Aluminium Cookware to Minimize

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    uminddece aluronndered

    vely inouj, 20kwares of alurent mns sucrs (Maminium

    1989) has established the Provisional Tolerable Weekly Intakeof 7 mg/kg body weight (equivalent to 60 mg/day for an adultman).

    The cooking in utensils like aluminium skillets, pressure cook-

    constant rate per unit area (Dietzel and Bhme, 2005; Karbouj,2008). pitting corrosion consists in the localised formation of pitsacross the passivation and metal layers. It is promoted by differentfactors, including the presence of precipitates of some secondaryphases (e.g. Al12Fe3Si2) in the aluminium matrix (Hollingsworthand Hunsicker, 1987).

    In this paper, we describe a simple treatment that can drasti-cally decrease the leachability of aluminium cookware. For

    Abbreviations: AD, Alzheimer disease; Al, aluminium; ICP-MS, inductivelycoupled plasma-mass spectrometry; S.H.E, Standard Hydrogen Electrode.* Corresponding author. Tel.: +33 4 76 49 01 85.

    E-mail address: karbouj_rim@hotmail.com (R. Karbouj).

    Food and Chemical Toxicology 47 (2009) 571577

    Contents lists availab

    Food and Chemi

    journal homepage: www.elsev1 Present address: 72 Avenue Rhin et Danube, 38100 Grenoble, France.anaemia, osteomalacia, and a neurologic syndrome known as dial-ysis encephalopathy (Malluche, 2002; Savory et al., 1986). Then,both in experimental animals and in human, aluminium is clearlyidentied as a potent neurotoxicant (Flaten et al., 1996; WHO,1997).

    TheWorld Health Organisation considered in 1986 that humansconsumed about 30 mg of Al/day on average, through water, foodsand drugs (WHO, 1986). In some conditions, the daily intake fromfood can be much larger than this average value (Karbouj, 2007).The Joint FAO/WHO Expert Committee on Food Additives (WHO,

    of a barrier layer of aluminium (III) (oxy)-hydroxide (Hollings-worth and Hunsicker, 1983). Transfer of aluminium to food duringcooking can arise from two competitive mechanisms:

    slow uniform dissolution of the (oxy)-hydroxy layer at thesolution interface, itself being regenerated by slow oxidation atthe metal interface. Under cooking conditions, uniform dissolutionof the aluminium (oxy)-hydroxide is kinetically controlled bythe detachment of the hydrated aluminium ion, itself governedby the surface proton adsorption. The dissolution occurs at1. Introduction

    Aluminium has been used extensipackaging (Baxter et al., 1989; Karbmeal, the cooking in aluminium coothe ingestion of important quantitiebody, aluminium ion can inhibit diffecompetition reactions with other iocalcium, phosphor, uoride and otheet al., 2005; Kaur and Gill, 2005). Alu0278-6915/$ - see front matter 2008 Elsevier Ltd. Adoi:10.1016/j.fct.2008.12.028foodstuffs, utensils and07). Depending on thecan expose humans tominium. In our humanetabolism processes byh as iron, magnesium,hieu et al., 2004; Aikoh(Al) is associated with

    ers, roasting pans, pots, saucepans, frozen dinner trays, foils andwrappers provide an important amount of aluminium, especiallyin the case of acidic dishes as tomato sauce for example (Ranauet al., 2001; cancar et al., 2004; Karbouj, 2007).

    1.1. Dissolution of aluminium

    In spite of the low redox potential (1.66 V versus S.H.E.), thecorrosion of aluminium is inhibited at 4 < pH < 8.5 by the presenceA simple pre-treatment of aluminium coaluminium transfer to food

    Rim Karbouj *,1, I. Desloges, P. NortierLGP2 UMR 5518 (CNRS, Grenoble INP, AGEFPI, CTP), 461 rue de la Papeterie, BP. 65, 38

    a r t i c l e i n f o

    Article history:Received 26 August 2008Accepted 15 December 2008

    Keywords:AluminiumLeachingFoodTreatment

    a b s t r a c t

    In this work, we studied alcommonly found in foods acooking is suitable for theresponding decrease of thstudied by scanning electchanges in the structure ato a surface uniformly covll rights reserved.ware to minimize

    Saint Martin dHres cedex, France

    nium leaching from cookware to food under the effect of citric acid that isbeverages. The authors showed that boiling the cookware in water prior torease of aluminium leaching into food by a factor up to sixty (with a cor-minium intake by consumers). The effect of the pre-treatment has beenmicroscopy and X-Ray diffraction and the effect has been attributed tomorphology of the passivation layer, from an initial heterogeneous layerwith ne needles of Boehmite (a-AlOOH).

