We Test Your Chopping Boards: How Dirty Are They? | Talking Point

Key Concepts

• Bacteria Count: The total number of active bacteria present on a surface.
• E. coli: A type of bacteria that can indicate fecal contamination and cause illness.
• Listeria: A type of bacteria that can cause serious infections.
• Salmonella: A type of bacteria that commonly causes food poisoning.
• Yeast and Molds: Fungi that can grow on food and surfaces.
• Biofilm: A protective layer formed by bacteria that makes them harder to remove.
• Porosity: The ability of a material to absorb liquids and smells, which can lead to bacterial growth.
• Scratch Resistance: The ability of a material to resist damage from knives, which can trap food particles and bacteria.
• Tempered Glass: A type of glass that is stronger and more resistant to breakage than ordinary glass.
• Stainless Steel: A durable and non-porous metal often used for kitchenware.
• TPU (Thermoplastic Polyurethane): A flexible and durable material that combines properties of plastic and rubber.
• UV Light Disinfection: Using ultraviolet light to kill bacteria and other microorganisms.

Chopping Board Cleanliness Test

This video investigates the cleanliness of chopping boards, exploring what contaminants might be present and how usage, material, and cleaning practices affect hygiene. Ten chopping boards from viewers, five wooden and five plastic, were collected for testing, alongside the presenter's own boards. The samples were sent to March Wood Laboratory Services for analysis of total bacteria, yeast, mold, biofilm-forming bacteria, and specific pathogens like E. coli, Salmonella, and Listeria.

Viewer Board Results and Analysis

The collected boards were ranked from cleanest to dirtiest. A "clean" board was defined as having "not detected" (ND) results for all microbiological parameters.

• Cleanest Board: A 6-month-old board with very few cuts, showing ND for all tested parameters.
• Dirtiest Board: This board had over 7 million bacteria, 80,000 yeast and molds, 5,000 biofilm-forming bacteria, and 21 E. coli. The presence of E. coli indicated fecal contamination.
• Biofilm: Defined as a protective layer that traps bacteria, making them harder to remove. Biofilms are responsible for over 80% of chronic human bacterial infections.
• Age vs. Cleanliness: The age of the board did not directly correlate with its cleanliness. A 4-year-old board was found to be cleaner than a 2-year-old board.
• Factors Affecting Cleanliness: The physical condition of the board, specifically deep cuts that trap bacteria and food material, and how the board is washed and stored, were identified as crucial factors. Keeping boards constantly wet promotes bacterial growth.

Presenter's Chopping Boards

The presenter, Diana, had two plastic chopping boards: one for raw meat and one for fruits and vegetables. Her boards were tested, and surprisingly, they came out as "clean" with no detected bacteria. This was attributed to their young age (less than one year old) and proper maintenance:

• Washing: Always left to dry after washing.
• Storage: Stored in their own casings with ventilation.
• Key Principle: Thoroughly drying the chopping board after each wash is essential, as moist conditions are ideal for bacterial thrive and reproduction.

Viewer Results Breakdown

The results were shared with the viewers who provided their boards.

• Elvin: His 1-year-old plastic board, used for raw chicken and raw meat (despite being a mixed-use board), tested as "not detected" for all bacteria. He maintained his board by washing with soap and sponge, rinsing with hot water, and hanging it on a rack. He also separated his boards for raw meat and vegetables.
• Olivia: Her board tested positive for E. coli. She was surprised as she washed her hands and the board before touching food. She used her board for raw meat (chicken, pork, fish) and vegetables, cutting vegetables first. Her storage method involved drying with a cloth and placing it near the basin, which was identified as a potential issue due to moisture and lack of ventilation.

Material and Usage Analysis

A graph plotting weekly usage against total bacteria count revealed:

• High Usage Boards (more than six times a week): Two plastic and one wooden board. Two of these had counts slightly above 1,000 bacteria, while one plastic board with the highest usage was the cleanest overall.
• Low Usage Boards (two to four times a week): One wooden board had a high count of almost 3,000 bacteria with significant yeast and mold. Another low usage board had almost 600,000 bacteria and traces of biofilm, making it the second dirtiest.
• Highest Bacteria Count: A plastic board used four to six times a week had both E. coli and biofilms.

General Observation: Plastic boards generally fared better than wooden ones. Frequent use did not necessarily determine dirtiness; low usage boards could harbor microorganisms.

Understanding Biofilms

A microbiologist explained biofilms as communities of bacteria within a surface, forming a slimy layer that traps them.

• Formation: A single bacterium attaches to a surface, multiplies, and within 6-12 hours, begins secreting a glue-like substance, forming a biofilm.
• Resistance: Biofilms are resistant to heat and chemicals, making them difficult to eradicate.
• Risk: Bacteria like E. coli and Listeria can remain on cutting boards within biofilms, increasing the risk of foodborne illness.
• Cleaning Effectiveness: Even after washing, bacteria can remain hidden within grooves. Hot water can reduce the bulk of biofilms but may not entirely eliminate them.
• When to Discard: Boards with significant discoloration or deep grooves that cannot be cleaned properly should be replaced.

Alternative Chopping Board Materials

Chef Anthony Yo discussed alternative chopping board materials:

• Tempered Glass: Non-porous, easy to clean, but noisy and can dull knives faster.
• Stainless Steel: Very easy to clean, hardy, but noisy, dulls knives, and has no grip. It is also heavier.
• TPU (Thermoplastic Polyurethane): Relatively non-porous, easy to clean, quiet, cushioned, and less likely to dull knives. It is scratch-resistant but not scratch-proof.
• Self-Cleaning UV Board (Plastic with Caddy): Comes with a caddy that uses hot air to dry and UV light to disinfect.

Key Factors for Maintenance:

• Porosity: Less porous materials are better as they absorb less moisture and smells, reducing bacterial growth.
• Scratch Resistance: Minimizes nicks and scratches where food particles and bacteria can get stuck.
• Grip: Important for safety to prevent the board from slipping.

Alternative Material Testing

Six chopping boards (four alternatives: glass, stainless steel, TPU, UV board, and two control boards) were tested.

• Methodology: Each board was cleaned with alcohol, then used to cut the same amount of raw meat with the same pressure and number of strokes. They were then washed with two pumps of dishwashing liquid and dried (the UV board in its contraption).
• Results:
  • Highest Bacteria Count: Wooden board (900), attributed to its porous nature and difficulty in drying.
  • Lowest Bacteria Counts: Stainless steel (no bacteria detected), attributed to its smoothness and resistance to deep scars. Plastic also had no bacteria detected due to its new, unmarred surface.
  • Low Counts: Glass (70), UV board (200).
  • Higher Counts: TPU (700), wooden (900). TPU boards, despite being touted as self-healing, can still develop micro-pockets for bacteria.

Conclusion and Takeaways

The main takeaway is that how you care for your chopping boards matters more than what it's made of.

• Recommendations:
  • Use separate chopping boards for raw meat and fruits/vegetables.
  • Wash boards thoroughly after each use, preferably with hot water.
  • Store boards in a well-ventilated area.
  • Discard boards if deep grooves or discoloration appear.