Packaging

Anuga FoodTec: Cold asepsis in packaging technology

Wednesday 04. March 2009 - Carefully filled - cold aseptic processes have established themselves as the state of-the-art technique when it comes to filling sensitive liquid and paste foods.

Cold aseptic processes have been used for decades for the preservation and filling of sensitive drinks like fruit juice and dairy products. Since the millennium these processes have experienced a real boom. That’s because the technology has been transferred for use with new packaging forms – for instance, PET bottles and new, microbiologically sensitive products, which have to be handled carefully to preserve as much value as possible. In this area, cold asepsis has proven to be the optimal process, as it can achieve good shelf life for food and drinks without the need for preservatives and demanding thermal treatment. The product which needs to be filled is made imperishable through a short and relatively moderate temperature exposure of less than 65°C before it is filled. It is then transferred into its freshly sterilised packaging in the aseptic cleanroom. The product is then sealed with a sterilised lid or sealing film. Today, the elimination rates in aseptic installations are 10-5 – and thus already exceed the required germ reduction figure set by the VDMA on sheet 8742. Aseptic filling is strongly advised for fruit juices, tea drinks, sports drinks, vegetable juices and mixed-milk drinks.

Wet and dry asepsis – similar yet different
Wet asepsis – the disinfecting of packaging with the help of peracetic acid in a germ free environment – enables very sensitive products with a ph-value of over 4.5 to be filled into plastic bottles made of PET, PE or HDPE without the need for pasteurisation. The emergence of hydrogen peroxide sterilization has opened up additional opportunities for cost savings and new fields of application for aseptic filling. Dry asepsis is based on the spraying of hydrogen peroxide into a hot and sterile airflow. Alternatively, the peroxide can be dripped onto a hot surface where it will completely evaporate and mix with the sterile airflow. The aerosol that is produced through this process creates a disinfecting effect that is based on the interaction of heat and active oxygen, which kills off all germs. After becoming oxygen and hydrogen, the peroxide dries up without leaving any residue, and the containers just need to be blown out with sterile air. Compared to wet asepsis, the costs for water and waste water are lower as no aggressive disinfectants have to be rinsed off with the use of rinsers. Depending on which process is being used, the outside of the containers is treated in the same way as the inside – with peracetic acid or with hydrogen peroxide. To sustain the sterile cleanroom conditions within such a plant, it is operated under slight pressure. Air is supplied through a HEPA filter (High Efficiency Particulate Air), which is installed in the ceiling. The air supply in the plant is controlled: in the filling and sealing area right through to when the filled bottle is discharged from the system, the air is streamed in the direction of transport of the bottles, and previously against the direction in which the container infeed runs.

The decision between a rotary and inline filling machine
Whilst rotary filling machines with a rotating filling carrousel, like the ones provided by KHS or Krones, are mainly used for the filling of drinks and dairy products, inline filling machines, such as the ones built by KHS, Finnah, Ampack Ammann or Oystar, have until now predominantly been used in the food and dairy industry. When it comes to choosing between the two technologies, it is not so much the branch that comes into question, as the location where the machine is to be set up, the desired capacities and the spectrum of products concerned. The decision between a rotary filling machine or an inline filling machine should be made individually after a discussion with the manufacturers.

A machine like the linear aseptic bottle filling machine FA10 from Ampack Ammann is used across the world for the filling of thin fluids, pastes and even high-viscosity products. Sensitive desserts, toppings or chunky products can be filled as easily as clinical and baby food. With regard to the inline filling machines from Finnah Engineering and Packaging, H2O2 sterilisation has proven to be very beneficial. H2O2 is used even in the form, filling and sealing machines to ensure the sterile filling of such products as desserts. The packaging materials, such as the base and sealing film, are passed through a heated H2O2 bath before they are processed. A sterilisation bath using either peracetic acid or hydrogen peroxide is also used for the screw-caps with any type of aseptic machine, whether rotary or inline. In general, rotary machines achieve higher rates of output.

Minimise the isolator as much as possible
The early aseptic filling concepts envisaged the use of a complete cleanroom with a separate housing of the filling system. In the past few years a lot of work has gone into ensuring that the actual aseptic zone as the isolator is as small as possible, and trying to rearrange as many components and functional units outside this area. The designer’s main responsibility is to ensure that strict hygienic design criteria are applied within the isolator. If the atmosphere of the cleanroom has been disturbed, for example, through the opening of a side door for emergency maintenance, the whole machine has to be freshly sterilised. The larger the isolation zone, the more time-consuming it is to sterilise. Today the cleanroom encompasses solely the isolator in the filling zone. For instance, in the mini isolator concept from KHS, the aseptic zone is only around one cubic metre in size. Therefore, the highest standards of hygiene can be assured in shorter cleaning phases and with reduced energy and cleaning costs. Per container slot, modern machines only require a cleanroom volume of around one litre within the aseptic zone. An interesting option for applications with special requirements concerning logistics and commissioning involves machines that can fill different products at the same time. These include the inline filling machines from Finnah, for example, and the rotary filling machines from Krones.

At Anuga FoodTec, from 10th to 13th March 2009 in Cologne, some of the most important technology suppliers will present their range of aseptic filling machines. Whether wet or dry, linear or rotary, all variations of aseptic bottle filling machines and their benefits will be presented to visitors at the fair in a comprehensible and comparable manner.