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Toxic and essential elements in Lebanese cheeseRola Bou Khozam a b , Pawel Pohl b c , Baydaa Al Ayoubi d , Farouk Jaber a e & RyszardLobinski b fa Analysis of Pesticides and Organic Pollutants Laboratory, Lebanese Atomic EnergyCommission, Beirut, Lebanonb Laboratoire de Chimie Analytique Bio-inorganique et Environnement, CNRS/UPPA,Hélioparc, Pau, Francec Faculty of Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego,Wroclaw, Polandd Statistics and Informatics Department, Faculty of Sciences-I, Lebanese University, Hadath,Beirut, Lebanone Laboratory of Analysis of Organic Compounds (509), Faculty of Sciences I, LebaneseUniversity, Hadath, Beirut, Lebanonf Department of Chemistry, Warsaw University of Technology, Warsaw, Poland

Available online: 11 Apr 2012

To cite this article: Rola Bou Khozam, Pawel Pohl, Baydaa Al Ayoubi, Farouk Jaber & Ryszard Lobinski (2012):Toxic and essential elements in Lebanese cheese, Food Additives and Contaminants: Part B: Surveillance,DOI:10.1080/19393210.2012.682611

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Food Additives and Contaminants: Part B2012, 1–10, iFirst

Toxic and essential elements in Lebanese cheese

Rola Bou Khozamab*, Pawel Pohlbc, Baydaa Al Ayoubid, Farouk Jaberae and Ryszard Lobinskibf

aAnalysis of Pesticides and Organic Pollutants Laboratory, Lebanese Atomic Energy Commission, Beirut, Lebanon;bLaboratoire de Chimie Analytique Bio-inorganique et Environnement, CNRS/UPPA, Helioparc, Pau, France;cFaculty of Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego, Wroclaw, Poland; dStatistics andInformatics Department, Faculty of Sciences-I, Lebanese University, Hadath, Beirut, Lebanon; eLaboratory of Analysis ofOrganic Compounds (509), Faculty of Sciences I, Lebanese University, Hadath, Beirut, Lebanon; fDepartment of Chemistry,Warsaw University of Technology, Warsaw, Poland

(Received 11 July 2011; final version received 2 April 2012)

Concentrations of 20 minor, trace and ultratrace elements relevant to human health (Ag, Al, As, Cd, Co, Cr, Cu,Fe, Hg, Li, Mn, Mo, Ni, Pb, Sb, Se, Si, Sn, V) were determined in four different varieties of the most consumedcheese in Lebanon (Halloumi, Double Creme, Baladi, Labneh) sampled at five different provinces (Grand Beirut,South of Lebanon, North of Lebanon, Mount of Lebanon and Beka’a) during the wet and dry seasons. Theanalyses were carried out by double focussing sector field inductively coupled plasma–mass spectrometry (ICP-MS) in order to avoid errors due to polyatomic interferences. Levels of toxic elements (As, Cd, Pb) were generallybelow the WHO permissible levels in dairy products. Concentrations of most elements were considerably affectedby the type of cheese, the geographical site and the season of sampling.

Keywords: cheese; analysis; Lebanon; trace elements; sector field ICP-MS

Introduction

Dairy products, and cheese in particular, are animportant part of the Mediterranean diet and representa considerable source of trace elements, both essential(e.g. Fe, Mn, Mo, Zn) and toxic (e.g. Cd, Hg, Sn andPb) (Yuzbas et al. 2009). The monitoring of differentvarieties of cheese available on the market for elementconcentrations is therefore important for consumers,manufacturers and health professionals (Kelly andBateman 2010). The trace element concentration pat-tern can also be a valuable parameter of the cheeseauthenticity and geographical origin (Suhaj andKorenovska 2008).

