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10 Moroccan Traditional Fermented Dairy Products

Abed Hamama

In Morocco 20 to 30 percent of all milk produced is still processed by private individuals. These dairy shops and farmers manufacture traditional Moroccan dairy products such as lben and raib (fermented milks), zabda (farm butter), and jben (fresh cheese). These products are made from raw milk, and their physical properties are similar to those of commercially produced buttermilk, yogurt, butter, and fresh cheese. Although they are usually made from cow's milk, milk from sheep, goats, and camels also can be used. These products are very popular in Morocco mainly because of their refreshing qualities.

Basically, all these traditional dairy products are prepared by simply allowing the raw milk to ferment spontaneously at room temperature (15 to 25C) for 1 to 3 days depending on the season. The coagulated milk is called raib. It can be consumed as such or churned in a clay jar to separate the liquid phase (lben) from fat (zabda). Jben is prepared by placing the coagulated milk in a cloth at room temperature and draining the whey. Salt is added to jben made in northern Morocco.

COMPOSITION AND MICROBIOLOGICAL CHARACTERISTICS

The Moroccan traditional fermented dairy products have been investigated (1-4) for their composition (Table 1) and their microbiology (Table 2). Data in these tables are average results only. In fact, a high level of variability for all the parameters was seen among samples of the same product. This heterogeneity is a consequence of the lack of standard procedures for preparation of these products.

Despite the acidic nature of these products (pH 4.0 to 4.5), they showed high counts of indicator microorganisms (e.g., coliforms, enterococci). This probably reflects poor hygienic conditions in the preparation of these products and/or poor bacteriological quality of the raw milk used for their manufacture.

TABLE 1 Average Physical-Chemical Composition of Moroccan Traditional Dairy Products

Composition

Lben(4)

Jben(3)

Raib(3)

Zabda(1)

pH

4.25

4.1

4.2

4.5

% lactic acid

0.81

1.04

0.62

0.77

% total solids

6.5

37.5

10.7

76.7

% fat

0.9

16.47

2.22

73.7

% protein

2.5

15.8

3.1

1.8

% lactose

2.7

4.1

4.2

1.2

% chlorides

0.17

0.5

0.17

ND

% ash

ND

1.26

0.54

ND

ND, not determined.

In addition to the indicator microorganisms, pathogens such as Salmonella sp., Yersinia enterocolitica, Listeria monocytogenes, and enterotoxigenic Staphylococcus aureus have been recovered mainly from samples of lben and jben. Although there are no epidemiological reports of outbreaks linking Moroccan traditional dairy products with diseases caused by these pathogens, their presence in these products indicates potential health hazards for consumers. Therefore, there is need to implement corrective procedures to eliminate or reduce this risk. This can be achieved by the use of heat-treated milk instead of raw milk and through the use of selected starter cultures for preparation of these products.

OBJECTIVES

The application of modern technology to Moroccan traditional dairy products aims to assure the following:

Large-scale production of these products year-round by replacing raw milk with dry milk and butter oil. This will solve the problem of seasonality in Moroccan milk production.

Production of dairy products with standardized chemical and microbiological composition so that their quality can be more easily controlled and standards for each product can be established.

TABLE 2 Average Microbiological Counts of Moroccan Traditional Dairy

Products (cfu/g or ml)

Microorganism

Lben(4)

Jben(3)

Raib(3)

Zabda(2)

Streptococci

7.6 x 108

5.1 x 108

1.4 x 108

5.0 x 106

Lactobacilli

1.0 x 103

3.2 x 108

2.6 x 106

2.4 x 105

Leuconostocs

1.7 x 105

2.6 x 108

2.8 x 106

1.8 x 104

T. coliforms

5.0 x 104

4.3 x 105

1.7 x 105

6.5 x 104

F. coliforms

1.0 x 103

2.7 x 104

4.2 x 103

2.1 x 104

Enterococci

1.0 x 105

2.4 x 105

2.2 x 104

8.6 x 104

Fungi

8.5 x 102

2.3 x 106

2.3 x 104

ND

Total flora

2.9 x 109

8.2 x 108

3.5 x 108

4.6 x 107

ND: not determined.

Elimination of massive contamination of these products and reduction of health hazards associated with these contaminations by using heat-treated milk and improving the sanitation and fermentation conditions.

Adoption of simple and standardized processes for the preparation of these products that could be easily applied in the dairy industry.

PRELIMINARY STUDY

Preparation of traditional dairy products using improved technological processes requires, for each type of product, determination of the characteristics that constitute an excellent-quality product. For this purpose, samples of each product were evaluated by a gustatory panel. The best products were then analyzed to determine their physical characteristics, chemical composition, and microbiological profiles. The objective of the study was to assess the censorial and compositional parameters (e.g., acidity, total solids) that the improved product should have to be acceptable to consumers.

