There are chips, as in fish and chips and there are chips, as in Heston's triple-cooked, Michelin three-star chips. Is there a quantum difference? Chef John Campbell (the Vineyard at Stockcross) and Chris Pittaras, current Central and Southern region Chip Shop Champion (the Plaice, Winchester) unravel the hype from the reality.
McCain's probably invests more in chip frying technology year on year than the Fat Duck's profits, and the techniques applied by luxury restaurants today originated in research done by food industry technologists.
For this Masterclass, Pittaras and Campbell prepared 10 samples, either cutting the potatoes by hand or using a standard 1cm x 1cm chipper (photograph 1). Pittaras said that he would normally use a larger-calibre chipper in his shop - 12.5cm (1/2in).
The oil should be drained and filtered and the fryer cleaned every day. How the blend of fresh and old oils is decided will depend on the quality and the amount of use they have had.
For this Masterclass, a standard fryer containing vegetable oil at 140°C was used for blanching. The oil blend was approximately 20% old oil combined with 80% new oil. This combination gives a better colour.
For finishing the chips at 185°C both used a blend of 50% freshly rendered beef dripping, 40% vegetable oil and 10% old oil - "similar to the original Harry Ramsden recipe", according to Pittaras. This gave an extra kick of flavour to the chips produced here, but both he and Campbell said they would not normally use it because of the growing number of vegetarian customers.
At the margins
Cutting by hand with a sharp knife may reduce the amount of oil absorbed, but it doesn't make a chip any crisper.
Blanching the potato in water before frying makes the mealy centre of a chip drier and more fluffy.
Once blanched in oil, it doesn't really matter whether the potatoes are left to cool before the final crisping or whether they are fried at once.
Deep-freezing chips is a helpful practical option where chips are fried to order. The technique mirrors the industrial food manufacturers' method. It has no adverse effect on quality.
Osmosis and chips
If you leave potatoes in water, either peeled or chipped, two things happen: the water permeates the potato and the starch from damaged cells leeches out. This is not going to help the frying process at all. Never soak raw chips or leave potatoes standing in water.
When you put potatoes in oil, the reverse happens. The water from the potato is drawn out and the oil is drawn in. By frying, the chef draws out some moisture. At the same time he needs the oil to crisp the surface.
Blanching a chip in water has marginal benefits. It cooks the centre, effectively - drawing out moisture. At the same time it creates a kind of starch wall between oil and the starchy meal. When fried, the chip will be crisp but require less oil.
The chip shop solution
The Plaice uses 25kg bags of fresh potatoes, which yield, after peeling, about 33 portions. Preselected for size, their price fluctuates around £5.50 a bag. Pittaras gets his potatoes from a merchant whose supplier does random frying tests before sending potatoes on to his clients.
From the autumn onwards Pittaras prefers Maris Pipers grown in Lincolnshire and Cambridgeshire. They are the classic English chipping variety: mealy, with a dry matter above 20%. In summer he may work with Wilja or Premier.
Preparing the potatoes
At the shop, the whole potatoes are "rumbled" to remove peel, and eyes are removed by hand. They are rinsed before chipping.
Note Many chip shops soak the chipped potatoes in a water and sodium metabisulphite solution, mainly to prevent browning. It has the disadvantage of creating an acid film on the chip surface which causes oil to break down more quickly.
Blanch at 140°C (Pittaras uses 130°C at the Plaice). Here he was working with a single portion. When working with a batch, the volume of oil to product would be a minimum 4:1, but he wants the temperature of the oil to drop and come back.
Pittaras blanches the potatoes until they are cooked (2). He tests this by hand, squeezing a chip between thumb and forefinger (3). Time isn't relevant here, because batch sizes vary in a work environment.
Fry at 185°C (180°C at the Plaice) (4). Fry until crisp and golden. Drain well.
Texture The surface forms a distinct, crisp case for the mealy inside. This is soft but still moist (7).
Flavour The potato taste is clean and persistent.
The hotel solution
Campbell points out that although the Vineyard boasts a two-Michelin-starred restaurant, it's also a hotel, and may serve as many as 40 portions of chips a day - demand is inconsistent. Campbell's solution is to freeze the blanched chips and finish them to order (5). He is currently working with a potato, Lover's Choice, similar in character to a Maris Piper, and insists that his produce undergoes no cold storage en route, as this would quickly affect the starch content.