Element concentrations in cheese depend on thosepresent in raw milk and, consequently, on the compo-sition of soil used for pasture and environmentalcontamination. They are influenced by the type (cow,goat, sheep) and genetic characteristics of animals, typeof pasture and stage of lactation and can undergoregional and seasonal variations (Merdivan et al. 2004;Ayar et al. 2009; Yuzbas et al. 2009). The trace elementconcentration pattern can also be considerably mod-ified in the course of different chemical and physicalprocesses during cheese production (salting and cur-dling) and by contamination from the ware used in theproduction process (Coni et al. 1996; Suhaj andKorenovska 2008; Yuzbas et al. 2009).

Indeed, the trace element composition is modified

during salting by the contribution from salt and other

ingredients added for casein coagulation. Also, osmo-

tic phenomena due to the high concentration of NaCl

result in a release of elements partially present in curds

in the form of simple ions (Al, Cd, Co and Sr) (Ayar

et al. 2009). Curdling (the partition of trace elements

between curd and whey) leads to an increase in

elements bound to casein and fat (e.g. Cd, Cu, Fe,

Zn) (Coni et al. 1996; Merdivan et al. 2004; Ayar et al.

2009) and to a decrease of those bound to low-

molecular-weight compounds (e.g. Ni bound to citrate

or Mg bound to lactose) (Coni et al. 1996). The natural

acidity of processing media is known to provoke the

demineralisation of casein micelles (Coni et al. 1995)

and to support the leaching of metals from the

containers used for storage of curd and cheese (Coni

et al. 1996; Merdivan et al. 2004; Vural et al. 2008).

White cheese in particular is known to pick up

elements from metal containers (Ayar et al. 2009).To date, a number of studies of the multi-element

survey of dairy products from different countries have

been reported: Italy (Coni et al. 1996; Gambelli et al.

1999), Spain (Canary Islands) (Garcia et al. 2005),

Turkey (Merdivan et al. 2004; Ayar et al. 2009),

Slovenia (Suhaj and Korenovska 2008) and Brazil

(Kira and Maihara 2007). However, despite the fact

*Corresponding author. Email: r.boukhozam@cnrs.edu.lb

ISSN 1939–3210 print/ISSN 1939–3229 online

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that cheese represents 6.5% of the Lebanese FoodBasket (Nasreddine et al. 2010) and is a potentialexport product, there is a remarkable paucity of dataon the trace element composition of cheese producedand consumed in Lebanon. The only study refers to atotal diet study where all kinds of dairy products werehomogenised together prior to determination of Fe,Mn, Ni, Zn, Cu, Co, Cd and Pb (Nasreddine et al.2010).

The goal of this study was an extensive survey of20 minor, trace and ultratrace elements (Ag, Al, As,Cd, Co, Cr, Cu, Fe, Hg, Li, Ni, Mn, Mo, Pb, Si, Sb, Se,Sn, V and Zn) in the four types of white cheese mostconsumed in Lebanon with regard to regional andseasonal variations.

Experimental

Samples

Forty samples of locally made white cheese mostcommonly consumed by the Lebanese population wereselected on the basis of their market share. They werecollected in 10 sites geographically representative to thewhole Lebanese territory. The types of cheese wereHalloumi (semi-hard cheese traditionally made ofunpasteurised sheep’s and goat’s milk and stored inits natural juice with salt-water), Double Creme (madeof cow’s milk enriched with cream to contain at least60% milk fat), Baladi (soft white pasteurised cheesemade of cow’s milk with a fat content of 22%) andLabneh (yoghurt made of cow’s milk, strained byremoving the whey). Cheeses were purchased in thetwo biggest cities at the most popular market in each ofthe five provinces of Lebanon: Grand Beirut, South ofLebanon, North of Lebanon, Mount of Lebanon andBeka’a region (Figure 1). In order to evaluate theseasonal variation of elemental composition of min-erals due to the different feeding and environmentalconditions, samples were collected in the dry seasonduring August (2010) and in the wet season in January(2011). Sampling and storage steps were optimised toreduce all possible contaminations, losses or alter-ations that could negatively affect reliability of data.Only plastic tools for handling and tubes for storagewere used during cheese preparation.

