1 Importance of Microbes in Foods

8/6/2019 1 Importance of Microbes in Foods

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FOOD MICROBIOLOGY

AND BIOTECHNOLOGY

Microbial Ecology of

Foods



Foods

LEARNING OBJECTIVESLEARNING OBJECTIVES

Microbial ecology of foods:

1.Importance of microbes in foods

2.Intrinsic factors affecting microbialgrowth

3.Microbial growth, death andsurvival in foods: meat, poultry,seafood's, dairy Products, fruits,

vegetable and grains



Importance of microbes infoods



FOOD MICROBIOLOGY

• The study of the microorganisms which

inhabit, create or contaminate food.

– It is a sub-discipline of food science.

– It encompasses the areas of food safety,food spoilage (food preservation), andfood fermentation.



FOOD MICROBIOLOGY

FOOD

SCIENCE

FoodMicrobiology

Food Safety

Food

Spoilage/Preservation

Food

Fermentation

Food

Engineering/Food Processing

Food

Chemistry





PRIMARY SOURCES OF MICROBES IN



PRIMARY SOURCES OF MICROBES INFOODS

•Microorganisms get in food

from both natural and external sources.

–Internal tissues of healthy plants(fruits and vegetables) andanimal (meat) are essentially

sterile and are not generallysources of microorganisms





•Natural Plant Sources:

– Surface of fruits, vegetables and grains– Damaged tissues and pores of some tubers

•Natural Animal Sources:

– Skin

– Hair

– Feathers

– Gastrointestinal tract

–Urinogenital tract

–Respiratory tract –Milk ducts





•External sources

–Air

–Soil

–Sewage

–Water

–Feeds

–Humans/other animals

–Food ingredients

–Equipment/Utensils

–Packaging

–Insects



Sewage

Seafood'sFood

Ingredients

Vegetables

Fruits

Manure

Soil

Meat AnimalsPoultry

Dairy Cows

Humans

Processing

Plant

PRODUCT

CONTAMINATION

g.

CONTAMINATION



MICROBES IN FOODS

• The microbial flora of food therefore

consists of:– The microorganisms associated with theraw materials;

–Microorganisms introduced duringharvesting, handling and processing;and

–Microorganisms surviving any

preservation treatment and storage.



Sources

ManRaw foods

Insects

Animals

Rodents

Environment

Dust

Soil

Refuse

R e a d

y-T o-

E at

F

o o d

MobileVehicles

Hands

Equipment

Cloths

Stationary

VehiclesFood orhandcontact

surfaces





Microorganisms can be both

beneficial and harmful tohumans.

IMPACT OF MICROORGANISMSIMPACT OF MICROORGANISMS

We tend to emphasize

harmful microorganisms(infectious diseaseagents, or pathogens),

but many moremicroorganisms in natureare beneficial than are



MICROBES IN FOODS

• The major concern of microbial presence in

food is due to undesirable properties. Mostare able to spoil foods and several arepathogenic.

• However there are others that have beneficialproperties:

– in food production,

– maintaining normal health of the gastrointestinaltract of humans; and

– controlling spoilage and pathogenic bacteria infood (Biopreservation)



The Good



FOOD PRODUCTION

• When certain microorganisms grow in foods, they

produce desirable flavors and textures, andmay also inhibit pathogenic organisms.

• Fermentation can make food more nutritious,tastier or easier to digest.

• It can also enhance food safety because it helps topreserve food and increase its shelf life, reducingthe need for refrigeration or other energy intensivepreservation methods.



• Several thousands of fermented products are

produced worldwide by natural or controlledfermentation of milk, meat, fish, eggs, fruits,vegetables and others.

• There are four categories of fermented foods– fermented meat products – sausages

– fermented diary products – yogurt, cheese

– fermented vegetable and fruit products– pickles, sauerkraut, soy sauce

– fermented beverages – wines, beer, rum

FOOD PRODUCTION



•Most fermentation bacteria belong to the

genera Streptococcus, Lactobacillus,Leuconostoc, Pediococcus, or Micrococcus.

