It is important to understand the difference between cleaning and sanitizing. Cleaning is defined as “the systematic application of energy to the surface or substrate, with the intention of removing dirt.” Sanitizing is “the process of reducing the number of microorganism on the surface to a safe level.”
Effective cleaning and sanitizing should always be a two step process. Surface must be cleaned first and rinsed before sanitizing. Any establishment must be kept clean; however, any surface that comes in contact with food must be cleaned and sanitized.
All food contact surfaces must be cleaned, rinsed and sanitized:
- After each use
- While working with another type of food
- At four hour interval in case of constant use
- Anytime while working, if the tool is being contaminated for doing other task
There are two different methods of sanitizing the surface, Chemical sanitizing and Heat Sanitizing.
It is important to understand that not all pathogenic micro-organisms need to be destroyed to make the food safe, as “small” amounts of consumed micro-organisms are dealt with by the body’s immune system. Therefore, during food handling and preparation, disinfection and sanitization are enough and there is no requirement for sterilisation. That is, provided that >99.99% of the micro-organisms are destroyed. The food/surface is now considered safe.
Micro-organisms are unseen enemies. It is important that the products used in the kitchen are effective in killing them without being too hazardous to the materials used to construct the building and/or its fixtures and fittings, or the cleaning operative. These products should not, in any way, affect the wholesomeness of the food, either by being toxic or by causing the food to be tainted.
However, most common product formulation specific to chemical sanitizers are:
The common chemical bactericides are hypochlorites which are salts of hypochlorous acid. The most useful is sodium hypochlorite which disinfects/sanitizes by oxidation of protein, and essential part of the structure of bacteria, viruses, fungi and yeasts.
Quaternary ammonium compounds (‘Quats’ or QAC’s)
Most of today’s commercial and domestic disinfectants utilise special kinds of surfactants called Quaternary Ammonium Compounds (‘Quats’ or QAC’s). Quats are increasing in popularity as they are effective against a wide range of micro-organisms, have low odour, have a residual action (i.e. continue to work for some time after application), are stable/easy to formulate with, less affected by soil and relatively non-aggressive to surfaces and the users.
So how do Quats kill micro-organisms?
Like us, bacteria and fungi are made up of cells. Amongst other materials, cells are made up of, or utilise, lipids (fats), proteins, a cell membrane (or wall) and enzymes. By destroying the structure or function of any of these materials, the cell dies. As a result, the micro-organism also dies. Viruses are slightly different, but also consist of proteins.
As cell walls have a negative electrical charge and Quats have a positive electrical charge, the Quat is attracted to the micro-organism. Being a surfactant, the Quat dissolves the lipids in the cell wall structure, weakening it. The chemical nature of the Quat then breaks through the cell wall, deactivating enzyme function and denaturising proteins. Denaturising of proteins is a process whereby chemical bonds are broken in the coiled-up protein, causing it to unravel. These chemical bonds can be broken by the action of heat or by chemical methods.
Whilst viruses do not have a lipid coating, they consist of proteins which can be denaturised by the chemical effects of Quats. Different types of sanitizers are biguanides, amphoteric surfactant, idophors, peroxy compounds, alcohols, aldedydes and ozone.
The most critical factors that influence the effectiveness of chemical sanitization are:
- Contact time
- Sensitivity, and
Where to sanitize !!
Sanitization is not a universal process applicable to all surfaces. It is to be done where micro-organisms are present at the higher level which has negative impact on the safety or the quality of food handled.
Areas to be sanitized are:
- Food contact surface
- Hand contact surface
- Cleaning materials and equipment
- Surfaces of fruits and vegetables to be consumed raw.