by Dave Arnold
I consider myself a fry-expert, and I believe almost anything can be fried to good or great effect. I deep fry steak, bacon, bones for stock, as well as the obvious stuff – like French fries.
A fry-cook can be judged by their fries. At the FCI we make really good onesâ€“ but we want to make the best. Our technique is basically Blanch, Dry, Fry, Fry. We are currently exploring these phases in excruciating detail in our search for the perfect fry. Today, Iâ€™ll walk you through our current recipe â€“and explore a simple alternative. Next Time, the first serious FF investigation: blanching.
The Perfect Fry:
Perfect French friesÂ are super crunchy on the outside with a good cooked-potato texture and flavor on the inside.Â They shouldnâ€™t taste too greasy.Â They should be salty.Â They should stay crispy for at least 10 minutes.Â Easy, right?
The Current Technique
- Select a variety of potato.
I use Idaho russets (there are several varieties of russeted potatoes; we usually get Burbanks). Nils, being from Sweden, thinks we should use other potatoes. Weâ€™ll find out.
- Peel potatoes and keep submerged in water.
While the peel has vitamins and flavor, it does not produce as nice a crust as the rest of the potato, plus it can hide rot and blemishes. Away it goes.
- Cut the potatoes with a French fry cutter and place in water to prevent oxidation.
The cutter we use is 3/8â€ square. We like this size, or slightly larger. Smaller fries have a very high crust-to-core ratio; shoestring fries are almost all crust. Super-thick fries are like baked potatoes with a French-fry crust. WeÂ go forÂ a middle ground. I have some evidence that hand-cut fries may be better. I donâ€™t know if the slight irregularity makes them better or if the sharp knife produces a better fry than the relatively dull French fry cutter.
- Optional: inject the French fries with a flavor â€“like vinegarâ€”or a texture-modifying enzyme like Novoshape (a pectin methyl esterase that strengthens the structure of the potato) using a vacuum machine; or soak them in a texture-modifying enzyme like Pectinex SP-L (an enzyme that breaks down pectin structure â€“some studies indicate that breaking down pectin at the surface of the fry can decrease oil absorption in increase consumer preference). Note that the two enzymes above do exactly opposite things, yet both can contribute to a better fried potato. Confusing.
- Optional: pre-blanch French fries in 55 C ( 131 F) water for 40 minutes.
Potatoes naturally contain the enzyme Pectin Methyl Esterase (see the previous cook-step). This pre-blanch activates that enzyme and strengthens the structure of the fry, but also changes it. This technique was discussed in depth by Jeffrey Steingarten in his first book The Man Who Ate Everything , so we call it the Steingarten technique. Steingarten used it for mashed potatoes. Heston Blumenthal picked it up and made it popular with chefs. It doesnâ€™t just work on mashed potatoes — it works for any potato preparation, and other vegetables too. Some people love this technique; some hate it. Nils and I donâ€™t enjoy the mashed potatoesâ€“ the texture reminds us of a very fine hominy grit or tiny, tiny bbâ€™s. Nils also dislikes the Steingarten technique for French fries because heâ€™s looking for a creamy interior. The ST emphasizes the crust; the fryâ€™s inside can lose its potato texture (creamy or fluffy, depending) and, at the extreme, can exhibit the phenomenon we call â€œhollow fryâ€: a crust with no internal potato structure. Nils cannot tolerate hollow fry. I am OK with the occasional hollow fry because, for me, crust is paramount.
- Rinse off fries and blanch in salty water until they are cooked through.
We blanch for many reasons: blanching with salt improves flavor by salting the inside of the fry;Â leaches out sugar, which reduces premature browning; kills enzymes (important if you canâ€™t fry right away or areÂ planning a pre-fry drying step); pre-cooks the potato so the first fry can be high-temp and short duration; and, lastly, blanchingÂ pre-pastes and pre-gelatinizes the starch,Â purportedly creating a barrier at the surface of the fry to prevent excess oil intrusion.
- Dry the fries with a convection oven, fan, or hair drier until the surface is leathery.
The drying step helps form the crust and dehydrate the potato. Studies show that partially dehydrating the fries reduces oil uptake when frying. Other studies show that overall dehydration isnâ€™t important, but the leathery surface formed by drying reduces oil uptake and forms a nice crust. Removing surface moisture also saves your oil from excess-water abuse.
- Choose an oil or fat for frying.
Finished French fries are up to 10 percent oil, so this choice makes a real difference. We normally use industrial fry oil because we are working on the stovetop and this oil can withstand the temperature abuse.
- Fry in hot oil (roughly 170 C, 340 F) untilÂ a crust forms (to test, we pull the friesÂ out of the oil and tap on them) but the fries are still blond.
