VARIOUS TEMPRATURES DURING STORAGE
4.3.2 Freeze drying activity
L. rhamnosus 1520, 2607 and 1521 in freeze dried preparations stored for up to 12 mo at-180C, 40C and 200C. Samples were taken at regular intervals for viable counts are presented in Tables 4.2a, 4.2b and 4.2c respectively. The viable counts of L. rhamnosus 1520
Chapter 4 ___________________________________________________________________________ 134 decreased (p < 0.05) from 9.60 to 8.22, L. rhamnosus 2607 10.65 to 8.64 and L. rhamnosus 1521 10.82 to 8.91 log CFU/mL over the 12 mo of storage at -180C respectively. The same strain stored at 40C over 12 mo revealed a higher decrease (p < 0.05) in viability and a greater drop in count from 9.60 to 7.25, 10.65 to 7.77 and 10.82 to 7.45 log CFU/mL respectively. All strains of freeze dried L. rhamnosus counts stored at 200C decreased significantly (p < 0.05), and no organisms were detected after 2 mo.
The counts of freeze dried L. casei 290 and L. zeae 15820 stored at -180C, 40C and 200Chave shown in Tables 4.2d and 4.2e. The viable counts of L. casei 290 and L. zeae 15820 were decreased (p < 0.05) 10.15 to 9.01 and 9.98 to 8.04 log CFU/mL over the 12 mo of storage at -180C. The same strains stored at 40C for 12 mo exhibited a larger decrease (p < 0.05) in viability from 10.15 to 7.51 and 9.98 to 7.10 log CFU/mL. The freeze dried Lactobacillus counts stored at 200C decreased significantly (p < 0.05), and no organisms were detected after 2 mo.
Freeze dried L. paracasei 292 and 279 stored for up to 12 mo at -180C, 40C and 200C are presented in tables 2f and 2g. Samples were taken at regular intervals as shown in tables. The counts of L. paracasei 292 and 279 were decreased significantly (p < 0.05) 10.1 to 8.25 and 9.95 to 8.15 log CFU/mL over the 12 mo of storage at -180C. The same strains stored at 40C for 12 mo revealed a decrease (p < 0.05) in viability and a greater drop in count from 10.1 to 7.81 and 9.95 to 7.58 log CFU/mL. The freeze dried L. paracasei counts stored at 200C decreased significantly (p < 0.05), and no organisms were detected after 2 mo.
The loss of viability after four months of storage at room temperature is possibly due to increase of metabolic and cellular activity within the all seven strains at 200C that may have led to exhaustion of nutrients stored within the cell. The microorganisms that were stored at frozen temperatures had maximum bacterial counts due to their lack of metabolic and cellular activity; therefore, any loss of viability was due to cells that were affected by freezing.
Chapter 4 ___________________________________________________________________________ 135 Freeze-dried probiotic microorganisms that were stored at refrigerated conditions had lower viability than those stored at frozen temperature due to slight metabolic and cellular activity at the refrigerated temperature.
Chapter 4 ___________________________________________________________________________ 136
4.4 Tables
Table 4.1 Proteolytic activity of all bacterial strains during storage at -180C1
OD at 340 nm
Probiotic
strains 0 Month 1 Month 2 Months 4 Months 6 Months 9 Months 12 Months ASCC 1520 0.26 ± 0.01 0.24 ± 0.04 0.23 ± 0.01 0.21 ± 0.06 0.22 ± 0.04 0.20 ± 0.04 0.22 ± 0.05 ASCC 1521 0.15 ± 0.03 0.17 ± 0.01 0.16 ± 0.02 0.17 ± 0.02 0.16 ± 0.02 0.18 ± 0.04 0.15 ± 0.01 CSCC 2607 0.24 ± 0.02 0.25 ± 0.03 0.22 ± 0.01 0.21 ± 0.05 0.23 ± 0.01 0.22 ± 0.05 0.24 ± 0.07 ATCC 15820 0.16 ± 0.01 0.18 ± 0.02 0.16 ± 0.03 0.14 ± 0.02 0.19 ± 0.08 0.14 ± 0.06 0.17 ± 0.05 ASCC 290 0.17 ± 0.04 0.14 ± 0.08 0.17 ± 0.02 0.19 ± 0.04 0.20 ± 0.06 0.18 ± 0.02 0.17 ± 0.01 ASCC 292 0.15 ± 0.01 0.16 ± 0.04 0.15 ± 0.01 0.17 ± 0.02 0.15 ± 0.01 0.19 ± 0.04 0.18 ± 0.09 ASCC 279 0.25 ± 0.02 0.21 ± 0.01 0.22 ± 0.01 0.23 ± 0.03 0.20 ± 0.05 0.23 ± 0.04 0.25 ± 0.2
