Deviations in raw milk quality are a challenge to farms with automatic milking systems. The problems are caused by bacteria that are resistant to heat treatment – the so-called thermo-resistant bacteria – or a too high level of free fatty acids which give the milk a rancid taste.

Within the framework of the FUTUREMILQ consortium, Associate Professor Lars Wiking and Postdoc Mette Marie Løkke from the Department of Food Science at Aarhus University are measuring the levels of free fatty acids.

- The problems with free fatty acids increased 10-15 years ago when automatic milking systems were introduced. It is a complex problem caused by many factors ranging from feed, milking frequency, pumping to the storing temperature of the milk,  Associate Professor Lars Wiking says.

He describes the aftertaste as “somewhat like billy goat”, while Mette Marie Løkke uses words like “the smell of parmesan cheese.

- One problem related to the rancidity caused by free fatty acids is that it is very volatile and changes over time, which makes it very difficult to measure. Therefore, several measurement methods have been applied, and the aim is to develop a rapid and mobile measurement method to be used on-farm, explains Mette Marie Løkke. She continues:

- We want to be able to bring our tool to a farm with problems and carry out measurements, push some buttons, measure again and see if the problem is solved. 

Today, the level of free fatty acids is included in the settlement criteria for some dairies, and this means that farmers are paid less for their milk if the level is too high.

A question of method

The researchers have spent quite some time developing methods and comparing different measurement methods to the reference methods.

The so-called BDI-method is the primary reference method, but it is expensive and cannot be performed quickly or directly at the farms and is therefore not used as a standard method.

However, other methods have the potential of becoming on-farm solutions: a small measuring device using infrared light seems promising.

- This is also the principle used in laboratories to measure fat and protein contents of milk. We still need a lot of testing to ensure that the method is not too imprecise, Mette Marie Løkke emphasizes.

When can you taste whether the milk is rancid?

Another method, examined as a part of the AU project efforts, is sensory experiments in which a test panel tastes milk samples with varying levels of free fatty acids in order to identify when you actually register the rancid taste.

The experiment demonstrated that test panel experiences varied significantly and that it is very difficult to identify and evaluate the rancid taste. The sensory experiments were compared to a series of other measuring methods to determine which method most accurately describes the aftertaste and thus is eligible as quality control. The aim is to find a quick type of quality control measuring according to the taste deviance.

Lars Wiking’s and Mette Marie Løkke’s results are now incorporated into the remaining project work. A so-called “measuring ambulance” (mobile monitoring system) to bring to the farm will be developed; it contains equipment able the measure milk quality in new ways.

Joint efforts on many fronts to improve milk quality

Anette Gravgaard from the Danish Technological Institute, AgroTech, is FUTUREMILQ project manager and she explains that – in addition to measurement methods – the project also includes efforts in relation to hygienic design and development of monitoring and early warning systems that make it easier to identify problems with heat-resistant bacteria and free fatty acids.

- Data from the 30 participating farms are now available and the individual farmer can follow and log his own quality parameters. We aim to develop methods that allow the farmer to currently correct the milking parameters that may cause problems and that also allow milking robot producers to utilize the knowledge achieved on hygienic design – and maybe also incorporate some of the measuring methods that we develop, says Anette Gravgaard.

At present a manual on hygienic design is being prepared – describing hot spots in the milk flow from robot to milk tank where problems may arise.

Strength lies in joint efforts

Quality manager of global milk production in Arla Foods dairy company, Helle Skjold, is a member of the FUTUREMILQ steering committee, and she states the following reasons for joining the project:

- The dairies are the end users of farm products and if we want to produce high-value products to ensure higher prices it is of the utmost importance that the milk quality is excellent. Therefore, our efforts to reduce the prevalence of free fatty acids and bacteria – including heat-resistant bacteria – are very important to us as well as to our farmers who are paid for their milk quality. For instance, cheese ripening takes several months and it is essential that the raw materials are as good and fresh as possible. Also, Arla sells a lot of liquid milk and the taste of this fresh milk is very important, she says.

Helle Skjold considers the consortium design an advantage, representing both research and the entire value chain:

- Automatic milking systems constitute a challenge. Therefore, it seems natural to team up with milking robot producers as technological development is essential in order to solve the problems. To us it is important that research is applied – and that is exactly what this consortium can do because all partners have helped define what they consider necessary.

Arla has participated in several of the project’s work packages and has made data from Arla’s analyses available, including annual screenings for heat-resistant bacteria.

Project facts

FUTUREMILQ is a four-year project running from April 2013 to October 2017. The budget is 23.2m DKK, of which 10.6m DKK is funded by the Danish Council for Technology and Innovation. The project is managed by AgroTech and project participants include a number of partners such as the Department of Food Science, iNANO, both Aarhus University, and SEGES.

Contact
Associate Professor Lars Wiking
Department of Food Science, AU
Mail: lars.wiking@food.au.dk
Phone: +45 8715 7805