Hygienic milking

Cleaning is a preventive measure to maintain optimal machine functioning, optimal milk quality and to keep animals healthy. Cleaning is the removal of organic and/or inorganic dirt which are residues from milk and water. When not cleaned properly, these residues provide ideal circumstances for bacteria to grow. This results in a high bacterial count (BC) of the milk and might result in spoilage of the milk. Besides, accumulation of dirt affects the functioning of the machine. Dirt can result in an increased risk of corrosion and malfunctioning of valves and sensors. In decision making during the milking process and for reports in Horizon, we rely on accuracy of sensors. For reliable data, measuring devices such as MQC should be cleaned properly.

Cleaning principles

Each type of dirt requires a specific cleaning detergent. To remove organic dirt, an alkaline product (high pH) is required. To remove inorganic dirt, an acid product (low pH) is required. Basically, every cleaning detergent consists of an alkaline or acid component combined with additives. Additives improve the cleaning performance of the main component. Additives improve the cleaning performance by e.g. helping to dissolve dirt in water, prevent scaling or inhibit corrosion. 

With only cleaning detergents, the milking system will not get clean and other parameters are needed for a successful cleaning. These parameters are no different from doing the dishes at home. At Lely, we use the tACT parameters to describe the cleaning process. For an effective cleaning, fulfilling the 4 tACT parameters is required. Besides chemicals / cleaning detergents the 3 other tACT parameters are time (cleaning duration), action (scrubbing or whirling water) and temperature. These 4 parameters are balanced. This means that reducing the effectivity of one parameter requires an increase in another parameter. Do you recognize this from doing the dishes? If you decide to do the dishes with cold water, it may take a bit longer. On the other hand, adding soap might shorten the time. One other key element needed for good cleaning is water. Water provides whirling action, it dissolves the chemicals and transfers the temperature to the system. Water implements the tACT parameters and enough water of good quality is essential for an effective cleaning.

Hygienic Milking - Nienke van der Meijden Chemical Engineer at Lely

Astronaut cleaning

To have as much time available as possible for milking, a short cleaning time is required. Considering the tACT parameters, this means that at least one of the other tACT parameters have to compensate for a short cleaning time. This is why Lely opted for cleaning at high temperatures, or heat cleaning. By using high temperatures, a powerful detergent and flush through cleaning, cleaning time can be reduced. This means a relatively low volume of water per cleaning and a short contact time for the cleaning solution compared to the cleaning of conventional milking systems. Cleaning of the Astronaut normally starts at a temperature of 95°C/90°C. Cleaning must continue for at least 2 minutes at 77°C (MQC measured).

Chemicals act more aggresive at higher temperatures. Products with ingredients such as chloride, sulfuric acid, nitric acid or which are high in silicate are not suitable for heat cleaning. To prevent damage to the stainless steel (corrosion) and rubber parts of the Astronaut during cleaning, it is important to use cleaning detergents that are suitable for heat cleaning.

Lely has developped two products especially for heat cleaning of the Astronaut, being Lely Astri Lin and Lely Astri Cid. Astri Lin is an alkaline cleaning detergent to remove organic deposits. Astri Cid is an acidic cleaning detergent to remove inorganic deposits. The additives contribute to handling varying water quality standards. It is recommended to conduct an alkaline wash (Lely Astri Lin) twice a day and an acid wash (Lely Astri Cid) once a day. The recommendation of cleaning three times a day is based on experience and the growthcycle of microorganisms. After 8 hours the number of microorganisms increase exponentianaly and the system needs to be cleaned – or reset – every 8 hours.


Source; Ruben Otten - Farm Management Support, Milking & Cooling specialist