This site is optimised to run in horisontal view. Please rotate your device before continuing.
Amit M. Kheradia
Amit M. Kheradia
Environmental Health and Sanitation Manager

PART 3: Cross-Contamination Control Strategies: Plant Layout and Process Control

In Part 2 of this series, we emphasised the need for hygienically designed equipment and premises necessary for producing safe and quality food. This blog will focus on the importance of laying out an appropriate food processing environment and controlling the processes effectively to minimise the risk of product contamination.


Global inspectional and audit non-conformances at food sites have revealed that inadequate operational precautions to control pathogen, allergen, or foreign material issues can negatively influence food safety assurance.


The top equipment and environmental sanitation non-conformances based on BRCGS Food Safety Issue 9 audits conducted between 1st February – 31st October 2023 were related to the following clauses:

  • Clause 4.11.1: Housekeeping and Hygiene – Sanitation (GHP)
  • Clause Chemical Control – Cross-contamination prevention
  • Clause 4.6.2: Equipment Design and Construction – Hygienic Design
  • Clause 4.4.8: State of Doors (both internal and external) – Sanitation (GHP)/Hygienic Design
  • Clause 4.4.1: Hygienic State of Walls – Sanitation (GHP)/Hygienic Design


Designing the Plant Layout

Ensuring a hygienic food processing environment starts with designing a factory with good infrastructure, that is easy to clean and maintain and is laid out in a way that minimises the risk of product cross-contamination.

Food safety begins with the design, construction, and layout of the plant that produces food.

Poor decisions regarding these may lead to an increased risk of food contamination.

  Some key plant infrastructure and layout considerations (illustrated above) are as follows:

  • The buildings, including the walls, ceilings, floors, junctions, fixtures, fittings, equipment, and transport vehicles associated with the food production facility or premises, must be maintained in a sanitary state. The food processing site must also be approved by the relevant authority.
  • The flow of the products (i.e., raw input, work-in-process, and finished outputs), called the process streams, must not create any potential for cross-contamination, i.e., there should be no looped or circular production flows:

High chance of cross-contamination

Some chance of cross-contamination


Negligible or no chance of cross-contamination

  • The air in contact with exposed food needs to be monitored for safety and quality. The flow of air should be from the packed or finished product zone to the exposed or raw materials zone, and not the other way around.
  • Effective barriers are essential. These include the segregation of different hygiene risk areas, e.g., separation of high-risk production areas from low risk, and pest control measures, including the use of window screens and bottom door seals.
  • The movement and control of traffic and personnel shall be sufficient to prevent the risk of product contamination and comply with the relevant legislation. For example, it is required by food safety standards and regulations that areas in which high-risk processes are conducted shall only be serviced by trained employees dedicated to that function.
  • Accumulation of waste shall not be allowed in food processing, handling, or storage areas. Hence, provisions must be made for the separating, storing, and removing of the waste to ensure minimal risk of contact with the food.


* The considerations given above are not an exhaustive list of plant design and layout requirements promulgated in various food safety regulations and standards.


Implementing Process Controls

Process control, from a food safety perspective, involves managing the plant operations in an effective and efficient way such that the risks of product contamination can be significantly minimised. Food safety hazards should be identified, the association risk should be assessed, and appropriate controls should be put in place.

This starts with the application of risk-based assessment methods, like Hazard Analysis and Critical Control Points (HACCP). HACCP can be used to identify food safety hazards, the Critical Control Points (CCPs) in the process where their control is critical to minimise risk from the hazard, and the application of appropriate controls to ensure this.

For example, the diagram below shows the process steps involved in the production of cooked, breaded chicken pieces made from raw ingredients:

The CCPs for this process are highlighted in the boxes with the thicker blue borders, i.e., sieving (foreign body hazard control), deep frying (microbial hazard control), blast cooling (microbial hazard control), and metal detection (foreign body hazard control).