1 Indication of proteolytic activity of Lactobacilli strains after incubation in RSM at 370C for 6h.
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Table 4.2a Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L. rhamnosus1520 stored for 12 mo (mean ± standard error)
Sampling time (mo)
Log10 CFU/mLa,b,e
Frozen (-180C) Refrigerated (40C) Room temp. (200C)
0c 9.60 ± 0.01a 9.60 ± 0.01a 9.60 ± 0.01a
1 9.12 ± 0.04a 9.05 ± 0.02a 7.25 ± 0.02b 2 8.89 ± 0.01a 8.21 ± 0.01b 5.88 ± 0.04c 4 8.66 ± 0.02a 7.90 ± 0.05b NDd 6 8.51 ± 0.04a 7.81 ± 0.1b ND 9 8.45 ± 0.06a 7.77 ± 0.07b ND 12 8.22 ± 0.02a 7.25 ± 0.21b ND
a Mean standard error (n=6), b Means the same row followed by different lower case letters
are significantly different (p<0.05). C 0 mo= initial counts immediately after freeze drying.
Chapter 4 ___________________________________________________________________________ 138
Table 4.2b Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L. rhamnosus2607 stored for 12 mo (mean ± standard error)
Sampling time (mo)
Log10 CFU/mLa,b,e
Frozen (-180C) Refrigerated (40C) Room temp. (200C)
0c 10.65 ± 0.1a 10.65 ± 0.1a 10.65 ± 0.1a
1 10.24 ± 0.01a 9.97 ± 0.03b 9.84 ± 0.04b 2 9.81 ± 0.02a 9.15 ± 0.04b 7.22 ± 0.02c 4 9.65 ± 0.03a 8.89 ± 0.01b NDd 6 9.15 ± 0.03a 8.51 ± 0.02b ND 9 8.91 ± 0.04a 8.12 ± 0.05b ND 12 8.64 ± 0.01a 7.77 ± 0.05b ND
a Mean standard error (n=6), b Means the same row followed by different lower case letters
are significantly different. (p<0.05). C 0 mo= initial counts immediately after freeze drying.
Chapter 4 ___________________________________________________________________________ 139
Table 4.2c Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L. rhamnosus 1521 stored for 12 mo (mean ± standard error)
Sampling time (mo)
Log10 CFU/mLa,b,e
Frozen
(-180C) Refrigerated (40C) Room temp. (200C) 0c 10.82 ± 0.08a 10.82 ± 0.08a 10.82 ± 0.08a
1 10.25 ± 0.02a 9.94 ± 0.01b 9.55 ±0.02b 2 9.80 ± 0.01a 9.40 ± 0.02b 6.88 ± 0.03c 4 9.65 ± 0.02a 9.08 ± 0.01b NDd 6 9.41 ± 0.01a 8.85 ± 0.04b ND 9 9.11 ± 0.04a 8.01 ± 0.02b ND 12 8.91 ± 0.02a 7.45 ± 0.05b ND
a Mean standard error (n=6), b Means the same row followed by different lower
case letters
are significantly different. (p<0.05). C 0 mo= initial counts immediately after freeze drying.
