English

Abstract

  Thirty samples of fermented wheat dough microflora, collected from different Tunisian bakeries, were characterised. Forty per cent of the samples contained approximately 106 cfu/g of mesophilic aerobic bacteria (MAB). Lactic acid bacteria (LAB) and yeasts dominated the microflora of these samples. They varied from 105 to 108 cfu/g. The LAB/yeasts ratio arising from microbial counts were varied between 1/1 and 200/1. More than 50% of the analysed samples were deprived of Enterococcus. The content of contaminating microflora like coliforms and mesophilic Bacillus ranged from 102 to 104 cfu/g. The ratio between LAB and coliforms were estimated to about 103/l for 26% of the analysed samples. This ratio is more important between LAB and mesophilicBacillus. The LAB/mesophilic Bacillus ratio was about 104 for 45% of the analysed samples. However, Micrococcaceae were absent in all samples. This study could be used with further information to establish the cooperative effect existing between LAB and yeasts during food fermentation and to point out an eventual antagonism effect between LAB and spoilage microflora  during bakery processing as showed for other fermented foods. The coliforms-like contaminating microflora serves as indicator on the hygienic quality of Tunisian bakery industry.   Key words: Fermented dough microflora, species ratio, lactic acid bacteria, yeasts, antagonism, bakery industry, bread quality, hygiene practices.