324 Modern Food Microbiology
thyme, and sassafras, Beuchat (in 1976) found that 100 ppm were cidal to V. parahaemolyticus in broth.
Growth and aflatoxin production by Aspergillus parasiticus in broth were inhibited by 200–300 ppm
of cinnamon and clove oils, by 150 ppm cinnamic aldehyde, and by 125 ppm eugenol.
23
The mechanisms by which spices inhibit microorganisms are unclear and may be presumed to
be different for unrelated groups of spices. That the mechanism for oregano, rosemary, sage, and
thyme may be similar is suggested by the finding that resistance development by some lactic acid
bacteria to one was accompanied by resistance to the other three.
221 Of nine spice oils tested for
activity against mycotoxin production by Aspergillus parasiticus and Fusarium moniliforme, the most
effective was eugenol at 0.25 ppm followed by cinnamic aldehyde; thymol and carvacol; oregano; and
mace oils—myristin.
98
Phosphates
These salts are commonly added to certain processed meats to increase their water holding capacity.
They also contribute to flavor, and they are antioxidative.
Food-grade phosphates range from one P (e.g. trisodium phosphate) to at least 13 (sodium polyphosphate). In the 1970s and 1980s, they were shown to possess antibotulinal activity, especially when
combined with nitrites. In one study, a combination of 40 ppm NaNO 2 , 0.26% potassium sorbate, and
0.4% sodium acid pyrophosphate (SAPP) delayed C. botulinum neurotoxin production in frankfurter
emulsions to 12–18 days compared to 6–12 days for controls at the same pH.
204 Using 13 Grampositive and 12 Gram-negative bacteria in culture media, 0.5% of 3 polyphosphates at pH 7 and 25
◦ C,
tripoly- and hexametaphosphate were the most effective, and the Gram-positive bacteria were more
susceptible than Gram negatives.
223 Filter-sterilized phosphate preparations were more inhibitory than
autoclaved in the above study. As noted in Chapter 7, sodium phosphate glassy at 0.5% delayed the
growth of Clostridium tyrobutyricum in cheese spreads for 3 weeks, and a 1% concentration effected
complete inhibition in the product that was inoculated with 5 × 10
5 spores.
120
Trisodium phosphate (TSP) was tested on whole chicken legs and excised chicken leg fragments
for its action against L. monocytogenes. Using an inoculum of ca. 10
8 cfu/ml, chicken parts were
dipped in 10 or 12% TSP, and sterile water as control.
27 After 5 days at 2
◦ C, TSP was found to be
more effective on excised skin than on whole legs for 9 of the 12 tested for a decrease of 4.28 logs for
excised products compared to a decrease of only 3.3 logs for whole legs.
27
As to the mechanism by which phosphates inhibit bacteria, Bacillus cereus cells and spores were
subjected to 0.1% or more of a long-chain sodium polyphosphate glassy (polyP) and the compound
was bactericidal to log-phase cells where it caused cell lysis (see Figure 13–5). Active growth of
cells was necessary for this effect. The inhibition of B. cereus spore germination and outgrowth were
effected by 0.1%, and a 1.0% concentration was sporicidal.
121 The antispore activity was antagonized
by divalent cations. While using L. monocytogenes in a culture medium, its inhibition by a long-chain
sodium polyphosphate was shown to be reversed by cations.
222 With the elongation of vegetative cells
by a polyP concentration of 0.05% after 4 hours, Maier et al.
121 concluded that polyP may affect
the cell division protein FtsZ and thus block polymerization of the Z ring. The FtsZ protein exhibits
Mg
2+ -dependent GTPase activity.
Medium-Chain Fatty Acids and Esters
Acetic, propionic, and sorbic acids are short-chain fatty acids used primarily as preservatives.
Medium-chain fatty acids are employed primarily as surface-active or emulsifying agents. The
thyme, and sassafras, Beuchat (in 1976) found that 100 ppm were cidal to V. parahaemolyticus in broth.
Growth and aflatoxin production by Aspergillus parasiticus in broth were inhibited by 200–300 ppm
of cinnamon and clove oils, by 150 ppm cinnamic aldehyde, and by 125 ppm eugenol.
23
The mechanisms by which spices inhibit microorganisms are unclear and may be presumed to
be different for unrelated groups of spices. That the mechanism for oregano, rosemary, sage, and
thyme may be similar is suggested by the finding that resistance development by some lactic acid
bacteria to one was accompanied by resistance to the other three.
221 Of nine spice oils tested for
activity against mycotoxin production by Aspergillus parasiticus and Fusarium moniliforme, the most
effective was eugenol at 0.25 ppm followed by cinnamic aldehyde; thymol and carvacol; oregano; and
mace oils—myristin.
98
Phosphates
These salts are commonly added to certain processed meats to increase their water holding capacity.
They also contribute to flavor, and they are antioxidative.
Food-grade phosphates range from one P (e.g. trisodium phosphate) to at least 13 (sodium polyphosphate). In the 1970s and 1980s, they were shown to possess antibotulinal activity, especially when
combined with nitrites. In one study, a combination of 40 ppm NaNO 2 , 0.26% potassium sorbate, and
0.4% sodium acid pyrophosphate (SAPP) delayed C. botulinum neurotoxin production in frankfurter
emulsions to 12–18 days compared to 6–12 days for controls at the same pH.
204 Using 13 Grampositive and 12 Gram-negative bacteria in culture media, 0.5% of 3 polyphosphates at pH 7 and 25
◦ C,
tripoly- and hexametaphosphate were the most effective, and the Gram-positive bacteria were more
susceptible than Gram negatives.
223 Filter-sterilized phosphate preparations were more inhibitory than
autoclaved in the above study. As noted in Chapter 7, sodium phosphate glassy at 0.5% delayed the
growth of Clostridium tyrobutyricum in cheese spreads for 3 weeks, and a 1% concentration effected
complete inhibition in the product that was inoculated with 5 × 10
5 spores.
120
Trisodium phosphate (TSP) was tested on whole chicken legs and excised chicken leg fragments
for its action against L. monocytogenes. Using an inoculum of ca. 10
8 cfu/ml, chicken parts were
dipped in 10 or 12% TSP, and sterile water as control.
27 After 5 days at 2
◦ C, TSP was found to be
more effective on excised skin than on whole legs for 9 of the 12 tested for a decrease of 4.28 logs for
excised products compared to a decrease of only 3.3 logs for whole legs.
27
As to the mechanism by which phosphates inhibit bacteria, Bacillus cereus cells and spores were
subjected to 0.1% or more of a long-chain sodium polyphosphate glassy (polyP) and the compound
was bactericidal to log-phase cells where it caused cell lysis (see Figure 13–5). Active growth of
cells was necessary for this effect. The inhibition of B. cereus spore germination and outgrowth were
effected by 0.1%, and a 1.0% concentration was sporicidal.
121 The antispore activity was antagonized
by divalent cations. While using L. monocytogenes in a culture medium, its inhibition by a long-chain
sodium polyphosphate was shown to be reversed by cations.
222 With the elongation of vegetative cells
by a polyP concentration of 0.05% after 4 hours, Maier et al.
121 concluded that polyP may affect
the cell division protein FtsZ and thus block polymerization of the Z ring. The FtsZ protein exhibits
Mg
2+ -dependent GTPase activity.
Medium-Chain Fatty Acids and Esters
Acetic, propionic, and sorbic acids are short-chain fatty acids used primarily as preservatives.
Medium-chain fatty acids are employed primarily as surface-active or emulsifying agents. The