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Milk increasingly packaged in PET and HDPE

drinktec 2009, which takes place from 14 to 19 September 2009 at the New Munich Trade Fair Centre, offers the right solutions for the producers of beverages, but also for producers of liquid food, in particular from the dairy industry. In terms of the technology employed, the manufacturers of beverages and the producers from the dairy industry use a wide range of identical or very similar machinery and systems. Already a large number of the exhibitors taking part in drinktec cater to companies from both segments.

ESL milk: Stays fresh longer
In the milk industry, process technology is focusing on machinery and systems for the product groups of milk, cream, aromatised milk-based drinks, fermented milk products like butter milk, kefir and drinking yoghurt with or without fruit or fruit pulp. In the case of drinking milk, the milk industry has for some time been trying out ways of keeping it fresh longer, while retaining the distinctive fresh-milk character. In general there are three types of drinking milk on the international market: non-pasteurised milk, pasteurised and UHT (ultra-high-temperature) processed milk. There are advantages and disadvantages to all three. Non-pasteurised milk is cooled and packaged fresh. It keeps only one to two days. Milk that is pasteurised using a conventional method can be kept for ten days, provided that the cool chain is unbroken. UHT or sterile bottled milk generally has a shelf life of three to nine months.

UHT milk, however, is not to everybody´s taste. The challenge is therefore to lengthen the time that normal pasteurised milk can be kept. There are three ways of producing ESL (extended shelf life) milk: using milk that has had the bacteria removed via separation, using microfiltered milk and using heat-treated milk.

For heating milk and milk-based products in order to pasteurise fresh milk, for ESL milk and for ultra-high-temperature processing the users have the choice between indirect processes , such as tubular or plate heat exchangers, or a direct process of steam-injection into the product. The heating systems are generally fully CIP-capable (cleaning-in-place) and built to a hygiene design. This ensures reliable systems technology with maximum microbiological safety. With UHT and ESL systems the core area, which must be able to be cleaned and sterilised, should also be surrounded by aseptic borders, so that during production sterile conditions can be maintained. This segment, too, is featured in the range on show at drinktec. After the last drinktec in 2005, one manufacturer of cleaning and disinfection agents and systems explained: “We came to this fair with high hopes – particularly in view of drinktec´s intensive coverage of the segment of milk beverages, which is another focus of our business. Our expectations were met in full. This confirms that drinktec is now the worldwide platform for innovations also in the area of milk processing.”

Trend towards cold milk skimming
In many cases the untreated milk is heated to around 55°C in the dairy and separated into cream and skimmed milk using a traditional milk separator. The cream is pasteurised and chilled separately using a cream pasteurizer. In some applications only the skimmed milk is degerminated, then mixed again with the cream and adjusted to achieve the desired fat content. In other dairies the homogenised cream is returned to the skimmed milk and the entire product degerminated before normal pasteurisation.

In some countries overseas, however, there is a trend towards processing milk in the state in which it arrives in the dairy, namely chilled. The working temperature for cold milk skimming is between 4 and 7°C. For the dairy this means significant energy savings, as the milk no longer needs to be heated up to skimming temperatures used previously. And that means lower production costs. Also, at the low temperatures the growth of microorganisms is considerably reduced.

Modular system is advantageous
This process technology can be supplemented where needed with a chiller, a vacuum degasser that removes air and also odorous substances from the product, or an integrated fully automatic CIP system. Reliable CIP systems ensure the highest possible microbiological safety. In addition process technology also stands for the required supply units such as water, steam, compressed air, cold, CO₂, energy etc.

In process technology in particular there is a strong trend towards modular systems. By building a system with fully prefabricated, connection-ready and tested units, the job of fitting valves, pumps, heat exchangers and of the controls is shifted from the customer to the factory of the manufacturer. At the customer´s factory, all that needs to be done is to provide connections for the product, hot water, water and electricity. With this kind of modular set-up, the amount of effort for integration and getting the system up and running is minimal. At the end of 2007 a large German dairy installed a new cold skimming system from a drinktec exhibitor in one of its European plants. The requirement was that the system had to be fully prefabricated and delivered to the customer ready to connect from the German works.

Reliable mixing technology
Also in demand, in addition to processes to lengthen product shelf life, are processes for blending liquids and dry substances. With milk products such as milk-based beverages, it´s not only the taste that is critical, but also consistency and stability in the packaging. For this a reliable mixing technology is important. This area of process technology is comparable with mixing non-alcoholic drinks, but has to be adapted individually to the individual dairy´s products and systems.

Process technology generally includes recipe-controlled automation and documentation that offers high process accuracy and optimum process transparency. These aspects are best covered by a supraordinate control system which controls all the stages of milk processing through to packaging and storage. This then of course ensures traceability in the production process. Also on show at drinktec 2009 will be the world of milk.