Chapter 8: Processing Plant Hygiene Analysis

Processing Plant Hygiene Analysis

Chapter 8: Processing Plant Hygiene Analysis

INTRODUCTION ...............................................................................................................................................................

CLEANING AND SANITATION ...........................................................................................................................................

SEVEN BASIC STEPS OF CLEANING AND DISINFECTION ...................................................................................................

SAMPLING GUIDE ............................................................................................................................................................

CONTACT AND EXPOSURE PLATES...................................................................................................................................

CONTACT PLATE SAMPLING ............................................................................................................................................

EXPOSURE PLATE SAMPLING ...........................................................................................................................................

LABORATORY ANALYSIS OF CONTACT AND EXPOSURE PLATES ......................................................................................

PERSONAL HYGIENE – THE FOOD HANDLER ....................................................................................................................

HAND SWABS ...................................................................................................................................................................

LABORATORY ANALYSIS OF HAND SWABS ......................................................................................................................

WATER ANALYSIS .............................................................................................................................................................

TARGET MICROBIOLOGICAL PARAMETERS FOR TREATED WATER ..................................................................................


Poultry Processing Plant Hygiene Analysis

Introduction

Poultry meat destined for human consumption may become hazardous to the end user when the

principles of hygiene and sanitation are not met or when the foods become contaminated by

pathogens from chickens (carrier birds or evisceration contamination), from the plant

environment during processing/preparation or from workers handling the product in the plant.

These foods may then become a vehicle for the transmission of infectious disease or bacterial

toxins to the consumers. Routine monitoring of the processing plant and worker hygiene in a

laboratory, allows for the early identification of potential sources of product contamination.

Raw foods (unprocessed poultry carcases) are likely to have relatively high microbiological

counts and certain enteric pathogens may be associated with these products and the health status

of the animals involved.

× What Happens if Hygiene Standards are not Applied?

If no acceptable standards of meat hygiene are applied then the door is left wide open for a range

of direct and indirect consequences.

- Loss of quality and shelf-life of the product.

- Loss of retailer and public confidence.

- Public Health risks (food poisoning, salmonellosis, listeriosis, E.coli O157 etc) with

potential plant shutdown and / or legal action.

- Production loss due to wastage.

- Shrinking profit margins.

- Illness of personnel and consumers.

- Loss of jobs.

- No guidance for accepted protocols and standards.

☺Advantages of Proper Hygiene Programs and Standards.

- Improved quality of product.

- Improved shelf-life.

- Increased efficiency and less wastage.

- Increased public confidence and sales.

- Improved safety conditions and health standards.

- Personal satisfaction and enhanced reputation for quality.

- Increased turnover of product and sales.

- Accepted microbiological targets for which to aim.


Cleaning and Sanitation

Through the regular and routine monitoring of critical control points within the plant, the

efficacy of cleaning and sanitation can be analysed. Such a monitoring program enables early

identification of potential problem areas which could lead to product contamination. This early

warning system allows for the implementation of control measures to reduce or eliminate the

possibility of contamination.

The production management in consultation with the manufacturers of cleaning and disinfecting

agents should lay down procedures for cleaning and disinfection of the premises using the

Hazard Analysis Critical Control Point (HACCP) system and establish their own Standard

Operational Procedures for all equipment, vehicles, utensils etc.

The Seven Basic Steps of Cleaning and Disinfection

1. Removal of loose material such as meat, fat, skin and bone from equipment, walls and

floors to facilitate cleaning.

2. Loosening pieces of rubbish, blood, faecal and other contaminants by means of dry

sweeping and removing them by picking them up. Pieces of meat, fat and skin in

particular must not be swept or washed into the drainage system.

3. Pre-washing all equipment, floors and walls with clean hot water (40°-50°C) to soften

and loosen the remaining particles.

4. Washing and scrubbing with detergents and hot water under pressure.

5. Rinsing with clean hot water (45°C) under pressure in order to remove the loosened

particles.

6. Disinfecting with a suitable disinfectant at the proper concentration.

7. Microbiological survey of the equipment, working tops and walls/doors to establish the

effectiveness of the cleaning and disinfection.


Sampling Guide

All samples collected from the processing plant to evaluate surface and environmental

contamination, must be collected after cleaning and disinfection has been completed and prior to

the plant starting up. The ideal time for sample collection is in the early morning following the

cleaning/disinfection procedure the previous day/evening. This allows time for the disinfectant

to work. It is no use taking samples from wet surfaces that haven’t dried from the disinfectant

application. Sampling from cleaned and dry surfaces in the morning also enables the early

delivery of samples to the laboratory for analysis.