Sample preparation and analysis

Samples were lyophilised and fine ground with a pestlein an agate mortar to facilitate subsequent digestion.The development of the analytical procedure wasdescribed in detail elsewhere (Bou Khozam et al.2011). In brief, a 0.25-g sample was hot-plate digestedat 85�C with a mixture of concentrated HNO3 andH2O2 (10:3) till a transparent solution was obtained.The solution was analysed by inductively coupled

plasma–mass spectrometry (ICP-MS) using a double-focussing sector-field mass spectrometer (Element XR,ThermoFisher, Bremen, Germany) fitted with aMicroMist glass concentric nebuliser (GlassExpansion, West Melbourne, Australia) and aCETAC ASX-520 autosampler (Omaha, NE).Isotopes of 20 elements were measured by DF-SF-ICP-MS in low resolution (300) mode: 7Li, 95Mo,107Ag, 111Cd, 118Sn, 121Sb, 202Hg, 208Pb; mediumresolution (4000) mode: 27Al, 28Si, 51V, 52Cr, 55Mn,56Fe, 59Co, 60Ni, 63Cu, 66Zn; and high resolution(10,000) mode: 75As, 78Se. De-ionised water(18.3MV cm) and Intra-analysed 69%–70% (m/m)HNO3 and 30% (m/m) H2O2 solutions (Baker,Deventer, the Netherlands) were used throughout tominimise the blanks. All samples were run in duplicate.Quantification was carried out by using matrix-matched standard solutions with 10 calibrationpoints. For the purpose of quality control and assur-ance, a certified reference material (NIST SRM 1549 ofnon-fat milk powder) was analysed (Table 1) with eachanalysis sequence (80 individual samples).

Statistical evaluation of data

Data were analysed by the Statistical Package forSocial Sciences (SPSS) for Windows (version 9.05).Student t test and one-way analysis of variance(ANOVA) were used to determine statistically signif-icant levels for differences in the mean values ofmeasured elements among subjects grouped by region

Figure 1. Geographical location of the sampling sites.

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and season. A probability level of 0.05 was consideredto be statistically significant.

Results

The determined concentrations of trace elements incheese samples are given in Table 2. They correspondto concentrations in the total sample wet weight. Eachreported concentration represents the mean value of allanalysed samples collected from the five regions inLebanon, and separately for two sampling seasons,that is, wet and dry. In addition, an inventory forsimilar studies with the reported concentrations fromother countries is included. Figure 2 shows thedistribution of the concentrations measured for eachelement with a reference to the interval of resultspreviously reported in the literature.

Discussion

For the purpose of further discussion, two groups ofthe determined elements were considered. One wasreferred to as toxic: Ag, Al, As, Cd, Hg, Pb, Sb and Sn;the other, including components of enzymes, areconsidered as essential: Co, Cr, Cu, Fe, Li, Mn, Mo,Ni, Se, Si, V and Zn. Note that at high concentrationsor when present at particular oxidation states, forexample, Cr(VI) or Se(VI), the latter elements can alsoshow toxic effects. First, the total element

concentrations found are discussed in the context oftheir corresponding permissible levels as reported byCodex Alimentarius regulations (Code 193-1995,amended 2010), and then variations observed betweendifferent cheese varieties, geographical distribution inLebanon and seasonal variations are interpreted.

To discuss differences in concentrations as afunction of element, season and geographical site,statistical analysis of the obtained data was carried outusing t tests for two independent samples at the 95%confidence limit (p5 0.05) for the set of results fromtwo studied seasons (Triola and Triola 2006; Weiss2008). Kolmogorov-Smirnov and Mann-Whitney testsby rank for independent samples were used forelements that do not fulfil the normal distributioncriteria (Caperaa and Van Cutsem 1988). The ANOVAtest at the 95% confidence limit was used to indicateany significant differences in geographical sites withinthe same season as all elements showed normaldistribution in each geographical site for each studiedseason (Triola and Triola 2006; Weiss 2008). Thenormality of elements was examined by theKolmogorov-Smirnov test.

