TRACE METALS CONCENTRATIONS IN CHEESE COLLECTED FROM KAFR-EL-SHEIKH GOVERNORATE, EGYPT

DISCUSSION

In view of the worldwide interest concerning contamination of the environment with heavy metals, cheese samples have been examined to determine the trace elements concentrations (heavy and essential).

The results of trace metal contents of different types of cheese samples collected from Kafr El-Sheikh Governorate were given in Tables 1&2. Lead concentrations of investigated cheese samples were in the range of 0.19+0.03– 0.44+0.04 mg/kg (the highest was in Ras & Gouda cheese and the lowest was in Feta cheese) (Table 1). Mean lead level of Herby cheese was reported by Mendil (2006) as 0.32 μg/g. While, Orak et al. (2005) reported lead levels of Turkish white cheese as 0.415 μg/g. Lead concentration of cheese samples from Southern Italy was reported by Caggiano et al. (2005) as in the range of 0.35–0.58 μg/g. Lead concentrations, exceeding the maximum limit of 0.02 mg/kg wet weight (EC Regulation, 2001) were found in all of examined cheese samples. FAO/WHO (1999) has set a limit for heavy metal intakes based on body weight. For an average adult (60 kg body weight), the provisional tolerable daily intake (PTDI) for lead is 0.214 mg. According to USDA (2005) and HC (2007), the amount of milk group that are recommended each day 2-4 (for children and teens) and 2-3 cups (for adults), the cup equal 50-60 gm cheese. The examined cheese samples constitute about 19-44% of the daily dietary intake of Pb.

The sources of contamination with lead are lead piping and lead-lined tanks in water supplies. Lead, due to its wide use in industrial processes, ranks as the metal of largest diffusion through the atmosphere, one could speculate that this could in part explain the high concentrations found. This rise could be a consequence of contamination during the cheese making process, since only metals initially present are bound to milk proteins (Coni et al., 1996), likewise cheese may be contaminated with lead from the contaminated salt and in case of Damietta cheese may picked up metals from tin containers. The further increase of lead levels in ripened cheese cannot be explained by water loss but was probably caused by environmental conditions at the ripening sites. The Pb contamination in cheese also could result from feeding cows with fodder collected from road sides and can be controlled by choosing the sources of the fodder without Pb contamination. Lead may accumulate in bone and lie dormant for years, and then pose a threat later in life during events such as pregnancy, lactation, osteoporosis, and hyperthyroidism and hyperparathyroidism, which mobilizes stores of lead in bones (HMRC, 2003).

Cadmium is found in low amounts in soil. It is transported via air and water from intensive industrial regions to the soil and water. It is considered to be the most important contaminant in modern times. Cd levels in examined cheese samples varied from 0.16+0.02 to 0.54+0.02 mg/kg in Cheddar and Edam cheese (Table 1). Nearly similar results (0.1-0.6 mg/kg) were reported by Vural et al. (2008). While, Orak et al. (2005) found that Cd level of white cheese samples from Turkey was 0.127 μg/g. Mean Cd content of cheese samples from Italy was 0.11 μg/g as recorded by Caggiano et al. (2005). The average Cd content of Otlu Lor cheese samples was reported by Kiliçel et al. (2004) as 0.20 mg/kg in Turkey. The Cd contents of cheese samples from several regions of Romania were noticed to be in the range of 0.003– 0.24 mg/kg (Hura, 2002).The results obtained by several researchers also show that the Cd contents of cheese vary over a wide range. A similar diversity in the Cd content of cheese was observed in this study. There is no maximum limit for Cd in milk or cheese, but the maximum limit in sweetened condensed milk and evaporated milk is 0.02 mg/kg and for milk powder is 0.03 mg/kg (Codex Alimentarius Commission, 2004).The high Cd content (0.09-0.7mg/kg) of examined cheese samples may be attributed to uncontrolled production and the use of contaminated water in the production process.

