- Category: Management
- Published on Tuesday, 20 November 2012 11:47
Navin Sethi lists the factors that should be considered while preparing cleaning and sanitation programmes
Since cleaning and sanitation is the most important aspect of a hygiene programme, sufficient time should be given to outline proper procedures and parameters. Detailed procedures must be developed for all food-product contact surfaces (equipment, utensils etc.) as well as for non food-product surfaces such as non-product portions of equipment, overhead structures, covers, walls, ceilings, lighting devices, refrigeration units, heating, ventilation and air conditioning systems, and anything else which could impact food safety.
The objective of cleaning and sanitation of food contact surfaces is to remove leftover food, which is a nutrient for bacteria to grow and to kill existing bacteria. It is important keep cleaned and sanitised equipment and surface dry to prevent bacteria growth.
Cleaning/ sanitising procedures must be evaluated for adequacy through evaluation and inspection procedures. Adherence to prescribed written procedures (inspection, swab testing, visual observation of personnel) should be continuously monitored, and records should be maintained to evaluate long-term compliance.
Water chemistry and its effect on cleaning
Water comprises approximately 95-99 per cent of cleaning and sanitising solutions. Water functions to:
- carry the detergent or the sanitiser to the surface
- carry soils or contamination from the surface.
The impurities in water can drastically alter the effectiveness of a detergent or a sanitiser. Water hardness is the most important chemical property with a direct effect on cleaning and sanitising efficiency.
Water can also contain significant numbers of microorganisms. In such cases, treatment and sanitisation of water may be required prior to use in cleaning regimes. Water used for cleaning, sanitising and importantly for rinsing must be potable and pathogen-free.
Properties of food soils
Food soil is generally defined as unwanted matter on food-contact surfaces. The primary source of soil is from the food product being handled. However, minerals from water residue and chemical residues are also soils. Microbiological biofilms also contribute to the soil buildup on surfaces.
As soils vary widely in composition, only one common kind of detergent is not capable of removing them. Many complex films contain combinations of food components, surface oil or dust, solvent insoluble components, and insoluble hard-water salts. These films vary in their solubility properties depending on factors like heat, soil age, soil condition-wet/ dry etc.
It is essential that personnel involved in cleaning and sanitisation process have an understanding of the nature of the soil to be removed before selecting the detergent. Improper use of detergents can react with soils, making them more difficult to remove (e.g., acid cleaners can precipitate protein). Many films and biofilms require more sophisticated cleaning, which are amended with oxidising agents (such as chlorinated detergents) for removal.
Soils may be classified as:
- Soluble in water (sugars, some starches, most salts);
- Soluble in acid (limestone and most mineral deposits);
- Soluble in alkali (protein, fat emulsions);
- Soluble in solvents.
The physical condition of soil deposits also affect its solubility.
Fat usually is present as an emulsion and can be rinsed away with hot water above the melting point of the fat. More difficult fat and oil residues can be removed with alkaline detergents, which have good emulsifying or saponifying ingredients.
In the food industry, proteins are the most difficult soils to remove. Food proteins range from simple proteins, which are easy to remove, to complex proteins, which are very difficult to remove. Heat-denatured proteins can be extremely difficult to remove.
Generally, a highly alkaline detergent with high dissolution property is required to remove protein soils. Wetting agents can also be used to increase the wettability and suspendability of proteins. Protein films may require chlorinated alkaline cleaners in addition to wetting agents.
Simple sugars are readily soluble in warm water and can be easily removed. Starch residues, individually, can also be easily removed with mild detergents. Starch with proteins or fats, can be easily removed by high alkaline detergents.
Mineral salt-based soils
Mineral salts can be either relatively easy to remove, or be highly cumbersome deposits or films. Calcium and magnesium are involved in some of the most difficult mineral films. Under conditions involving heat and alkaline pH, calcium and magnesium can combine with bicarbonates to form highly insoluble complexes. Other difficult deposits contain iron. Salt layers can also cause corrosion of some surfaces. Difficult salt films require an acid cleaner for removal. Sequestering agents such as phosphates or chelating agents are often used in detergents for salt film removal.
Under certain conditions, microorganisms (bacteria, yeasts, and molds) can form invisible films (biofilms) on surfaces. Biofilms are difficult to remove and usually require cleaners as well as sanitisers with strong oxidising properties to remove them.
Lubricating greases and oils
These deposits (insoluble in water, alkali, or acid) can often be melted with hot water or steam, but often leave a residue. Surfactants can be used to emulsify the residue to make it suspendable in water and flushable.
Other insoluble soils
Charred or carbonised soil may require organic solvents.
The surface characteristics
Cleaning ability of a surface is the primary consideration in evaluating cleaning effectiveness.
Surface composition: Stainless steel like 300 series stainless steel or equivalent is the preferred surface for food equipment and is specified in many industry and regulatory design and construction standards. Other grades of stainless steel may be appropriate for other applications. For example, 400 series stainless steel is used for handling high fat products, meats, etc. For highly acidic, high salt, or other highly corrosive products, corrosion resistant material like titanium is recommended.
Other ‘soft’ metals like aluminum, brass, copper, or mild steel or nonmetallic surfaces like plastic, or rubber are also used on food contact surfaces. Surfaces of soft metals and nonmetallic materials are generally less corrosion- resistant and care should be taken in their cleaning.
Aluminum is readily attacked by acids as well as highly alkaline cleaners, which can render the surface non-cleanable. Plastics are subject to stress cracking from prolonged exposure to corrosive agents.
Detergents can be significant contributors to the waste discharge (effluent). Primary concern being pH, many publicly owned treatment works limit effluent pH to the range of 5 to 8.5. So, it is recommended that in applications where highly alkaline cleaners are used, that the effluent be mixed with rinse water (or some other method be used) to reduce the pH. Recycling/ reclaiming of CIP cleaners is also becoming a common practice in larger operations. Other concerns are phosphates, which are not tolerated in some regions of the world, and the overall soil load in the waste stream which contributes to the chemical oxygen demand (COD) and biological oxygen demand (BOD).
(The author is senior application specialist – Laundry & Kitchen, Diversey India Pvt. Ltd)