Mathurin Coffi Nago

The microbiota of Lafun, an African traditional cassava food product

Lafun is a fermented cassava food product consumed in parts of West Africa. In the present work the microorganisms (aerobic bacteria (AB), lactic acid bacteria (LAB) and yeasts) associated with the fermentation of Lafun under traditional conditions have for the first time been studied using a combination of pheno- and genotypic methods. During Lafun fermentation the AB count ranged from 6-7 log(10) CFU/g at the beginning to 9 log(10) CFU/g at the end. Similarly, the number of LAB increased from 5 log(10) CFU/g to 9 log(10) CFU/g during the process while the yeast load increased from 3 log(10) CFU/g at the onset of the fermentation to 5-6 log(10) CFU/g at the end of the fermentation. A total of 168 isolates (31 AB, 88 LAB, and 49 yeasts) were isolated and identified by means of phenotypic tests, PCR-based methods and 16S rRNA gene sequencing. The aerobic bacteria were mostly identified as belonging to the Bacillus cereus group (71%). The B. cereus isolates lacked the genetic determinant specific for cereulide producers but harboured several genes encoding the heat-labile toxins hemolysin BL and nonhemolytic enterotoxin as detected by PCR. The other aerobic bacteria isolated were Gram negative and identified as Klebsiella pneumoniae and Pantoea agglomerans. The dominant LAB were identified as Lactobacillus fermentum (42% of LAB isolates) followed by Lactobacillus plantarum (30%) and Weissella confusa (18%). Seven isolates remained unidentified and constitute probably a novel LAB species. The predominant yeast species associated with Lafun fermentation were Saccharomyces cerevisiae (22% of yeast isolates), Pichia scutulata (20%), Kluyveromyces marxianus (18%), Hanseniaspora guilliermondii (12%), Pichia rhodanensis (8%) and Candida glabrata (8%) as well as Pichia kudriavzevii, Candida tropicalis and Trichosporon asahii at lower incidence (<5% each).

Weissella beninensis sp. nov., a motile lactic acid bacterium from submerged cassava fermentations, and emended description of the genus Weissella

Four Gram-positive, catalase-negative, short rod-shaped or coccoid, heterofermentative lactic acid bacterial strains (2L24P13(T), 1L48P15, 1L24P31 and 1L24P34) with unusual phenotypic and genotypic properties were isolated from submerged fermenting cassava on MRS agar. All strains were motile, grew at 15 degrees C, produced dl-lactic acid from glucose with gas formation and produced ammonia from arginine. Acid was produced from d-fructose, d-galactose, d-glucose, lactose, maltose, d-mannose, melibiose, d-raffinose, sucrose, N-acetylglucosamine and d-mannitol, but not from d-arabinose or xylose. 16S rRNA gene sequence analysis revealed that the strains belonged to the genus Weissella and were most closely related to Weissella ghanensis LMG 24286(T). Low DNA-DNA reassociation values were obtained between the isolates and W. ghanensis DSM 19935(T). Based on the genetic and phenotypic results, the strains are considered to represent a novel species, for which the name Weissella beninensis sp. nov. is proposed. The type strain is 2L24P13(T) (=DSM 22752(T)=LMG 25373(T)).

Development of starter culture for improved processing of Lafun, an African fermented cassava food product

Aims:  To select appropriate micro‐organisms to be used as starter culture for reliable and reproducible fermentation of Lafun.

Volatile compounds profile and sensory evaluation of Beninese condiments produced by inocula of Bacillus subtilis

BACKGROUND Three Beninese food condiments (ABS1(24h), IBS2(48h) and SBS3(48h)) were produced by controlled fermentation of African locust beans using inocula of pure cultures of Bacillus subtilis, BS1, BS2 and BS3, respectively. Quantitative and qualitative assessments of the volatile compounds in the condiments produced have been performed using the Likens-Nickerson simultaneous distillation-extraction method and GC-MS analysis, followed by a sensory evaluation in comparison with the spontaneously fermented condiments. RESULTS A total of 94 volatile compounds have been found including 53 compounds identified in relatively high concentrations and were subdivided into seven main groups with the predominance of four major groups: pyrazines, aldehydes, ketones and alcohols. Compared to the spontaneously fermented condiments, volatile compounds identified in controlled fermented condiments have been found in high number and in concentrations which varied according to the inoculum of B. subtilis used. The condiments produced with starter cultures scored significantly (P < 0.05) higher for odour than the spontaneously fermented condiments. But the overall acceptability (7/10) of the two types of condiments was similar. CONCLUSION The investigated B. subtilis, BS1, BS2 and BS3 can be considered as potential starter cultures for the fermentation of African locust beans to produce good quality of Beninese food condiments.