spoilage of the nabulsi cheese


[Characteristics]   [Production]  [Preservation]  [Spoilage]







  Although Nabulsi cheese is boiled and kept in brine with high salt concentration, cheese could be spoiled. This spoilage is usually in the form of deterioration in the flavor and appearance of the cheese and the brine, which are sometimes accompanied by red discoloration (Yamani, 1997). It is believed that the cause of the bad flavor is microbes that are able to withstand the high salt concentration, The origin of such microbes could be the salt used in cheese production (Yamani, 1997). Members of Halobacteriaceae, a family of Archae bacteria which is characterized by production of red to orange colonies, (Grant and Laresn, 1989), could be isolated from spoiled Nabulsi cheese which showed red discoloration (Yamani, 1997). Such red discoloration could be demonstrated by the addition of members of halobacteriaceae to Nabulsi cheese and further storage of the cheese (Saleh, 1998).

Other types of microorganisms may also play a role in the spoilage of the Nabulsi cheese. Species of moderately halophilic bacteria and species of non-halophilic extreme salt tolerant bacteria were the main part of the microbial flora of Nabulsi cheese, their presence may affect the sensory quality and keeping ability of the Nabulsi cheese (Yamani, 1997).

A major problem is the boiling step, which seems to be difficult to mechanized, where manual boiling is time consuming, costly and results in lack of product uniformity, especially in composition and shape. Furthermore, packing of cheese in large cans is economical and suitable for long term storage, it is not practical for home storage or retail because repeated opening of the can during consumption may lead to contamination and spoilage. (Humeid et al., 1990)

The long storage period of Nabulsi cheese and the fact that this cheese is stored under non-refrigerated conditions encourage the growth of Halobacteriaceae, which are known as slow growing bacteria (Grant & Larsen, 1989).

The main sources of salt in Jordan are the water of the Dead Sea and the Azraq Oasis. Previous report has shown that halobacteria were isolated from the Dead Sea (Oren, 1986; Turki, 1992) and from Azraq salt (Yamani, 1996). The halobacteriaceae in Nabulsi cheese may have come from the salt, especially when crude salt (cheaper) is used in its production (Saleh, 1998). These bacteria may become endemic in the dairies especially when the cheese production is not done under hygienic condition (Saleh, 1998).


- Humeid, M. A., Tukan, S. K. and Yamani, M. I. 1990. In Bag Steaming of White Brined Cheese as a Method for Preservation. Milchwissenschasft.

- Grant, W. D. and Larsen, H. 1989. Extremely Halophilic Archaeobacteria. Order Halobacterials ord. nov. In: Pfenning, N., (editor), Bergey's Manual of Systematic Bacteriology. V. 3. Williams and Wilkins, Baltimore.

- Saleh, M. I. 1998. A Study of the Halophilic Bacteria of Nabulsi Cheese, and their Effect on the Quality of the Product. Master Thesis, University of Jordan, University of Jordan, Amman, Jordan.

- Yamani, M. I. 1997. Halophilic Bacteria and the Spoilage of the White Brined Cheese of the Nabulsi Type. The 8th Arab Conference of Biological Sciences and the 4th Jordanian Conference of Biological Sciences. Amman, Jordanian Society for Biological Sciences

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