At it like knives

27-Aug-2007 - Last updated on 13-Mar-2017 at 17:08 GMT

Related tags Pork Meat

Slicing, dicing and cutting is the unlikely setting for some of the latest automated innovations in food processing, explains John Dunn

Britain's food industry may not be renowned for its eager adoption of automation, particularly the glamorous stuff such as robotics, laser scanners and vision systems. Yet, ironically, one of the least glamorous corners of the industry is now going ape for automated systems.

Slicing, cutting and dicing machine builders and suppliers are bringing the latest automation to food factories. Vision systems and robots are slashing give-away in fixed-weight packs of sliced meats and cheese and raising throughput. High frequency ultrasonic knives are giving a squeaky clean cut to products from candy bars to Black Forest Gateaux and scything through machine clean-up times. The reason is simple. Major retailers and supermarket chains want fixed-weight packs of pork chops, ham, salami, and sliced cheese. They don't want slices that have too much fat in them or too many holes.

Neither do they want crumbs and pastry debris and chocolate smudged across the white cream centres of their pre-cut portions of gateaux and cream cakes. But they do want their sandwich wedge packs and tortilla wraps to show perfectly clean cuts across the fillings, whether it's sticky brie or cooked chicken.

The result is that food manufacturers are increasingly turning to automation in their cutting and slicing operations to help them give their customers what they want without increasing their own waste, give-away and labour costs. Even meat chopping and dicing is feeling automation's wind of change, albeit a mild zephyr. "We have launched a new dicer; rather than put meat in one end and it comes out at the other end cubed, we now weigh it," says Ross Layton, sales consultant at meat and cheese cutter and slicer supplier Treif.

Why has it taken the meat industry so long to adopt such a seemingly simple piece of automation? Layton is bemused. "I have no idea. A lot of food factories supply diced meat and bacon in 5kg or 10kg bags. And in the past people would be content to stand over a big tote bin full of diced meat coming out of the machine and scoop it into bags or boxes and then manually weigh them.

"Our Argon dicer has scales at the end of the conveyor to take a standard container. The diced meat falls onto the conveyor and into the box or bag on the scales. You program it to load say 10kg and once the bag or box reaches 10kg the dicer stops. And when you put a new bag or box on the scales, it starts again. It is really simple, it doesn't cost much more and it saves a hell of a lot of labour."

New meat slicer makes an impact

But it is Treif's new Falcon Conti portion control slicer for meat products such as pork chops that turned heads at the meat industry show in Frankfurt earlier this year. "You just put loins on the conveyor belt which takes them to the machine where they are gripped and sliced automatically," says Layton. The machine uses laser scanners to find the area of the loin face, calculate the average density of the loin and work out how thick to cut each slice to produce a fixed weight chop. The chops pass over a weight checking sensor which then feeds back to the slicer to automatically adjust the thickness of the cuts for the next loin. "The Falcon Conti is the only machine in the world that can do fixed-weight slices for both bone-in and boneless meat products," says Layton.

AEW Delford is also finding growing interest in fully automating the slicing of cooked meats and cheese, particularly for more 'natural' products such as premium sliced ham where there tends to be less consistency between each 'log' or block of product on the slicing line. The more natural trend means that hams, for example, will not have been compressed so much and will still have holes where the bone has been removed, says Tony Ambrose, marketing director at AEW Delford. They will also have ribbons of fat running through and maybe cracks across the face, he says.

This presents a challenge for fixed-weight slicing, says Ambrose. "You can laser-scan the product to work out its average density, but holes or fat are not consistent through the product. And 'old' systems that use checkweighers to feed back to the slicer would result in substantial give-away."

More automation in the form of its PolySlicer 3000 Vision for cooked meats and cheese is the answer, suggests AEW Delford. The new slicer uses a patented vision system to scan the front face of the product after each slice. This detects and measures areas of fat and voids to work out the density of the product and thus calculate how thick to cut it to give an accurate fixed-weight slice. One customer, supplying a major supermarket with fixed-weight packs of 'more natural' ham, has slashed its give-away by 90% with the new machine, says Ambrose.

The machines can be integrated with the ABB FlexPicker robot to automatically pick up stacks of slices for packing into trays and thermoformers, says Ambrose.

Demand for high quality cutting

But supermarkets don't just want fixed weight packs. They also set high standards for the quality of their sliced meats and cheeses, says Ambrose. "They don't want an area of fat larger than X; they don't want a ribbon of fat wider than Y; they don't want a hole bigger than Z. They don't want blood spots." With a vision system mounted on the robot, you can detect all these quality defects, he says.

However, the robot packer can be slower than the slicer. So AEW has used this mismatch in speeds to eliminate the time taken to load new product into the slicer.

Designed for short, irregular-shaped blocks of product, such as hams, that have to be gripped individually in the slicing machine, AEW Delford's vertical buffer system runs the slicer faster than the robot can handle. One-in-six stacks of slices, say, is removed and kept in the buffer store, so the robot runs at optimum speed. When a product block needs replacing, these stacks are fed from the store to the robot to ensure it continues packing while a new block is loaded. This can give a 20% increase in output by not stopping the robot while blocks of product are changed, says Ambrose.

It is an open secret that Mars cuts all its candy bars with ultrasonic knives and that Marks & Spencer pioneered the use of ultrasonic cutting for its sandwich wedge packs. Most suppliers of cake and gateaux slices use ultrasonic knives. Before it sold its Birds Eye frozen foods business, Unilever had been experimenting with ultrasonics for slicing through blocks of frozen fish. "Ultrasonic cutting used to be a niche business," says Paul White, sales manager at ultrasonic technology supplier Branson Ultrasonics. "Certain major food companies have been using it for years and have kept quiet about it. Today ultrasonics is taking off, particularly for sandwich cutting."

Ultrasonic cutting in the food industry uses a guillotine slicing action in which the blade vibrates in the direction of cut at ultrasonic frequencies of 20-40kHz. The rapid acceleration and deceleration of the blade throws off food sticking to it and prevents smearing and smudging. Hence its wide use in cutting delicate products such as gateaux, cream slices and sandwiches.

The ultrasonic energy fed into the blade creates a localised heating effect so that an ultrasonic knife can melt its way cleanly through a bar of chocolate or nougat, or through a block of frozen fish, without melting the main mass of the product. "Ultrasonics is being used in a big way for cutting gateaux, pizzas, and cheesecake," says White.

Ultrasonics will also cut cleanly through cakes high in fruit and nuts, he says. "It will cut through the nuts without disturbing the nut itself." White has also seen one baker use an ultrasonic knife to score slits in the top dough before baking. "One petfood manufacturer uses it because their product has a white outer and a brown inner layer. A normal mechanical blade would drag the dark brown inner across the white surface of the cut outer layer. While that would be OK for the pet, it didn't look good. So they turned to ultrasonics."

But there is one food that ultrasonics has not yet been able to crack, says White. "We do have a problem with sushi. It's the combination of sticky rice and the wrapper." FM