antimicrobial used in food for its food presevation to increase its shelf life. also for good nutritive food

2. Introduction
• An antimicrobial is an agent that kills microorganisms or
stops their growth
• Antimicrobial agents have long been researched for their
effectiveness to kill or inhibit growth of microorganisms in
and on foods.
• This has been done in an effort to increase food safety for
the consumer, as well as to increase the shelf life of food
products.
• It should be added to the food during processing, and is
either removed, converted into normal food constituents or
functional additives that leave insignificant nonfunctional
residuals
• The use of any antimicrobial depends on several factors,
such as desired effect, legal limits of use and effect on the
food.

3. SELECTION OF
ANTIMICROBIALS
• It is not an easy process to select the appropriate
preservation system for a particular food product.
• The target pathogen or spoilage microorganisms must be
identified first.
• The possible preservation systems must be evaluated via
model studies and studies in the food product.
• Selection of the proper antimicrobial depends on several
primary factors:
1. Antimicrobial Spectrum
2. Physicochemical Properties of the Antimicrobial
3. Food-Related Factors

4. ANTIMICROBIAL SPECTRUM
• The initial selection of the antimicrobial is normally based
on an assessment of the overall microbial spectrum of the
chemical.
• The antimicrobial spectrum should involve an evaluation of
the compound against
1. various types of microorganisms (e.g., bacteria, yeasts,
molds)
2. forms of those microorganisms (vegetative cells vs.
spores).
3. Even species, strain, and Gram reaction (positive vs.
negative) can have dramatic influences on apparent
activity.
• The antimicrobial spectrum of a compound is generally
determined by following the growth of organisms in the
presence of various concentrations of the antimicrobial.

5. PHYSICOCHEMICAL PROPERTIES OF THE
ANTIMICROBIAL
• The overall microbial spectrum, the mode of action,
and the efficacy of compounds are largely
dependent on the chemical and physical properties
of the antimicrobial.
• The polarity of a compound is probably the most
important physical property.
• High volatility can also result in a noticeable odor,
which contributes to an off-flavor in a food product.

6. Considerations in the Use of
Food Antimicrobials
• SANITATION
1. An antimicrobial is never a substitute for good sanitation in a
food processing plant, and low microbial loads must always be
sought.
2. Few, if any, regulatory-approved antimicrobials are able to
preserve a product that is grossly contaminated. In addition,
although food antimicrobials will extend the lag phase or
inactivate low numbers of microorganisms, their effects can be
overcome.
3. If the number of microorganisms contaminating a food product
is high, significantly higher quantities of an antimicrobial may
be needed.

7. FOOD-RELATED FACTORS
• The chemical reactivity of the antimicrobial
with other food components can significantly
affect activity. Reaction with lipids, proteins,
carbohydrates, and other food additives can
result in an overall decrease in the activity of
the antimicrobial compound.
• A sensory evaluation is often needed to
assure that antimicrobials do not directly
or indirectly through chemical reaction
alter the color, flavor, or texture of a food
product

8. • TOXICOLOGIC SAFETY
1. It is obviously essential that an additive for use as a
food antimicrobial be safe for human consumption.
2. It is also important that the antimicrobial be
metabolized and excreted by the body. The
compound or its breakdown products should also not
result in buildup of residues in body tissues.
3. They occur in nature, it is often thought that naturally
occurring antimicrobials are less toxic than synthetic
compounds. This is not always true. A naturally
occurring antimicrobial must be shown to be nontoxic
either by animal testing or by its continuous
consumption by consumers as a food over a long
period.

9. • LABELING
1. Consumers are reportedly concerned about the
presence of synthetic chemicals in their foods and would
prefer natural compounds.
2. A potential problem with natural antimicrobials is that if
they are highly purified, they may need to be approved as
food additives. This would involve very expensive and
time-consuming toxicological testing.
3. In addition, the compound would probably have to be
listed using a chemical name on a food label. This, of
course, would defeat the purpose of using a natural
compound. For that reason, less purification may be
better.

10. 4. If a product is simply an “extract of” a commonly
consumed plant or animal food product, it is much less
likely to require complex regulatory approval for use. This
is only possible if the product from which the extract is
taken is known to be nontoxic.
• ECONOMICS OF USE
1. A food antimicrobial will not be useful to the food industry
unless it is inexpensive enough and has the ability to pay
for itself based on reducing spoilage and minimizing food
borne illness.
2. Extensive studies at a pilot-plant level are necessary on
any food additive to prove its overall usefulness. In many
cases, an additional 2 or 3 days of shelf life can
significantly help to offset the cost of using an
antimicrobial. The efficiency of these compounds can be
extremely important in determining the overall economics
of their use.

11. • ACTIVITY VALIDATION METHODS
1. Currently, there are few standardized methods for
validation of the activity of regulatory-approved food
antimicrobials.
2. If antimicrobials are to be used exclusively as inhibitors of
pathogens in food products, assays need to be
developed that evaluate the activity of these compounds
against the pathogen they are designed to kill.
3. The reason for these assays is that various conditions of
process or storage could reduce the effectiveness of the
compound. For example, it is known that peptides, such
as nisin, are susceptible to inactivation by enzymes in
foods.
4. Therefore, just as thermal processes need validation, so
should there be validation for the activity of food
antimicrobials.

