THE SOURDOUGH MICROFLORA - CHARACTERIZATION OF HOMOFERMENTATIVE LACTIC-ACID BACTERIA BASED ON ACIDIFICATION KINETICS AND IMPEDANCE TEST

Forty-one strains of Lactobacillus plantarum, L. farciminis, L. alimen tarius, L. acidophilus and L. delbrueckii subsp. delbrueckii isolated from Italian wheat sourdoughs and 5 ATCC type strains (one per species ) were characterized on the basis of 7 parameters of acidification kin etics and 3 impedance test parameters. Statistical cor relations were found between the total change of conductance and the latency phase of acidification and between the maximum rate of conductance and acidifi cation. Data from 6 parameters of acidification kinetics were evaluate d by using Principal Component Analysis which indicated the difference s between strains and allowed them to be divided into 4 groups. Almost all the type strains showed a different acidification activity with r espect to the strains isolated from the sourdoughs. These differences were confirmed during sourdough fermentation using representative stra ins of the different groups.