Concentrations of toxic and essential elements

The source of the contamination by toxic elements incheese likely results from the contamination of waterused for its production. Similar studies were done inother countries showing different concentration levelsbecause of the seasonal weather changes and thedifferences in the manufacturing processes. On theother hand, a high content of Pb in cheese could berelated to a strong tendency of casein to bind the Pbions (Ayar et al. 2009). Additional sources of thecontamination of cheese with Pb could be additivessuch as CaCl2 and the release of heavy metals fromequipment to milk that may occur at relatively hightemperatures (Yuzbas et al. 2009).

The mean concentrations of toxic elements for allanalysed samples follow the sequence Al4 Sn4Pb4As4 Sb4Cd4Ag4Hg. It should be notedthat As and Pb concentrations in cheese samples werebelow respective permissible levels as set by the CodexAlimentarius for dairy products (As: 0.1–1.0 mg g�1,Pb: 0.02 mg g�1, Code 193-1995, amended 2010). Thereported results in this study related to the mostfrequent contaminants, that is, As, Cd and Pb, showedthat concentrations of these elements in Lebanesecheese are much lower than those reported for similarproducts from other countries, for example, Turkey.

The results for Sn and Sb are to our knowledge thefirst data ever reported on these elements in cheese.Because Sn is used to coat cans and containers, it couldbe a source of the contamination from food packaging(Blunden and Wallace 2003; Shimbo et al. 2007).

Table 1. Analytical results of non-fat milk SRM.a

Isotope

NIST SRM 1549

Certified Found

7Li – 50.0127Al 2b 1.90� 0.1828Si 550b NM52Cr 0.003� 0.001 0.002� 0.00155Mn 0.26� 0.06 0.24� 0.0156Fe 1.78� 0.1 1.98� 0.0759Co 0.0041b 0.003� 0.00163Cu 0.71� 0.1 0.702� 0.02866Zn 46.1� 2.2 44.7� 1.151V – 50.00260Ni – 50.00375As 0.0019b 50.00378Se 0.11� 0.01 �0.195Mo 0.34 b 0.34� 0.02107Ag 50.0003b 50.001111Cd 0.0005� 0.0002 50.0007118Sn 50.02b 50.002121Sb 0.00027 50.0006202Hg 0.0003� 0.0002 50.0008208Pb 0.019� 0.003 0.018� 0.001

Notes: aMean� SD (n¼ 3).bConsensus or informative value.

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Table 2. Concentrations of toxic (Ag, Al, As, Cd, Hg, Pb, Sb and Sn in ng g�1) and essential (Cu, Cr, Co, Fe, Li, Mn, Mo, Ni,Se, Si and V in mg g�1) elements in analysed cheese samples collected from wet and dry seasons, in addition to similar studies fromother countries.

This studya

Element Wet Dry Other studies Type of cheese and country References

Al 2.3� 0.3(0.66–7.89)

2.3� 0.3(0.062–17.9)

2.8 and 8.85.33.5/dry weight

Drained yoghurt andcheese, Turkey

White cheese, TurkeyGoat cheese, Italy

Ayar et al. (2009)Merdivan et al. (2004)Coni et al. (1996)

As 2.2� 0.6(0.4–13.9)

7.0� 0.7(0.4–15.9)

99 and 32 Drained yoghurt andcheese, Turkey

Ayar et al. (2009)

Cd 0.14� 0.04(0.002–1.28)

19 and 12120/dry weight0.61

Drained yoghurt andcheese, Turkey

Goat cheese, ItalyGoat cheese, Canary Island

Ayar et al. (2009)Coni et al. (1996)Rubio et al. (2006)

Pb 32.4� 0.8(1.5–180.9)

20.7� 2.0(2.4–70.0)

1100 and 9200.14/dry weight

Drained yoghurt andcheese, Turkey

Goat cheese, Italy

Ayar et al. (2009)Coni et al. (1996)

Sn 0.037� 0.004(0.002–0.39)

0.002� 0.027(0.0002–3.74)

N.A.

