MICROSTRUCTURE AND DISTRIBUTION OF MICROORGANISMS WITHIN MATURE SERRACHEESE

The distribution of micro-organisms in mature Serra, a traditional Por tuguese cheese made from unpasteurised ewes' milk without added starte r culture, was examined by light microscopy and electron microscopy. F our populations of micro-organisms were recognized according to their position within the cheese: (i) those present as apparently axenic col onies within the curd matrix; (ii) bacteria growing along curd junctio ns; (iii) yeasts and bacteria present in the smear on the surface of t he cheese and (iv) bacteria found in cracks which penetrated the outer part of the cheese from the rind. Two types of crystals were observed , together with contaminants of vegetable origin and somatic cells ori ginating from the milk.