m

-2C, m+1

-1C, m

Chemical Methods

C

H2CO

HC O

C

O R1

R2COOH2C

O

H

Irradiated Cheese

C14:1 C15:0

Palmitique : C16:0

10 20 30 40 Min.

15 20 Min.

C16:1

C17:0Stéarique : C18:0

C16:2 C17:1Oléique : C18:1

M. Bergaentzlé et al., 1994, Food Chem., 51, 177-182

Analysis of volatils hydrocarbons- CG

Alkylcyclobutanones

O

2-DCB (n=10) : 2-Décyl-cyclobutanone (myristique/ C14:0)

2-dDCB (n=12) : 2-Dodécyl-cyclobutanone (palmitique/C16:0)

2-tDeCB (n=14) : 2-(tétradéc-5'-ényl)-cyclobutanone (oléique/C18:1)

2-tDCB (n=14) : 2-Tétradécyl-cyclobutanone (stéarique/C18:0)

2

10 20 30 40 min

-tDeCB

2-dDeCB

Milk powder irradiated at 5 kGy

Analysis of 2-alkyl-cyclobutanones_ CG/MS

M. Bergaentzlé et al., 1994, Food Chem., 51, 177-182

EN 13784 : 2001 DNA Comet Assay of irradiated food stuffs-screening method

Biological Methods - DNA Alterations

EN 1788:2001 - Detection of irradiated food using Direct Epifluorescent

Filter technique/Aerobic plate count (DEFT/APC)-Screening method

Biological Methods-DEFT/APC

Basis: relative changes in microflora due to differential sensitivity of µo detected by Differential Epifluorescent Filter Technique (DEFT) and Aerobic Plate Count (APC).

Suitable materials: bacteria etc.

Suitable foods: foods with a natural microflora

Equipment: simple microbiological lab equipment + fluorescent microscope

Advantages: Simple

Disadvantages: changes not radiation specific; need knowledge of microflora.

� 2007 : 6436 samples submitted to detection test 3.14% non conform (lack of labeling, products not authorized to be irradiated)

� 2003 : 5000 samples submitted to detection test 2.1% (lack

of labeling)

� Main method used : TL

� Main products tested : food supplement, spices, dehydrated products

CONTROL OF IRRADIATED FOOD IN EU

Source : journal officiel de l’Union Européenne