Cold-aseptic filling

As consumer demand grows for preservative-free ‘natural’ beverages and for products with additional benefits, aseptic food and beverage processors are increasingly turning towards cold filling. This system allows processors to implement these consumer-oriented product concepts and introduce beverages that have been bottled gently, with no additional thermal stress, as is the case with hot fill, and no added preservatives.

Aseptic, cold-aseptic, sterile, beverage-sterile — many terms are used to describe ‘aseptic filling’. The process involves bottling a product at ambient temperatures without tunnel pasteurisation or hot filling and without the use of preservatives or cold sterilising agents. The products are only briefly heated before filling. Aseptic filling is recommended for beverages such as fruit juices, tea beverages, sports drinks, vegetable juices, milk-based mixed drinks, UHT milk, near-water drinks and flavoured waters. It can be used for both still and carbonated beverages.

Drinks cartons have been filled aseptically for decades. Cold-aseptics is the state-of-the-art process, but with relatively low throughput volumes and a firm commitment to the suppliers of the packaging material. Aseptic filling is ‘relatively’ new to PET containers, but has been undergoing practical testing for over a decade. Basically, two processes have emerged, ‘dry’ and ‘wet’ sterilisation, both with specific advantages and disadvantages.

In the ‘wet’ aseptic process, containers are sterilised using peracetic acid (C₂H₄O₃) and steam. The steam from the peracetic acid/steam mixture is used solely as a carrier medium, distributing and activating the disinfectant. It ensures that the entire surface is moistened and also disinfects the atmosphere. This minimal use of disinfectant makes highly effective germ reduction possible. At the same time, the fasteners are disinfected with peracetic acid in a fully automated process in a dipping bath.

In some cases, instead of the commonly used wet sterilisation process using peracetic acid, a dry sterilisation process using H₂O₂ (hydrogen peroxide) is recommended. H₂O₂ is the classic and widely used disinfectant in the milk industry in particular. H₂O₂ is also the disinfectant commonly favoured by users changing from carton packaging to aseptic PET filling. Users who have to contend with high water and wastewaster costs are also advised to use dry sterilisation.

Another sterilisation option that is on the horizon is plasma sterilisation.

Improved microbiology

The microbiological safety of the aseptic filling process has been increased through a wealth of measures. For example, treatment for the exterior of the bottle has been improved, the sterile area has been divided off from the non-sterile area even more rigorously and hygienic materials such as stainless steel have replaced plastic.

Cold-aseptic filling is now a widely used process that is consistently being adapted to new demands. For example, rising energy prices are having an effect on energy efficiency in mechanical and plant engineering, and thus companies are focusing on economic efficiency. For this reason, the cleanrooms are getting smaller and smaller when aseptic processes are used, thus reducing energy requirements, improving operations, saving time and money, and increasing operational safety.

Only a fully integrated system can ensure the efficiency of a cold-aseptic process. The peripheral equipment must be right and do the groundwork for the aseptic process, or be aseptic itself. For example, this applies to the process technology for the flash pasteuriser or ultra-high temperature system, to the mixer with sterile buffer tank, the aseptic fittings and to the media preparation of disinfectant solution, sterile water, sterile air, steam and inert gas.

A cold-aseptic filling system can replace hot-filling processes, or bottle and can filling systems that use tunnel pasteurisers. There must always be an integrated approach in which equal attention is paid to filling safety, operating costs and operating safety, and which factors these aspects in during implementation. The opportunities provided by cold-aseptic filling mean that filling plants are investing in the future of their company, which will be able to implement new, consumer-oriented product concepts.