Frozen potato catalogues name their products by the size of the cut. The phrase 7x7 is a code summarising the whole behaviour of a product.
What does 7x7 mean?
The figures give the cross-section of the baton.
Seven millimetres wide, seven millimetres thick.
A thin baton, square in section.
Other widespread sizes are 9x9, 10x10 and the wedge cut.
The smaller the cut, the more batons at the same weight.
A kilogram of 7x7 holds around four hundred batons; that figure falls to around two hundred and forty at 10x10.
| Size | Surface/volume | Cooking time | Stays hot | Oil uptake |
|---|---|---|---|---|
| 7x7 | Highest | 2.5-3 minutes | 4-6 minutes | High |
| 9x9 | High | 3.5-4 minutes | 7-9 minutes | Medium-high |
| 10x10 | Medium | 4-5 minutes | 10-12 minutes | Medium |
| Wedge | Low | 6-8 minutes | 15-18 minutes | Low |
What does the surface-to-volume ratio change?
That ratio is the source of every behaviour in frying.
The total surface area of a kilogram of 7x7 runs around forty percent above 10x10.
More surface means more crisp crust.
It also means more oil absorbed.
And it means faster cooling.
Those three results together explain why 7x7 is both the crispest fry and the fastest to deteriorate, and the fit with a menu follows from that balance.
How long do they cook?
A thin cut means a short cook.
Two and a half to three minutes at a hundred and seventy-five degrees.
Past that the potato darkens and leaves a bitter taste.
Cut too short, the centre never cooks.
The window is narrow; a deviation of fifteen seconds changes the result markedly.
A fryer timer therefore becomes obligatory in operations using 7x7, and cooking by eye does not give consistent results.
Why do they stay hot so briefly?
A thin baton carries little mass.
Little mass means little stored heat.
7x7 fries fall below serving temperature within four to six minutes of leaving the fryer.
The moisture at the surface evaporates at the same time and the crispness disappears.
That period runs fifteen to eighteen minutes for wedges.
The difference runs threefold; that explains why 7x7 works on fast-service menus and causes trouble on slow ones.
Which menus do they suit?
The product gives its best result on menus where service runs fast.
Fast food and burger menus; two or three minutes between order and service.
Café snack menus; they go straight to the table.
Cinemas and event venues; the customer eats immediately.
They do not work for takeaway; after a fifteen-minute journey the fries are both cold and soft.
Nor do they suit a hotel buffet; 7x7 fries waiting there become unservable within ten minutes.
How much oil do they absorb?
A high surface area means high oil uptake.
Fat runs 14 to 18 grams per hundred in 7x7.
Ten to thirteen at 10x10.
Eight to eleven in wedges.
Calories follow: 290 to 330 per hundred grams in 7x7.
That difference creates a gap of around eighty calories at the same portion weight, and it is an item to count in the nutritional calculations for a menu.
What about the cost?
The size of the cut does not directly affect the price per kilogram; the same potatoes yield product at different sizes.
But the rate of waste differs.
End pieces and broken batons run higher in a 7x7 cut; waste in production runs 8 to 12 percent.
Five to eight percent at 10x10.
That difference passes into the wholesale price and 7x7 generally runs 5 to 10 percent higher per kilogram.
But the gap narrows once the cost per portion gets calculated; because thin fries look bulkier the portion weight can fall slightly.
How does the portion get set?
A standard portion of 7x7 runs a hundred and thirty to a hundred and fifty grams.
A hundred grams alongside a main course.
A large portion runs two hundred grams.
They go into a paper carton or a bowl.
The carton does not get filled to the top; a little space stays clear, since fries spill from a carton filled to a peak.
A measure gets used at service; portioning by eye leads to deviations in weight with thin fries because of the illusion of volume.
How do 7x7 fries get stored and prepared?
The conditions of storage for a frozen product directly affect the result of frying.
The product stays at minus eighteen degrees.
Ice crystals grow and cell walls break in potatoes that partly thaw and refreeze.
Those potatoes come out soft and greasy when fried.
The product stays in an airtight container once the pack opens; ice crystals gather at the surface in an open pack.
Those crystals make the oil spit during frying.
The product does not get thawed; it goes into the fryer straight from frozen.
Little goes into the fryer at a time; where the oil temperature falls the cooking lengthens and the potato absorbs more oil.
That effect shows more strongly in a thin cut, and the calories of a portion come out above the figure calculated.
Which sauces go with 7x7 fries?
A thin cut changes how sauce behaves too.
Because the surface area runs high the sauce gets absorbed fast and the fries soften.
The sauce therefore does not go over the fries; it comes alongside in a separate pot.
Ketchup, mayonnaise and barbecue sauce are the most widespread.
Garlic yoghurt gets used too, though its water runs high and softens the fries quickly; it is the sauce least suited to a thin cut.
