Deep-fried food is still a best-seller on British menus - but greasy food isn't. The benefits of investing in effective methods of maintaining oil, especially filtration, are likely to be heightened by rising concern about the health risks of long-life processed oils. Bruce Whitehall investigates
Cholesterol, acrylamides, obesity: caterers are well-used to the negatives of fried food. But while chips, fried chicken, tempura, battered fish, goujons and other menu staples stubbornly remain as popular as ever, the latest headline grabber - trans fats - could ultimately prove more influential on customer behaviour.
A worrying source of trans fats are vegetable oils that have been subjected to a heat-based hardening process known as hydrogenation. Such oils have been a boon to caterers for more than 30 years, enabling a key kitchen resource to last longer and deliver a more stable flavour, with lower saturated fat content than lard and palm-based solid fats.
But there has also been sufficient scientific evidence linking trans fats to increased risk of coronary heart disease for legislators in several major US cities to follow the lead set by New York and outlaw them from restaurants. This also happened in Denmark in 2003.
Most of the world's largest restaurant chains have already made moves to find alternatives to long-life oils, and these are likely to be influential on UK consumer perceptions.
For example, McDonald's plans to introduce a new oil with less than 2% trans fatty acid content at all of its 1,200 UK restaurants by late 2007. Orchid Group last month became one of the first UK pub operators to perceive a benefit, promoting its switch to non-hydrogenated oil across its 305-strong estate as part of other healthy food initiatives.
Caterers wanting to switch from oils that are high in trans fats have alternatives available that typically do not entail higher purchase prices. However, there are potential snags.
Popular oil varieties such as rapeseed and sunflower are, without hydrogenation, less robust and prone to deteriorate faster in repeated use in a deep fryer. This raises questions about the treatment of the oil in daily frying, and highlights the importance not just of choosing the most suitable oil but of specifying fryers that ensure the oils are correctly heated and adequately maintained.
The best protection for caterers is to tighten up regular oil maintenance procedures as necessary - for instance, accurate temperature control, correct food handling and basic precautions such as not overloading baskets.
To filter oil and remove carbonised matter, most fryer suppliers offer at least a gravity strainer tank, but manual discharge has two main snags. The tank must be left for some time to cool to a safe temperature, and the job is unpleasant and messy - with risks of making the floor slippery - so staff try to avoid it.
Barry Hill, marketing manager at Falcon Foodservice, points out that spills in these cases happen in the most dangerous spot imaginable - right in front of fryers. "Even if staff remember to wipe it up, there is still a greasy surface," he says.
For users of small fryers, portable units such as the £400 Newlife from Rowlett Rutland simplify transfer of the oil (cooled to less than 80°C) to the filter and back into the fryer. The table-top unit can be left to filter oil at a rate of about 10 litres in 10 minutes, and particularly suits fryers with no convenient drain tap.
Mobile filtering machines or fat tenders can be moved close to fry-tanks. Versions with bidirectional electric pumps suck out the oil and pump it back after filtering. The Merlin, from Steve Hill Services, can be used with high-efficiency reusable Superpad filters costing £1.25 each, or with regular paper filters costing 32p each.
Another specialist supplier is Carlson Filtration, with its Filtercorp vacuum filters and Supersorb carbon filter pads.
Built-in filtering systems are optionally available on several makes of fryers, with prices starting from £1,200. US examples include Frymaster (Enodis UK), Pitco (Frialator International), Anets and Alto-Shaam (Equip Line), Keating (Malibu Corporation), Elite (Imperial), Henny Penny (ServEquip) and most pressure fryers. European-made fryers with optional filter systems include Valentine, Infinity and Fri-Fri (Falcon Foodservice Equipment) and Electrolux.
For many caterers daily frying activity is often too small to justify investment in specialised filtering, so Lincat, which makes 29 different fryers starting at £199, promotes such features as optimum wattage density on elements to help reduce the rate at which the oil breaks down.
Filtration in action
Offering a Mediterranean-style experience at its four beach cafés and shops in Cornwall and Devon, the Venus Company is a champion of local food sourcing and environmental awareness. The latter extends to equipment efficiency, as with the Valentine twin-tank fryers used at each branch for cooking fries, hash browns, chicken fillets and goujons.
Owner Michael Smith found that the addition of built-in filters, now used daily, has significantly improved quality and safety. "We used to regularly suffer minor burns as staff touched elements and other parts when cleaning fryers," says Smith. The number of incidents has dropped dramatically, while the push-button process saves 15 more minutes of staff time each day. A Fastron computer has cut energy use, with the oil temperature allowed to fall from 180°C to 130°C if the fryers are not used for 15 minutes.
Best-known for soups, stews and griddled dishes, "noodle canteen" pioneer Wagamama uses deep fryers for popular dishes such as dim sum. After trials of several international makes, the chain's development chef, Jason Pettit, chose twin Anets MX-14EGU gas fryers supplied by Equip Line.
Integral Filter Mate units clean and return batches of as much as 50kg of oil and have a low-profile design which allows them to fit under each pair of fryers. One tank can be emptied and filtered while the other continues to fry, thus reducing downtime while oil is drawn from both the top and bottom of the fry-tank, so no residue is left.
