Determinacion De La Peroxidacion Lipidica (Mda)

Food and Chemical Toxicology 48 (2010) 3031–3034

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Food and Chemical Toxicology
journal homepage: www.elsevier.com/locate/foodchemtox

Mineral content and microbiological examination of some white cheese in Jeddah, Saudi Arabia during summer 2008
Magda M. Aly a, Madeha N. Al-Seeni b, Safaa Y. Qusti b, Nagwa M. El-Sawi b,*
a b

BiologyDepartment, Faculty of Science, King Abdul Aziz University, Saudi Arabia Biochemistry Department, Faculty of Science, King Abdul Aziz University, Saudi Arabia

a r t i c l e

i n f o

a b s t r a c t
Different local and exported white cheese samples were collected from different markets in Jeddah during September 2008. Trace and heavy metals including Pb, Zn, Mn, Cu, Fe and Cd were analyzed usingatomic absorption spectrometry. The concentration of the tested metals was in the range, Fe++ > Zn+++ > Mn++ > Pb++ > Cu++ > Cd++. The mean concentration of 7.63, 7.19, 0.5, 0.47, 0.16 and 0.14 lg/g was recorded for Fe, Zn, Mn, Pb, Cu and Cd, respectively. The concentration of iron ranged from 3.5 to 11.9 lg/g, zinc from 3.4 to 10.5, manganese from 0.12 to 1.0, lead from 0.14 to 1.14, and copperfrom 0.09 to 0.22. Yeasts and fungi were counted on Sabouraud and Potato Dextrose media and incubation was carried out at 25 °C for 7 and 5 days, respectively. Yeast count and fungi count of cheese were ranged from 0.1 to 0.44 CFU/g and from 0.123 to 1.11 CFU/g, respectively. Three out of 20 samples of cheese were contaminated with toxigenic fungi with 5% contamination level. Aflatoxin G1 was recordedin three samples using immunoadsorbent column chromatography with a range from 7 to 13 ppm. Ó 2010 Elsevier Ltd. All rights reserved.

Article history: Received 20 January 2010 Accepted 7 May 2010

Keywords: Heavy metals Cheese Aflatoxin G1 Yeast and fungi

1. Introduction During the last 25 years, there has been a continued increase in milk production and consumption of fermented dairyproducts (Dairy Facts, 2004). Fermented dairy products are cheese, yogurt and fermented milk. They are fermented by the addition of a starter culture such as lactic acid bacteria which are responsible for the production of lactic acid from lactose that gives the product its characteristic flavor. Cheese are classified into three types (soft, semi-soft and hard) according to their appearance (McGee,2004). The type of cheese depends on the relative humidity, the quantity of lipids, the method used, and the type of salting and storage. Cheese are exposed to different types of contamination during manufacture with different kinds of heavy metals such as cadmium, nickel, lead, copper and mercury (Ayar et al., 2009). It causes many health problems such as weakness, heart failure, induced cancerdiseases (McCally, 2002) and also affects the kidney. The concentration of heavy metals and trace element in cheese was determined by many researchers (Park, 2000; Zukowska and Biziuk, 2008). It is well established that Pb++ and Cd++ are toxic to human beings and children are more sensitive to these metals than adults. Metals such as Cu++, Fe++ and Zn++, are essential micronutrients and have a varietyof biochemical functions in all living

* Corresponding author. Tel.: +966 509385079; fax: +966 26953367. E-mail address: dr_nelsawi@yahoo.com (N.M. El-Sawi). 0278-6915/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.fct.2010.05.016

organisms. While Cu++, Fe++ and Zn++ are essential, they can be toxic when taken in excess; both toxicity and necessity vary from oneelement to another (Tripathi et al., 1999). Cheese like other types of food is exposed to contamination with microorganisms during the production process including fermentation, renneting, salting in brine, packaging and ripening. Fresh cheese such as cottage and white cheese may be subjected to spoilage by coliforms, yeast and molds that enter as post-pasteurization contaminants (Karlikanova...