Bacteria will multiply when conditions are favorable
Fermented Sausages
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Traditionally Made Fermented Sausages
Bacteria -
Yeasts - Molds
Bacteria Survival Tables
USA & Canadian Fermentation Standards
Starter
Cultures
Safety Hurdles
Equipment
Bacteria will multiply when conditions are
favorable but will become lethargic when temperatures drop lower. When
temperatures are high enough they will die, some of them will not
survive in an oxygen absent atmosphere. Keeping them in check is of
utmost importance during the manufacture of fermented and air-dried products as
these products are normally not heat treated which is the most effective
method for killing bacteria. In the following table we have compiled
data that indicates the physical parameters which can be regulated in order
to control the growth of bacteria.
It should be noted that when the two
hurdles (or more) are applied (pH drop, drying, sugar, starter culture
etc), their cumulative strength is magnified and bacteria are
constrained more effectively. Adding salt and nitrite creates the
first hurdle against the growth of bacteria and as the acidity of the
sausage increases and moisture continues to evaporate, the sausage
becomes more stable and contains less and less bacteria.
The first 24 hours are the most crucial and
moisture removal must be slow enough to permit lactic acid bacteria to
grow. Lactic bacteria Lactobacillus
and Pediococcus
like other species need moisture to live and will not produce lactic
acid if the Aw - water activity drops below 0.93 which can happen during
fast drying.
Accelerated drying will decrease moisture
levels in the outside area of the sausage and will inhibit curing and
color fixing bacteria
Staphylococcus, Kocuria (also known as
Micrococcus)
from doing their job.
The resulting hardened and dried surface area of the
meat will not be red, it will be grey which will subsequently show on a
sliced sausage.
Factors Affecting the
Growth and Control of Pathogenic Bacteria
Name
Temperature in
º C
Min pH
Min Aw
O2
needs
Minimum
Optimum
Maximum
Salmonella
7
35 - 37
45
3.8
0.94
FA*
Clostridium botulinum
3
18 - 25
45
5.0
0.96
OA*
Clostridium
prefringens
12
44 - 49
50
5.5
0.93
OA*
Staphylococcus aureus
6
37
48
4.2
0.85
FA*
Campylobacter jejuni
30
42
45
4.9
0.98
MA*
Listeria monocytogenes
- 1.5
37
45
4.4
0.92
FA*
Escherichia coli
0157:H7
7
37
46
4.4
0.95
FA*
Shigella
7
35 - 37
47
4.0
0.91
FA*
Bacillus cereus
4
30 - 37
50
4.3
0.91
FA*
Clostridium perfringens
is less strictly anaerobic than Clostridium botulinum and
can tolerate some exposure to oxygen.
Clostridium botulinum is
pathogen associated with deadly "food poisoning".
Significant growth of
Staphylococcus aureus occurs at 15.6º
C (60º
C) and higher and after fermentation the sausages should be
dried below this temperature. Fermentation tables are based
on this fact.
more on above bacteria at:
http://www.wedlinydomowe.com/fermented-sausages/bacteria-yeasts-molds.htm
FA*: Facultative
anaerobic feels comfortable in oxygen but can live without it as
well
OA*: Obligate
anaerobic cannot grow in presence of oxygen
MA*:
Microaerophile bacteria like very little of oxygen (5%) and low
levels of CO2 (carbon dioxide-10%)
As seen in the table
Staphylococcus aureus is quite resistant to drying
Fermentation Temperatures of Commercial Lactic Acid Bacteria
Name
Temperature range in
º C
Lactobacillus curvatus
22 - 37
Lactobacillus farciminis
22 - 32
Lactobacillus plantarum
25 - 35
Lactobacillus sakei
21 - 32
Pediococcus acidilactici
25 - 45
Pediococcus pentosaceus
20 - 37
Source: Chr. Hansen
Page added on
May 2, 2008.
This section will be expanded in time and photos will be added.
Copyright © 2008 WedlinyDomowe.com All rights reserved
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