Contact and Exposure Plates

Figure 1 Figure 2

These 55mm diameter Rodac® contact plates are designed for the detection of surface bacterial

and fungal contamination. Contact plates are prepared by pouring Standard Plate Count Agar

(which supports the growth of bacteria and fungi) into Rodac® plates to create a convex

meniscus which then bulges above the sides of the plate (Figure 1). This plate surface can then

come into direct contact with the surface being sampled. All plates should be marked with their

production date and expiry date (Figure 2).

Figure 3

90 mm diameter exposure plates are also prepared with Standard Plate Count Agar and are

designed to monitor aerosol environmental loads of bacteria and fungi (Figure 3).


Figure 4 Figure 5

Following collection of the plates from the laboratory it is important that the cold chain is

maintained and all plates should be transported on ice in their sealed containers (Figure 4).

Plates must also be stored at 4oC (not to be frozen) and preferably remain in their sealed packets

or containers until used. If any plates appear opaque, have a ground glass texture and/or are

cracked with bubbles in the media, they should be discarded (Figure 5). To prevent plates

freezing move the plates away from the back of the fridge to a slightly warmer part eg: near the

door or turn the temperature control up slightly.

Contact Plate Sampling

Remove the lid from the Rodac® contact plate ensuring that the plate is held on its side.

Fingers must not come into contact with the media.

Check to ensure the agar has a convex meniscus (ie. the agar must bulge above the sides

of the plate), before proceeding.

Figure 6

Place the plate, agar side down, on the surface you wish to sample and apply gentle

pressure to ensure the entire surface area of the agar comes into contact with the surface

being sampled (Figure 6).


Lift the plate and replace the lid, again holding the sides to ensure there is no

contamination of the agar surface of the plate.

Seal plates with masking tape around the edges.

Figure 7 Figure 8

Clearly label each plate by completing its adhesive label, corresponding to the surface

sampled (Figure 7).

Complete the details of each plate collected on a laboratory submission form (Figure 8).

Figure 9 Figure 10

Contact plates are sealed with masking tape are then placed in a plastic bag/sleeve

(Figure 9). Plates are inverted with the agar surface facing down (√) to prevent

condensate from the lid (arrow) contaminating the agar surface (Figure 10). Plates

transported with the agar surface facing up (×) are prone to condensate wetting the agar

which interferes with laboratory analysis.


Exposure Plate Sampling

Figure 11

Remove the lid from the exposure plate, ensuring there is no contamination of the agar,

and leave it standing open for 20 minutes in the area you wish to monitor (Figure 11).

After 20 minutes, replace the lid on the plate, again holding the edge to ensure there is no

finger contamination of the agar surface of the plate.

Seal plates with masking tape.

Figure 12 Figure 13

Clearly label each plate by completing its adhesive label as to the site monitored (Figure

11).

Plates are sealed with masking tape and packed inverted with the agar surface facing

down to prevent any condensation wetting the agar surface.

Complete the details of each plate collected on a laboratory submission form (Figure 13).


Figure 14

Two or more marked “control plates” are supplied with each batch of plates (Figure 14).

These plates should be subject to the same conditions as the sampled plates but remain

unopened and returned to the laboratory with the sampled plates. These control plates

allow for the evaluation of possible contamination during plate preparation and transit to

and from the laboratory

Figure 15 Figure 16

Contact and exposure plates are taped together in stacks and inverted with agar surfaces

facing downwards. They are then placed into a plastic bag/sleeve together with the

control plates (Figure 15).

The plates are then placed in a cooler box and transported on ice at 4°C to the laboratory

(Figure 16).


Laboratory Analysis of Contact and Exposure Plates

On receipt of plates at the laboratory the ambient temperature of the sample container is recorded

to check that the cold chain has been maintained during transit. If the cold chain has been

broken increasing temperatures will favour bacterial multiplication. If rising ambient

temperature persists for a few hours, bacterial multiplication exits the lag phase and enters the

logarithmic phase with massive bacterial overgrowth.

Figure 17

Once unpacked contact and exposure plates plus the control plates are then incubated aerobically

at 37°C for 24hours after which they are read and given a bacterial scoring / count (Figure 17).

Figure 18 Figure 19

The plates are then incubated at 22°C for a further 24 hours for fungal growth (black arrows) and

a fungal score / count is then performed (Figure 18). At the same time the presence or absence

of important fungal pathogens such as Aspergillus spp are recorded (Figure 19).

The control plates are used to verify the procedure and following incubation there should be no

bacterial or fungal growth observed.


Below is an example of a count / scoring system utilized to analyze the significance of contact

plate and exposure plate bacterial / fungal growth.

