chapter 8: processing plant hygiene analysis
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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 ..................................................................................
Processing Plant Hygiene Analysis
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.
Processing Plant Hygiene Analysis
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.
Processing Plant Hygiene Analysis
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).
Processing Plant Hygiene Analysis
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).
Processing Plant Hygiene Analysis
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.
Processing Plant Hygiene 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).
Processing Plant Hygiene Analysis
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).
Processing Plant Hygiene Analysis
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.
Processing Plant Hygiene Analysis
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
Processing Plant Hygiene Analysis
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.
Processing Plant Hygiene Analysis
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
Processing Plant Hygiene Analysis
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).
Processing Plant Hygiene Analysis
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.
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