Avoiding cross-contamination

Though invisible to the human eye, bacteria are
omni-present in kitchens – both at home and in restaurants. They can
affect food taste, but more importantly they can also impact the safety
of the food we eat.

Though invisible to the human eye, bacteria are omni-present in kitchens – both at home and in restaurants. They can affect food taste, but more importantly they can also impact the safety of the food we eat. Many bacteria live and can grow very rapidly in food particles, especially in moist foods with temperatures between 5 and 60 degrees Celsius. Left untreated, they can cause salmonella or E. coli food poisoning and other serious illnesses.

The best defence against the dangers of bacteria is a clean kitchen. And while it’s extremely difficult to make cooking and food preparation surfaces and utensils fully bacteria-free, there are many steps foodservice professionals can and should take to both reduce the amount of bacteria present, and lower the likelihood of cross-contamination of bacteria between food ingredients and prepared dishes.

First Line of Defence
Hands are one of the major causes of cross-contamination. Bacteria that can cause illness are often present on hands, so it is important to wash hands frequently throughout the day. Washing hands before doing dishes helps to ensure that bacteria living on hands are not transferred into the dishwater. And, washing hands after doing each task associated with food preparation helps to minimize the transfer of bacteria from raw to cooked foods, cold foods to hot, etc.

Hot and Cold
At the top of the list is making certain cooked foods and raw foods remain separated. This means using different cutting boards and utensils for cooked and uncooked foods during the preparation process, and making sure to wipe prep surfaces clean after every use.

Proper Storage
It is equally important to store foods properly, both in terms of temperature and containers. Foods that are meant to remain cold should be stored at temperatures under 5 degrees Celsius. Foods meant to be hot should be held at temperatures above 60 degrees Celsius. And all foods must be stored in food-grade packages, wrappings and containers.

Cleansing and Sanitation
The ideal method for cleansing and sanitization is a three-step process. In restaurants, this is completed in a three-compartment sink – in which one sink is dedicated to each step. And while some products claim to clean and sanitize all in one step, contentious foodservice pros continue to stress the importance of separately performing each step of the three-step process.

Cleaning Sink – Be certain the water in the cleaning sink is hot, ideally between 49 and 60 degrees Celsius. Hot water helps to break up baked-on, caked-on food particles and to melt dried grease. This temperature is also necessary to activate the grease cutting and cleaning chemicals formulated into dish detergents.

But chemicals added to the cleaning sink need to be strong enough to get the job done, too. Professional grade detergents should include surfactant and solvent systems that work together to breakdown tough grease and clean effectively.

In this step of dishwashing, a brush or cloth may be used to scrub food surfaces and completely remove all soils. However, the brush or cloth must be cleaned between uses to clear food particles that may become trapped in the bristles or fibres, which can cross-contaminate the next batch of dishes.

Rinsing Sink – Though the rinsing process is perhaps the most intuitive, there are three techniques often used in restaurant kitchens to ensure all dish detergent has been removed from food surfaces and items are rinsed thoroughly. The first is to rinse the food surfaces under running water. The second is to dip the surface in and out of rinse water in the sink compartment. The third is to soak the clean dishes in a sink compartment filled with clean rinse water.

Whatever option is used, it is imperative to change the rinse water as soon as soap begins to rise to the rinse water’s surface.
Sanitization Sink – Sanitization is the crucial third and final step to further reduce bacteria and other micro-organisms that may be remaining on the already washed and rinsed food surfaces including pots, pans and cooking utensils.

There are two common types of sanitizers: chlorine and quaternary. Because it is a common household product, chlorine bleach can be used for cleaning in the home. But many foodservice professionals do not find chlorine stable enough for use in a professional setting. Food particles tend to break down the chlorine after only a few uses, requiring the sanitizing sink to be changed over more frequently. And, without the benefit of bubbles as an indicator – as in the cleaning sink – it is not as easy to tell when it’s time for a sanitizing sink to be changed over.

One of the key advantages of quats is their stability. Free chlorine is not stable in solutions, so it deactivates over time. The process is accelerated in higher temperature solutions, in the presence of food residues, or in lower pH solutions. Thus, many operators choose quaternary ammonium sanitizers to maximize the effective life of their sanitizer solution and reduce concerns of deactivation.

Whichever sanitizer is used, it is important to follow the instructions on the packaging to ensure correct amounts are mixed with the sink water. Too little will not effectively get the job done, and too much will leave a film on the food surface and will require additional rinsing, which can remove the sanitizer and negate its ability to remove bacteria from the surface.

And finally, let all clean cookware and utensils air-dry. Drying a sanitized surface with a towel can start the cross-contaminate process all over again, since towels can contain tiny particles of food and bacteria.

Foods provide a warm, moist environment where bacteria can thrive. Ingredients such as meat, fish, dairy products, eggs, cooked rice and cut melons are a ready-made incubator, and bacteria seem to know just how to use them. Though it’s impossible to rid the kitchen of all bacteria, the suggestions included here will help keep food preparation and cooking surfaces – as well as kitchen tools – clean and sanitary.

Lynn Helmers and Rich Kussin work as product research and development technicians for Proctor & Gamble’s Foodservice division in Cincinnati.