    2008 Elsevier Ltd. All rights reserved.

    le at ScienceDirect

    cal Toxicology

    ier .com/ locate/ foodchemtox

  • Assemblage of the study of the aluminium transfer

    1. Heating circulator bath 2. Peristaltic pump 3. Reactor 4. Aluminium sample 5. Sample Handler 6. Thermostat 7. Watson-Marlow Bredel Bioprene tubing 8. Solution 9. Refrigerant 10. pH-meter 11. Electrode 12. Temperature probe

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    Fig. 1. Experimental device.

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    Fig. 2. Dissolved total [Al] (mg/L) as a function of the time and temperature ofleaching (Citric Acid 10 mmol/L). (a) Without pre-treatment (leaching: 84 C); (b)With pre-treatment 5 h at 20 C (leaching: 84 C); (c) With pre-treatment 5 h at94 C (leaching: 84 C); and (d) With pre-treatment 5 h at 94 C (leaching: 100 C).

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    Fig. 3. Dissolved total [Al] (mg/L) as a function of the time of pre-treatment at 84 C(Citric Acid 10 mmol/L). (a) Without pre-treatment (leaching: 84 C) and (b) Withdifferent pre-treatments time at 94 C pre-treatment.

    572 R. Karbouj et al. / Food and Chemical Toxicology 47 (2009) 571577

  • icalR. Karbouj et al. / Food and Chemeconomical reasons, one cannot prevent peoples to usealuminium kitchen utensils such as pots, pans, and coffee perco-lators and others, but one can educate users to simple gesturesthat can contribute to reduce the total dietary intake ofaluminium.

    Fig. 4. Photographic images bToxicology 47 (2009) 571577 5732. Materials and methods

    2.1. Reagents

    Citric acid monohydrate (crystallized), was purchased from SIGMAALDRICH (St.Quentin Fallavier, France). Samples (2.5 15 cm2) were cut out of Aluminium Foil

    y SEM of the foil surface.

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    574 R. Karbouj et al. / Food and Chem(99.5% pure), from ALUPLUS dALFAPAC (Paris, France), purchased in a departmentstore, verifying that all packages were from the same batch. For all leaching experi-ments, deionised water was used (Elga, Villeurbanne, France).

    2.2. Instrumentation

    The experimental device included: a peristaltic pump (Sci-Q 323 E, Watson-Marlow, Falmouth, Cornwall, England), a pH-meter (Haana 211, Tanneries, France)and a heating circulator bath (Model C1-B3, HAAKE, Germany). Polypropylene alu-minium-free bottles (WVR International GmbH, Darmstadt, Germany) were usedfor storage of all samples. (See Fig. 1)

    2.3. Pre-treatment

    The aluminium foil was used either as such or pre-treated. Pre-treatment con-sisted in dipping the foil for a given time (0, 15, 30, 60 or 300 min) into water atambient (20 C) or near-boiling temperature (94 C).

    2.4. Dissolution experiments

    Samples of aluminium foil (2.5 cm 15 cm) were tested by the contact in areactor together with 275 ml of citric acid 1.0 102 mol/L at near-boiling temper-ature (84 or 100 C), for 10, 30, 60 or 300 min. These times of reaction with citricacid were selected because they are different times of preparation or cooking ofcommonly consumed foods and beverages, like dairy products, berries and citrusfruits (i.e. lemon, black-currant, red-currant). The temperature was chosen as closeas possible to the boiling point, considering practical limitations of the device. Theow rate in the reactor was set to 1.8 L/min, as preliminary experiments showedthat the dissolution is not affected by mass transport at the corresponding velocity(Karbouj, 2008).

    2.5. Analysis

    Aluminium content in water was measured at the Central Analytic Departmentof the National Centre for Scientic Research (Service Central dAnalyse, CNRS,Vernaison, France) using inductively coupled plasma-mass spectrometry (ICP-MS)analyses with an X7 series quadrupole instrument (Thermo Electron Corporation,Cergy-Pontoise, France).

    Scanning electron microphotographs were performed at the LGP2 on a QUANTA200 from FEI, tted with an X PGT probe (Sahara SDD) for chemical analysis, datawere treated using Spirit software. 50 60 70 80

    ta angle ()

    of the foil surface.

    Toxicology 47 (2009) 571577Crystalline phases on aluminium foil were determined by XRD at the ScienticResearch Laboratory (Consortium des Moyens Technologiques Commun, CMTC) ofGrenoble Institute of Technology using a PanAnalytical XPert Pro MPDDiffractometer.

    Additional chemical analysis were also realised at the CMTC using a Jeol 6400SEM tted with Brker SDD EDS probe.

    3. Results and discussion

    The amount of aluminium in solution after contact of non