Table 2
Summary of the physical properties of solutions containing the main protective molecules used for
the long-term stability of lactic acid bacteria determined by DSC (Tg
0 ) and FDM (Tcoll)
Concentration (%, w/w)
Tg
0
2 (
C)
Tg
0
1 (
C)
Tcoll (
C)
Fructose
20
À57
À44
À43
Glucose
20
À56
À44
À42
Galactose
10
À55
À42
À41
Sucrose
20
À46
À33
À31
Trehalose
20
À40
À29
À26
Lactose
10
À38
À28
À27
Maltose
20
À40
À29
À27
Raffinose
20
À37
À26
À24
Kestose
20
À38
À28
À26
Nystose
20
À38
À28
À23
Fructofuranosylnystose
20
À35
À23
À21
Pentaisomaltose
20
À30
À19
À18
Inulin (from chicory)
10
À30
À17
À15
FOS (from chicory)
10
À27
À17
À15
Glucidex 2
20
À4
N D
Glucidex 6
20
À7
À3
Glucidex 12
20
À11
À8
Glucidex 19
20
À11
À10
Sucrose/glucidex 6 mixture
25:75 (%:%)
20
À15
À11
50:50 (%:%)
20
À32
À23
À17
75:25 (%:%)
20
À43
À30
À25
Sucrose in saline solution
20
À50
À34
À32
CP/PS, ratio 1:2 (g/g)
À51
À36
À27
DSC differential scanning calorimetry, FDM freeze-drying microscopy, Tg
0 glass transition temperature of the maximally
freeze-concentrated phase, Tcoll collapse temperature, FOS fructooligosaccharides, ND not determined
Glucidex are maltodextrins of different DP kindly provided by Roquette Fre `res (Lestrem, France); CP, cell pellets
obtained from cultures of Lactobacillus delbrueckii ssp. bulgaricus CFL1 in mild whey medium [15]; PS, protective
solution composed of 20% (g/g) of sucrose in saline solution
The solutions were prepared with demineralized water, and the measurements were performed in triplicate according to
the protocols described in the current chapter. The median values are reported in the table, and the interquartile ranges
were around 1
C
Physical Properties and Freeze-Drying of Bacteria
707