Sb 0.44� 0.40(0.0–8.84)

1.2� 0.4(0.109–4.68)

N.A.

Hg 4LOD 1.006� 0.006(0.02–2.52)

N.A.

Ag 0.32� 0.1(0.04–2.34)

0.08� 0.02(0.02–0.5)

N.A.

Cr 0.035� 0.004(0.01–0.12)

0.0011� 0.0001(0.0005–0.002)

0.04/dry weight0.03 and 0.080.010.070.170.21

Goat cheese, ItalyCottage and mozzarella

cheeses, ItalyCreamy cheese, SpainPetit Suisse cheese, BrazilWhite cheese, TurkeyBryndza cheese, Slovakia

Coni et al.(1996)

Gambelli et al. (1999)Lendinez et al. (2001)Kira and Maihara (2007)Merdivan et al. (2004)Suhaj and Korenovska (2008)

Co 4.2� 2.5(0.1–10.3)

27.2� 19.0(0.1–200)

15/dry weight23 and 1.81540

White cheese, ItalyCottage and mozzarella

cheese, ItalyWhite cheese, Turkey

Coni et al. (1996)Gambelli et al. (1999)Merdivan et al. (2004)

Cu 0.48� 0.06(0.11–4.37)

0.860.220.89/dry weight0.500.80

Bryndza cheese, SlovakiaPetit Suisse cheese, BrazilGoat cheese, ItalyWhite cheese, TurkeyFresh goat cheese, Canary

Island

Suhaj and Korenovska (2008)Kira and Maihara (2007)Coni et al. (1996)Merdivan et al. (2004)Garcia et al. (2005)

Fe 2.4� 0.15(0.54–5.98)

2.4 and 1.03/dry weight2.25.429.1� 0.1

Cottage and mozzarellacheese, Italy

Goat cheese, ItalyGoat cheese, Canary IslandWhite cheese, TurkeyPetit Suisse cheese, Brazil

Gambelli et al. (1999)Coni et al. (1996)Garcia et al. (2005)Merdivan et al. (2004)Kira and Maihara (2007)

Li 0.029� 0.003(0.003–0.37)

N.A.

Mn 0.33� 0.02(0.06–1.09)

0.18� 0.01(0.03–0.37)

0.220.34/dry weight0.350.07

Brynzda cheese, SlovakiaGoat cheese, ItalyPetit Suisse cheese, BrazilWhite cheese, Turkey

Suhaj and Korenovska (2008)Coni et al. (1996)Kira and Maihara (2007)Merdivan et al. (2004)

Mo 0.050� 0.003(0.0002–0.131)

0.28 White cheese, Turkey Merdivan et al. (2004)

Ni 0.022� 0.002(0.003–0.07)

0.07� 0.01(0.01–0.24)

1.20.410.01/dry weight

White cheese, TurkeyBrynda cheese, SlovakiaGoat cheese, Italy

Merdivan et al. (2004)Suhaj and Korenovska (2008)Coni et al. (1996)

(continued )

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Sb is added to increase the hardness of Pb and as

catalyst for the production of polyethyleneterephtha-

late (Keresztes et al. 2009). The concentrations of these

two elements in the analysed cheese samples vary in a

non-systematic way according to the type of cheese

within the same season and due to season variation. Ag

has been largely documented for its use as a sterilisa-

tion agent of drinkable water and for post-harvest

cleaning of seafood, fruits and vegetables (Gopal et al.