• They preserve food by converting thesugars needed by competingmicrobes to lactic acid and other acids,which inhibits the growth of some

organisms

FOOD PRODUCTION



FOOD PRODUCTION

• Acetobacter and Gluconobacter are

used in the production of vinegar.

• Yeasts, usually Saccharomyces, is

used to produce ethanol and CO2, andin the processes of brewing and baking



•Food supplements that benefit

from the effects of microorganisms include:

•Vitamins–Vitamins have major usage as food

and feed supplements. Due to theircomplex nature, two are producedby microorganisms- vitamin B12 and

riboflavin

FOOD SUPPLEMENTS



•Amino Acids (glutamic acid, aspartic acid)

– The most important amino acids producedcommercially are glutamic acid, asparticacid, phenylalanine, and lysine

–Aspartic acid and phenylalanine are theingredients of the artificial sweeteneraspartame, a non-nutritive sweetener of dietsoft drinks and other foods sold as low-calorie

or sugar-free products

FOOD SUPPLEMENTS



•Probiotics are products containing living

microorganisms, which on ingestion incertain numbers exert health benefitsbeyond inherent general nutrition

•For example active Yogurt may containLactobacillus bulgaricus, Lactobacillusdelbrueckii , Lactococcus thermophilus,

and/or Streptococcus thermophilus

BENEFICIAL BACTERIA - GI TRACT



• Probiotics benefit the GI tract by:

– Providing protection against entericpathogens•normal metabolism creates unfavorable

conditions for pathogens e.g. acid production,competition for nutrients)

– Supplying enzymes to help metabolize foods•lactase

– Detoxify harmful food components and

metabolites that can cause cancers– Stimulate the intestinal immune systems

– Improve intestinal peristaltic activity.

BENEFICIAL BACTERIA - GI TRACT



•Food-grade bacteria and yeasts

produce different antimicrobialcompounds, such as:

– organic acids,

– diacetyl,

– H2O

2,

– reuterin,– bacteriocins,

– enzymes

BIOPRESERVATION



• These compounds may have

bacteriostatic, bacteriocidal,fungistatic and fungicidal actionagainst organisms involved in foodspoilage and food-borne disease.

•Because they are from safemicroorganisms they can be usedas food biopreservatives.

BIOPRESERVATION

AGRICULTUREAGRICULTURE



Microorganisms are important in

the agricultural industry:

•Biological control and bioinsecticides

– The control of an agricultural pest(insect) or disease causing organism by

a microorganism or microbial toxin toprevent infection of a plant

•Vaccines





•Fertility of soil and symbiotic

associations with plants– Mycorrhizaea, a fungus-plant root

association


– Rhizobium (nitrogenfixation) •Bacteria in nodules on roots,

convert atmospheric nitrogen

into fixed nitrogen that theplants use for growth. Theactivities of the bacteriareduce the need for costly andpolluting plant fertilizer.




• Ruminant Animals

– Important in farm animals that have a rumen, in whichmicroorganisms are responsible for carrying out thedigestion process. Without them these animals couldnot survive on nutrient poor food like hay and grass.


• Cycling of nutrients– Responsible for the cycling

of important nutrients likecarbon, nitrogen andsulphur



The Bad

THE BAD



THE BAD

•Most food-related illnesses have historically been

attributed to one of five major groups of pathogenic bacteria:

1. Salmonella and Shigella

2. Clostridiumbotulinum

3. Clostridium perfringens• These have been joined by theemerging pathogens: Yersinia

enterocolitica, Escherichia coli, Listeria

monocytogens, and Campylobacter jejuni.

4. Bacillus cereus5. Staphylococcus

aureus.

THE BAD



THE BAD

•Viruses do not reproduce in foods and are

not competitors in this sense (the food actsonly as a carrier).

• Yeasts and molds usually grow moreslowly than bacteria and are rarely aproblem in foods that support bacterialgrowth. If allowed to grow howeverthey will cause food spoilage.



WHAT DO YOU THINK ?

incidence of foodborneillness from 1970’s till now

Generally Trending UPOr

Generally Trending Down

Or

Holding Steady

FOODBORNE ILLNESSES NOT REDUCEDFOODBORNE ILLNESSES NOT REDUCED



Foodborne & waterborne

diseases are still a majorcause of death in manydeveloping countries and

developed.


