Chapter 1 & 2, Food Microbiology

8/13/2019 Chapter 1 & 2, Food Microbiology

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CHAPTER 1

INTRODUCTION OF FOOD MICROBIOLOGY

Food supply consists basically of plants and animals or

product derived from them, it is understandable that our food

supply can contain microorganism in interaction with food.

These microorganisms use food supply as a source of

nutrients for their own growth. These will cause 2

possibilities:

Either Result in deterioration of food !spoil"#

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These interactions between microorganisms and food

give beneficial to human

How microorganisms can caus !"riora"ion o# "$ #oo!%

%hen they utili&e the nutrients of the food, it involved

changes in the food compound li'e synthesis a new compound

that cause spoiling of the food or produced en&ymatic changes

and contributing off(flavours by mean of brea'down of

product.


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s a food biological preservative by using antimicrobial

metabolites ta'en from certain microorganisms in order to

control pathogenic and spoilage microorganisms in foods#.

Pro(io"ics

s a concentrated supplement of beneficial live cells of

bacteria friendly bacteria# culture ta'en orally intended to

improve our health by promoting our bodys natural immunity

and improving digestion system.

BAD +UNDE.IRABLE-

Foo!(orn !isas

s a disease cause by consumption of contaminate during

various stage of handling between production and

consumption by many pathogenic microorganisms bacteria,

molds and viruses#.

Foo! s&oi,ag

s a condition of contaminate food due to:

/rowth of microorganisms in food

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The action of microbial heat stable en&ymes

)icroorganisms used food supply as a source of nutrients by

their own growth.


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0poilage leads to wastage of food and economic loss.

PROBIOTIC.

1efinition:

+robiotic is a concentrated supplements of beneficial live bacteria

culture ta'en orally intended to improve our health. t is a friendly

bacteria which play vital role in 'eeping us fit and healthy.

+robiotics means !for life"

The good friendly bacteria are good because they promote the

bodys natural to 'eep our body fit and to help our digestion.

dvantages

3. -y increasing the absorption of mineral and vitamins and it

also can improve digestion system especially of mil' product.

n our food, only vitamins that properly absorbed and digested

are useful. +robiotics also improve lactose intolerance.

2. Ta'ing probiotics can support out immune system which is

fight bad bacteria and infection in 'eeping s cope from being

run down. t produced antimicrobial substances that can deter

various bad bacteria. t is so important because many of the

disease begin in the intestinal tract.

4. +roduced specific protein that act as antigen and stimulates

the immune system.


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5. ncrease the absorption of calcium, important mineral in the

prevention of osteoporosis.

6. +reventing intestinal tract infections that are cause by

Candida spp. andHelicobacter pylori.

7. 8ormalising bowel elimination problems and promoting

regularity.

9. lean the colon and improve constipation.

;. Fights pathologicals moulds, yeast, fungu, viruses, parasites

and bacteria.

lymphoctes and related antibody production.

3?. 0upporting healthy liver function.

33. lleviating bowil wind, bloating and bleaching.

32. ssisting in cholesterol management.

The e@ample of probiotics in food

)il'( baby mil' nowadays is added withLactobacillus acidophilus

andBifidusbacteria.

Aogurt( rich with live bacteria culture such asLactobacillus

bulgaricus and Streptococcus thermophillus.

heese( friendly bacteria that is added in cheese isLactobacillus.

-uttermil'(Lactobacillus bulgaris


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0ide effect of probiotics to human

Even though probiotic are beneficial bacteria, sometimes it can

cause indirect or long term side effect especially if ta'en

inappropriately.

Factors that can produce side effect:

a# +robiotics supplement in food are not safe or not wor'ing

inside the body.

b# +roduct that has been ta'en food# did not deliver probiotics

to specific area to perform its function.

c# 8ot all probiotics product in mar'et today are created

sufficiently enough for body necessity. 0ome of them are over

concentrated and some are less than minimal reBuirement.

0ide effect that occurs include:

a# E@cessive drainage syndromes.

b# Ceadache.

c# 1iarrhea.

d# -loating.

e# onstipation.

f# +roduction of intestinal gas.

-acteria in the intestine

The variable and greatest number of bacteria lives in large intestine.

Lactobacillus acidophilus guard small intestine.

Bifidobacterprotect large intestine.


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Lactobacillus bulgarium is a travelling transient bacteria that aids

the two it bases through our body.