The oil temperature is high because we have already cooked the potatoes – we are only working on crust formation. Â Â This step should be fast.
- Shake the hell out of the fries as they come out of the oil, and allow them to cool.
Studies show that most oil absorption takes place after the fries are removed from the oil, asÂ theyÂ are cooling down (see bibliography).
- Optional: freeze the French fry.
Freezing acts like partial dehydration. When the frozen fries are finished, they liberate water freely, leading to rapid dehydration and good crust formation with a porous interior. Pre-frozen fries are crunchier than fresh and stay crisper longer after they are fried, but they tend toward hollow fry. Nils hates this step; I like it.
- Finish-fry in very hot oil, 195 C (385 F), till crispy and golden brown.
- Shake the hell out of the fries.
I have been told our fry technique is complicated.Â I donâ€™t think so.Â It is easy to do â€“especially in bulk. In our last Harold McGee class someone asked us about a technique published in the July 2009 Cooks Illustrated,Â which advocates throwing raw potatoes in cold oil and cooking them in one step by heating the oil.Â We tried it.
Here is a magnified view of the interior and crust of the French fry.
We didnâ€™t like the results.Â The friesÂ had a fantastic crust â€“right out of the fryer. Â Unfortunately, they wilted quickly compared to our normal fry.Â Within a couple of minutes, we didnâ€™t want to eat them at all.Â Our standard fries are good even when cold. I think the cold-cooked French fries wilted because they were too high in moisture.Â The Cooks Illustrated folks solve this problemÂ by using a thinner fry â€“ just 1/4 inch. Less interior means less moisture. Less moisture means less wilting.Â Less interior also means less textural difference and less potato flavor. Another problem with this technique:Â Â the interior of the fry isnâ€™t salted.Â Once you taste a fry that’s salted from the inside, you wonâ€™t go back.
Cooks Illustrated claims their technique makes a less oily fry than their controlÂ double fry, and they have lab resultsÂ to prove it.Â Â Their photo ofÂ twice-fried fries looks terrible; super greasy.Â Â They stacked the deck in their favorÂ by using a crummy double-fryÂ technique.
ï»¿A Partial French Fry Bibliography
G. Lisinska, A. Tajner-Czopek, L. Kalum, The effects of enzymes on fat content and texture of French fries, Food Chemistry, Volume 102, Issue 4, 2007, Pages 1055-1060, ISSN 0308-8146, DOI: 10.1016/j.foodchem.2006.06.042. (http://www.sciencedirect.com/science/article/B6T6R-4KPNB54-2/2/31a208ecef7f46a3110c4a0739f14543)
Grazyna Lisinska, Grazyna Golubowska, Structural changes of potato tissue during French fries production, Food Chemistry, Volume 93, Issue 4, December 2005, Pages 681-687, ISSN 0308-8146, DOI: 10.1016/j.foodchem.2004.10.046. (http://www.sciencedirect.com/science/article/B6T6R-4F2V56S-9/2/23a2e2a28c50cb7eaea1b17113edd45a)
Eric Zhiqiang Liu, Martin G. Scanlon, Modeling the effect of blanching conditions on the texture of potato strips, Journal of Food Engineering, Volume 81, Issue 2, July 2007, Pages 292-297, ISSN 0260-8774, DOI: 10.1016/j.jfoodeng.2006.08.002. (http://www.sciencedirect.com/science/article/B6T8J-4MY0THD-1/2/0e5bca9574b45642d2c2d69c692902cc)
Andrea Bunger, Pedro Moyano, Vanessa Rioseco, NaCl soaking treatment for improving the quality of french-fried potatoes, Food Research International, Volume 36, Issue 2, 2003, Pages 161-166, ISSN 0963-9969, DOI: 10.1016/S0963-9969(02)00131-X. (http://www.sciencedirect.com/science/article/B6T6V-47CWC3B-5/2/f03b11a378184cb4b42f5fd079b93828)
A. Kita, G. Lisinska, G. Golubowska, The effects of oils and frying temperatures on the texture and fat content of potato crisps, Food Chemistry, Volume 102, Issue 1, 2007, Pages 1-5, ISSN 0308-8146, DOI: 10.1016/j.foodchem.2005.08.038. (http://www.sciencedirect.com/science/article/B6T6R-4MH44VC-2/2/8be3c0666e0f99d253f992bb5498dec8)
Franco Pedreschi, Pedro Moyano, Oil uptake and texture development in fried potato slices, Journal of Food Engineering, Volume 70, Issue 4, October 2005, Pages 557-563, ISSN 0260-8774, DOI: 10.1016/j.jfoodeng.2004.10.010. (http://www.sciencedirect.com/science/article/B6T8J-4DWH268-4/2/45d527de325ef9cb183f5ed79aedf35a)
Franco Pedreschi, Pedro Moyano, Effect of pre-drying on texture and oil uptake of potato chips, LWT – Food Science and Technology, Volume 38, Issue 6, September 2005, Pages 599-604, ISSN 0023-6438, DOI: 10.1016/j.lwt.2004.08.008. (http://www.sciencedirect.com/science/article/B6WMV-4DFK6R6-2/2/b3d475670701ce77732cd9601b01d5bb)
A. H. Khalil, Quality of french fried potatoes as influenced by coating with hydrocolloids, Food Chemistry, Volume 66, Issue 2, August 1999, Pages 201-208, ISSN 0308-8146, DOI: 10.1016/S0308-8146(99)00045-X.
