Dr. Sudarshan Rao

7/27/2019 Dr. Sudarshan Rao

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Microbiological criterion and value ofsampling

Dr. V. Sudershan Rao

National Institute of Nutrition ICMR

Hyderabad


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Microbiolo ical CriteriaMicrobiolo ical CriteriaA microbiological criterion defines the limit above which aA microbiological criterion defines the limit above which afood is considered to be contaminated at an unacceptablefood is considered to be contaminated at an unacceptableeve w t a m croeve w t a m cro--organ sm, ts tox n or meta o te an sorgan sm, ts tox n or meta o te an s

therefore considered to be unsafe for consumption.therefore considered to be unsafe for consumption.A microbiological criterion also contains the followingA microbiological criterion also contains the followingcomponen s:componen s:

the sampling plan (the number of samples of a food that the sampling plan (the number of samples of a food thats ou e ta ens ou e ta en

the laboratory method (the method which should be used the laboratory method (the method which should be usedto test the food)to test the food)

the stage in the food chain where the criterion applies the stage in the food chain where the criterion applies the corrective action to be taken when the criterion is not the corrective action to be taken when the criterion is notmet (the action to be taken when there are unsatisfactorymet (the action to be taken when there are unsatisfactoryresults).results).


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ProcessProcess hygienehygiene criteriacriteria:: TheseThese criteriacriteria indicateindicate if if thetheproductionproduction processprocess isis operatingoperating inin aa hygienichygienic mannermanner.. TheyThey areareapplicableapplicable toto foodstuffsfoodstuffs atat variousvarious stagesstages throughoutthroughout theirtheirproductionproduction processesprocesses..

FoodFood safetsafet criteriacriteria:: TheseThese criteriacriteria definedefine thethe acce tabilitacce tabilit of of aafoodfood inin termsterms ofof itsits microbiologicalmicrobiological safetysafety.. TheyThey areare applicableapplicabletoto foodfood placedplaced onon thethe marketmarket andand throughoutthroughout thethe shelfshelf--lifelife ofofthethe foodfood..


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Microbiological criterion under Indian regulations

Canned meat &meat roducts 2002Total Plate Count 1000cfu/g

E. coli 0/25g

Staph aureus 0/25gClostridum botulinum 0/25g

Clostridium perfringens 0/25g

Frozen mutton, goat, beef &buffalo meat (2002)

Total Plate Count 1,00,000cfu/g

Salmonella 0/25g

E. coli 100cfu/g

Staph aureus 100cfu/g

ostri um otu inum c u g

Clostridium perfringens 30cfu/g


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Microbiological criterion under Indian

u

Spices(2006)

Salmonella 0cfu/25gFrozen prawns, Raw (2005)

Total Plate count Not more than 5,00,000 cfu/g

E. coli ot more than 20 cfu/

Staph aureus Not more than 100 cfu/g

Shigella 0 cfu/25g

Vibro cholerae 0 cfu/25g

Vibro parahaemolyticus 0 cfu/25g


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Frozen prawns, Cooked (2005)

, ,E. coli 0 cfu/25g

Staph aureus 0 cfu/25g

Salmonella 0 cfu/25g

Shigella 0 cfu/25g

Vibro cholerae 0 cfu/25

Vibro parahaemolyticus 0 cfu/25g

,

Fruit beverages (2005)

ota p ate ount ot more t an c u mYeast and Mould count Not more than 2cfu/ml

Coliform 0/100ml


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Yoghurt/Dahi(2006)

Total Plate Count Not more than 10,00,000cfu/g

Coliform Not more than 10cfu/g

E. coli 0cfu/gSalmonella 0cfu/25g

Shigella 0cfu/25g

Yeast & mould Not more than 100cfu/g

naero c pore coun c u g

Listeria monocytogens 0cfu/g


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Components of Microbiological Criteria as per

Codex1. A statement of the organisms of concern and /or their toxins

.

3. A sampling plan, when and where sampling to be taken

4. M cro a m ts cons ere appropr ate to t e oo

5. The number of sample units that should conform to theses limits

What is sampling plan?

It is a statement of the criteria applied to a lot based on appropriate

methods. It should have a sampling procedure and decision

criteria.