CHAPTER 2

CHARACTERI.TIC. OF PREDOMINANT

MICROORGANI.M IN FOOD

Mo&$o,og) an! s"ruc"ur o# microorganisms

a- Mou,!s

Eucaryotics cellsD

)ulticellular

8on motile, filamentous and branched

ompose of large numbers of filaments called hyphae

which are aggregated and called mycelium

Reproduction occurs from spore formation

Eg:penicllium spp

(- Yas"s

Eu'aryotic cellsD

*nicellular

$val, spherical or elongated

8on motile, can see budding formationEg: Sacchromyces cerevisiae

Eu'aryotic cellsD ( generally are:

arger cells 2? to 3??m#

ells have rigid cell walls and thin plasma membrane


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ytoplasm contains organelles such as mitochondria and

vacuoles

c- Bac"ria

+ro'aryotic cells

*nicellular

Three morphology forms:

0pherical cocci# eg:streptococcus spp

-acilli rod# ( eg: bacillus spp

urved coma# eg:

an be motile or non motile

The cytoplasmic materials are enclosed in a rigid wall on the

surface and a membrane beneath the wall

The organelle does not enclosed in a separate membrane

-acterial are grouped as:

/ram negative G contain outer membrane which is compose

of lipopolysaccharides due to many

en&ymes, antibiotics, salts, etc#

/ram positive G have thic' wall composed of several layers of

mucopeptide and teicnoic acids

!- 3iruss

8on cellular entities

)ost important: bacteriphages bacterial viruses#

Hirus contain nucleic acid 18 and R8# and protein


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FOOD .POILAGE

3. 8TR$1*T$8

Food spoilage can be defined as any changes in the

visual, smell and te@ture of food that ma'es it

unacceptable for consumption.

)ost serious economic problem in food processing

industry.

Foods are subIect to attac' by microorganisms in a

variety of ways. 0uch attac' is harmful to the Buality of

food.

Foods are organic substance and hence provide adeBuatenutrients for the growth of wide varieties of microbes.

The physical and chemical characteristics of food and

how it is stored determine the susceptibility to microbial

attac'.

0poilage may be due to one of the following:

a. /rowth and activity of microorganisms.

b. nsects.

c. ction of en&ymes to the plant and animal food.

d. hemical reactions.

e. +hysical changes free&ing, burning, drying,


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pressure#

2. TA+E $F F$$1 0+$/E

a. +hysical spoilage

1ehydration of vegetable

b. hemical spoilage

$@idation of fat

-rowning of fruits and vegetables

c. )icrobial spoilage

/rowth of microorganisms

En&yme production

4. RTER J +R)ETER0 00$TE1 %TC F$$1

0+$/E

$dour

Te@ture

0hape

Formation of slime

olour

Flavour /as production


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5. 0EK*E8E $F EHE8T0 8 F$$1 0+$/E

)icroorganisms have to get into the food

from a source or more

LFood environment should favour

the growth of microbes

LFood need to be stored under the growth

condition for a sufficient length of time:

To allow sufficient number necessary to cause

spoilage or changes in food. To allow the produced en&yme to spoil the food.

6. C$% 0+$/E $F F$$1 0 1$8E -A

)R$$R/80)0M

These microorganisms use the food as their source of nutrients

for growth. -y increasing their numbers, utili&ing nutrients,producing en&ymatic changes and contributing off flavours by

means of brea'down of a product or synthesis of new

compoundsN microorganisms can spoil the food.


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7. %CA 1$E0 A$*R F$$1 $8T8 )R$$R/80)0M

The interaction between microorganisms, plant and

animal are natural and constant. The food supply

consists basically of plants and animals and products

derived from themN it is understandable that our food can

contain microorganism in interaction with the food.

Food are derived from the soil directly or indirectly#

which is the habitat for most microorganisms.

)icroorganisms can also originated from e@posure to

air, water or from natural microflora present in food as

commensals.

9. 00FT$8 $F F$$1

+erishability is a function of moisture content w#.

0table food are those with low moisture content

low w# whereas unstable foods have high water

contenthigh w#

To avoid any spoilage, food must be stored under

condition that microbial growth is slow or do not occur

at all.


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Foods can be classified into three groups based on ease

of spoilage:

. 0table or non perishable foods.

Foods which do not spoil unless handle carelessly.

E@ample: 0ugar, flour and dry beans.

. 0emi perishable foods.

f these foods are properly handled and stored, they

will remain unspoiled for a fairly long period.E@amples: potatoes, apples and nuts.

. +erishable foods.

This group includes most of our important daily

foods that spoil readily unless special preservative

methods are used. E@amples: meats, fish, mil',

vegetables, eggs and etc.


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IMPORTANT MICROORGANI.M. IN FOOD

. )+$RT8T )$1 /E8ER

3. /enusAspergillus

%idely distributed and contain many species

important in food.

0eptate hyphae and produce ase@ual spores on

conidia.

OerophilicN causing spolage in grains, Iams, nuts

and vegetable.

E@ample:Aspergillus flavusproduce alfato@in a

'ind of mycoto@in#

0trains used in food processing:

i. A.oryzae : hydroly&e starch in sa'e

production.

ii. A.niger : citric acid production.

2. /enus Geotrichum

0eptate hyphae and produce arthrospore.