M. A. Garcia, C. Ferrero, N. Bertola, M. Martino, N. Zaritzky, Edible coatings from cellulose derivatives to reduce oil uptake in fried products, Innovative Food Science & Emerging Technologies, Volume 3, Issue 4, December 2002, Pages 391-397, ISSN 1466-8564, DOI: 10.1016/S1466-8564(02)00050-4. (http://www.sciencedirect.com/science/article/B6W6D-46X2K6R-4/2/0e2495ec788044cd7e26a02822558e60)
Pedro Bouchon, Chapter 5 Understanding Oil Absorption During Deep Fat Frying, In: Steve L. Taylor, Editor(s), Advances in Food and Nutrition Research, Academic Press, 2009, Volume 57, Pages 209-234, ISSN 1043-4526, ISBN 9780123744401, DOI: 10.1016/S1043-4526(09)57005-2.
Franco Pedreschi, Ximena Travisany, Carolina Reyes, Elizabeth Troncoso, Romina Pedreschi, Kinetics of extraction of reducing sugar during blanching of potato slices, Journal of Food Engineering, Volume 91, Issue 3, April 2009, Pages 443-447, ISSN 0260-8774, DOI: 10.1016/j.jfoodeng.2008.09.022. (http://www.sciencedirect.com/science/article/B6T8J-4TKPV7J-3/2/0f02d3a296b2301f0ec1f23baceeef5e)
Nathalie Santis, Fernando Mendoza, Pedro Moyano, Franco Pedreschi, Petr Dejmek, Soaking in a NaCl solution produce paler potato chips, LWT – Food Science and Technology, Volume 40, Issue 2, March 2007, Pages 307-312, ISSN 0023-6438, DOI: 10.1016/j.lwt.2005.09.020. (http://www.sciencedirect.com/science/article/B6WMV-4HK03HS-1/2/def2a2f033b4915c2a39cb4357799816)
75 thoughts on “The Quest For French Fry Supremacy Part 1”
To dry the fries I read that using a cyrovac to vacuum pack the fries, is the best way to dry them. Is this technique practical?
I don’t think so. I heard Heston Blumenthal does it that way, but I also heard he has a BOC Edwards dry vacuum pump attached to his machine. That pump can handle the vapor. If you didn’t have something like that you’d need a cold trap.
Hi Nils and David,
would a presoak in a saline solution help with overall flavor or would it affect the cell wall negatively retaining moisture? Is the blanch necessary because they are water soluble starches or would steaming be effective for the first cook? We’re working on techniques for some mass production. Thanks for any info.
I am dealing with blanching in the next post. As for saline soak (as opposed to blanching) check out the article in the bibliography on NaCl soaks. We haven’t done any steaming tests. Maybe we should. Steaming wouldn’t remove the soluble reducing sugars. How mass is the production?
For the restaurant, in the neighborhood of 400-500# per week. We could probably give them a proper salted water blanching. The steamer option seems to keep the integrity of the potato better. We’re going to see if from steaming to tepid salted water will help-but I’m thinking they do need submersion for the water soluble sugars??
We have never tried the combi. Sounds like a good idea –except for the sugars and salt. If you had a vacuum tumbler you could inject the salt/leach out sugar then combi then fry.
I would agree with Nils that there is a better potato. The Bintje potato is one that is often used in Belgium and Holland (the Holy Lands of Fries), and when we get the Bintjes in, they make fun of the fries we usually make. And the fries we usually make are really good.
One of the tests we plan on running is types of potatoes. We are trying to get a good list together right now.
Would soaking in slaked lime (calcium hydroxide) be worth trying? Not exactly sure what it does to the surface pectin, but it does create a firmer exterior for things like fried sweet potatoes and for Mexican sweets such as candied fruits and vegetables. I’ll be giving this a try in the next week.
I dunno Tavarino. Lye would definitely cause the potatoes to brown very quickly, which could be a problem.
Lye is Sodium Hydroxide.
