3.2. Effect of enterocin AS-48 in foods and coconut milk inoculated
with endospores of
G. stearothermophilus
In food and coconut milk samples inoculated with a cocktail of
G. stearothermophilus
strains CECT 43 and CECT 49 endospores,
viable cell counts in the untreatedcontrols increased rapidly during
the first day of incubation for the samples from canned corn, can-
ned peas and also coconut milk (
Fig. 2
A, B, C). The highest cell
concentrations reached in canned peas inoculated with endospores
(day 3 of storage) were lower compared to the corresponding
samples inoculated with vegetative cells. In all the food and drink
samples tested, a bacteriocin concentration as low as 1.75
m
g per g
or ml of food was sufficient to reduce viable cell counts below
detection levels from day 1 to the end of the storage period.
3.3. Trypsin rescue of bacteriocin-treated endospores
When endospores of
G. stearothermophilus
CECT 43 were chal-
lenged with enterocin AS-48 without addition of trypsin, the short
bacteriocin treatment was sufficient to achieve a 3.0 log reduction
of viable counts (
Table 1
). By contrast, viable counts from samples
challenged with AS-48 and then treated with trypsin were 2.8 log
units higher (
P
<
0.05) compared to samples treated with AS-48
alone. These results indicate that trypsin caused inactivation of AS-
48 before the bacteriocin could kill the spores, and suggest that
residual bacteriocin or bacteriocin adsorbed on the spores was
responsible forkilling aftertheshort-timetreatment inthe samples
treated only with bacteriocin
3.2. Effect of enterocin AS-48 in foods and coconut milk inoculated
with endospores of
G. stearothermophilus
In food and coconut milk samples inoculated with a cocktail of
G. stearothermophilus
strains CECT 43 and CECT 49 endospores,
viable cell counts in the untreatedcontrols increased rapidly during
the first day of incubation for the samples from canned corn, can-
ned peas and also coconut milk (
Fig. 2
A, B, C). The highest cell
concentrations reached in canned peas inoculated with endospores
(day 3 of storage) were lower compared to the corresponding
samples inoculated with vegetative cells. In all the food and drink
samples tested, a bacteriocin concentration as low as 1.75
m
g per g
or ml of food was sufficient to reduce viable cell counts below
detection levels from day 1 to the end of the storage period.
3.3. Trypsin rescue of bacteriocin-treated endospores
When endospores of
G. stearothermophilus
CECT 43 were chal-
lenged with enterocin AS-48 without addition of trypsin, the short
bacteriocin treatment was sufficient to achieve a 3.0 log reduction
of viable counts (
Table 1
). By contrast, viable counts from samples
challenged with AS-48 and then treated with trypsin were 2.8 log
units higher (
P
<
0.05) compared to samples treated with AS-48
alone. These results indicate that trypsin caused inactivation of AS-
48 before the bacteriocin could kill the spores, and suggest that
residual bacteriocin or bacteriocin adsorbed on the spores was
responsible forkilling aftertheshort-timetreatment inthe samples
treated only with bacteriocin
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