2010). Despite their recognised toxicity effects, it

should be noted that no permissible limit in milk and

dairy products for Ag, Al, Cd, Hg, Sn and Sb has been

found in regulations related to food safety.Regarding the concentrations of essential elements

for the analysed cheese samples, they follow the

sequence Co5Mo5 Se5Li5Ni5V5Mn5Cu5Fe5 Si5Zn. The high concentration of Zn

could be explained by the general abundance of this

element and the fact that 95% of its total content is

retained by casein micelles during cheese production.

The reported concentration for Zn in Lebanese cheese

is similar to that reported for Italian mozzarella and

goat cheese (Conti et al. 1996; Gambelli et al. 1999) or

Turkish white cheese (Merdivan et al. 2004) and much

higher than those reported for corresponding products

from other countries (Garcia et al. 2005; Kira and

Maihara 2007). Fe, Mn and Se showed concentration

levels similar to those reported for cheese products in

previous studies (Coni et al. 1996; Gambelli et al. 1999;

Merdivan et al. 2004; Garcia et al. 2005; Kira and

Maihara 2007; Suhaj and Korenovska 2008; Ayar et al.

2009).Only in case of Cu, higher values were obtained than

those reported from other countries (Coni et al. 1996;

Merdivan et al. 2004; Garcia et al. 2005; Kira and

Maihara 2007; Suhaj and Korenovska 2008), whichcould be due to the use of the metallic equipment duringmanufacturing. Cr and Ni showed similar concentra-tions as the values reported from Italy, but lower thanthose reported from Slovakia and Turkey (Coni et al.1996; Gambelli et al. 1999; Lendinez et al. 2001;Merdivan et al. 2004; Kira and Maihara 2007; Suhajand Korenovska 2008). Similarly, Mo and V showedconcentrations lower than that found in other countries(Merdivan et al. 2004; Suhaj and Korenovska 2008).

Effect of seasonal variation

There are marked changes in milk composition overthe season, which arise from the interactive influence oflactation, diet and environmental factors. The qualityof milk products is highly affected by forage, whereto itconfers a specific organoleptic and nutritional profile.Feed is based on local forage resources with acombination of fresh pasture in the summer and localconserved forage for the rest of the year. Thedehydration factor in feed is reflected by a differencein mineral composition of the produced milk. Add tothat, during the wet season herds that had access tohigher-digestibility pasture or were fed more cerealgrain–based concentrates produced more milk but withlower concentration of hard materials as proteins andfats. Note also that some elements, even when presentat equivalent total concentrations in milk collected inwinter and in summer, respectively, may behavedifferently during the manufacturing process withconsequent seasonal differentiation of the concentra-tion levels in finished cheese.

Statistical data analysis for detection of anypotential difference in elemental composition due to

Table 2. Continued.

This studya

Element Wet Dry Other studies Type of cheese and country References

Se 0.12� 0.02(0.01–0.32)

0.04–0.070.08 and 0.16

Cottage and mozzarellacheese, Italy

Drained yoghurt and whitecheese, Turkey

Gambelli et al. (1999)Ayar et al. (2009)

Si 4.1� 0.3(1.09–9.55)

2.8� 0.5(0.56–6.21)

N.A.

V 0.0096� 0.0004(0.0003–0.03)

0.08� 0.01(0.01–0.37)

0.15 Bryndza cheese, Slovakia Suhaj and Korenovska (2008)

Zn 16.2� 0.5(2.7–43.2)

21.5� 1.5(2.329–69.04)

26.019.0/dry weight17.74.86.53.2� 0.2

Mozarella cheese, ItalyGoat cheese, ItalyWhite cheese, TurkeyCottage cheese, ItalyGoat cheese, Canary IslandPetit Suisse cheese, Brazil

Gambelli et al. (1999)Coni et al. (1996)Merdivan et al. (2004)Gambelli et al. (1999)Garcia et al. (2005)Kira and Maihara (2007)

Notes: aMean� standard deviation values and ranges.(min.–max.) for all samples collected from 10 sampling sites and comparable data from literature data. N.A.¼ not available.