Slaked lime is Calcium Hydroxide.
Regardless, I can assure you that slaked lime doesn’t cause sweet potatoes to brown quickly. I’ll give it a try on white potatoes tomorrow to see what happens.
Whoops! Misread your comment (skimmed to fast). I’ve been looking into getting some Cal to do nixtamalization experiments. What happens to wheat or rye as opposed to corn? Anyway, Tell us what happens.
OK, soaked for 4 hours in Cal solution. Crust was slightly thicker and slightly tougher. Not an improvement, IMO.
Thanks for running the test Tavarino
Thanks for this awsome blog.
I used to work at Falai and took your course “Sous vide…” and the “Hydrocolloids” a year ago. I have a couple of questions that I’m sure you can iluminate me.
First, is there any difference in quality and size, etc ,between a Polyscience Circulator(350 I gusse) and the Roner. The roner costs double of the circulator!!!
Second, can the the alginate bath solution or the calcium bath solution used for spherification, once prepared and used, be used more times than once? Can I use it once, put in the refrigerator, than used again and again when need it?
Sorry to bother but I couldn’t get those answers from anywhere or anyone.
Roner costs more because it is re-labled. They usually sell units built into baths –which I don’t like. Polyscience is about to release a new circulator which should be a game-changer –it is built for chefs. All circulators (except the old Lauda’s, which are terrible) work about the same. We have always used Polyscience because they support chefs.
Thanks a lot, Dave.
Another question that came up:
can the the alginate bath solution or the calcium bath solution used for spherification, once prepared and used, be used more times than once? Can I use it once, put in the refrigerator, than used again and again when need it?
But eventually a stored alginate bath that has been used over and over will probably gum up (unless you have a good sequestrant). Calcium baths last but eventually the calcium will get used up.
I’ve always felt there is a big disconnect between what people should expect from a french fry and what people should expect from what we in the UK call a chip. As a child I was always told that french fries is just the American term for chips, but they do really seem to be different.
You couldn’t have fish and chips with thin, super-crispy french fries, surely. I like the smooth, creamy, self-steamed flavour and texture of chips from the chip shop, wrapped in paper to bring home to enjoy in front of the TV (with one eye on the cat, who likes them nearly as much as I do).
But maybe that’s cultural expectation? I like crispy french fries too – I feel very strongly that they go much better with burgers.
But that’s probably cultural expectation too.
I think you are correct. They are two different things.
Very nice review, and as usual with your posts , you are up to finding the perfect recipe no matter how much effort.
As a non professional cook I would like to comment on the cold oil technique.
When I want some fries fast, I take some quality potatoes (Bientje or Desiree or some other mealy potato.)
I cut them to ca. 1 cm with a knife, I wash and rinse them, shake the water of and pre salt them.
Then they go into the cold oil to start cooking and then frying all at once, on a high output gas burner outside on my BBQ.
Once they are swimming up in a nice bubbly inferno, I take em out (never checked temp, but could be round 180C).
I wait till oil is nearly smokin hot (I use olive oil, so it must be close to 200C.) I put em back in to finish em of . (Last step: more saltâ€¦)
Maybe not perfect, but very nice and loved by most everybody I serve them to.
Plus a lot less effort than most other recipes. It can be done in a spontaneous matter in parallel to grilling stakes and preparing a saladâ€¦.
Another topic I love to hear more about is what oil/fat to use. I love olive oil though it is maybe slightly decadent â€“ what the heckâ€¦
In 1986 I was participating in a science fair in Philly, PA, and was testing French fries from major outlets for their chemical composition. One surprising finding to me was that they all contained cholesterol. One or two years later, main stream media discovered that all fries were made with lard as frying fat, which explains my finding. Golden Arches said this was not for cost but for quality reasons. Nevertheless they changed their recipe in response to public pressureâ€¦
I never did fries in lard meself. Has anybody done so and can tell a difference? What other fat is recommended (Dave, if I may say so, for someone who controls all the other variables he can think of â€œindustrial fry oilâ€ sounds rather lame, LOL)
Another idea I never tried was spicing the oil, like sesame or chilly (or truffle) oil. Anybody done sucha thing?
We use Whole Harvest Smart Fry Brand Soy Oil. They somehow get the smoke point up to 484F (I think that is about 15 degrees higher than normal). It says it contains an “antifoaming agent” but I can’t figure out which one. They must remove the most easily broken fractions because it can withstand a lot of abuse. We buy 35 pound containers, but the website says it is also available by the boxcar or in 2000 pound “totes,” although I don’t know anyone who can tote a ton.
