A large diversity of lactic acid bacteria species is involved in the fermentation of wheat used for the manufacture of lemzeiet

Abstract

Algerian couscous named lemzeiet is manufactured from fermented wheat. Historically performedin underground silos called matmor, the fermentation of wheat is now generally carried out in plastic jerrycans withor without addition of vinegar at the beginning of the fermentation. Culture-dependent and culture-independentmethods (PCR-TTGE) were used to characterize lactic acid bacteria and to determine their dynamic and diversity over a two-year period, with and without the addition of vinegar.Fungi, physicochemical characteristics, and volatile compoundprofiles were also monitored. The isolates obtained from different stages of fermentation and from both processes were characterized by coupling different molecular methods (16SrRNA/pheS/rpoA gene sequencing, speciesspecific PCR, RAPD and PFGE). PCR-TTGE revealed very similar profiles for both processes. Sixty-nine isolates were identified as belonging to six genera of 16 species(Enterococcus, Lactobacillus, Leuconostoc, Pediococcus, Weissella, and Streptococcus). The profiles of volatile aroma compounds showed a marked effect of the fermentation process, compared to non-fermented wheat, with 35 of the 40 volatiles detected at amounts 20- to 30-fold higher in fermented wheat samples. This study gives the first insight into lactic acid bacteria population diversity and activity in fermented wheat and will contribute to a better control of the fermentation process

First Insight into the Technological Features of Lactic Acid Bacteria Isolated from Algerian Fermented Wheat Lemzeiet

“…Our results showed that many strains of pediococci and enterococci seem to dominate the kinetic acidification. This corroborates the previous study on the characterization of the lemzeiet microbiota, where P. pentosaceus and E. faecium were described as dominant from the first stage of the fermentation [17]. L. curvatus (L84), L. brevis (L120), and L. mesenteroides (L70) also showed good acidifying abilities.…”

“…have been described by many studies as the best antifungal agents compared to other LAB species [23,46,47]. Moreover, in our precedent study, on lemzeiet, we had highlighted that fermentation process allows the disappearance of fungi flora over time, which reinforces the fact that LAB strains exerted an antifungal activity and make the product safer for consumption [17]. Indeed, LAB are naturally present in many foods and have a long history of safe use in fermentation process [1].…”

“…It plays an important role in the microbiota of fermented cereals by providing the substrates necessary for the growth of non-amylolytic LAB [10,37]. Reduced sugars, peptides, and amino acids affect the taste of fermented foods and, particularly, are important precursors for volatile flavor compounds [17,38]. In the present work, no strain with lipolytic activity was detected.…”

“…Forty-eight LAB strains, isolated from lemzeiet and identified by molecular technics in a previous study [17], preserved in the Centre International des Resources Microbiennes -Bactéries d'Intéret Alimentaire (CIRM-BIA, INRA-Rennes, France, www6.inra.fr/cirm_eng/Food-Assoc iated -Bacte ria), were analyzed in this study (Table 1). Stored at −80 °C in MRS broth medium (Biokar Diagnostics) added to (1/1) with 30% (v/v) glycerol, they were cultured twice in the same broth at 30 °C for 24 h before each experiment.…”

“…Fermented wheat is used to manufacture the Algerian couscous called lemzeiet [16]. A previous microbial study on lemzeiet showed that fermentation process allows the disappearance of fungi flora over time through the establishment of LAB characterizing the microbiota of this fermented wheat [17]. It revealed a high level of LAB species and strains diversity during the different stages of maturation with a marked effect of the fermentation process on the profile of volatile aroma compounds.…”