Aseptic processing - process and hygiene
By Philip Richardson - 7 November 2016
The aim of aseptic processing is to produce a sterile product through heat processing. In contrast to canning, the product and the packaging are sterilised separately and the package is filled under carefully controlled aseptic conditions.
The product is sterilised continuously as it travels though a heating pipe. Because the product needs to flow through the pipe easily, aseptic processing is only suitable for liquids or suspensions with small solids, like soups.
Improved sensory and nutritional quality
Heating during aseptic processing can be controlled more accurately than in canning, so the problem of overcooking can be more easily managed. It can potentially produce higher quality long-life products without compromising product safety.
Originally aseptic processing was used mainly to extend the shelf life of dairy products. However, there was swift extension of the approach into the juice market. This has also been driven by a desire to remove chemical preservatives and move towards clean label.
With many new packaging materials being unsuitable for in-pack processing and the increased number of materials that can be blow moulded into containers, the opportunities for aseptic technology have further expanded to other products - including custards, desserts and other drinks.
Process validation and good hygiene
Robust validation approaches are essential to all forms of aseptic technology.
Theoretical modelling can be used to confirm that the thermal process required has been delivered. If the products include solids and liquids, then more direct measurements of microbiological inactivation will be required. It is also important to remember that pre-sterilization of the packaging is also required and this is usually achieved using a combination of chemicals (e.g. hydrogen peroxide) and heat.
The delivery of a sterile product also relies on the hygienic design of the process, packaging and pipe work. Unlike in canning, the aseptic equipment comes into direct contact with the food. The same pieces of pipe work contain food over a long period of time. At times during cooling, the product will be at an ideal temperature for microbial growth. Equipment must be designed so that it can be cleaned easily between product runs, with no areas where food can become trapped.
While normal good practice standards of hygienic design are adequate for much of the line, higher and more stringent standards are required for areas where product is handled after the heat process and during filling - where potential recontamination of the product may occur.
A combination of temperature measurements and microbiological inactivation tests is key at the commissioning stage to demonstrate that the plant can deliver commercially sterile products.
Aseptic technology offers food and drink manufacturers opportunities to extend shelf life, reduce additives and explore new pack formats. If you’d like to discuss any aspect of aseptic technology - from the design or commissioning of plants and product development to providing evidence of compliance with retailer, national or international standards - please get in touch.