I have fried in Lard. Tastes great but isn’t that stable (in my fryer), which seems strange. Most old school big players used hydrogenated fats. We will be testing it out. Doughnuts, for instance, should only be fried in hydrogenated fat or they will taste oily when cold. French fries, on the other hand, sometimes taste greasy cold if fried in crisco (I have used it many times).
It is interesting that you do cold oil plus a second fry. I’ll try that one as well. Most of the problems with the cold oil were caused by excess moisture. Maybe the second fry takes care of some of that.
A “tote” is a unit used by petroleum distributors for orders too small to fill (and clean) a tank truck. It’s about 250 gallons. Just sayin’.
Beef kidney fat makes excellent fries but is cost prohibitive and unstable. But still, for experimental purposes…
Awesome factoid on the tote Chris K.
In some of her later writings, Julia Child (of blessed memory) bemoaned McD’s switch from lard.
I thought they used to use beef tallow. Jeffrey Steingarten prefers rendered horse fat (he never shies away from such choices).
I also use the cold oil technique for weekday home french fry prep, so don’t feel bad. As a shortcut and time saver, I think it’s perfectly defensible. That said, with the time to blanch and double fry, you’ll probably get a more balanced result. I also have found that the cold oil fries don’t hold their crunch all that long and sometimes produce a hollow interior. Then again, at home, they don’t sit around that long.
Regarding your question about subbing sesame, truffle, etc oils for part of the frying oil – don’t do it. Aromatic compounds tend not to withstand high temps (especially sustained high temps) and the breakdown product can have off flavors. You would be better off seasoning with a seasoned salt, like a chili salt, or using say grated truffle. I do fry in beef tallow and duck fat (not together), or some combo of that kind of animal fat and I enjoy the flavor but I haven’t done a side by side with vegetable oil alone to determine whether the differences among the fats (more or less saturated, etc) make any difference in texture.
as a shortcut and time saver, you should consider doing the blanch, dry, fry, FREEZE, fry.
Once they’re frozen, you can keep them in the freezer until you need them, then simply do the quick finish fry during the week.
We sometimes freeze before second fry just for taste reasons. Freezing affects the texture of the fry. I like them Nils doesn’t.
Hi, I have publised a very brief summary of this post in my blog in Spanish (obviously mentioning your blog). Please let me know if this is ok with you guys.
Sure Inigo, Thanks.
If memory serves me right from when I worked at McD’s 20 years ago, it was tallow not lard for the fries.
At home I render down my own beef fat from trimmings. Not the same as true tallow but close I think. I have not tried fries but the rendered beef fat does make superior hashbrowns.
I have also read allusions to, not the actual report, that the FDA found that fat absorption in fried foods fried in vegetable based oils was higher than that in meat based. The lard and tallow may actually be healthier in the long run. I would love to see some scientific exploration on that.
yep I also meant tallow not lard.
This was more a language problem on my side, sorry.
I spent some time working at The Hind’s Head in the UK and the triple cooked chips were really good. Like an American steak fry. The secret seemed to be in the slight damage to the exterior in the blanching phase. I have had similar results at home with tossing slightly overcooked thick cut chips in a bowl to “mechanically” damage the outside. This is finished with an oil blanch and finally frying to finish.
With the triple cooked chips method why should you still fry the fries twice? The blanching cooks the fries, so shouldn’t you just be able to put the dried and blanched fries in hot oil to crisp the exterior.
The first fry forms the foundation of the crust and dehydrates the potato some more. The second fry does the crisping. I don’t think they will stay crunchy as long if you do it all in one shot.
Great post — really love the explanations. We’re looking forward to seeing how all the tests come out. If you do any oil comparisons, we’ve been excited about rice bran (alone or with a little duck fat). Has a high smoke point and the food comes out really light.
How much does rice bran oil cost?
Ah, well. That might be an issue. Since we’re buying for home use, it isn’t too much to spend $20/gallon because other oils are easily $10-15. We find that price at a Korean market, but you can find cheaper online before shipping. This place sells larger quantities for $8.40/gallon (http://www.honestfoods.com/topricbranoi.html), but I don’t know what you might be able to find wholesale.
What does the industrial price spectrum look like?
I’ll ask the storeroom on Monday. Cooking oil prices have been pretty volatile over the last few years and I don’t do the purchasing at the school directly.
Would you really use a volatile oil for cooking?
(Sorry, couldn’t resist.)
Hey! You forgot Step 13.5! Salt!
Right you are Rochelle!