12. • SENSORY EFFECTS
 Another major factor that needs to be addressed when
applying antimicrobials is their potential impact on the
sensory characteristics of a food. Many antimicrobials
must be used at high concentrations to achieve activity
against target microorganisms. Obviously, compounds
that negatively affect flavor and odor or contribute
inappropriate flavors and odors would be unacceptable.
In addition to adverse effects on flavor, odor, or texture, it
would be unacceptable for a food antimicrobial to mask
spoilage because spoilage may protect consumers from
ingesting food borne pathogens.

13. • RESISTANCE DEVELOPMENT
1. Because the activity spectra are often different for each
antimicrobial, the micro flora contaminating a food product
significantly influences the choice of the antimicrobial needed.
2. One should be cautious, however, not to select an
antimicrobial solely according to its ability to control the
predominant microorganism present.
3. Because of their specificity, selecting antimicrobials that
control some genera but not others may result in selecting for
and creating favorable conditions for growth of other
organisms.
4. Potential food antimicrobials should not contribute to the
development of resistant strains nor alter the environment of
the food in such a way that growth of another pathogen is
selected. There has been much interest in the effect of
environmental stress factors (e.g., heat, cold, starvation, low
pH/organic acids) on developed resistance of microorganisms
to subsequent stressors. Microorganisms exposed to a stress
may become more resistant and have enhanced survival to
subsequent stresses.

14. 5. There has been much interest in the effect of environmental
stress factors (e.g., heat, cold, starvation, low pH/organic
acids) on developed resistance of microorganisms to
subsequent stressors. Microorganisms exposed to a stress
may become more resistant and have enhanced survival to
subsequent stresses.
6. Although this increased resistance may be a problem in
application of organic acids for controlling pathogens, it has
not been shown to occur in an actual food processing system.

15. Common Antimicrobial
Agents
• Benzoic acid
• Acetic acid
• Nitrates and Nitrites
• Sulphur dioxide
• Antibiotics
• Phosphates

16. Antimicrobial Agents
• Benzoic acid
• Disrupts cell membrane
function/inhibits enzymes
(moulds, yeasts, some
bacteria)
• to preserve fruit juices,
fruit beverages, pickled
vegetables, olives

17. Antimicrobial Agents
• Acetic acid
• Acetic acid is a weak
organic acid. Unlike a
lot of other food
additives, acetic acid is
commonly used in
home cooking.
(vinegar)
• Pickled food, salad
dressing, mayonnaise

18. Antimicrobial Agents
• Nitrates and
Nitrites
• Nitrates and nitrites are
frequently added to
processed meats like
bacon, ham, sausages
and hot dogs.
• They function as
preservatives, helping
to prevent the growth
of harmful bacteria.

19. Antimicrobial Agents
• Phosphates
• Phosphorus is found
naturally in dairy, meat, and
plants. It's needed to help
cells work properly.
Phosphates enhance flavour
and moistness in deli meats,
frozen food, cereals, cheese,
and baked goods, as well as
in sodas and prepared iced
tea mixes
• Inorganic phosphorus used
in restaurant foods

20. Antimicrobial Agents
• Sulphur dioxide
• It is used as a
preservative for dried
apricots and other dried
fruits owing to its
antimicrobial properties,
(it is sometimes called
E220 when used in this
way.) As a preservative,
it maintains the
appearance of the fruit
and prevents rotting

21. FUTURE OF
ANTIMICROBIALS• Antimicrobials will undoubtedly continue to be needed to
provide the food supply that will be demanded in the
future. The global economy in which we live results in
foods being transported throughout the world. If foods are
to arrive in the condition expected, preservatives will be
needed.
• Food scientists, regulators, and consumers will be better
able to determine whether the risks outweigh the benefits
for selected additives now available and for some
compounds of potential future value. The information
should also serve as a basis for selection of any new
antimicrobial developed in the future.

22. • The future of research in the area of food
antimicrobials will likely be on two fronts.
1. First is the expansion of information on the antimicrobial
spectrum of natural antimicrobials. This research will be more
focused on the appropriate use of natural antimicrobials or
utilization of compounds in situations in which they are
compatible. Appropriate or compatible use would involve using
these compounds in foods in which they add to the positive
sensory characteristics of the product in addition to improving
food safety or increasing shelf life.
2. A second major area of research involves use of
antimicrobials in combinations with each other and with
traditional or novel processing methods. To more effectively
apply antimicrobials so that synergistic activity is possible will
require knowledge of the mechanisms of action of the
compounds. Attaining synergistic activity with antimicrobial
combinations requires that the components have different
mechanisms. In addition, natural antimicrobials will be
increasingly looked on as adjuncts in hurdle technology and
used with milder nonsterilizing, nonthermal processing
methods such as high hydrostatic pressure or pulsed electric
fields

23. Strawberry dipped in
Antimicrobial film

24. Without Antimicrobial
Coating

25. With Antimicrobial Coating

26. Thank You