Filter tips
At around 10.30am every Monday, a small van pulls up outside the Chicago Rock Cafe in Sutton, Surrey. A stainless steel contraption is wheeled into the kitchen. Within about 20 minutes, all oil in the restaurant's three Fri-Fri fryers has been passed through a pressurised cleaning process and fed back to the tanks, ready for use.
The Chicago Rock Cafe, an American-themed diner which opened in February this year, is one of a small but growing number of catering establishments to contract out a key part of its frying oil maintenance.
You can own the best fryers available - from high-profile brands such as Valentine to fryers such as Garland's Masterjet (which is regarded by many as the Rolls Royce of deep-fat fryers). Yet no matter what the pedigree of the fryer, get the oil and its filtration system wrong and the fryer can be an enemy rather than a lucrative friend.
So how do you get your oil filtration system right and get the best from your deep-fat fryer?
A service called FiltaFry carries out the job for the Chicago Rock Cafe, charging £20 per visit, which also includes thermostat inspection and other basic equipment checks. The charge covers operations using up to 45 litres of oil. Above that figure, 20p per litre is added.
Is it worth it? The 65-cover restaurant deep-frys a lot of chips, plus Cajun onion rings, breaded prawns and battered mushrooms, using a basic all-purpose vegetable oil priced at £12.85 per drum. "The oil almost comes back to new," says head chef Keith Greaves. In effect, the Monday "deep-clean" means that oil remaining from the weekend, when the restaurant does most of its business, can be retained rather than dumped.
On Greaves's reckoning, the restaurant's oil expenditure has dropped from £50 per week to about £25. It's a modest saving but contracting out the job also cuts out an unpleasant task. On other days of the week, kitchen staff carry out basic oil maintenance by letting the oil cool down and then opening the valves in the bases of each fry tank to let the oil pass through a gauze-type sieve. It is then poured back into the fryers.
This deals only with visible particles of burnt matter in the oil, whereas the FiltaFry, which can deal with oil at full operating temperature, is designed to remove minute traces of debris down to two to three microns. It thus actively purifies the oil, removing most of contaminants which cause the oil to break down and reduce cooking quality.
The secret lies partly in the pressurised filtering process and partly in the filtering medium. The portable filtering machine is fitted with two sets of hoses, one to suck dirty oil from the tank, the other to feed back the cleaned oil. In between, the oil passes, at a pressure of 2-3bar, through a circular metal pre-strainer and then through a circular solid wood-fibre block which is about 150mm thick.
This patented technology was developed from research initially carried out in Switzerland. UK developer Inativ International quotes trials by an independent test house to show that, in an application where the oil was previously dumped, the weekly clean could extend oil life three to five times.
The powerful US-made pump moves the oil at rates of seven to 15 litres per minute, enabling a typical fryer to be emptied and refilled within a couple of minutes. The main disadvantage visible at the Chicago Rock Cafe was the physical challenge of moving the 50cm x 65cm filter machine via the three steps leading into the kitchen.
A basement kitchen without a goods lift would seem a virtual impossibility for FiltaFry operators, who run the scheme on a franchised basis.
It is possible to buy a FiltaFry machine outright at a cost of £2,500. Each filter cartridge, which is good for about 7-8 separate sessions, costs £7.50.
The Welcome Break motorway service area at Newport Pagnell owns a FiltaFry machine in order to clean the oil in the fryers in its two Granary restaurants and one Little Chef unit.
According to operations manager Henry Cavelot, the machine was purchased mainly because the previous mobile filtering system entailed delays while the oil cooled. "With a 24-hour service that posed a problem." The FiltaFry can take the oil at 180º C, ensuring no breaks in production.
Fish frying
One question mark over contracting out a job such as oil maintenance lies in the frequency of getting the job done. "If you are a very busy unit, like ours, you may need to filter your oil during a shift," says Fred Capel, proprietor of Chez Fred fish and chip restaurant in Bournemouth. "You can't just wait for someone to come round". In fact, on a busy day Capel finds it necessary to filter some of his tanks three times to ensure that the oil is constantly in peak condition.
