Microbial quality control of raw ground beef and fresh sausage in Casablanca (Morocco).

Author:Cohen, Nozha


While foodborne diseases remain an important public health problem worldwide, one of the most significant food safety hazards is associated with foods of animal origin (Mead, 1994). In Morocco from 2000 to 2004, 7,118 cases of foodborne diseases were reported, among which 86% were of bacterial etiology (Cohen, Ennaji, Hassar, & Karib, 2006). According to the same references, 21.3% of the bacterial foodborne diseases were caused by the consumption of red meat and meat products, and 14.7% of cases occurred in the city of Casablanca.

Foodstuffs such as ground meat and fresh sausages are a significant portion of the diet of a large active population in Morocco. These products are highly perishable, with a pH value not lower than 5.5 and water activity ([a.sub.w]) equal to or higher than 0.97. Since no fermentation process takes place during storage at 4 [degrees]C, the hygienic quality of the raw materials is the main factor affecting the final value of the product (Casalinuovo, Cacia, Scognamiglio, & Bontempo, 2001).

In Moroccan traditions, ground meat product is made principally of beef and mutton, with or without the addition of salt, red chili, caraway, pepper, parsley, garlic, and onion, depending on local preparation and consumer order. The meat and the beef fat are ground together. The different spices and herbs are added after mixing. Fresh sausages are produced from beef and beef fat, and with or without the addition of salt, different aromas, spices, pepper, and garlic. The meat and fat are ground together in pieces, and after mixing, herbs are used to fill natural casings from sheep. The sausages are hand kneaded and stuffed without good aseptic techniques. These products are usually displayed for sale at room temperature or sometimes at refrigeration temperature. Fresh sausage products are often sold in parts displayed at ambient temperatures and are refrigerated overnight only.

Scientific experiments since the late 19th century have documented the antimicrobial properties of some spices, herbs, and their components (Mei-chin, & Wen-shen, 2002; Sara, 2004; Shelef, 1983; Zaika, 1980). Other studies have reported that spices and herbs themselves may be highly exposed to bacterial contamination, based on conditions in which they were ground and harvested. Moreover, contaminated spices have been reported to be causes of foodborne illness and spoilage (Kneifel & Berger, 1994; Pafumi, 1986).

In this paper, we describe the hygienic quality of ground beef and fresh sausages produced in Casablanca, with the following objectives: (i) to determine the prevalence and levels of pathogenic and nonpathogenic bacteria present in these products, (ii) to analyze the effect of spices and herbs; seasonality; and location distribution on the prevalence of such microorganisms, and (iii) to screen pathogenic strains of E. coli by molecular microbiology methods.


Sample Collection

Samples were collected during the period of April 2002 to March 2004. Two hundred and fifty samples of raw ground beef (n = 150) and fresh sausages (n = 100) were randomly collected from butchers (n = 84), supermarkets (n = 83), and fast-food shops (n = 83) in Casablanca, Morocco. Two sampling types of meat products were considered. Samples with spices (n = 115) were divided into ground meat (n = 71) and fresh sausages (n = 44), and samples without spices (n = 135) were divided into ground meat (n = 79) and fresh sausages (n = 56). Two sampling periods were used. The hot season (April to September) has temperatures varying between 25[degrees]C and 39[degrees]C and relative humidity between 32% and 72%. In this period, samples of ground meat (n = 75) and fresh sausages (n = 48) were collected. The cold season (November to March) has temperatures varying between 5[degrees]C and 20[degrees]C and relative humidity between 56% and 84%. In this period, samples of ground meat (n = 75) and fresh sausages (n = 52) were also collected.

At two-week intervals, approximately 200 grams of each product were collected in sterile plastic bags, labeled, kept on ice, and returned to the laboratory of Institut Pasteur du Maroc (Casablanca) within two hours. All samples were stored at 4[degrees]C upon arrival to the laboratory and processed the same day. A portion (25 g) of each sample was placed aseptically into a separate sterile stomacher bag containing 225 ml of 0.1% sterile peptone water, and homogenized with a MIX I[TM] mixer (AES Laboratory, Combourg, France). The suspension was then 10-fold serially diluted in 0.1% sterile peptone water for bacterial analyses.

Bacteriological Analysis

Viable cell counts were performed by the spread-plate method after 10-fold serial dilutions in 0.1% weight by volume (w/v) peptone solution as follows:

* Aerobic plate counts (APCs) were carried out on plate count agar and incubated at 30[degrees]C for 72 hours.

* Fecal coliforms (FC) counts were carried out on Violet Red Bile Lactose agar incubated at 44[degrees]C for 24 hours. Typical colonies were considered as round, red-to-pink, 0.5-2 mm in diameter, and surrounded with a red-to-pink halo.

* E. coli counts were carried out on RAPID'E. coli agar incubated at 37[degrees]C for 18 to 24 hours. Typical E. coli colonies were considered as violet-to-pink. Presumptive E.coli colonies were checked for Gram and were characterized by using Kligler test, then typical colonies (Gram-negative bacilli, lactose-positive, glucose-positive, and gas-positive) were confirmed by using Enterobacteriaceae API 20E, commercial kit (Biomerieux).

* S. aureus counts were carried out on Baird-Parker agar with egg yolk-potassium tellurite emulsion plates and incubated at 35[+ or -] l[degrees]C for 24 to...

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