mikpang 6.1. pengendalian mikroba perlakuan sanitasi

8/12/2019 MIKPANG 6.1. Pengendalian Mikroba Perlakuan Sanitasi

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Department of Food Science and Technology

Bogor Agricultural University

MICROBIAL CONTROL:

CONTROL BY SANITATION

CONTROL BY HIGH TEMPERATURE

CONTROL BY LOW TEMPERATURE

Winiati P. Rahayu



Mechanism of Antimicrobial Action :

Denature proteins/ produce stress protein

Sublethally injured. Injury in :

Cell wall

DNA

Ribosomal RNA

Enzymes Dead damaged in some functional and

structural component

Bacterial spores : lose spore coat, Inability to germinate

Inability to outgrow Methods

www.accessexcellence.or

g


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Basics Steps of a Cleaning Procedure:

Pick up debris, Prerinse and wet, Wash with

cleaning agent, Rinse, Inspect, Sanitize,

Prevent recontamination.

Sanitizing: Heat, iradiation, chemicals

Chemicals are used most often in foodprocessing

facilities :

Chlorine, iodophor, quats, acid

Chlorine :Works on a broad range of microorganism,cheap, no rinsing required at 200 ppm or less, available

as liquid or granules, not affected by hard water



Ideal Sanitizer :

Destroys all types of vegetatives bacteria, yeasts, and molds

quickly

Works well in different environments (i.e., soiled surfaces, hard

water, different pHs, soap or detergent residues)

Does not irritate skin, nontoxic

Cleans well

Dissolves in waterStable as purchased (concentrate) and as used (diluted)

Easy to use

Readily available

Inexpensive

Easy to measure

No offensive odor


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Control By High Temperature

The pasteurization :

63/72 oC for 30 min/15 second (LTLT/HTST)

& Ultra, exp: 140oC for 0.01 second

Canned foods are sometimes called commercially sterile to

indicate that no viable organisms can be detected by usual

cultural methods or the number of survivors is so low as to be

of no significance under the conditions of canning and storage

www.hyewonp

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mis.dost.gov.p

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Water In the presence/increases of water (humidity, moisture,

water activity), the heat resistance of microbial cells

decrease

Water allows for thermal breaking of peptide bonds.

Fat In the presence of fats, the heat resistance of some m.o.

increases.

The heat protective effect of long-chain fatty acid of

Clostridium botulinum the long-chain fatty acid are

better protectors than short-chain acids.

Factor Affecting of Heat Resistant

Salts Some salts may decrease aw, and thereby increases

heat resistancewww.t

hereefshop.com.au


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Proteins and other substances

During heating, protein have a protective effect on m.o.

pH M.o. are most resistant to heat at their optimum pH of

growth (generally about 7.0)

When pH is lowered or raised from the optimum value

increase in heat sensitivity

Carbohydrates Sugars causes an increase of heat resistance in

m.o.

The effect is at least in part due to the decrease in

aw.caused by high concentrations of sugars.uchovani.jidla.navajo.cz

www.chemistryland.com



Number of m.o.

The larger the number of m.o., the higher is the degree of heat

resistance

The mechanism of heat protection by large microbial populations

is due to the production of protective substance excreted by the

cells

Age of m.o.

Most resistant to heat while in the stationary phase of growth

(old cells) and less resistant during the logarithmic phase

Growth temperature

The heat resistance of m.o. tends to increase as the temperature

of incubation increase

A decrease in heat resistance : presence of heat-resistant

antibiotics, SO2, and other microbial inhibitors

Inhibitory compound


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Time and temperature

The longer the time of heating, the greater the

killing effect of heat

As temperature increases, time necessary to

achieve the same effect decreases

Effect of ultrasonics

The exposure of bacterial endospores to ultrasonic

treatments just before or during heating result in a

lower heat resistance of spores

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hetipsbank.com



Psychrophilic m.o. are the most heat sensitive, followed by

mesophiles and thermophilies

Sporeforming bacteria are more heat resistant that non-sporeformers

Thermophilic sporeformers are more heat resistant than mesophilic

sporeformers

Gram + bacteria tend to be more heat resistant than Gram -

Yeasts and molds tend to be fairly sensitive to heat

Heat Resistant of M.O

Yeasts ascospores are only slightly

more resistant than vegetative

yeasts

The asexual spores of molds tend to

be slightly more heat resistant than

mold mycelia www-zis-chwww.alken-murray.com


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Thermal death time

Thermal death time (TDT) is the time necessary to kill agiven number of organisms at a specified temperature

Dvalue

D value is decimal reduction time or the

time required to destroy 90% of the m.o.

