Flow diagrams

A flow diagram is a step-by-step picture of how a food is made. Codex calls it a systematic representation of the sequence of steps used in the production or manufacture of food. It is the map for your hazard analysis.

Why does it matter? Hazards are found step by step. If a step is missing from the diagram, its hazards will be missing from the plan.

A simple diagram for a cafe dish might run: purchase, delivery, chilled storage, preparation, cooking, hot holding, service. A second branch could show cooling, chilled storage, reheating and service. Use one box for each step, with arrows to show the order.

A good diagram shows all the inputs, such as ingredients, packaging and water. It shows the order of the steps and how they connect. It shows any work done by another company, any rework, and where finished food and waste leave the process.

Rework means sending food back into an earlier step. A bakery may put broken biscuits into a new mix, for example. Rework can carry an allergen into a product that should not contain it, so it should appear on the diagram.

Products that follow the same steps can share a diagram. All your hot soups may follow one route. A dish that is cooled and reheated cannot share a diagram with one that is served straight away. A complex operation can be split into smaller diagrams that link together.

Then confirm the diagram on site. Codex says this should be done during all stages and hours of operation. That means walking the floor at different times: on the early shift, on the late shift, at the weekend and during a busy service. Someone who knows the operation well should do it. Then correct the diagram.

Here is an example. The diagram for a restaurant says cooked rice goes straight to a blast chiller. A late-shift check finds that the rice is left on the side until the kitchen closes. This gives Bacillus cereus time to grow. Either the practice must change or the plan must change. A diagram that shows what should happen, rather than what does happen, is no use.

Keep the diagram up to date. A new oven, a new supplier or a new delivery service can all change the route food takes.