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/row and forming a yeastli'e cottony, creamy

colony.

$ften grow on dairy products. E@ample:

Geotrichum candidum

4. /enusMucor

%idely distributed

8onseptate hyphae and produce sporangiophores

0ome species are used in food fermentation and

others can cause spoilage of vegetables e.g:Mucor

rouii

5. /enus!hizophus

Cyphae are aseptate and form sporangiophores

ommon in spoilage of foods and vegetables

!hizophus stolonifer : common blac' bread mould

6. /enuspenicillium

%idely distributed and contain many species


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0eptate hyphae and form conidiophores on a

brushli'e conidia head.penicillium ro"uerfortii and

#enicillium camembertii are used in cheese

production.

0ome species can cause spoilage in fruits,

vegetables, grains, bread etc.

The can also produce mycoto@in

-. )+$RT8T AE0T /E8ER

3. /enussaccharomyces

ells may be round, ovate, and elongated.

Reproduction is by budding or by acospore formation.

S.cerevisiae is employed in many food industries

e.g bread manufacturing, wines, alcohol etc.

S.fragilis ands.lactis is important in mil' and mil'

products because they are common spoilage

microorganism.

2. /enus $orulopsis

/eneral spoilage yeast.


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0poils a variety of food products e.g.: beer, mil'

products, fruit Iuices and some refrigerated foods.

4. /enus Candida

)any spoil foods with high acid, salt and sugar form

pellicle on the surface of liBuids.

0ome can cause rancidity in butter and dairy products

e.g: Candida lipolytica.

an form pseudohyphae or true hyphae with many

budding cells.

5. /enus!hodotorula

Red, pin' or yellow yeasts may caused

discolourations on food such as in meat, fish and

sauer'raut.


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6. /enus#ichia

$val or cylindrical yeasts may form pseudomycelia.

scospores are round or hat shaped.

Form pellicle in beer, wine and brine.

. )+$RT8T -TER /E8ER

3. /enusBacillus

1ifferent species may be mesophilic or thermophilic,

lipolytic or proteolytic.

0pores produce by this bacteria are generally heat(resistant.

0ome species may cause foodborne diseases

Bacillus cereus# and food spoilage in canned

products Bacillus coagulans andBacillus

stearothermophillus#

The soil is an important source of this species.

2. /enus Clostridium

Rod shaped cells, anaerobic and form endospores.


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Found in soil, marine sediments, animal and plant

products.

0ome are pathogens e.g.: Clostridium botulinum andClostridium perfingens while others are important in

food spoilage.

C.perfingens cause stormy fermentation in foods

disruption of curd in mil'#

4. /enus%scherichia

Found in faces, gram negative rod isolated from the

intestinal tract of warm blooded animals.

E.g. %scherichia coliused as an indicator of

sanitation in the coliform and fecal coliform group.

)any strains are non(pathogenic but some can be

pathogenic to humans and animals foodborne

disease#.

5. /enusLactobacillus

Rod shaped facultative anaerobic, non(motile,

mesophilic.

an be homo or heterolactic fermentors.


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Found in plant sources, mil', meat and feces.

*sage:

i. Food bioprocessing:L. bulgaricus&

L. lactis.ii. +robiotics:L. acidophilus

0poilage:

i. %ine or beer production.

ii. heese ma'ing.

iii. an survive pasteuri&ation.

6. /enus#seudomonas

/ram negative, aerobic, rod shaped, motile.

mportant in fish and meat spoilage.

E.g:#.aeruginosa and#.fluorescens.

7. /enus Staphylococcus

S. aureusare freBuently involved in foodborne

diseases.

t usually gives yellow to orange growth.

)any beta haemolytic, coagulase positive strains are

pathogenic and produce enteroto@in which causes

food poisoning.


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9. /enus Streptococcus

Streptococcus pyogenes 'important in foodbornediseases. cause of human septic sore throat, scarlet

fever. an be found in raw mil'.

Strep. $hermophillus is important in cheese ma'ing

and yogurt.

1. GRUOP. OF BACTERIA IMPORTANT IN FOOD

BACTERIOLOGY

3. actic cid -acteria

2. cetic cid -acteria

4. -utyric cid -acteria

5. +ropionic cid -acteria

6. +roteolytic cid -acteria

7. ipolytic cid -acteria

9. 0accharolytic -acteria

;. Thermophilic and Thermoduric -acteria


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4. Fecal coliform and coliform group

1efinition: 0hort rods, aerobic or facultative

anaerobes, gram negative, non(spore forming bacteriawhich ferment lactose with gas forming.

)aIor genera:%scherichia& %nterobacter

The fecal coliform groups includes coliforms capable

of growth at an elevated temperature 55.6P#

mucor


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geotrichum

nuros&ora +moni,ia#


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r$i4o&us

as&rgi,,us

Documents

Chapter 1 & 2, Food Microbiology