10 food irradiation _detection scl strasbourg
TRANSCRIPT
Aérial : Parc d’innovation – Rue Laurent Fries – BP 40443 – 67412 ILLKIRCH Cedex – Tel : 03 88 19 15 15 - Fax : 03 88 19 15 20Site web : www.aerial-crt.com – e.mail : [email protected]
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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
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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