Food Additives and Contaminants: Part B 5

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Figure 2. Distribution of sample concentrations comparing mean value (X) and median value (M) from each season (wet anddry) with a reference to the interval of results previously reported in literature.

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Figure 2. Continued.

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seasonal variation showed that results for most

elements are normally distributed except for Ag, As,

Cd, Cu, Sn and V in samples from the wet season and

Ag, Al, Cd, Co, Li, Sb and Sn in samples from the dryseason. The analysis of data shows that the concen-

trations of Al, Cd, Co, Cu, Fe, Li, Mo, Pb, Zn and Sn

are unaffected by the season. Ag, Cr, Mn and Si were

found to have higher mean values during the wetseason, whereas As, Ni, Sb, Se and V showed the

opposite trend (Figure 2). This tendency could be

related to a swifter dehydration of cheese in the dryseason (Coni et al. 1996).

It seems that the variation of Ag occurs largely in

Beirut compared to other provinces during dry season

and is likely to be due to contamination. Cr showed thehighest seasonal variation. In dry season, it occurs at

ultratrace level (0.0005–0.002 mg g�1) with a much

higher concentration during the wet season (0.01–

0.12 mg g�1). In the case of Mn, hard cheese from dryseason contained twice as much of Mn than from the

wet season, but for soft cheese no significant difference

was detected. For Si, the seasonal variation is clearlyshown in the North. V and Sb showed a higher

influence by seasonal variation as it has higher levels

during the dry season. The seasonal variation of As is

also more obvious when relating to the region. Asconcentrations were 30% higher during the dry season

within Beirut, Beka’a and South region and by 70%

for the North region regardless of the type of cheese.

The seasonal variation for Se is negligible.Concentration of Ni is higher by 40% for all samples

within the five regions during the dry season.Previously, a certain seasonal and manufacturing

variability in concentrations of Zn but not of Cu andSe was reported for different types of goat cheese

(Garcia et al. 2005). Erdogan et al. (2004) reported an

opposite hypothesis that seasonal differences do notchange concentrations of such trace elements as Cr,

Cu, Fe, Mn and Zn in cows’ serum, milk, liver and

kidney samples.

Effect of regional distribution

Normality assumptions of the data on each elementand each geographical region within one season were

conducted. ANOVA test showed that no significant

changes have been noticed between mean concentra-tions of elements as assessed in five regions during the

dry season. During the wet season, Cd, Cr, Co, Cu, V

and Ag showed significantly higher values for the

South of Lebanon. A similar observation was reportedby Garcia et al. (2005), who found no significant

differences between the content of several elements in

goat milk dairy products originated from different

areas in Canary Islands.

The principal exceptions were as follows:

(1) Higher concentrations of some elements (Agand Fe) during dry season in the Great Beirutregion (0.21 ng g�1 and 3.56 mg g�1, respec-tively) in comparison with 3 and 2 timeslower values in the other regions, respectively.A high Sb level of 3.35 ng g�1 was observed inBeka’a compared to 0.5, 0.87 and 1.6 ng g�1 inthe other four regions.

(2) Significantly higher concentration of Cd, Co,Cr, Cu and V during the wet season in theSouth of Lebanon and for Hg from the Beirutregion.

(3) Excessively high concentrations of Sn measuredin most of the samples from the South ofLebanon (values varying from 1 to 3.7 mg g�1)apparently resulting from the use of tin-coatedcontainers. To a lesser extent (0.25 mg g�1), thisphenomenon was observed for the Mount ofLebanon region.

