How a high-tech robot is running a UK cheese cave

Alongside son Tom, he runs Westcombe Dairy near Shepton Mallet in Somerset. The business trades on being one of only 4 cheddar producers in the county using unpasteurised milk.

The basic principles of the production process for this handmade cheese haven’t changed for centuries. You couldn’t get much closer to the traditional way of doing things than this.

Even though the business might be steeped in tradition, the Calvers themselves are not ones to stand still.

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Running 2 herds of cows totalling 380-head alongside the cheese factory, they’ve had to move with the times, constantly altering their breeding to produce the right raw material for the plant and using the most up-to-date technology to ensure productivity and high welfare standards for their cows.

While much has changed in the milking herds over the past 20 years, the processing side of things has seen little alterations. But there has been a gradual growth in scale that sees some 150t of cheese leave the farm gates each year.

That was up until 2 years ago when the family decided to make a bold move to invest in a state-of-the-art cheese ‘cave’.

Cheddaring

The ‘cheddaring’ process is still very much a manual job, with whey driven out of the curds by cutting, stacking and tearing. Then follows 3 days in a hydraulic press. Of equal importance is how the cheeses are handled, stored and aged. That has a huge influence on the taste and texture of the finished product.

For decades the aging process for Westcombe Cheddar has taken place in insulated, converted farm buildings – an old cow stall. But maintaining a constant environment with consistent temperature and humidity in such a setup is a tricky, costly process.

And then there’s the issue of turning and brushing the cheeses. For the 12-18 months they’re in the store, the cylindrical forms must be up-ended about 25 times. Initially, it needs to take place every week, but as the rinds harden it happens less frequently.

Very soon moulds start to grow on the outside of the muslin cloth that holds the lard covering on each cheese. One of the main issues when storing cheeses in the traditional way is mites can eat into and damage the cheese. Therefore each truckle must be brushed to knock off the mites. Until now that’s been a manual job.

“With each cheese weighing 24kg it’s a very physical process and, in truth, it never really got done properly because it’s just so hard to find people prepared to do it,” says Richard Calver.

“And then there’s the issue of human error. Inevitably, handling such big heavy lumps, some get knocked. That often leads to a crack which air can get into, creating blueing – and buyers don’t like that in a cheddar.

“We knew we needed to do something about our storage and handling set-up. We wanted to recreate the natural cave-type environment, but with more control of humidity and temperature. A more consistent atmosphere leads to more consistent cheese with less cracking and blueing.”

French influence

10 years ago, the Calvers went to visit a company called Marcel Petit, which ages Comté cheeses in an underground Napoleonic fortress close to the French-Swiss border.

With demand for its famous Fort Saint Antoine cheese growing rapidly, the business was struggling for storage capacity in the underground tunnels that had served as the ideal aging environment since the mid-1960s.

These Alpine cheese-makers strongly believe in the concept of “affinage lent” – slow maturation. The business was struggling with how it would extend its storage capacity while maintaining those same cool, consistent conditions that the ancient tunnels provide. Short of digging into the mountains once again, the options looked limited.

The only other option was a concrete structure built into the hillside with vaulted ceilings to recreate the environment found in the tunnels.

Richard and Tom saw how well the concept worked and decided to build something similar back home in Somerset, integrating a robotic cheese-handling and turning system.

“The idea was proven to work, so we contacted some specialist firms here in the UK,” says Richard.

“But none could build us a straight-sided store with vaulted ceilings for sensible money. Their designs all had arched spans reaching right down to ground level. That hangar-type approach means lots of wasted space.

“So we approached the French firm that had built the Fort Saint Antoine store. They were only too happy to be able to have a second use for the moulds they had built for the original building. They obtained a grant from the French government which meant their quote was far more competitive than anything we’d already got.”

The build

The ground works were done by a local building firm ready to receive the precast concrete structure. As the pillars that form the uprights arrived they were bolted into position and then the precast arches were craned in.

Overlapping with the cross members by just 10mm, they were then stitched together with steel lattice-work and poured concrete. Next, reinforcing steel and formwork shuttering was put in place for the poured concrete walls.