The tolerable daily intake of Cd established by the World Health Organization (WHO, 1996) is 0.060 mg/day for adult women and 0.070 mg/day for adult men. The contents of Cd in examined Cheddar cheese samples constitute about 53.3% (for women) and 45.7% (for men) of dietary daily intake, while Ras cheese samples constitute about 93.3% (for women) and 80% (for men) of dietary daily intake of Cd, except that, all examined cheese samples exceeded the permissible maximum daily intake of Cd recommended in the health criteria by WHO. Cadmium has a very long half-life in the body (10 to 30 years) and can build up over a long time. Over 80% of the body burden resides in the kidneys. Toxic contents of this element lead to renal insufficiency and metabolic abnormalities via enzyme inhibition (Hura, 2002).

The heavy metal contents of cheese varies due to the factors such as differences between species, characteristics of the manufacturing practices and possible contamination coming from the equipments during the process (Yüzbasi et al., 2003 and Caggiano et al., 2005). Oxidation of containers and equipments were affected by some parameters such as pH, quality of raw materials of containers and equipments. Enhancement of oxidation increases the metal contents of samples. Metal contents of used milk affect the metal levels in cheese. In addition, storage containers influence to metal levels. Therefore, heavy metal content of cheese varies in a big range.

Iron is an essential element for life and for our diets. Low iron levels can cause anemia. 40, 20, 13.3, 60, 20 and 33.3% of examined Cheddar, Gouda, Processed, Feta, Damietta and Kareish cheese samples respectively, were below the detection limit of Fe (0.01 mg/l)(DL= 3 × standard deviation of the mean of the blank determinations). The lowest iron concentration was found as 2.90+0.85 mg/kg in Edam cheese samples and the highest was 24.4+12.73 mg/kg in Damietta cheese samples (Table 2). Iron value for Herby cheese samples from Van-Turkey have been reported by Mendil (2006) as 12.5 μg/g and for Turkish white cheese was 3.610 μg/g as estimated by Orak et al. (2005).

As it can be seen in Table 2, Copper could be detected in all of examined samples except in Kareish cheese the Cu could be detected in 86.7% of the examined samples. Highest Cu level of examined cheese samples was found as 4.18+0.71 mg/kg in Cheddar cheese, while the lowest in processed cheese as 1.45+0.14 mg/kg. Mendil recorded Cu levels of Herby cheese from Van- Turkey as 0.13 μg/g (Mendil, 2006). Mean level of Cu in white cheese samples was 0.629 μg/g previously reported by Orak et al. (2005). Cu contents of various cheese samples were found in the range of 0.20–0.50 μg/g by Ferreira et al. (2005). On the other hand, Garcia et al. (2006) noted copper levels of fresh cheese and semi-hard cheese from Tenerife-Canary Islands as 0.80 and 0.86 μg/g, respectively.

Mean Zinc concentrations ranged from 21.72+1.19 to 43.18+0.53 mg/kg. The minimum and maximum Zn levels were found in Feta and Edam cheese samples, respectively (Table 2). Zn values are reported to be 0.35–4.50 mg/100 g  (Gambelli et al., 1999).

 If we take into consideration the recommended dose for daily diet (Recommended Daily Allowance- RDA) according to IMNAS (2000) and IMNAS, FNB (2001) of 8 mg/day Fe for men and 18 mg/day for women; 1.5-3 mg/day Cu and 12-15 mg/day Zn, from Table 2, it can be observed, that by normal consumption of 200 g cheese/day, the examined cheese samples constitute about 7.25-60% for men and 3.2-26.7% for women of Fe; 9.3-27.3% of Cu and 28-57.3% of Zn daily intake. The supply of Fe, Cu and Zn was within the recommended daily intake.

In conclusion, in all types of examined cheese samples, extremely toxic heavy metals Pb and Cd were detected above the toxicity levels but, the levels of Fe, Cu and Zn were within the recommended daily intake. 

REFERENCES

AOAC "Association of Official Analytical Chemists" (2005): Lead, Cadmium, Zinc, Copper, and Iron in foods, Atomic Absorption Spectrophotometry after microwave digestion, Official Method 999.10. Official Methods of analysis of AOAC international, 18^th ed.

