Lemzeiet, a traditional algerian fermented food: first characterization of lactic acid bacteria flora

Algerian couscous named Lemzeiet is manufactured from fermented wheat and characterized by a brown color and a particular flavors especially appreciated by consumers. Historically performed in underground silos (Matmour) during several years, the fermentation of wheat is now generally carried out in plastic jerrycans or drums during around one year with or without addition of vinegar at the beginning of the fermentation. Most of the cereal- based fermented foods involve lactic acid fermentation including Lemzeiet. The aim of this work was to determine the dynamic and the diversity of lactic acid bacteria populations over two years, in the presence or absence of vinegar. Culture dependent methods were used and 147 isolates were selected based on phenotypic characteristics. 70 were retained for molecular characterization. They were identified by coupling different molecular methods (16S rRNA/pheS/rpoA genes sequencing and specific PCR) and the clonal diversity was investigated with randomly amplified polymorphic DNA (RAPD) and pulse-field gel electrophoresis analysis (PFGE). The population of lactic acid bacteria evolved during the period of fermentation. It was dominated by Lactobacillus and Pediococcus species in the wheat fermented without vinegar, and by Enterococcus and Pediococcus species in the presence of vinegar. We also observed a high level of intra-species diversity. Analysis of aroma compounds by head space trap-gas chromatography-mass spectrometry is under progress to determine the impact of the lactic acid bacteria populations on the final aroma profile of products. These results give a first insight in lactic acid bacteria population diversity in Lemzeiet and will contribute to a better control of the fermentation process.