LABAN PROCESSING BY THE USE OF NATURALLY SELECTED  THERMOPHILIC STRAINS OF LACTIC ACID BACTERIA

BENNANI  F.  FAID M. and ELYACHIOUI  M.

ABSTRACT

Up to now all the research works carried out on laban in Morocco have been focused on Lactococcus because the traditional fermentation is usually done under ambient temperatures which may range between 22 and 28°C in Morocco. Thermophilic lactic acid bacteria had not been investigated yet. In the present investigation, thermophilic strains of lactic acid bacteria belonging to Streptococcus thermophilus were isolated from natural fermented raw milk. Milk samples from non treated cows and not fed on industrial feeds were incubated at 45°C until curdling. 5% (v/v) of the coagulum were used to inoculate a sterilized milk which was incubated at 45°C until curdling. This operation was repeated 4 times. The last subculture was used to isolate strains of the species S. thermophilus. 57 isolates were collected, characterized and selected for their acidifcation properties of milk at 45°C. The most efficient strains were used in laban preparation at a high scale and the obtained product was compared to the traditional laban and to laban from the retail market by a sensory evaluation. Results indicated that most of the strains were identified as S. thermophilus and that these strains were different from those used in laban from the retail market. The sensory assessments showed that the product was higher in scores than the traditional laban and than the products exhibited in the retail market.

 corresponding author: faidmohamed@yahoo.fr