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By: Eric Ainslie, Ice Pigging Process Engineer
in search of a sterile pig
Avoiding microbial contamination of food products is an ever-present challenge for food producers, especially in an increasingly demanding consumer and retailer environment. The consequences of product recall as a result of microbial contamination remain high, and with both financial and reputational damage at stake, producing a consistently high-quality product remains a priority across the spectrum of food and FMCG producers.
Conversely, the traditional use of preservatives and controls that inhibit microbial growth in food are in decline, with the general drive for fewer additives playing an important role in removing certain preservatives from ingredient lists. As a result, processed foods are often more sensitive to bacteriological contamination, so preventing the introduction of bacteria in the processing cycle now becomes the major means of ensuring a consistent and safe product reaches the consumer.
SUEZ’s Ice Pigging technology offers a step-change in plant efficiency by preventing product loss, reducing waste, reducing water and power consumption and by speeding up times between product changeovers. But can the AQL500 Ice Pigging machine fit into the demanding environment of most FMCG factories? Does the machine stack up when it comes to a hygienic design?
Here at SUEZ, we have been on a mission: to create the most hygienic ice pig in the world. This mission was divided into two different areas of focus: creating an Ice Pigging machine that was easily cleanable and ensuring that the correct operational regime was used to compliment it.
AQL500 Hygienic Design
The AQL500 is the world’s only Ice Pigging machine designed from the ground-up with hygienic operation in mind. The design of the machine follows principles and guidance set out by EHEDG (European Hygienic Engineering Design Group) such as:
Although EHEDG guidance is comprehensive, as a new technology there are aspects of the machine where no guidance exists and where novel engineering solutions have been introduced to ensure that hygienic principles are followed. Key areas are:
Agitation of ice
When the ice mixture is held in storage awaiting use, it must be agitated to prevent separation of the mixture. In order to produce such a mechanism in a hygienic manner, a number of engineering challenges had to be overcome. After multiple designs, prototyping and testing, solutions were identified to overcome all of these challenges.
The machine now incorporates a novel agitation system that ensures no contact between ice and any bearings, yet ensures the system has no crevices, nor metal-on-metal contact and can still be cleaned.
Cleanability of the Ice Production system
One of the key capabilities of the AQL500 is that it produces the correct ice in one pass through the freezing system. The ice freezing system is unique in its ability to produce ice at the appropriate consistency and quality for effective Ice Pigging. However, the geometric requirements of the freezing system presented hydraulic challenges for surrounding pipework when considering cleaning mode since correct hygiene dictates specific flow rates to achieve effective cleaning in all pipework. To counteract these contradictory requirements, a series of bypass valves have been introduced to divert cleaning fluid at different flow rates and allow flow around the freezing system, as well as creating a suitable cleaning flow rate for the conduits either side.
The strategy for considering cleaning in place (CIP) was to look at the most challenging and likely scenario: a hot chemical wash, followed by a sterilisation cycle carried out at over 90⁰C. There were some minor problems with the compatibility of the ice pump with this regime due to the high temperature range between ice production) and CIP. This was solved by the introduction of a bypass. For each new application, cleaning cycle duration of the machine needs to be examined carefully, however, the design for clean-ability should minimise the time required for machine cleaning. Verification of the cleaning process has been carried out using thermal mapping of all the routes within the machine, ensuring full coverage with the cleaning fluid. In addition, swabs have been taken at key points to confirm the success of the cleaning cycle.
There were several considerations as to the regularity of the cleaning protocol. The first factor is to provide the AQL500 with a clean feed solution, using enclosed tanks that are cleaned prior to use and changed once the solution was been exhausted. This minimises contamination by carryover from outside the system. Secondly, the solution that is used to produce the ice will typically have a maximum time period at which it can be kept at ambient temperature after production, before there is a microbiological risk. This time period is used to define the time between cleaning cycles of the machine and can be verified by further microbiological testing onsite. The solution is typically made from water and an ingredient already used within the product, establishing a better understanding for the customer.
Is all this really necessary?
A very clean cleaning system might seem like an odd contradiction, but the introduction of a new process like Ice Pigging into an established and stable production line carries a risk which can’t be taken lightly. Extra finishing to achieve the correct surfaces, more complex sealing solutions and additional processes…it’s true that hygienic equipment demands a premium. One that comes as a direct result of higher-priced hygienic components in order to achieve simplicity in design. But given the potential issues that could be introduced from a poorly designed machine, is it not a wise investment to remove this risk?
When assessing how the process should be implemented, the type of product which is being recovered or cleaned and the current standard of the plant, will both have a large impact on the level of cleanliness required. We work with our customers to determine the level of hygienic design that is appropriate for the specific installation and the cleaning regimes which must be employed in order to maintain safety standards.
Installing Ice Pigging as a safe, cost-effective, product recovery and pipe cleaning solution is our business. We are very proud of the hygienic design credentials of the AQL500 and welcome any food or FMCG producer to get in touch to challenge us on its design.