Caggiano, R.; Sabia, S.; D’Emilio, M.; Macchiato, M.; Anastasio, A. and Ragosta, M. (2005): Metal levels in fodder, milk, dairy products and tissues sampled in ovine farms of southern Italy. Environmental Research, 99, 48–57.

Codex Alimentarius Commission (2004): Joint FAO/WHO Food standard programme codex committee on milk and milk products, Auckland, Newzealand, 26-30 April, 2004.

Coni, E.; Bocca, A.; Coppolelli, P.; Caroli, S.; Cavallucci, C. and Trabalza, S. (1996): Minor and trace element content in sheep and goat milk and dairy products. Food Chemistry, 57, 253–260.

EC Regulation (2001): Setting maximum levels for certain contaminants in foodstuffs.  Official Journal of the European Communities. L 77/1.

FAO/WHO (1999): Expert committee on food additives. Summary and conclusions, 53 ^rd meeting, Rome, 1–10 June.

Ferreira, K. S.; Gomes, J. C. and Chaves, J. C. (2005): Copper content of commonly consumed food in Brazil. Food Chemistry, 92, 29–32.

Gambelli, L.; Belloni, L.; Ingrao, G.; Pizzoferrato, L. and Santaroni, G. P. (1999): Minerals and trace elements in some Italian dairy products. Journal of Food Composition and Analysis, 12, 27–35.

García, M. I.; Puerto, P. P.; Baquero, M. F.; Rodríguez, E. R.; Martín, J. D. and Romero, C. D. (2006): Mineral and trace element concentrations of dairy products from goats’ milk produced in Tenerife (Canary Islands). International Dairy Journal, 16, 182–185.

HC "Health Canada" (2007): Eating well with Canada's Food Guide. HC pub.:4651. Available on line at: www.healthcanada.gc.ca/foodguide.

HMRC (2003): Heavy Metal Remediation Committee of the Vashon Maury Island Community Council. Available at:www.vmicc.org/comm_metals.html. 

Hura, C. (2002): Chemical contaminants in food and human body, 1990–2000. Cermi Press, Iasi, ISBN 973-8188- 01-6.

IMNAS (2000): Institute of Medicine, National Academies of Sciences, Dietary Reference Intakes. Application in Dietary Assessment, National Academy Press, Washington DC. 2000.

IMNAS, FNB (2001): Institute of Medicine, National Academies of Sciences, Food and Nutrition Board, USA Nutrient Database for Standard Reference, Washington DC., 14 June 2001.

Kiliçel, F.; Tarakçi, Z.; Sancak, H. and Durmaz, H. (2004): Mineral and heavy metal contents of Otlu Lor. Journal of Agricultural Sciences, 14, 41–45.

Mendil, D. (2006): Mineral and trace metal levels in some cheese collected from Turkey. Food Chemistry, 96, 532–537.

Orak, H.; Altun, M. and Ercag, E. (2005): Survey of heavy metals in Turkish white cheese. Italian Journal of Food Science, 17, 95–100.

Tripathi, R. M.; Raghunath, R.; Sastry, V. N. and Krishnamoorthy, T. M. (1999): Daily intake of heavy metals by infants through milk and milk products. The Science of the Total Environment, 227, 229A–235A.

USDA "United State Department of Agriculture" (2005): Dietary Guidelines for Americans. Chapter 2. Available on line at: www.healthierus.gov/dietaryguidelines.

Vural,  A.; Narin, I.; Erkan, M. E. and Soylak, M. (2008): Trace metal levels and some chemical parameters in herby cheese collected from south eastern Anatolia-Turkey. Environ. Monit. Assess., 139:27–33.

WHO (1996): Guidelines for drinking-water quality, 2 ^nd ed. Vol. 2. Health criteria and other supporting information. Geneva: World Health Organization.

 Yüzbasi, N.; Sezgin, E.; Yıldırım, M. and Yıldırım, N. (2003): Survey of lead, cadmium, iron, copper and zinc in Kasar cheese. Food Chemistry, 20(5), 464–469.