Food Protection with Chemicals, and by Biocontrol 327
of L. monocytogenes, vacuum packaged, and stored for 60 days at 4.5
◦ C; and bratwurst for 84 days
at 3 and 7
◦ C. Sodium lactate at ≥3% and combinations of ≥1% lactate and 0.1% diacetate prevented
growth of the pathogen on wieners for 60 days at 4.5
◦ C.
68 Inclusion of the agents was more effective
than dipping. Potassium lactate at 2 or 3% was found to be effective in preventing the growth of
a 5-strain mixture of L. monocytogenes in frankfurters.
152 With a pathogen inoculum of up to 500
cfu/package, storage in nylon-polyethylene bags, and incubation at 4
◦ or 10
◦ C for 60 or 90 days, a 4 to
5-long reduction of pathogen was found in lactate-treated meats compared to uninoculated controls.
To control growth of Clostridium perfringens in cooked vacuum-packaged restructured roast beef,
the following compounds were assessed: Sodium citrate (2 or 4.8%, pH 4.4–5.6); sodium lactate (60%
solution, 2 or 4.8%); sodium acetate (0.25%); and sodium diacetate (0.25%). The meat was inoculated
with a three-strain mixture of C. perfringens spores, vacuum packaged, cooked at 75
◦ C for 20 minutes,
and slow cooled for 18 hours.
165 Spores were not destroyed by cooking, but growth was reduced to
<1 log over the 18-hour cooling period by the citrate, lactate, and diacetate additives.
165
In a study to determine the effect of sodium diacetate (up to 0.5%) and sodium lactate (up to
2.5%) on cook-in-bag turkey breast, the product was inoculated with 9–30 spores of a psychrotrophic
Clostridium sp., vacuum packaged, cooked to an internal temperature of 71.1
◦ C, chilled, and incubated
at 4
◦ C for up to 22 weeks.
127 Spoilage occurred within 6 weeks with no inhibitors, but products that
contained either 0.25% diacetate or 1.25% lactate did not spoil until 13 weeks.
ANTIBIOTICS
Historically, antibiotics are secondary metabolites produced by microorganisms that inhibit or kill
a wide spectrum of other microorganisms. Most of the useful ones are produced by molds and bacteria
of the genus Streptomyces, and a few by Bacillus and Paenibacillus spp. Many of the clinically useful
agents now in use are synthetic products.
Two antibiotics have been investigated extensively as heat adjuncts for canned foods: subtilin and
tylosin. Chlortetracycline and oxytetracycline were once widely studied for their application to fresh
foods, whereas natamycin is employed as a food fungistat. According to the Animal Health Institute,
22 million pounds of antibiotics were sold in the United States in 2002 for use in both farm and
companion animals, a slight increase over 2001. Ninety percent of these agents were used to treat,
control, and prevent diseases.
In general, the use of chemical preservatives in foods is not popular among many consumers; the
idea of employing antibiotics is even less popular. Some risks may be anticipated from the use of any
food additive, but the risks should not outweigh the benefits overall. The general view in the United
States is that the benefits to be gained by using antibiotics in foods do not outweigh the risks, some of
which are known and some of which are presumed. Some 15 considerations on the use of antibiotics as
food preservatives were noted by Ingram et al., and several of the key ones are summarized as follows:
1. The antibiotic agent should kill, not inhibit, the flora and should ideally decompose into innocuous
products or be destroyed on cooking for products that require cooking.
2. The antibiotic should not be inactivated by food components or products of microbial metabolism.
3. The antibiotic should not readily stimulate the appearance of resistant strains.
4. The antibiotic should not be used in foods if used therapeutically or as an animal feed additive.
The tetracyclines are used both clinically and as feed additives, and tylosin is used in animal feeds
and only in the treatment of some poultry diseases (Table 13–9). Neither nisin nor subtilin is used
of L. monocytogenes, vacuum packaged, and stored for 60 days at 4.5
◦ C; and bratwurst for 84 days
at 3 and 7
◦ C. Sodium lactate at ≥3% and combinations of ≥1% lactate and 0.1% diacetate prevented
growth of the pathogen on wieners for 60 days at 4.5
◦ C.
68 Inclusion of the agents was more effective
than dipping. Potassium lactate at 2 or 3% was found to be effective in preventing the growth of
a 5-strain mixture of L. monocytogenes in frankfurters.
152 With a pathogen inoculum of up to 500
cfu/package, storage in nylon-polyethylene bags, and incubation at 4
◦ or 10
◦ C for 60 or 90 days, a 4 to
5-long reduction of pathogen was found in lactate-treated meats compared to uninoculated controls.
To control growth of Clostridium perfringens in cooked vacuum-packaged restructured roast beef,
the following compounds were assessed: Sodium citrate (2 or 4.8%, pH 4.4–5.6); sodium lactate (60%
solution, 2 or 4.8%); sodium acetate (0.25%); and sodium diacetate (0.25%). The meat was inoculated
with a three-strain mixture of C. perfringens spores, vacuum packaged, cooked at 75
◦ C for 20 minutes,
and slow cooled for 18 hours.
165 Spores were not destroyed by cooking, but growth was reduced to
<1 log over the 18-hour cooling period by the citrate, lactate, and diacetate additives.
165
In a study to determine the effect of sodium diacetate (up to 0.5%) and sodium lactate (up to
2.5%) on cook-in-bag turkey breast, the product was inoculated with 9–30 spores of a psychrotrophic
Clostridium sp., vacuum packaged, cooked to an internal temperature of 71.1
◦ C, chilled, and incubated
at 4
◦ C for up to 22 weeks.
127 Spoilage occurred within 6 weeks with no inhibitors, but products that
contained either 0.25% diacetate or 1.25% lactate did not spoil until 13 weeks.
ANTIBIOTICS
Historically, antibiotics are secondary metabolites produced by microorganisms that inhibit or kill
a wide spectrum of other microorganisms. Most of the useful ones are produced by molds and bacteria
of the genus Streptomyces, and a few by Bacillus and Paenibacillus spp. Many of the clinically useful
agents now in use are synthetic products.
Two antibiotics have been investigated extensively as heat adjuncts for canned foods: subtilin and
tylosin. Chlortetracycline and oxytetracycline were once widely studied for their application to fresh
foods, whereas natamycin is employed as a food fungistat. According to the Animal Health Institute,
22 million pounds of antibiotics were sold in the United States in 2002 for use in both farm and
companion animals, a slight increase over 2001. Ninety percent of these agents were used to treat,
control, and prevent diseases.
In general, the use of chemical preservatives in foods is not popular among many consumers; the
idea of employing antibiotics is even less popular. Some risks may be anticipated from the use of any
food additive, but the risks should not outweigh the benefits overall. The general view in the United
States is that the benefits to be gained by using antibiotics in foods do not outweigh the risks, some of
which are known and some of which are presumed. Some 15 considerations on the use of antibiotics as
food preservatives were noted by Ingram et al., and several of the key ones are summarized as follows:
1. The antibiotic agent should kill, not inhibit, the flora and should ideally decompose into innocuous
products or be destroyed on cooking for products that require cooking.
2. The antibiotic should not be inactivated by food components or products of microbial metabolism.
3. The antibiotic should not readily stimulate the appearance of resistant strains.
4. The antibiotic should not be used in foods if used therapeutically or as an animal feed additive.
The tetracyclines are used both clinically and as feed additives, and tylosin is used in animal feeds
and only in the treatment of some poultry diseases (Table 13–9). Neither nisin nor subtilin is used