This value is equal to the reciprocal of the slove ofthe survivor curve an is a measure of the death rate

of an organism

Thermal Destruction of M.O

www.hyewonpack.com



5 10 15 20 25 30

10

100

1000

570

340

65

19

4.5

1.3

D240=8

(1.250)

01

Survivors(logscale)

Time of heating (min)

Rate of destruction

curve. Spores of

strain F.S. 7 heated at

240

o

F in canned peabrine pH 6.2.

Thermal death time curve

F value This value is the equivalent time, in minute, at

250oF of all heat considered


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zvalue

D

values,minutes(logscale)

oF220 230 240 250 260

10

100113

31

8

2.3

0.65

=17.5

0

1

mis.dost.gov.ph

www.retort.com.tw.jpg



12- D concept

The 12-D concept refers to the process lethality

requirement in the canning industry and implies that the

minimum heat process should reduce the probability of

survival of the most resistant C, botulinumsporesIf D = 3 minutes

12 D = 36 minutes

This concept is observed only for foodsabove pH 4,6

If it is assumed that each container of food

contain only one spore of C. botulinum, F0

may be calculated by use of the general

survivor curve equationwww.jamesfood.com


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Examples

Z = 17.5

140oF in 3.5 minutes

157.5oF in 0.35 minutes

122.5oF in 35 minutes

F0 = Dr(log alog b)

F0

= 0.21 (log 1log 1012)

F0 = 0.21 X 12 = 2.52

For high acid = 5 D

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Control by Low Temperature


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Foodborne m.o. grow slowly at temperature above

freezing and generally stop at subfreezing temperatures

The rate of enzyme catalyzed is dependent ontemperature

The temperature coefficient (Q10) may be generally

defined as follows :

(Velocity at a given temp. + 10oC)

Velocity at T

Q10 =

The Q10for most biological system is 1.5-2.5Temperature is effect to RH, pH, other parameters of

microbial growth



There are three distinct temperature ranges for low-

temperature stored foods

1. Chilling : between refrigerator (5-7oC) and

ambient 10-15oC temperature

2. Refrigerator temperatures : between 0-7oC

3. Freezer temperatures : at or below18oC

www.personal.psu.edu www.otawa.ca


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Bacterial species and strains can grow at or below

7oC, Growth at temperatures < 0oC is more likely for

yeasts and molds than bacteria.

Bacteria have been reported to grow at20oC and

around12oC.

The lowest recorded temperature of growth for m.o. of

concern in food is34oC (pink yeast).

Foods that are likely to support microbial growth at

subzero temperatures include fruit juice concentrates,

bacon, ice cream, and certain fruits. These products

contain cryoprotectants that depress the freezing point

of water.

Need blancing before freezingwww-global_b2b_network-

com

www.denniskunkel.com



Effect of Freezing on Microorganisms

There is a sudden mortality immediately on freezing,

varying with species

The proportion of cells surviving after freezing die

gradually when stored in the frozen state

This decline in numbers is relatively rapid at

temperatures just below the freezing point, especially

about2oC, but less so at lower temperatures, and it is

usually slow below20oC

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At temperatures -2oC, water different types of

bacteria, molds, and yeasts can grow in a foodbut the lag and exponential phases become longer

Cells of some mesophiles and thermophiles can :

Sublethally injured

Die if the temperature drops below 4.5oC

The rate of freezing and the lowest temperature

of freezing dictate the extent of microbial damage

from ice crystal



On freezing and thawing :

Microbial cell are found to suffer sublethal (repairable)

injury

Cell wall and cell membrane are injured

DNA strand break

Ribosomal RNA degradation

Inactivation/activation of some enzymes

Sublethally injured cell : injuries of structural and

functional are reversible

Lethally/dead cell : irreversible


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Nature of Microorganisms

Some m.o. are capable of growing as low as10oC.

Many mesophilic and thermophilic bacterial cells can

be sublethally injured and many die with time at low

temperature above freezing.

Vegetative cells of m.o. can sustain sublethal injury

and die at temperatures below10oC.

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