The answer to this demanding requirement, both at Chez Fred and at Whitecaps restaurant in High Barnet in North London, where Capel is a partner, lies in the use of Dutch-made Florigo fish and chip frying ranges. These differ from traditional British frying ranges in several ways. For a start, the tanks are circular and relatively small: 15 litres for chips and 20 litres for fish.
The range also has a built-in drain outlet and motorised filtering system. This makes it possible to switch off one pan when empty of food and filter immediately, passing the hot oil through a long-life Miroil filter basket and pumping it back, ready to fry, in less than five minutes, without interruption to work on the other pans.
Such speed would just not be possible with mobile filtering units, Capel feels. "They do a good job but there is nothing quite like the speed of a built-in filtering system."
He also sees the Florigo small pan design as an investment in frying quality. "You are frying in smaller quantities but more often, so ultimately you are giving customers a fresher product and there is less oil standing hot doing nothing in quiet periods," he points out.
The outcome of the filtering system is that Capel never has to dump any of his oil. With about 40% taken up in the food during a busy day, he simply keeps topping up. "Frankly, if I was given the choice of having brand-new oil in my pans every day, with no financial penalty, I would still have my existing oil. Having already cooked in it, you get that extra bit of colour in the finished product. The food can look incredibly bland when cooked in a whole tank of brand-new oil."
Another useful feature on his frying range is a computer control system called Stork-Tronic. This is also designed to maximise oil usage by eliminating the problem of temperature over-run.
When a conventional fryer thermostat control is set to, say, 190ºC, power input stays fully on until that temperature is reached, which can mean that the oil actually goes as high as 205-210ºC. "It's a bit like a car going flat out at 100mph - you need more time to put the brakes on," explains Capel.
Computer control provides this time, trimming the power input gradually as the oil nears the desired set temperature. Result: less stress on the oil, and better-quality food. A further potential benefit of computer control is in dealing with solid fats, ensuring they are fully melted before switching the power to full. However, in Capel's case this feature isn't needed as he is one of a growing number of fish fryers to use only liquid vegetable oil.
Losses in millions
The benefits of built-in filtering and computer control in fryers are well-established in the high-volume fast food business but are still not widely specified in hotels and industrial catering. This represents a loss of millions of pounds annually in prematurely discarded oil.
A good demonstration of just how tangible the savings are in mainstream catering can be found at the GEC Marconi Sensors factory in Basildon, Essex. With about 1,700 people on site, the staff catering operation serves about 300-400 large portions of chips each lunchtime plus deep-fried mushrooms, fish, scampi and other battered dishes.
When catering manager Colin Chapman replaced an ancient frying range two years ago, he decided to specify a built-in filtering system. He chose a suite of three Garland high-output gas fryers with an integral Filter Magic system, which takes the form of fourth section matched in with the fryers. Its top comprises a heated dump for holding food, with a halogen light hanging over, so no space is wasted.
Each fryer is, in effect, plumbed in directly to the filtering system so it is possible to filter-clean the oil from each tank simply by pressing a button. One feature Chapman especially likes is the ability to pump between fryers, which makes it possible to clean out one tank and then replenish with oil from another, thus saving time and providing maximum operational flexibility.
This ease of use has a tangible pay-off. With the old frying suite, a kitchen porter had to spend about two hours every day manually draining off each tank, filtering the oil, cleaning the tanks and pouring the oil back in. "Because it so easy to do, the chefs are prepared to do it, and more frequently," says Chapman. "They normally won't touch anything which they see as a kitchen porter's duty but they actually quite enjoy playing about with a bit of technology."