Selection of Starters

Microbiological analysis of the different traditional fermented dairy products showed that an important proportion of their microflora was represented by lactic acid bacteria. Lactic streptococci were predominant in lben, raib, and zabda, while streptococci, lactobacilli, and leuconostocs were found in jben at almost the same average levels (10e8 cfu/g or ml) (colony forming units). From each product isolates from the predominant lactic flora were identified using biochemical tests. The principal species found in lben, raib, and zabda were Streptococcus lactis, and S. diacetylactis, while S. lactis, Lactobacillus cased casei, and Leuconostoc lactis were the main species recovered in jben.

Owing to the nature of traditional Moroccan dairy products (fresh fermented products), the major criterion considered for selection of lactic starters was their acid production ability at different incubation temperatures. Production by lactic strains of certain substances contributing to the overall aroma of these products also was taken into account. Thus, several lactic strains were retained to be used for preparating improved products.

Manufacture of Traditional Dairy Products from Heat-Treated Milk

To prepare each type of product, a simple and economically feasible technology, which industrial dairy plants could easily adopt, was used.

The improved processes proposed for use with raib (fermented milk) and jben (fresh cheese) are as follows:

Manufacture of raib:

Reconstitution of dry milk to 90 percent water and 10 percent solids.

Pasteurization at 63C for 30 minutes.

Addition of calcium chloride and storage at 7C for 10 hours.

Addition of fresh pasteurized milk (60 percent of the total volume).

Inoculation (S. lactis, S. diacetylactis @ 3.0 percent).

Distribution into plastic containers and incubation at 30C for 3 to 4 hours.

Refrigeration at 4 to 6C.

Manufacture of jben:

Reconstitution and pasteurization of powdered milk.

Addition of calcium chloride and storage at 7C for 10 hours.

Addition of fresh pasteurized milk (60 percent of the total volume).

Inoculation (S. lactis, S. diacetylactis, L. cased cased @ 3.0 percent).

Storage of inoculated milk at 20 to 25C until 0.25 percent lactic acid is formed.

Addition of rennet (5 to 10 milliliters/100 liters).

Fermentation at 20 to 25C until 0.60 percent lactic acid is formed.

Curd cutting and whey draining.

Unmolding when titratable acidity reaches 0.9 percent lactic acid and total solids content reaches 28 to 30 percent.

Cutting of cheese into suitable pieces (150 grams/piece).

Surface dry salting, if desired (I percent salt) and wrapping.

RESULTS

This study is still in progress. The final results regarding censorial quality, chemical composition, and microbiological quality of traditional dairy products made with the improved technology are not yet available. Nonetheless, preliminary data obtained for raib and jben are very encouraging:

Sensorial quality: Laboratory samples of improved raib and jben gave similar or even higher sensory scores than market samples. The characteristics considered in this evaluation are mainly acidity, texture, and aroma.

Chemical composition; Because standard procedures were used for making raib and jben, the samples obtained had uniform compositions. This information will be useful in establishing standards for these products.

Microbiological quality: The use of heat-treated milk in the manufacture of raib and jben had a profound effect on the microbiological quality of the products. The improved products were free from pathogens such as S. aureus, Salmonella, L. monocytogenis, and Y. enterocolitica. They were either free of or contained very few coliforms (<10 cfu/g). Their microbiological quality was substantially improved compared with currently marketed traditional products.

CONCLUSIONS

Although data on all traditional dairy products are not yet available, information on the quality of laboratory-made raib and jben indicates that the use of modern technology in their manufacture has enhanced their bacteriological quality and reduced the risks of dairy-borne infections. This new technology has also begun to establish standards for these products.

In addition, the manufacture of traditional dairy products at an industrial scale will increase the production of these products and assure better distribution and marketing.

On the other hand, the use of dry milk, which is more economical than raw milk for preparing products such as raib and jben, has the advantage of being available any time of the year. This is very important in Morocco, where seasonal variabilities in milk production are a major problem for the dairy industry. Furthermore, the availability of dairy products that are rich in nutrients (e.g., proteins, fat) at a modest price and throughout the year will contribute to reduced malnutrition especially among children in rural areas.

REFERENCES

1. El Marrakchi, A.M., M. Berrada, M. Chahboun, and M Benbouhou. 1986. Etude chimique du smen marocain. Le Lait 66:117-133.

2. Hamama, A. 1989. Studies on the hygienic quality of certain Moroccan dairy products. Ph.D. thesis, University of Minnesota.

3. Hamama, A., and M. Bayi. 1991. Composition and microbiological profile of two Moroccan traditional dairy products: raib and jben. Journal of the Society of Dairy Technology.

4. Tantaoui Elaraki, A., M. Berrada, A. El Marrakchi, and A. Berramou. 1983. Etude du lben marocain. Le Lait 63:230-245.