VIABILITY OF LACTIC BACTERIA SUBMITTED TO DEHYDRATION - IMPORTANCE OFTHE DEHYDRATION KINETICS

Dehydration of Lactobacillus plantarum by glycerol addition (water dep ressor) has allowed to show the great importance of the kinetics of wa ter potential decrease on cell viability. Thus, wathever the final wat er potential was, an optimal kinetics of water potential variation was determined which allow to maintain a viability higher than 80%. Decre asing rate and level of water potential have been proved to influence cell viability in the same way during air drying at 25 degrees C. In t his case, optimal kinetics of dehydration preserved 40% of viable cell s. This viability was higher than 80% when a nutritional stress was re alised before dehydration and when cells were rehydrated at 37 degrees C. A high preservation of dehydrated cells was observed for 3 months at -317.9 MPa (a(W) = 0.100); and after rehydration, stressed cells ex hibited an acid production similar to a control. (C) Inra/Elsevier, Pa ris.