Chapter 4 ___________________________________________________________________________ 140
Table 4.2d Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L. casei 290 stored for 12 mo (mean ± standard error)
Sampling time (mo)
Log10 CFU/mLa,b,e
Frozen (-180C) Refrigerated (40C) Room temp. (200C)
0c 10.15 ±0.02a 10.15 ±0.02a 10.15 ±0.02a 1 9.95 ± 0.01a 9.64 ± 0.04b 9.78 ± 0.01b 2 9.81 ± 0.08a 9.44 ± 0.01b 7.15 ± 0.04c 4 9.71 ± 0.01a 9.11 ± 0.04b NDd 6 9.37 ± 0.02a 8.77 ± 0.01b ND 9 9.15 ± 0.1a 7.95 ± 0.05b ND 12 9.01 ± 0.03a 7.51 ± 0.06b ND
a Mean standard error (n=6), b Means the same row followed by different lower case letters
are significantly different. (p<0.05). C 0 mo= initial counts immediately after freeze drying.
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Table 4.2e Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L.zeae 15820 stored for 12 mo (mean ± standard
error)
Sampling time (mo)
Log10 CFU/mLa,b,e
Frozen (-180C) Refrigerated (40C) Room temp. (200C)
0c 9.98 ± 0.2a 9.98 ± 0.2a 9.98 ± 0.2a
1 9.85 ± 0.01a 9.75 ± 0.05b 8.10 ±0.06c 2 9.60 ± 0.05a 9.40 ± 0.04b 7.52 ± 0.01c 4 9.18 ± 0.04a 8.77 ± 0.01b NDd 6 8.95 ±0.05a 8.10 ± 0.06b ND 9 8.55 ± 0.01a 7.95 ± 0.02b ND 12 8.04 ± 0.1a 7.10 ± 0.04b ND
a Mean standard error (n=6), b Means the same row followed by different lower
case letters
are significantly different. (p<0.05). C 0 mo= initial counts immediately after freeze
drying.
d ND = not detectable. eOne way analysis of variance of means in the same row
Chapter 4 ___________________________________________________________________________ 142
Table 4.2f Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L. paracasei 292stored for 12 mo (mean ± standard error)
Sampling time (mo)
Log10 CFU/mLa,b,e
Frozen (-180C) Refrigerated (40C) Room temp. (200C)
0c 10.1 ± 0.05a 10.1 ± 0.05a 10.1 ± 0.05a 1 9.98 ± 0.02a 9.85 0.02b 9.56 ± 0.02c 2 9.80 ± 0.01a 9.74 ± 0.03b 6.88 ± 0.01c 4 9.64 ± 0.03a 9.10 ± 0.02b NDd 6 9.25 ± 0.08a 8.84 ± 0.4b ND 9 8.94 ± 0.01a 8.17 ± 0.1b ND 12 8.25 ± 0.04a 7.81 ± 0.09b ND
a Mean standard error (n=6), b Means the same row followed by different lower
case letters
are significantly different. (p<0.05). C 0 mo= initial counts immediately after freeze drying.
d ND = not detectable. eOne way analysis of variance of means in the same row
Chapter 4 ___________________________________________________________________________ 143
Table 4.2g Viable microbial count (log10 colony-forming units (cfu)/mL) of
freeze dried L. paracasei 279stored for 12 mo (mean ± standard error)
Sampling time (mo)
Log10 CFU/mLa,b,c,d
Frozen
(-180C) Refrigerated (40C) (20Shelf 0C) 0c 9.95 ± 0.06a 9.95 ± 0.06a 9.95 ± 0.06a
1 9.78 ± 0.01a 9.68 ± 0.02b 8.40 ± 0.02c 2 9.41 ± 0.2a 9.49 ± 0.04b 6.48 ± 0.01c 4 9.16 ± 0.05a 8.77 ± 0.2b NDd 6 8.80 ± 0.04a 8.41 ± 0.1b ND 9 8.50 ± 0.02a 7.94 ± 0.04b ND 12 8.15 ± 0.05a 7.58 ± 0.01b ND
a Mean standard error (n=6), b Means the same row followed by different lower
case letters
are significantly different. (p<0.05). C 0 mo= initial counts immediately after freeze
drying.
d ND = not detectable. eOne way analysis of variance of means in the same row
Chapter 4 ___________________________________________________________________________ 144