The vaulted ceiling panels were then lowered in, the joints filled with more concrete and finally the whole roof covered with a membrane, gravel and soil, blending it back into the Mendip hills.

“Despite the fact that we want the store to stay at a relative humidity of about 85-90%, we needed the structure to be completely watertight so we could control it ourselves. That meant double-tanking the walls and making sure gutters and drains around it functioned properly to channel water away.

“The building process was relatively straightforward – just like a Lego set only with bigger blocks.”

Tina-the-turner

The next phase was to get the shelving in place that would accommodate the cheese rounds 12 high. Once again this was designed and made in France from slow-cured spruce specifically to work with the cheese turning robot the Calvers had chosen.

“We approached French robotics specialist JNJ to supply us with a machine to do the turning and brushing job automatically.

“Despite building hundreds of similar machines for the European market they had never made one to handle the uniquely sized cheddars we produce. But they had the expertise and for less than the cost of a self-propelled forage harvester, they supplied us with Tina-the-Turner.”

Looking much like an unmanned forklift gliding almost silently up and down the rows of cheeses, the JNJ robot uses an array of laser and ultra-sonic sensors to guide itself through the store.

A belt-fed fetching arm lifts the cheeses off the shelf on to a turntable. Once there, they are inverted, brushed and vacuumed, as required. Simultaneously, the conveyor arm retrieves another, which is swapped for the first once the process is completed. That way no part of the machine is ever standing idle.

Each cylindrical block has an electronic chip with the muslin wrap, which enables the Calvers to register its position. This means that every one of the 5,000 cheeses on the shelves can be located in seconds and its records retrieved.

“For traceability purposes the chip system is brilliant. We know exactly what day the cheese was made, which herd the milk came from, how many times it has been turned, etcetera.”

“Since we’ve had the robot we’ve never had to turn or clean a cheese manually. It’ll process just shy of 100/hour – more than double what is possible by hand. Unlike a human, who can only really do the work for a couple of hours at a time, Tina can work 24 hours if we want it to. That makes the expense pretty easy to justify – we no longer have the labour cost and the job gets done properly.”

Keeping cool

Being buried in the side of Westcombe Hill, with the help of readily available cool spring water, the store temperature is now much easier to maintain at a steady 10.5C.

Deep inside the slopes of the farmland, water remains at a constant 5-7C. It is pumped to the surface and runs through a heat exchanger to cool a closed circuit of cooling water down to 2.4C. That runs in copper pipework through the vaulted arches of the store roof.

As the air around the pipes cools, it sinks, providing a natural refrigeration effect, cascading down through the shelves of cheeses. It is far more energy efficient than a conventional store with electricity-hungry fan units whirring away constantly to keep the temperature stable.

“Thankfully we’ve got [photovoltaic] panels providing electricity for the store and a microbrewery that we have on site, but energy use has dropped massively thanks to the underground set-up.

“The other big bonus of the cooling system is that without fans blowing air through the store, we don’t have a rapid drying effect any longer. That helps to reduce cracking and the subsequent blueing that can devalue the final product.”

But it’s not a completely closed setup. As the cheeses mature they give off ammonia so each evening the air in the store is changed. Sucked out at floor level, fresh air is drawn in through underground ducting that means temperatures are kept as low as possible, even in summer months.

Distinctive flavour

While getting fresh air into the store is critical now it’s up and running, it was important  there wasn’t too much when it was first commissioned. For five weeks prior to the first cheeses going in, air from the old store was pumped across every night to “seed” the new store with the fungal spores that give Westcombe cheddar its distinctive flavour.

In the same way it was important the cheeses already in the store were moved across to the new building in one go, carrying all the vital bugs and bacteria with them.

All in all, the combination of having Tina-the-Turner cosseting the cheeses and having the store half-buried in the hillside at Westcombe has meant cheddar production has become a more efficient, consistent process, allowing the Calvers some breathing space to think about expansion to cope with rapidly growing demand for their artisan product.

“Having a robot working in our new energy-efficient underground cheese cellar doesn’t detract from our roots, it just means we now do the job better,” concludes Mr Calver.

“Using modern technology in a traditional process is the only way we can continue doing what we do. It’s meant that Westcombe Cheddar will always remain a traditional hand-made cheese.”