Controller and recorder selection for food and beverage plant

Tight control of food and beverage processing is essential to ensure that customers receive safe, high-quality products. The choice of controller or recorder for a particular process depends on the process itself and the level of sophistication required. Food regulators are not really concerned about the type of device or control scheme used; all they want is to ensure that the resulting product is safe and that they can find out what went wrong if there is a problem.

In terms of safety, traceability is the key issue for both operators and consumers. Recent events concerning the contamination of foodstuffs with the Sudan 1 dye have shown how important it is to ensure that there is a system capable of tracing potential faults back to a root cause. In this way, it is possible to ascertain exactly how, when and why problems occurred and the number of batches likely to have been affected so that measures can be taken to minimise health risks and allay public concern.

As far as maintaining consistent quality goes, repeatability is the overriding consideration. Unlike many other industries, food and drink manufacturers tend to work in batches, often with many hundreds of items to be added, cooked and processed in a single day. In this context, multi-recipe controllers can ensure that each of the many possible products follows its own unwavering formula in terms of ingredients and processing profile.

Advances in technology have created a bewildering array of control options, from simple single-loop controllers through to more advanced control requirements with an array of features and options to match any application. But when it comes to choosing which devices are best suited to food processing, there are some fairly basic considerations that should be taken into account.

Solving problems

Food processing is time- and temperature-sensitive, so being able to control these factors tightly is paramount. Previously, if there was a problem midway through the process, it would often fall to the operator to problem-solve on a case-by-case basis, potentially leading to waste and inconsistencies, and increasing the margin for error. Now the technology has progressed to a stage where variables can be programmed in advance, with controllers effectively regulating production processes according to certain predetermined rules.

An example of this is multi-recipe controllers. These ensure that production conditions are maintained within a set band, usually relating to temperature, pressure or time. They can be programmed to act in a certain way in case that band is broken. So, for example, if the steam supply runs out 15 minutes into a 20-minute process, the device could either stop the process, send an alarm, restart at the 15-minute mark, or start the whole process again, depending on the programming.

The key benefit of this technology is that it removes the responsibility from staff and ensures that any production problems are automatically handled according to a set routine, thereby improving product quality and reducing waste.

Operator choice

The influence of operators on the choice of control and recording equipment is often overlooked. They may not be responsible for the purchasing budget, but plant operators are the people who will have to work with devices every day.

Unnecessary legwork is a nuisance for operators, so the first consideration is to choose controllers and recorders that can be positioned on the plant floor, rather than in a remote control room or cabinet. That means choosing devices that can stand up to being hosed down on a daily basis as the food plant is cleaned.

Look for equipment that offers protection to IP65 as a minimum and preferably IP66, as is the case with ABB's Commander range of control products. The equivalent US standards are NEMA 3 and NEMA 4. Not only will this be more convenient for plant operators, but it will also save money by eliminating extra cabling and cabinets.

Operator preferences also come into play in the way information needs to be displayed. For instance, an experienced operator on a batch process will be familiar with how a typical circular paper chart should look for each batch. They can see at a glance if there was a problem from the shape of the traces.

However, for process engineers and quality controllers, paper charts are a nightmare. Retrieving a specific file eight months down the line is easier said than done, so in most cases potentially valuable data is simply ignored unless there is a problem.

A videographic recorder feeding all the data to a memory card or other storage device makes it far easier to retrieve data about problem batches. For example, if an item of process plant such as a pasteuriser or mixer failed, it would be possible to identify exactly which batches of products were affected so that action could be taken quickly. More importantly, this approach also offers the possibility of looking at long-term trends for valuable information in terms of, say, improved quality, preventive maintenance and asset management.

The answer is to opt for an electronic recorder with a sufficiently large display so that it can mimic the visual impact of a paper chart recorder. That is one reason why ABB's Screenmaster 3000, with its 30cm screen, has proved so popular in the food industry.

Data security

As mentioned previously, regulators internationally are not particularly concerned about how food manufacturers control their process, as long as it is demonstrably safe. What they are concerned about is accountability and traceability.

The American Food and Drug Administration (FDA) rules on the traceability and security of electronic records, 21 CFR part 11, are having a major effect on data recording and record keeping in general. Even though these rules are not legally binding for food manufacturers outside the USA, they are becoming the de facto standard worldwide among food companies keen to be seen to meet the most stringent requirements possible.

21 CFR part 11 stipulates three main requirements that electronic records and signatures must meet in order to provide an acceptable alternative to paper records of the manufacturing process. These requirements cover security, e-signatures and the management of the recorded data.

Modern videographic recorders, such as ABB's SM series, should meet all of these criteria. Security can be preserved by various measures including password protection and allocation of user-specific access rights that enable the recorders to recognise individual operators. In this way the number of people that can make configuration changes is limited to a small and easily identifiable group. Any alterations that are made are also recorded by an internal audit trail, which logs who made any changes and when.

An electronic signature should only be made by an operator with the correct access rights. For example, ABB's videographic recorders have a user-specific password-protected menu, from which the operator can elect to 'sign' for the data recorded by typing in a message. This 'signature' is then time stamped and logged by the recorder to provide a trail of all changes made, including when they were made and who authorised them.

Where data management is concerned, the requirement is that recorded data has to be managed and preserved to the same standards of data integrity as during the recording process and that the risk of unauthorised tampering or alteration of recorded data is eliminated.

In the case of ABB's videographic recorders, specialised analysis software is available that enables all data recorded to be downloaded for easy viewing and analysis of recorded process data. The security of data files created by an SM recorder is ensured by the use of binary encryption which preserves the integrity of the recorded data.

Avoiding microbial contamination

While chemical or other contamination is always a possibility, the major concern for food manufacturers is, inevitably, microbial contamination. Whether you are looking at the cooking process or the sterilisation of equipment between batches, it is essential to be sure that any micro-organisms are destroyed.

ABB recorders now incorporate a function designed to do just that. The ability of heat to kill micro-organisms in a given time increases exponentially with temperature. The time taken to cook a product or sterilise equipment can therefore be reduced if the process takes the heating and cooling phases into account. This results in a complex logarithmic function, known as the Fvalue, which can now be built into the recorder to help optimise the process.

Optimising a process based on the Fvalue can have a major effect on energy efficiency. For example, an increase in the sterilisation temperature of just one degree from 121 to 122degC reduces the time needed to kill a given number of micro-organisms by 26 per cent.

At a time when fuel prices are continuing to rise and environmental taxes are still biting, this kind of potential saving is certainly valuable. In fact, according to the Carbon Trust, adopting the latest control and monitoring techniques can yield energy savings of between 2 and 6 per cent on a typical UK industrial site.

Add this to the process benefits and reduced wastage that better control provides, and there can be no real argument – it is time to switch.