The Dishwasher in the Kitchen: A Guide to High-Volume Sanitation

The dishwasher is designed to wash a high volume of plates, cups, cutlery, and crockery in a consistent manner that is unaffected by human error. In a commercial environment, the dishwasher in the kitchen acts as a barrier against food-borne illness by utilising thermal disinfection—a process difficult to replicate consistently through manual washing.

2.0 How the Machine Operates

A commercial dishwasher operates via two separate heating systems. The first heats the wash tank water, where detergent is introduced via an automated chemical dispenser. The second system, often referred to as the “booster,” superheats the water to ensure the final rinse reaches temperatures necessary for sterilisation.

The standard wash cycle typically operates between 50°C and 65°C. However, the critical phase is the rinse cycle, which performs three distinct functions:

• Detergent Removal: Clearing away chemical residues from the crockery.
• Thermal Sterilisation: Utilising water at +80°C to destroy pathogens.
• Rapid Drying: Facilitating “flash drying” to remove moisture.

3.0 The Science of Rinse Aid and Moisture

During the final cycle, a rinse aid is added. Despite the name, this chemical does not “aid in rinsing” in the traditional sense. Instead, it acts as a surfactant, allowing water to sheet off the equipment so it dries properly.

As established in our research on how bacteria grow, microorganisms such as Salmonella and Staphylococcus aureus require moisture to survive and proliferate. If items emerge from the dishwasher completely dry, the survival rate of these bacteria is significantly reduced. This eliminates the need for tea towels, which are notorious vectors for cross-contamination in the kitchen.

4.0 Efficiency: Machine vs Manual Washing

While the initial purchase cost of a commercial dishwasher is a consideration, the long-term benefits to the business are substantial:

• Energy and Water Efficiency: Modern water-efficient models use approximately 15 litres per wash—significantly less than the 60 litres typically required for manual wash-and-rinse basins.
• Sanitation Reliability: Manual washing rarely maintains temperatures above 45°C, which is insufficient for killing Listeria monocytogenes or removing heavy grease. The dishwasher’s +80°C rinse provides a level of extra sanitation that hand washing cannot match.
• Time Management: A machine can cycle through hundreds of items in the time it takes a staff member to manually scrub a fraction of that volume.

5.0 Correct Operational Procedures

To ensure the dishwasher in the kitchen remains an effective tool for food safety, staff must follow these protocols:

1. Pre-Heating: Switch the machine on well before service and run two empty cycles to ensure the wash tank and booster have reached their target temperatures.
2. Pre-Rinsing: Always scrape and rinse items before stacking. Excess food debris will clog the wash arms and contaminate the recirculated wash water.
3. Correct Crating: Use the appropriate crates for the task—cutlery in baskets, glasses in slotted racks. Never over-stack or “nest” items, as this prevents water from reaching all surfaces.
4. Hollow Items: All cups, bowls, and hollow items must be placed upside down to prevent them from filling with dirty wash water.
5. Air Drying: Items emerging from the machine will be too hot to handle. Allow them to air dry and cool naturally. Do not use towels, as this introduces a risk of cross-contamination.

6.0 Domestic Application

The habits learned in a professional kitchen should translate to your home kitchen. Pre-scraping, avoiding overloading, and ensuring hollow items are upside down are universal rules that improve the hygiene of any dishwasher, regardless of size.

For more information on maintaining a hygienic environment, read our guide on Cleaning and Sanitising Best Practices or explore the technical details of bacterial survival on surfaces.