At the Park Club, a 27-acre sports and leisure getaway in west London, executive chef Derek Smith and his team serve as many as 600 covers a day during the summer, and deep-fried dishes such as dim sum, tempura prawns and chicken goujons are popular with the club's 6,000 members.
But Smith found shortcomings in recovery time with his existing fryers, taking at least two minutes to regain the desired temperature between loads. Installation of a pair of Frymaster MJH50 fryers, supplied by Enodis UK, resolved this issue, while additional built-in equipment such as a fry computer and Footprint filtration system have - in an environment where members are conscious about their cholesterol intake - contributed to significant improvements in oil quality. Consumption has reduced by two-thirds.
"We filter daily, but it only takes four minutes to do each tank, simply by turning a lever," Smith comments.
Fryers have a "pivotal role" in serving more than 7,000 meals each day at the Butlins Minehead holiday centre. Dave Knight, guest catering manager, relies on a suite of six 75lb Elite fryers, all with built-in filter systems. A 175,000BTU burner jet-injection system ensures rapid oil heat-up and recovery, for less oil absorption and better tasting food. Supplier Imperial Catering, which offers both Side Car and Space Saver filter systems handling oil at rates as high as 23 litres per minute, points out that effective filtering can have a big impact on the life of a fryer, reducing running costs, spillage and wastage.
Key maintenance points
Fryers are among the most commonly used items of cooking equipment and are the cause of many personal injury accidents and fire hazards. To reduce risks and minimise maintenance issues:
Change the oil if it smokes at normal operating temperature, if it looks dark or if it's cloudy when hot.
If clean oil smokes at normal temperature settings, it might be overheating because of a faulty thermostat, so get it checked before it all catches fire.
All fryers are fitted with a safety thermostat to stop them overheating. If it trips out, you might be able to reset it, but call a service engineer to check it. Don't reset it more than once.
Before draining the oil, ensure the fryer is switched off long enough for the oil to cool to 60°C or lower. Don't leave it switched on at low temperature or the oil might overheat when the level drops below the thermostat probe.
When refitting electric heating elements after daily cleaning, lower them carefully into position and don't damage the thermostat probes.
Never switch the fryer on without checking that the oil is at the operating level.
Regularly empty the oil and filter it before pouring it back into the pan.
Ensure that the ventilation fitted above the fryer is clean and operational.
Source: Serviceline (01438 363000)
Carlson Filtration 01282 811000
Enodis UK 01252 371000
Equip Line 01895 272236
Falcon Foodservice Equipment 01786 455200
Frialator International 01925 821280
Lincat 01552 875500
Malibu Corporation 0161-874 5400
Imperial Catering 01509 260150
Rowlett Rutland 01372 453633
ServEquip 0845 390 9808
Steve Hill Services 01452 521081
Valentine 0118 957 1344
Expect to pay about £270 for a good-quality single-basket, single-tank model featuring: all-stainless-steel fabrication a timer lift-up or lift-out elements for easy cleaning a front-mounted tap for emptying the oil into a container for filtering and reuse thermostatic control with fail-safe top temperature cutout to maintain accurate oil temperature and ensure safe operation 13amp, 3kW output and a nine-litre oil capacity. This should produce about 7-8kg of frozen-cooked chips per hour.
Expect prices of about £420 for a twin-basket, double-tank version (2 x 3kW output, 2 x 9 litres). Each tank will have independent heating controls/thermostat and timer, and the total capacity is about 14-16kg of frozen-cooked chips per hour.
The more power, the faster the recovery time and the higher the output after the cold chips hit the oil. At the top of the range in electric counter-tops are the more strongly built medium-duty double-tank fryers, costing up to £1,900, with power outputs of 9kW per tank, producing as much as 45kg of chilled-cooked chips per hour.
Prices for a single-tank light- to medium-duty electric floorstanding fryer start at about £500 for a reasonable-quality base model. Its capacity of seven litres and 6kW power input is capable of producing 14kg of frozen-cooked chips per hour. A double-tank version with 2 x 6kW power, loading and producing 28kg chips per hour, should cost about £900. Filtration is achieved on these models using a tap and a separate filter/sieve mechanism.
The gas equivalent of a base model will cost about £1,000 but deliver 12kW of power, with a 120-litre capacity yielding about 16.5kg of frozen-cooked chips per hour.
Mid-range, medium- to heavy-duty freestanding fryers such as a 12kW single-tank 20-litre unit capable of producing 32kg of chips per hour will cost from £1,500, while 22kW mid-range fryers producing 45kg of chips cost from £1,900.
Heavy-duty high-output fryers such as an electric double-basket double-tank fryer with 38-litre capacity and a 35kW power draw will cost about £3,500 and will produce 54kg of chilled-cooked chips per hour. The equivalent gas model with 30 litres capacity will cost about £500 more, but will produce as much as 64kg per hour.
At the top end of the fryer market are computerised and automated fryers, popular with the fast-food chains, in particular, because they help to guarantee consistency by controlling the cooking time and temperature and then lifting the product out of the oil via an automatic basket lift.
Computer control will add from about £1,000 to the cost price of the fryer, with automatic basket lift options costing upwards of £1,200.
Source: Mike Nunn, of Dentons Catering Equipment (020 7450 0480), a member of the Catering Equipment Distributors Association (CEDA)