(4) The use of metal containers for heat treatmentin manufacturing processes of cheese wasevoked as a probable source of Al and Cu(Coni et al. 1996; Merdivan et al. 2004). It canexplain the presence of 4.2mg g�1 of Cu in twosamples from the Mount of Lebanon (meanconcentration of Cu in dairy products fromBeirut of 0.19mg g�1; Nasreddine et al. 2010)and exceptionally high values of 17.4 and18.0 mg g�1 of Al in double creme fromJounieh (Mount of Lebanon) and in Labnehfrom Chtoura (Beka’a). Natural acidity ofyoghurt and other related dairy products, thatis, strained yoghurt or Labneh cheeses, canenhance corrosion of pots and release of Al. Inaddition, milk fat may be associated withoxidation processes and corrosion occurred incontainers (Vural et al. 2008).

(5) Higher level of Cd and Pb was shown in Mountof Lebanon (0.36 ng g�1 compared with 0.06–0.18 ng g�1 for others regions) and for Pb51.36 ng g�1 in addition to 38.5 ng g�1 inBeirut compared with values distributedwithin 7.4–13.78 ng g�1 for other regions.

Effect of cheese type

Because the elemental distribution pattern is affectedby local and physiological factors influencing themetabolic fate of an element and the element behaviourduring the sequence of biochemical processes takingplace during cheese production, it can be reflected inthe finished product.

The loss of water content at various stages ofproduction of hard cheese is one of the reasons ofexpected enrichment in trace elements in comparison

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with soft cheese. This enrichment was found to occur

for most of essential elements and was not observed for

toxic elements as Cd, Sb and Sn (Gambelli et al. 1999).Our data confirm this trend. Higher concentrations

of Cu, Fe, Mn, Se and Zn were found in hard cheesevarieties. For Zn, Halloum and Baladi cheeses were

found to contain 6–7 times higher concentrations than

double creme and Labneh cheeses, regardless of the

season. In case of Mn, Halloum, double creme andBaladi from dry season showed a higher mean

concentration (0.42 mg g�1), which is 5 times more

than Labneh cheese (0.09 mg g�1). Similarly, the highest

mean concentrations of Cu and Fe were established forHalloum and double creme as hard cheeses (mean

concentrations of 0.47 and 0.51 mg g�1 for Cu and 2.6

and 3.2mg g�1 for Fe, respectively). The lowest mean

concentrations of Cu (0.26 mg g�1) and Fe (1.8 mg g�1)were found for Labneh cheese.

No differences in mean concentrations due to type

of cheese were found for Co, Cr, Li, Mo, Ni, Se, Si and

V. For the toxic elements Cd, Pb, As and Hg, the effect

of cheese type on toxic element level was much lesspronounced. For Sb, higher concentrations were

determined in Halloum hard cheese than in Labneh.Note that white cheese with a lower fat level tends

to pick up metals from Sn containers and from

naturally contaminated salt used in its production.Thus, controlled conditions of the industrial cheese

production or use of non-Al-containing materials for

production and packaging, preservation and storage of

cheeses in glass jars certainly help to maintain muchlower risk of contamination by metals (Ayar et al.

2009).

Conclusions

Sector-field inductively coupled plasma mass spectro-

metry allows the routine rapid determination of multi-element concentration patterns in cheese. The obtained

set of data represents a first larger scale survey of

essential and toxic elements in Lebanese cheese vari-

eties as a function of geographical location andproduction season and is a first step towards issuing

norms regulating trace elemental content. It offers a

tool for controlling possible secondary contamination

or loss of essential elements during cheese processing,storage and packaging with regard to product quality

or health risk. Lebanese cheese constitutes an impor-

tant source for nutrition elements such as Se, Co, Mn

and Zn. No elevated levels of toxic elements As, Cdand Pb were detected. The acquired data allowed an

insight into possible relationships between seasonal

(wet and dry seasons) and geographical variations. The

multi-elemental trace concentration pattern can be aparameter of geographical origin of cheese, but a larger

study of cheese samples with traceable history andguaranteed authenticity is necessary.

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