Wetenschap - 31 mei 2001

PhD researcher makes new cheese with bacteria from cow saliva

PhD researcher makes new cheese with bacteria from cow saliva

A Wageningen PhD researcher hunted down more than one hundred lactic acid bacteria strains used for making cheeses. She found them on farms in Southern Europe, in the saliva of cattle, on grass and in the soil.

The Western cheese making industry uses lactic acid bacteria from specialised manufacturers. While these have led to more efficient cheese production, the end products taste increasingly alike. Egyptian Eman Hussien El-Sayed Ayad went in search of new strains to help restore diversity in the cheese world.

Cheese manufacturers have for a long time selected industrial bacteria on the basis of characteristics such as the production of long sugars, which give cheese a firm structure, resistance to viruses and the ability to split proteins. Industrial bacteria perform better on these criteria than the wild strains found by Ayad.

Cocktail

Nevertheless she managed to make cheese using about a dozen of the wild strains she collected, by mixing these with industrial cultures. "This way you can make new types of cheese," explains Dr Gert Smit of Nizo food research, who supervised Ayad. "Some wild strains impart a new smell or taste." Coming up with the right cocktail was not a simple task, admits Smit. "Not all bacteria can work together. Sometimes one strain will make an antibiotic, which another strain might not be able to survive."

On the basis of Ayad's research Nizo has acquired a new patent, which it hopes to be able to use if it finds a manufacturer interested in developing new products.

Eman Hussien El-Sayed receives her PhD on 1 June. She was supervised by Jan Wouters, Professor of Dairy Technology, Wageningen University.

Willem Koert

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