Bacterial Scoring Interpretation

Score Count (CFU/plate) Interpretation

0 0 Acceptable

1 1 – 10 Acceptable – low contamination rate

2 11 - 50 Moderate contamination – Needs attention

3 >50 Unacceptable

*CFU = Colony Forming Unit

Fungal Scoring Interpretation

Score Count (CFU/plate) Interpretation

0 0 Acceptable

1 1 - 5 Acceptable – low contamination rate

2 6 - 10 Moderate contamination – Needs attention

3 >10 Unacceptable


Personal Hygiene – The Food Handler

The health of processing plant workers poses a risk for food safety. Sick food handlers may

spread food-borne infections through direct cross contamination of bacteria from infected

workers to the product. Contamination of hands from visiting toilet, coughing/sneezing etc / or

from infected wounds, cuts, boils etc, are the prime sources of product spoilage via the food

handler. Processing plant managers must ensure that every person working in a food-handling

area maintains a high degree of personal cleanliness at all times during plant operations. It is

imperative to ensure that the principles of Good Hygiene Practices (GHP) and Good

Management Practices (GMP) are stringently applied in the processing plant. (See Chapter 10)

Sampling Guide

Hand Swabs

Figure 20 Figure 21

Peel back the sterile packaging of the transport medium swab to expose the swab cap and

top of the sealed transport medium (Figure 20).

Remove the cotton ended swab holding it by its plastic cap only.

Roll the cotton ended swab over the point of the underside of the index or middle finger

(from finger tip to the first joint) of one hand (Figure 21).

Remove the top of the transport medium sleeve.

Push the swab into the transport medium until the plastic cap fits snugly into the sleeve.


Figure 22 Figure 23

Clearly label each swab by completing its adhesive label (Figure 22).

“Before and After” hand swabs are collected: prior to hand washing and sanitation and

post washing, sanitation and drying.

Complete the details of each swab collected on a laboratory submission form (Figure 23).

Place the swab/s in a cooler box maintained at 4°Cand transport to the laboratory.

Laboratory Analysis of Hand Swabs

On reception at the laboratory hand swabs are plated out on selective media for the following

target organisms

Total Coliforms

Escherichia coli

Staphylococcus aureus

Hand Swab Standards:

Target Organisms Count Before Washing

Target (CFU/plate)

Count After Washing

Target (CFU/plate)

Total Coliforms 0 0

Escherichia coli 0 0

Staphylococcus aureus 0 0

High counts prior to washing but returning to target post washing would indicate that

intervals between hand washings need to be reduced.

Persistence of counts post washing imply possible problems with washing technique,

contact times of sanitizers, incorrect soap and sanitizer concentrations, heavy soiling

prior to washing etc


Water Analysis

No abattoir or meat processing premises can be operated without the supply of suitable quality

water. Water samples collected from processing plants are submitted primarily to determine

whether the water supply meets the Standard Microbiological Safety Requirements (eg: total

viable counts, total coliforms and faecal E .coli). (SANS 241)

Sample submission

Figure 24 Figure 25

Sterile, plastic bottles (500 ml) should be pre-ordered from the laboratory prior to the

collection of samples (Figure 24).

If sampling from a tap let water run for a few seconds before collecting the sample and replace

the cap immediately.

Bottles must be filled to the top.

Each container must be clearly labeled as to where the sample was collected and on what date.

This information should be written on the body of the bottle with a waterproof permanent ink

marker. Avoid only labeling the lid as the lid and bottle could become separated during

analysis, placing the test results under question.

Samples should be transported to the laboratory at 4°C in leak proof sealed containers. Ensure

that the submission form is sealed in the plastic sample envelope to avoid spoiling by leakage

or the smudging of any details completed on the submission form (Figure 25).


Target microbiological parameters for treated water

Total viable count (TVC) at 22°C after 72 hours. Up to 100 per ml.

Total viable count (TVC) at 37°C after 48 hours. Up to 100 per ml.

Coliform bacteria (total coliforms). Less than 1* per 100 ml.

E. coli. (Indicates faecal contamination) Zero^

*Presence should be considered as a low level positive and water origin should be re-sampled. If

levels are above 3 per 100 ml in two consecutive samples, then this may indicate contamination

in the water distribution system and this requires further investigation.

^ If Escherichia coli is detected in the sample this would indicate fecal contamination and this

poses a serious food safety risk and urgent action must be taken.

Further Reading:

1. Hubbert W T, Hagstad H V, Spangler E, Hinton M H, Hughes K L. 1996. Food Safety and Quality

Assurance – Foods of Animal Origin 2nd

edn. Blackwell Publishing, Iowa.

2. Picard J A. 2007. Bacterial cell counting techniques In: Applied Veterinary Bacteriology and Mycology

(AVB 811) Department of Tropical Diseases, University of Pretoria.

3. SANS 241

4. 2006. Guidelines for Canadian Drinking Water Quality.

Chapter 8: Processing Plant Hygiene Analysis

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