For each of these CCPs, the control required and its critical limit need to be defined, and these must be continually monitored to ensure that they are achieved at all times.

In the example below, for the CCP of deep frying, the control has been defined as cooking at the correct temperature for the correct time. The time and temperature are then defined in the critical limit, i.e., 160°C for 5 minutes.

Process Step
Deep frying
Hazard & Cause
Survival of pathogens (Salmonella) due to undercooking (low oil temperature or too short a frying time)
Cook at correct oil temperature & for correct time.
Critical Limit
Oil temp 160˚C

Frying time 5 minutes
Fryer operator to check oil temp. and frying time at start-up and every 15 minutes following that and record in frying log
Corrective action
Fryer operator to:
  1. Stop in-feed and divert output.
  2. Dispose of product made since last good check
  3. Inform the production manager & ask an engineer to fix the problem
  4. Record actions in log

HACCP also requires the establishment of Corrective Actions if monitoring indicates that the critical limits have not been achieved. In the example above, these Corrective Actions are to stop the product feed; divert the output; dispose of the product since the last good check; inform the Production Manager; call an Engineer to fix the problem; and log the actions taken.

Corrective actions can also include root cause analysis, which will help identify appropriate corrective and prevention actions.

Visualisation tools like the Fish-Bone Diagram can help in such efforts by deep-diving into the variable factors (such as internal and external environments, personnel competencies, equipment, materials, methods and measurement parameters) responsible for influencing food safety culture in a food processing environment.

Other Cross-contamination Control Strategies

There are many other ways by which product contamination may happen at a food site. The table below lists some common examples, and indicates how the use of colour-coded tools and the segregation of production areas by colour can both serve as preventative controls to further minimise the risk of product cross-contamination:

Type of contamination Examples of contamination incidents in a processing plant Colour-coding recommendations
Cross-contamination: transfer of microorganisms such as pathogens, chemicals, or physical materials from food or a surface to another food or food-contact surface.

Shovel for scooping raw meat was used to handle processed products

Use different coloured shovels for raw and cooked product handling


A tube brush for cleaning drains was found on a cookie conveyor

Use different coloured tools for drains; hang them on dedicated tool racks or shadow boards of the same color


A white tub trolley for handling rejects was used to store cooked pasta

Use separate coloured tubs for different purposes, based on risk

Cross-contact: unintentional incorporation of a food allergen into another food through accidental transfer

Paddle for stirring wheat dough was then used for soya product that should not contain wheat; soy product labels did not list wheat as an ingredient – undeclared gluten allergen hazard

Use different colour-coded paddles for use with each controlled allergen

Other important cross-contamination prevention controls to consider are as follows:

  • Good personal hygiene practices, including handwashing, glove use, use of hairnets, overalls, and captive footwear, etc. 
  • Equipment used for servicing amenities (e.g., change rooms, toilets, and breakrooms) must not get mixed up with those from the food production zones. For instance, as a critical precaution, tools used for cleaning toilet rooms shall not be used to clean food processing areas.
  • Also ensure that trolleys, vehicles, waste disposal equipment, bins, and trash storage areas are maintained in a serviceable condition and are sanitised regularly to minimise the risk of cross-contamination and prevent the attraction of pests.

Please visit our web page on Site Surveys to discover how we can help you develop your colour-coded site plan.

Colour-coded area segregation can be used as an effective contamination control strategy, to reinforce the message that the people, equipment, and products dedicated to that stay within that area, especially if the protective clothing and equipment used are similarly colour-coded.

Additional resources on colour-coding are available on our website:

Future blogs in this series will offer further support related to the following equipment and facility sanitation challenges:

PART 4: Cross-Contamination Control Strategies: Managing Your Hygienic and Environmental Monitoring Zones

PART 5: Cross-Contamination Control Strategies: Creating Better Sanitation Programs

PART 6: Cross-Contamination Control Strategies: Dealing with the Pest Problem, Product Storage, and Transport Sanitation