My dad had a shop in Vancouver that sold nothing but french fries and I worked there for about 10 years. We had developed a similar process. We used russets as well and we used a diabetes tester to check for sugar content. Peels stayed on and we had the same size cutter but cut directly into a garbage can full of ice water. This leaches out quite a bit of the starch. They soaked in the water ideally for at least a few hours. Scoop out basket full and let them hang dry for a while (we had a rack that held 25 baskets. We had a row of 4 fryers at 4 different temperatures, the first was for blanching. Then after blanched (surface looks leathery), they would rest for about half an hour before then went to the next fryer. There were basically escalating temperatures and reducing wait times between stages. In all it was about 45 min to an hour from first drop in oil til serving. If times got too long you had to throw them out because they lost too much moisture and tasted dry. Constant balancing act but we had nice crispy fries, strong earth flavour, and nice and chewy in the middle. It’s been 10 years since my dad retired and I still haven’t tasted a fry that came close.
Sounds like it was a nice setup
Hi Adam, Thank you for posting your french fry set up. Very informative and helpful. I’m unemployed and looking to start a similar set up as your dad had. Is there any way I can get in touch with you. I am in Canada (East Coast) Cheers.
Dave, I have a couple of questions, assuming I understood all of your post correctly 🙂
1.Can one do a soak in saline to salt the inside of the fry, and the double frying method with the initial blanching in oil followed by a final fry? How do you think this would work?
2. I know some places with great fries don’t do a blanch; they just let the cut fries soak in water. Could one do a soak in a saline solution to “salt” the inside of the fry…no blanching? What if slaked lime (clacium hydroxide) was added to a blanch or soak? Or do you feel the blanching is necessary…and how long is it in the salt water….so I’m counting 2 blanches.
Tavarino tried the slaked lime and didn’t have good results. I have read studies about a saline soak, but only connected with a water blanching step. THe people you know who made the fries without the blanch, what size fries were they? Last week we did 28 different blanching regimens, including none, and the no blanch lost on our tasting. It is true we only let them soak for an hour or so.
And just a quick follow up, let me see if I understand the steps correctly.
1. Preblanch cut fries in non salted water 40 mins.
2. Blanch again in salted water for ?? mins.
3. Initial fry in oil.
4. final fry in oil.
Basically, you’d say “Throw out the typical soak in water or salt water in the fridge” in favor of blanching, correct? The potatoes should only be in water for short amounts of time to prevent oxidation and such?
1 and 2. Next week we’ll post what we think the best blanching is, but we only blanch in salted boiling water (3% salt) for about 4.5 minutes. We only blanch longer if the temperature of the water drops a lot (but that changes the fries cause they undergo enzymatic changes). We only blanch in water 1 time (before that they are soaking in water (no salt) just to make sure they don’t go brown and to leach out some free starch and sugar. After the blanch we usually dry them out.
We don’t do a prolonged soak. I think the blanching takes care of that stuff –but we have soaked them (if we have to do something else before the blanch) without them changing much.
Oh, and what salt content should the salt solution be?
We use about 3%
On the idea of mechanically damaging the exterior, Heston stresses on this point for his roast potatoes. the potato develops more surface area for the oil and makes the exterior more crisp and flavorful.
I wonder what happens if one trys frying quickly (say for 30 seconds), letting it cool, then frying it again and repeating it. I remember a post earlier on the optimum way to cook steak was to flip quickly and continuously.
I don’t know whether it is the increased surface are that makes them more crisp. We usually overcook our potatoes as well. I wonder what the oil uptake would be if you increased the frying to 3 or more times.
Oh boy. We already spend a ludicrous amount of time making fries, but how could I not share this article with the rest of my kitchen?
Thanks for making our restaurant a little less profitable.
But seriously, thanks for helping us make our cooking a little bit better all the time.
Just wait for the blanching post. Luckily, I think one of the easier blanches will win. We have one more round of tastings.
Blumenthal dosn’t use the Steingarten technique. He hydrates the starch but at around 70Â°C which would kill off that enzyme. That enzyme also toughens up the skin of the chip resulting in a less crispy fry. you want the fries to break apart a little when boiling to increase surface area and in turn increase crunch. be carefull of cooking in too much salt because it will also toughen up the skin and you’ll be left with a very flat surface that doesnt fry up well.
e-mail me if this makes sense to you!
I have to go re-read Blumenthal’s recipe for fries. He certainly uses the Steingarten technique on mashed potatoes in his Family book (he writes about it). I recently read what the inactivation time of pectin methylesterase was in various vegetables in the range of 50-80 c was, but I can’t remember. More importantly, I wonder how long it takes his cooking water to get back to 70C after he places the potatoes in. There is a significant difference in the texture of potatoes blanched from a cold water start (that is in our next fry post) presumably because of enzyme activation.
We have done a lot of tests using Novoshape pectin methylesterase vs pectinex SP-L which is a pectin lyase. We have been able to get crunchy results with both. Again, we’ll give our results in the next post. I haven’t found any papers on Pectin Methylesterase and french fries. I’d love to see some.
