Spelt and emmer flours: characterization of the lactic acid bacteria microbiota and selection of mixed starters for bread making

Aims: This study aimed at characterizing the lactic acid bacteria microbiota and selecting mixed endogenous starters to be used for sourdough fermentation of spelt or emmer flours. Methods and Results: Identification of lactic acid bacteria was carried out by partial sequencing of the 16S rRNA, recA, 16S/23S rRNA spacer region and pheS genes. Spelt flour showed the largest biodiversity, while Lactobacillus plantarum dominated in emmer flour. Isolates were subjected to RAPD-PCR analysis and screened based on the kinetics of growth and acidification, quotient of fermentation and liberation of free amino acids (FAA) during sourdough fermentation. After selection, mixed starters were used according to a two-step fermentation process. Wheat flour was fermented by the same starters. Spelt and emmer sourdoughs had slightly higher pH than wheat sourdoughs but titratable acidity, concentration of FAA and phytase activity were higher. Specific volume and crumb grain of emmer and, especially, spelt breads approached those of wheat breads. Sensory analysis confirmed the suitability of spelt and emmer for bread making. Conclusions: The sourdough biotechnology was indispensable to completely exploit the potential of spelt and emmer flours. Significance and Impact of the Study: Results filled up the lack of knowledge on the lactic acid bacteria microbiota and technological performances of spelt and emmer flours.