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USFDA refusals on account of presence of

Salmonella

AugustAugust 77

JulyJuly 2626

JuneJune 2424MayMay 99

AprilApril 1717

MarchMarch 1515


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False negative at the time of shipping and positive

Could it be due to

- error n samp ng

- Improper laboratory methods used ?

Impact

- Food safety objective is defeated

- Economic loss to the countr

- Effect on the image of the country


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A well designed sampling plan

can define the robabilit of detectin

microorganism in lot

particular organism


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Choice of plan to should take into account

1.Risks to ublic health associated with hazard

. uscep y o e arge group o consumers

3.Heterogeneity of distribution of micro

organisms when variable plans are employed


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Decision Tree for Sampling plan

Organism of Concern

Presence or absence tests No

Yes Measure y count

-

-

No Acce t the resence of this or anism?

Yes

C= 0 C> 0


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Essential elements of sampling plan

1.The microbe or rou of microbes of concern or interest2. Number of samples tested (n)

.

4. Microbiological limit (s),

. Accepta e (< m)

. Marginally acceptable (>m andM)

5. Number of samples which fall into each category of

microbiological limits( ie acceptable /marginal/unacceptable)

plan


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Types of Sampling

Two class attributes plan

One limit

Two attributes Less than or equivalent

More than the limit

Three class attributes plan

Three attributes Less than or equivalent GMP limit

ore an u ess an azar ous m

More than hazardous limits


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Too Big: Too small:

Requires Wont do

too many

resources


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Binomial probability of detecting defective units with

defectives

Probability of detecting defective units

No of samplesNo of samples

testedtested

00 11 22

55 0.860.86 0.1330.133 0.0080.008

1010 0.740.74 0.2280.228 0.0320.032

2020 0.540.54 0.3360.336 0.0990.099

5050 0.220.22 0.3370.337 0.2560.256


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Calculation of sample number based on expected levels of

Binomial distribution: CI 95%, RP=20%

15%15% 544544

25%25% 288288

35%35% 178178

40%40% 144144

45%45% 117117

50%50% 9696


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Ref: Dahms S, Mitt.Lebensm, Hyg, 95, 32-44 (2004)


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Ref: Dahms S, Mitt.Lebensm, Hyg, 95, 32-44 (2004)


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Sampling Plan for Salmonella (USFDA)

Food Cate or I :- This includes the foods that would not normall besubjected to a process lethal to Salmonella between the time of samplingand consumption. they are intended for consumption by the aged, the infirm,and infants.

Food Category II :- This includes the foods that would not normally besubjected to a process lethal to Salmonella between the time of sampling

Food Category III :- Food that would normally be subjected to a process

lethal to salmonella between the time of sampling and consumption

Sam le size Cate or I 60 units

Category II 30 units


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Category I &II All High risk foods, nuts and nut products, oils,

coffee-tea candies and prepared salads

Cate or III Processed rains , fresh ve etables, ve etable

oils and food additives


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a mone a n ee

n=20 c=0 m=0

All the samples must be negative

If one sam le is ositive, entire lot is re ected

To make more effective sampling plan increase the

number


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Sampling Plans

Microbiological limit in foods

nn cc mm MM

APCAPC 55 33 1010 1010

S.aureusS.aureus 55 11 101022 101044

E.coliE.coli 55 22 1010 101022

SalmonellaSalmonella 1010 00 00 00


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Market samples of Poultry products in Hyderabad

FoodFood nn 101066 101044 101022

Levels ofStaphylococcus aureus contamination

ChickenChickenfried ricefried rice

9494 88 22 77

ChickenChicken

noodlesnoodles

9494 1212 33 55

eve s o a mone a con am na on

FoodFood nn 101066 101044 101022

ChickenChicken

fried ricefried rice

9494 00 00 00

ChickenChicken

noodlesnoodles

9494 11 00 00


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Plan stringency in relation to degree of health hazard and

conditions of use


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Ref: Modern Food Microbiology, Seventh edition, 2005


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Example of effective use of Microbiological

criteria and sampling design of ICMSF with

HACCP

Rutgers Food Service Program

17 years experience30 million meals

1600 food samples (1983-89)

.

No foodborne illness

Ref : James Jay . Modern Food Microbiology 2005


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Thank you for your kind attention

Dr. Sudarshan Rao

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