I am curious about the salt. I have seen salt making the surface less brown and salt as a dehydrator. What is the mechanism of salt toughening the skin?
Heston’s roast potatoes are awesome! I cannot stress how important the damage is to the potato I do a version by taking a whole russet. Cut it into six pieces. soak. Cook in water until nearly falling apart. cool. Blanch in oil to develop crust. Fry to eat. One thing I have never tried is to first blanch in a stock or flavored liquid. I am reminded of how good potatoes cooked with a pot roast are.
We do a lot of work blanching in vinegar –but that not only affects flavor– it affects texture.
Have you tried using a starch solution such as crispy coat UC?
My home method is to microwave a russet whole. Let it cool. Quarter it. Dip in a crispy coat slurry (or cornstarch/powdered sugar slurry). Sheet it out to dry. Fry @ 350.
Changing the Nuke times makes for interesting textures!
Howdy Senor Bullfrog,
We used to do some starch dipping –but haven’t in a long time. Maybe we’ll try again.
A couple weeks ago I actually did a lot of research on how to make the perfect fry, so I might as well post it here.
How to Make the Perfect French Fries
When choosing the type of potato to make the perfect French fries there were certain factors that had to be looked at. First, the percent of dry matter (starch) and the percent of water that was in the potato. Also, the sugar content played a role into the decision of what type of potato to use. The average percentage of starch to water in a potato is 17 % starch to 78 % water. The other 5 % of the potato is irrelevant to making French fries. Heston Blumenthal of the Fat Duck discovered that to make the perfect French fry the percent of starch would be 22.5% of the potato. If the potato had more than 22.5 % starch it had a tough, leathery exterior when fried and if the potato had less than 22.5 % starch the potato tasted bland and did not crisp up well. The potatoes that were consistently closest to this percentage were the Maris Piper and the Arron Victory potato. Some other potatoes that are good for French fries are Russet potatoes, Idaho potatoes, King Edward potatoes, and Sante potatoes. If there is too much sugar content in the potato it prevents the fries from crisping. The extra sugar makes the potatoes brown before they crisp so if you wanted to have crisp potatoes you would have to â€œburnâ€ them if the potato had high sugar contents. The sugar content in the potato increases after the potato has been harvested or if the potato is kept in a chill place like a refrigerator. To make sure that your potato does not have a high sugar content either get potatoes that have just been harvested and that have not been sitting in a factory garage for months or you can get potatoes that were frozen the day they were harvested (I do not know if they have these). Potatoes are typically harvested in September, so that would be the prime time to use the very fresh potatoes.
When choosing the fat in which you want to fry you potatoes there are a few things to consider. What is the smoke rate of the fat? Does the fat impart any pleasant or unpleasant flavors? Do you want the potato to not get any flavor from the fat at all? A high smoke rate for frying is key because if the smoke rate of the fat is below 400 degrees the fat will break down and cause the fries to taste burnt and fishy. Some oils that have high smoke rates are canola (486 degrees), peanut (448 degrees), safflower (509 degrees), and beef tallow (420 degrees), and horse tallow (475 degrees). Horse tallow is used by Alain Passard, owner of Lâ€™Arpege, to make his French fries. In America I believe a lot of people would consider using horse tallow unethical. Beef Tallow gives a great flavor to fries that can only be matched by horse tallow. Also letâ€™s say you had extra duck fat around you can use that to make fries, but duck fat would impart a good flavor, but that might not be wanted in the end result of the French fries. Oils like canola, safflower, and peanut do not give of much flavor because they usually have Vitamin E. Vitamin E prohibits the transfer of flavors between the oils and the potatoes being fried. There is no best fat for frying, but if you want your fries to have an extraordinary flavor that most fries donâ€™t have use beef tallow. McDonalds was using beef tallow in America up to 1983 for their fries, but McDonalds stopped using it because people did not like how the fries were so unhealthy. If you want fries with neutral flavor use canola oil, safflower oil, our peanut oil. Just make sure whatever fat you are using that it is very clean.
