Preservation by freezing of potentially probiotic strains ofLactobacillus rhamnosus
- 272 Downloads
The aim of this work was to detect the best conditions to preserve by freezing potentially probiotic strains ofLactobacillus rhamnosus isolated from food. Four strains isolated from Parmigiano Reggiano cheese, the commercial strainLactobacillus GG and the type strain ATCC 7469T were used in the present study. Two different pre-incubation times (5 and 24 h), three protective media (Skim milk, Skim milk plus glucose and MRS plus glycerol) and two storage temperatures (−20 and −80 °C) were used for a preservation period of 90 days. A sensible loss of survival of the strains was detected and the acidifying activity decreased depending on the different factors analysed. Moreover, plate counts performed in MRS plus bile salts evidenced that a considerable percentage of cells suffers damages deriving from cold. This study showed that the growth phase of the cells plays an important role for the resistance to the storage by freezing. Finally, Skim milk had the best protective action, showing the highest activity at −80 °C.
Key wordcryotolerance freezing protective media probiotic lactobacilli
Unable to display preview. Download preview PDF.
- Coppola R., Iorizzo M., Sorrentino A., Sorrentino E., Grazia L. (1996). Resistenza al congelamento di lattobacilli mesofili isolati da insaccati e paste acide. Industrie Alimentari, 35: 349–356.Google Scholar
- Font de Valdéz G., de Giori G., de Ruiz Holgado A., Oliver G. (1983). Protective effect of adonitol on lactic acid bacteria subjected to freeze-drying. Appl. Environ. Microbiol., 45: 302–304.Google Scholar
- Gilliland S.E., Speck L.M. (1974). Frozen concentrated cultures of lactic acid bacteria — A review. J. Milk Food Technol., 37: 107–111.Google Scholar
- Golberg I., Eschar L. (1977). Stability of lactic acid bacteria to freezing as related to their fatty acid composition. Appl. Environ. Microbiol., 33: 489–496.Google Scholar
- Johnson M., Ray B., Speck M.L. (1984). Freeze injury in cell wall and its repair inLactobacillus acidophilus. Cryoletters, 5: 171–176.Google Scholar
- Korpela R., Peuhkuri K., Lahteenmaki T., Sievi E., Saxelin M., Vapaatalo H. (1997).Lactobacillus rhamnosus GG shows antioxidative properties in vascular endothelial cell culture. Milchwissenschaft, 52: 503–505.Google Scholar
- Leach R.D., Sandine E. (1976). Numerical relationship between strains in frozen concentrates of lactic streptococcal starter cultures. J. Dairy Sci., 59: 1392–1397.Google Scholar
- Stadhouders J., Hup G., Jansen L.A. (1971). A study of the optimum conditions of freezing and storing concentrated mesophilic starters. Neth. Milk. Dairy J., 25: 229–239.Google Scholar