Preparing the potatoes
Whole potatoes are hand-peeled and chipped. In a gastronomic situation, where finish is critical, he would cut them by hand.
Note With a very sharp knife this will cause less damage to the cell structure on the chip surface. After frying, the chip may have absorbed less oil but might seem to be less crisp.
Blanch chips in a pan of simmering water for eight minutes. Drain and cool (6). Blanch chips in oil at 140°C for six minutes. Drain, cool and blast freeze.
Fry in oil at 185°C till crisp. Drain and sprinkle with "vinegar salt" (see below).
Texture The surface forms an even, very crisp case. The mealy part is quite dry and fluffy.
Flavour The potato taste is clean and persistent. For the purpose of this exercise Campbell compared both fresh and frozen chips, hand- and machine-cut. Results were comparable.
John Campbell's vinegar salt
Combine 750g coarse salt and 750ml sherry vinegar on a tray. Leave in a hot part of the kitchen until the vinegar has evaporated and the mixture is dry. Blend to a fine powder.
What makes a good chip
â- Potato storage (5-10Â°C) and its condition when processed.
â- Its dry matter as a percentage of weight.
â- The quality and condition of the frying medium.
â- Correct temperature management when frying.
â- The ratio of oil or fat to the product.
Other potato varieties
Campbell prepared portions of chips with two varieties that are not normally recommended for frying:
â- Yukon Gold In this case the surface of the chip became a darker mottled brown (8).
â- Milva In this case there was some blistering of the crisp surface that was also too brown to be attractive.
These results reflect excess caramelisation. It could have several causes. This could be a result of the varieties themselves, their storage (either under controlled atmosphere or cold damage) or the soil in which they were grown.
Apart from his role as executive chef at the two-Michelin-starred Vineyard at Stockcross, near Newbury, Berkshire, John Campbell (left in picture) is coâ'author of the current 11th edition of the classic catering manual Practical Cookery. With a first-class degree in international culinary arts from Thames Valley University, Campbell is passionate about the science, history and creative aspects of cookery.
Chris Pittaras is the third generation of chip fryers in his family. His parents and grandparents both had shops on Merseyside and he grew up working for them. He has owned the Plaice, in Winchester, for 12 years and is the current Central and Southern region Chip Shop Champion.
The chippy, the chef and the food manufacturer
They all have the same goals, but they may come at them from different angles.
In the industrial situation, the manufacturer wants the maximum yield of chips for the minimum cost, so it will control every nano-stage of the business, from potato field trials to the life of its oil based on 1Â°C changes of temperature, or the use of chemicals to enhance crispness stability.
The chip shop is also concerned with yield and oil use, but it trusts its potato merchant to supply its needs and uses its experience to produce the product its customers like.
Chefs, at least the creative ones, are looking for an edge that will make their chips better than anyone else's. If they find a better variety of oil or potato than the manufacturer can either afford or acquire in quantity, they'll use it.
A little science
To assess suitability of potatoes for chipping, potato merchants are interested in the potatoes' specific gravity, their percentage dry matter and starch levels. There is a basic table for measuring these. In practical terms potatoes should fall within the following range:
Specific gravity 1.076-1.1
Dry matter 20.4-24.9%
As a general rule the higher the specific gravity of the potato, the higher the chip yield and the lower its oil content. A variety unsuited to chipping might contain as much as 45% oil one that is suitable, prepared in the same way, might have about 30%.
‘Pommes frites' in the classical repertoire
Allumettes 6cm x 5mm x 5mm
"Chips" aka potato crisps
Copeaux deep-fried potato ribbons
Frites 6cm x 1cm x 1cm
Mignonettes 5cm x 7.5mm x 7.5mm
Paille deep-fried potato julienne
Pont Neuf 7cm x 2cm x 2cm
"Saratoga" deep-fried thin slices from large potatoes
Soufflés 6cm x 4cm x 3mm
â- See our equipment feature on fryers, page 41
Photography by Lisa Barber (www.lisabarber.co.uk)