Milking Parlour (CIP) Cleaners

• Alkaline cleaners
• Acid cleaners
• Disinfectants

Alkaline cleaners: The theory

Milk contains fats, proteins, sugars and minerals. These tend to stick to the surfaces of the milking and cooling equipment, and effective dairy chemicals are needed to ensure they are removed during the cleaning process.

Whilst sugars are soluble in water, fatty acids and minerals are not, and proteins are only partially so. A well-formulated alkaline dairy chemical will contain ingredients which ensure that these substances are effectively removed from the plant surfaces.

Alkaline cleaners consist of three basic ingredients:

• Alkalinity – emulsifies fat;
• Chlorine – breaks down protein;
• Sequestration agents: tie up and remove dissolved solids.

Alkalinity

Alkalinity is generally included in alkaline dairy cleaners either as potassium hydroxide or as sodium hydroxide. They act by breaking up the fats and combining with the resulting fat particles to form soap in a process called saponification.

Alkalinity also helps in the removal of proteins by breaking up the long molecular chains of proteins into smaller pieces.

However, the total alkalinity of a detergent is comprised of active and inactive alkalinity, and the percentage that is active (and hence effective) varies between products. The pH is also important: an effective alkaline detergent will deliver a pH of 10.5 – 11.5 and an active alkalinity of at least 200ppm in the wash solution.

Chlorine

Chlorine breaks down proteins into peptides that are more easily removed in the cleaning process. It also destroys bacteria so is an effective sanitiser. To break down proteins the wash solution needs to contain at least 200ppm chlorine, whilst effective sanitation requires only 100ppm.

However chlorine will also react with substances that are used in components of the milking machine, particularly rubber and, to a lesser extent, silicone. Products containing excessive amounts of chlorine will therefore cause premature deterioration of service parts of the milking machine.

Sequestration agents

Sequestration agents tie up dissolved solids and carry them away in the wash solution. Higher levels of sequestration agents improve the effect of active alkalinity, thereby aiding the break-up of fats and proteins.

The amount of sequestration agents needed to be effective will vary according to the quality of the water used for plant cleaning and hence the level of dissolved solids (hardness, iron, etc).

Powder or liquid?

Alkaline cleaners may come either as a powder or a liquid. Powders are unsuitable for use in automatic wash systems and are generally only supplied in smaller pack sizes, making them less cost effective for milk producers with larger milking parlours, who are probably looking to benefit from savings made when buying larger quantities. However, powder cleaners are often more effective in hard water, and they remain popular with smaller producers in such areas or those using private water supplies.

Acid cleaners: The theory

Hard water scale sticks to glass and stainless steel surfaces, where it can harbour milk and bacteria, and prevent alkaline cleaners and disinfectants from cleaning effectively.

Traditionally alkaline cleaners were used in the circulation cleaning of milking machines. An occasional acidic wash containing milkstone remover was used to prevent a build-up of hard water deposits and other minerals. Modern research coupled with the development of milking machines into larger, more complex installations means that we now recommend the use of an acid detergent in one wash each day.

Acid cleaners consist of three basic ingredients:

• Acidity to dissolve milkstone, chalkstone, pyruvates and iron oxide;
• A disinfection component to kill bacteria;
• Surfactants to de-attach fats and proteins from surfaces.

Acidity

Acidity is generally provided by phosphoric acid, nitric acid or sulphuric acid. They dissolve hard water deposits and milkstone leaving plant surfaces clean and shiny with no crevices or corners that enable the build-up of milk solids and harbour bacteria.

Surfactants

Surfactants de-attach milk fats and proteins from the surfaces of the milking machine, helping in the cleaning process and enabling effective disinfection.

Disinfectants: The theory

Why use a disinfectant in the final rinse?

Thermoduric bacteria, which cause milk spoilage and reduce the keeping quality of milk, are becoming more of a problem to milk buyers. These bacteria survive pasteurisation and so it is necessary to prevent thermoduric bacteria from entering milk at farm level. They often arise as a result of poor teat preparation and inadequate terminal disinfection (i.e. final rinse disinfection after the main wash cycle).

The most popular disinfectant is peracetic acid as this works immediately on contact and there is very little risk of milk supply contamination as the disinfectant breaks down to oxygen and water.

Peracetic acid is generally used at very low doses (50ppm) , so is economic to use. It can also be used on bulk tanks as a final disinfectant and to disinfect clusters during milking between cows. Another application is for the disinfection of single service udder cloths and medicated wipes.