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Keywords:

  • freeze-drying;
  • lactic acid bacteria;
  • malolactic fermentation;
  • viability

Abstract

Aims:  The effects of protective agents, rehydration media and freezing temperature on the viabilities of Lactobacillus brevis and Oenococcus oeni H-2 when subjected to freeze-drying were investigated.

Methods and Results:  Several protectants and rehydration media were tested to improve the survival after freeze-drying. The cells were also frozen at −65 and −20°C to check the effect of freezing temperature on the viability.

Conclusions:  The best protectant and rehydration medium to obtain the highest viability after freeze-drying varied with the species of bacteria. Yeast extract (4·0%) and sodium glutamate (2·5% ) gave maximum viability of L. brevis and O. oeni (67·8% and 53·6% respectively). The highest survival of L. brevis and O. oeni were obtained when rehydrated with 10% sucrose and MGY medium respectively. When the bacterial cells were frozen quickly (−65°C) than slowly (−20°C), L. brevis and O. oeni both showed increased viability after freeze-drying.

Significance and Impact of the Study:  The viabilities of L. brevis and O. oeni after freeze-drying were shown to be strain specific and dependent on protective agents, rehydration media and freezing temperature.