Full Length Research Paper

Use of lactic strains isolated from Algerian ewe's milk in the manufacture of a natural yogurt

Chougrani Fadela¹*, Cheriguene Abderrahim¹ and Bensoltane Ahmed²

¹Laboratoire de Microbiologie, Département de Biologie, Faculté des Sciences, Université de Mostaganem, BP 227 Mostaganem 27000 Algeria.

²Laboratoire de Microbiologie Alimentaire et Industrielle, Département de Biologie, Faculté des Sciences, Université d'Oran Es Senia. Algeria.

*Corresponding author. E-mail:chougranifadela@yahoo.fr.

Accepted 29 February, 2008

Fifty three strains of thermophilic and mesophilic lactic acid bacteria were isolated from the ewe’s milk. Identification reveals the presence of nineteen strains (36%) of Lactobacillus sp., seventeen strains (32%) of Lactococcus sp., nine strains (17%) of Streptococcus thermophilus and eight strains (15%) of Leuconostoc sp. The strains were characterized for their technological properties. A high diversity of properties among the studied strains was demonstrated. On the basis of technological characteristics, two strains (Lactobacillus bulgaricus and Streptococcus thermophilus) were screened with respect to their acid and flavour production for the preparation of a natural yogurt and compared to a commercial starter cultures. Sensorial analyses revealed that the product manufactured on the basis of the isolated strains have a cohesiveness and adhesiveness corresponding to standard products. The pH and the acidity recorded are also within accepted levels during all the period of conservation.

Key words: Lactobacillus bulgaricus, Streptococcus thermophilus, yoghurt, cohesiveness, adhesiveness, Algerian ewe’s milk.