The financial savings are also very real in terms of weekly oil usage. "You hear all these stories about how much oil you can save, but this has been much greater than anyone's expectations." Chapman estimates his kitchen was getting through about 120 litres per week. That same amount of oil is now sufficient for about two months' frying.
He adds he can normally tell with oil when it has lost its capabilities because it boils rather than fries and it starts frothing. Its improved condition owing to the Garland filtering system means that it kept going, with just small daily top-ups.
The filtering is carried out by passing the oil through a filter paper sprinkled with natural diatomaceous earth (derived from volcanic ash) whereas before it was passed through a much more open mesh gauze. Finer filtering helps the oil last longer and also means that the fryers stay cleaner.
"The old fryers used to become carbonised around the edge with very fine deposits getting burnt on," Chapman points out. Pump-back of filtered oil into each tank is via a shower-type attachment. This causes the oil to flush down the sides of the tank, which also aids cleaning.
Oil maintenance also benefits from the very deep cold zone in the base of the Garland fry-tanks that serves to catch larger particles of cooking debris and keep them well away from the food. The high performance and high quality of Garland does not come cheap, admits Chapman. Current list price of a suite similar to that at GEC is £12,243, with the Filter Magic system adding about £4,508. But Chapman believes investing in the Garland equipment was a sound move. He reckons that the equipment has now been virtually paid for from oil savings alone.
Mr Chapman also looked at the potential of a built-in computer system but was warned off by engineers in his company, who felt that there would be too much potential for the equipment going wrong.
Zoo chips
Like most big family leisure attractions, Chester Zoo sells a lot of chips and built-in filtering, operated daily, is standard on the Pitco fryer suites operated at its four catering outlets. "It makes a tremendous difference," says catering manager Sue Clews.
Until this year, the zoo relied entirely on powerful gas-fired fryers but its most recently opened outlet was out of reach of mains gas so it was decided to install equivalent electric Pitco fryers. Which works best? Clews has not had a full year of operation so cannot yet compare energy costs fully but operationally she finds little to choose between the two fuels, thanks in part to the tube-fired design of the Pitco gas models.
"Performance is our key need, with the fryers switched on at 10am and switched off at 7pm at night and working continuously all day. I don't think there is difference between the two fuels. Electricity is more direct in heating the oil, but gas is cheaper. So, over the year, we expect it to even out."
Mobile filter machines
For most caterers concerned about the extra cost of fryers with built-in filtering, there are plenty of options in portable and mobile filtering units, from table-top units such as the Rutland Newlife, costing a few hundred pounds, to wheeled units such as those of Bitterling Engineering, costing around £2,000 for a 10-gallon capacity mobile machine. Ian Acocks, Bitterling sales co-ordinator, says that most hotels and restaurants still have done little or nothing to mechanise their filtering operations.
That's also the view of (FAST) International, another specialist filter machine supplier. "Everybody with a fryer should at least be thinking of a portable fat filter if they are not using a built-in filter system," says managing director Steve Loughton.
But he is not sure about the viability of bringing in outside oil cleaning contractors. "One of our filtering machines costs about £1,700 complete so it does not take long to pay for it, and you can use it whenever you need it. Compare that with paying £20-30 for someone to visit with a filtering machine once a week, where you are going to get perhaps 50 filters for the price of one of our machines."
Neil McCloud, sales manager of Filtercorp Europe, believes that many of the existing filtering systems on the market can be improved using more specialist types of filtering media than filter paper plus diatomaceous earth. Filtercorp's answer, now adopted across the Burger King chain in the UK and elsewhere is a carbon-impregnated filter pad which is claimed to filter down to half a micron.
"You might get as much as 20 microns with paper and powder if used correctly but it can be as high as 50 microns," he suggests. The fineness of the filtering is claimed to deal with common oil problems such as trace metals and alkalinity from trace amounts of soap or detergent and meat plasmas getting into the oil. Each single-use pad costs just over £1 compared with about 60p for disposable paper filters.