Incidence of foodbornediseases inVenezuela(From CDC)

FOODBORNE ILLNESSES IN U S AFOODBORNE ILLNESSES IN U S A



FOODBORNE ILLNESSES IN U.S.A.FOODBORNE ILLNESSES IN U.S.A.

FOODBORNE ILLNESSES IN CANADAFOODBORNE ILLNESSES IN CANADA



FOODBORNE ILLNESSES IN CANADAFOODBORNE ILLNESSES IN CANADA

FOODBORNE ILLNESSES IN AUSFOODBORNE ILLNESSES IN AUS



FOODBORNE ILLNESSES IN AUS.FOODBORNE ILLNESSES IN AUS.







•One would expect the incidence

to be significantly lower due to:

increased public awareness of bacterial food-borne illnesses,

regulations and technologiesgeared towards food safety

increased sanitation.





•Food-borne illness is not being reduced

because of the following:1.Controlled food processing is oftenpreceded by relatively uncontrolled food

production and followed by mishandling in distribution or sale or in thepurchaser’s kitchen.





2. Increased volumes of

products from a singlemanufacturing source throughwider distribution networks and

increased mass cateringmay all lead to more massivecontamination and bigger

food-borne outbreaks.





3. Canning, which generally kills

pathogens, has been partiallyreplaced by freezing which maypreserve them, resulting in larger

numbers of viable organisms in thefood supply.

4. The worldwide distribution of food, serves unintentionally tospread food-borne microbes.





5. In underdeveloped countries where

foods are especially prone totemperature abuse, the growingreliance on pre-processed and

street vended meals, enhancesthe chance of infection similarly increased consumer preference

in industrialized nations forfresh undercooked, or rawfoods has the same effect.





6. There is a lag (often due to expense andprocedural delay) in transferring newtesting technologies into the regulatorychain.

7.Animal husbandry has been markedlymore intensive over the years. As a resultmicrobes can spread more easily fromanimal to animal and a higher proportion

becomes asymptomatic carriers of human enteric pathogens.





8.Finally the public is still notsufficiently informed orconcerned to be able to

distinguish bad from goodpractices in the food industryand particularly in catering.

COST OF FOODBORNE ILLNESSESCOST OF FOODBORNE ILLNESSES



•Every year there are about

–76 million foodborne illnesses inthe US (26,000 /100,000 inhabitants)

–2 million in the United Kingdom(3,400/100,000 inhabitants)

–750,000 in France (1,210 /100,000inhabitants).

COST OF FOODBORNE ILLNESSESCOST OF FOODBORNE ILLNESSES

COST OF FOODBORNE DISEASESCOST OF FOODBORNE DISEASES



COST OF FOODBORNE DISEASESCOST OF FOODBORNE DISEASES

• CDC estimates that in 2000 foodborne diseases

cause– 76 million illnesses,

– 325,000 hospitalizations,

– 5,000 deaths each year.,

• USD estimate the costs associated with five majorbacterial foodborne pathogens to be $6.9 billion.

• FDA 2005 estimates the cost of foodborne illness is

$10–$83 billion annually.”

•Foodborne illness cause largemedical and financial burdens.

Th U l



The Ugly



FOOD SPOILAGE



FOOD SPOILAGE

•With an increasing world

population there is increasesignificance on food spoilage

which with some produce andsome countries could reach25% or more.

PREVALENCE OF UNDERNOURISHMENT



% total population

Country groups1990-1992 1995-1997 2000-2002 2004-2006

Developing Regions 20 18 17 16

Sub-Saharan Africa 32 32 30 28

Latin America and theCaribbean

12 11 9 8

Eastern Asia 15 12 10 10

Eastern Asia (without China)

8 12 13 12

Southern Asia 24 21 21 22

Southern Asia (without India)

24 25 22 22

South-Eastern Asia 24 18 18 15

Western Asia 6 9 8 8

WORLD 16 14 14 13

PREVALENCE OF UNDERNOURISHMENT

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1 Importance of Microbes in Foods

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