490 ◾ Fundamental Food Microbiology
before their incorporation. This law, however, granted an exemption to substances used for a long time,
found to be safe, and considered as generally regarded as safe (GRAS) substances.
In recent years, the possible effect of different preservatives and other additives on human
health from long-term use through different foods has been questioned. Many of them are of
nonfood origin or added at a level not normally present in foods, and some are synthetic. The
effect of interactions of the different preservatives in the body, consumed through different foods,
especially in children and debilitated and elderly people; the possible cumulative effect from the
consumption over many years; and their interactions with each other and with other chemicals
(e.g., medications) have not been determined. Many health-conscious consumers are interested in
foods that do not contain any preservatives, especially those not normally found in foods or present in a much lower concentration than that added to foods. This has resulted in the search for
preservatives that are either naturally present in the food of plant and animal origin or produced
by safe food-grade microorganisms used to produce fermented foods. They are also designated
as biopreservatives. 2 Some of these have been used, not always as preservatives, for a long time in
foods and have been found to be safe (such as lactic, acetic, and propionic acids), whereas others
have not been used directly as preservatives. Although many of them have been unknowingly
consumed through foods without any adverse effects (such as bacteriocins of many lactic acid
bacteria), they probably have to be tested for safety and regulatory approval before use in foods.
objectives
Antimicrobial chemicals are used in food in relatively small doses either to kill undesirable microorganisms or to prevent or retard their growth. They differ greatly in their abilities to act against
different microorganisms. Some are effective against many microorganisms (broad spectrum),
whereas others are effective against either molds and yeasts or only bacteria (narrow spectrum).
Similarly, some compounds are effective against either gram-positive or gram-negative bacteria or
bacterial spores or viruses. Those capable of killing microorganisms are designated as germicides
(kill all types), fungicides, bactericides, sporicides, and viricides, depending on their specificity of
killing actions against specific groups. Those that inhibit or retard microbial growth are classified
as fungistatic or bacteriostatic. However, under the conditions in which most antimicrobials are
used in foods, they cannot completely kill all the microorganisms or prevent their growth for a
long time during storage. They can also cause injury.
influencing Factors
Several factors need to be considered in evaluating the suitability of an antimicrobial agent as a food
preservative, 1,3,4 based on their antimicrobial properties, suitability for application in a food, and ability
to meet regulatory requirements. Regarding antimicrobial properties, a compound that kills (-cidal)
instead of controlling growth (-static) is preferred. Similarly, a compound with a broader antimicrobial
spectrum is more suitable for application in foods so that it is effective against many types of microorganisms important in foods (namely, molds, yeasts, bacteria, and viruses) as compared with one that
has a narrow spectrum. Also, a compound effective not only against vegetative cells but also against
spores is preferred. Finally, it should not allow development of resistant strains. Most compounds do
not meet all these requirements. Many times, more than one compound is used in combination to
increase the inhibitory spectrum. In addition, food environments may restrict growth of many types
before their incorporation. This law, however, granted an exemption to substances used for a long time,
found to be safe, and considered as generally regarded as safe (GRAS) substances.
In recent years, the possible effect of different preservatives and other additives on human
health from long-term use through different foods has been questioned. Many of them are of
nonfood origin or added at a level not normally present in foods, and some are synthetic. The
effect of interactions of the different preservatives in the body, consumed through different foods,
especially in children and debilitated and elderly people; the possible cumulative effect from the
consumption over many years; and their interactions with each other and with other chemicals
(e.g., medications) have not been determined. Many health-conscious consumers are interested in
foods that do not contain any preservatives, especially those not normally found in foods or present in a much lower concentration than that added to foods. This has resulted in the search for
preservatives that are either naturally present in the food of plant and animal origin or produced
by safe food-grade microorganisms used to produce fermented foods. They are also designated
as biopreservatives. 2 Some of these have been used, not always as preservatives, for a long time in
foods and have been found to be safe (such as lactic, acetic, and propionic acids), whereas others
have not been used directly as preservatives. Although many of them have been unknowingly
consumed through foods without any adverse effects (such as bacteriocins of many lactic acid
bacteria), they probably have to be tested for safety and regulatory approval before use in foods.
objectives
Antimicrobial chemicals are used in food in relatively small doses either to kill undesirable microorganisms or to prevent or retard their growth. They differ greatly in their abilities to act against
different microorganisms. Some are effective against many microorganisms (broad spectrum),
whereas others are effective against either molds and yeasts or only bacteria (narrow spectrum).
Similarly, some compounds are effective against either gram-positive or gram-negative bacteria or
bacterial spores or viruses. Those capable of killing microorganisms are designated as germicides
(kill all types), fungicides, bactericides, sporicides, and viricides, depending on their specificity of
killing actions against specific groups. Those that inhibit or retard microbial growth are classified
as fungistatic or bacteriostatic. However, under the conditions in which most antimicrobials are
used in foods, they cannot completely kill all the microorganisms or prevent their growth for a
long time during storage. They can also cause injury.
influencing Factors
Several factors need to be considered in evaluating the suitability of an antimicrobial agent as a food
preservative, 1,3,4 based on their antimicrobial properties, suitability for application in a food, and ability
to meet regulatory requirements. Regarding antimicrobial properties, a compound that kills (-cidal)
instead of controlling growth (-static) is preferred. Similarly, a compound with a broader antimicrobial
spectrum is more suitable for application in foods so that it is effective against many types of microorganisms important in foods (namely, molds, yeasts, bacteria, and viruses) as compared with one that
has a narrow spectrum. Also, a compound effective not only against vegetative cells but also against
spores is preferred. Finally, it should not allow development of resistant strains. Most compounds do
not meet all these requirements. Many times, more than one compound is used in combination to
increase the inhibitory spectrum. In addition, food environments may restrict growth of many types