I think everyone agrees that perfect fries are crisp on the outside and fluffy and tender on the inside. To achieve this there are numerous steps that need to be made. When cutting the potato for French fries the knife you are using or whatever you are using to cut your potatoes has to be extremely sharp. If the knife is not extremely sharp when it cuts through the potato it creates a rigid cut (whenever you have a sharp knife and you cut something the surface that you cut should be very smooth). When this rigid cut goes into the fat that you are frying in it will cause oil to get stuck in the crevices on the surface resulting in greasy fries. All of your fries have to be uniform in size so there is equal browning throughout. If you cut your fries too thin the whole fry will be crispy but there will be no fluffy interior. If you cut your potatoes too thick the crust will be cooked before the inside of the fry gets cooked. Once fries are cut to Â¼ inch slices put them in salted cold water for at least an hour. There are many reasons to do this. One reason is that the salted water prevents the potatoes from oxidizing. Secondly, if there is too much water content in your potato the water will leach out of the potato to form equilibrium with the salted water (osmosis). Thirdly, putting the potatoes in the salted water will remove the excess starch that is on the surface of the potatoes. If the excess starch is not removed from the potato when the potato is frying the steam will get trapped inside of the potato which will make the potato have an unpleasant gummy texture. Also, if the steam gets trapped inside of the potato it cannot â€œblockâ€ the oil from coming into the potato. If the oil is not stopped from reaching the inside of the potato, the potato will be very greasy. Fries need to be cooked twice in a big vat of oil and in small batches of potatoes so the fat does not lower drastically in temperature and so the fries do not stick together. The potatoes must be extremely dry before put into fryer. Some ways to dry the potatoes completely are using a dissactor, a cyrovac, or a salad spinner (the most practical way). There is an initial par cook in the fat at a temperature of 275 degrees to cook the inside of the potato and then there is a second fry at 375 degrees that crisps the outside of the potato. You must initially par cook the potatoes in the fat because the starch in the potato has time to dissolve and glue to the outer cell walls to make them thicker and has a more robust flavor. Also, potato cells have granules of starch, which swell when the cellular water is heated, which forms a â€œpureeâ€ inside of the potato that gives the fries there fluffy texture. After the first period of frying the potatoes should be cooked through but not crispy. If the fat for the pre cook is too hot the potatoes will not get cooked all the way through on the inside and if the fat is too cold the fries will turn out to be too greasy. Once all of the fries have been precooked again in small batches, crisp the fries up in the same fat that was used to precook them, but instead at a much higher temperature. Make sure not to puncture the fries because that will make the inside of the fry collapse, like a soufflÃ©, and the fry would not be as fluffy. The second the fries come out of the fryer drain them and then season them with good sea salt and any other flavorings you wish to impart in the fries. You season right after the fries come out of the fryer because the remaining fat that is still on the fries will make the seasonings stick to the fries. Serve the fries to the diners as quickly as possible. Maybe serve with some sort of vinegar sauce because vinegar (malt vinegar) pairs great with fries.
have you all explored doing the initial cooking with whole potatoes? (ST) also we have found that for large russets 2hr at 65C works great and the potato flavor intensifies
also, instead of a soak have you tried a dry cure on the ST cooked potatoes, should dry and damage cell surface etc and be easier to dry further, like pre salting meat
keep up the tests, great reading
I am very interested in the idea that the damage is important. I see chefs talking about it but it isn’t in the literature. I too cook my potatoes till they are overdone –but I wonder whether it is the physical damage (a bumpy surface) or the pasting of the starch that is important –the literature seems to indicate the latter.
what literature indicates that its pasting of starch?
G. Lisinska, A. Tajner-Czopek, L. Kalum, The effects of enzymes on fat content and texture of French fries, Food Chemistry, Volume 102, Issue 4, 2007, Pages 1055-1060, ISSN 0308-8146, DOI: 10.1016/j.foodchem.2006.06.042. (http://www.sciencedirect.com/science/article/B6T6R-4KPNB54-2/2/31a208ecef7f46a3110c4a0739f14543)
They use a pectolytic enzyme to break down the structure on the outside of the fry. They do this, they say to allow rapid and complete swelling of the starch which forms a better boundary against oil absorption as opposed to starch whose swelling is inhibited by the pectin structure. So I guess the destruction of the pectin is important (as We have seen in our recent tests) but I don’t think the bumpy surface is.
If it is important to get the oil off the fries quickly, perhaps you could centrifuge them – e.g. in a salad spinner. Might be more efficient than draining.
Interesting you should say that Dan, there is a company that makes a centrifuge/fryer combo that reduces the oil content of fried foods significantly.
How bout steaming the fries instead of blanching in water? I wonder if that’ll make a material difference.
Hi Beth. We’ve done some preliminary steaming tests and they look promising. In those tests we salted the soak water and salted prior to steaming. We haven’t done time or side by sides.
Love the article. I find not many chefs can explain why things are done a certain way..
One question I had was – is there anyway to salt the interior of a potato without boiling it? I am trying to make an artistic edible french fry however when I boil the potato it becomes very soft and loses the structure I want.
I have tried soaking them in cold salt water but the potato doesn’t appear to absorb the salt.
Do you have access to a vacuum machine?
For anyone that is looking, Pectinex Ultra SP-L is available at http://www.modernistpantry.com/pectinex-ultra-spl.html.
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