Testing the Secrets for Crispy Roast Potatoes 

Sponsor: Visit mistplay.com/Stache & use my code STACHE50 inside the app to get 50 free points!

I wish you’d tested a potato batch parboiled with only water for comparison purposes

Kenji was a test cook and editor for americas test kitchen, serious eats, cooks illustrated and nyt cooking (sometimes). Safe to say hes spearheaded a many technique and recipe

For super crispy potatoes (uk version). Use good floury potatoes (maris piper are excellent). Parboil them (But not too much). Drain and allow to steam dry. Dry the pan put the potatoes back in. Add plenty of salt, a teeny whiff of white pepper and a good dusting of flour. Put the lid on and shake the daylights out of them to rough up the surface and coat the fluff in flour. Lid off, good dose of oil and toss gently to coat. Into a very hot oven, like inferno hot, on the top shelf and in your thinnest roasting tin - pre-heated with just enough oil to stop them sticking, no more. Turn occasionally. Cook till golden brown and crunchy. Anyone eating these will fall in love with you!

FYI pH is a log scale so citric acid with a pH of 2 is actually 10 times as acidic (concentration of H+ ions) as vinegar with its pH of 3.

UK chef Gary Rhodes taught us the secret to the perfect roast potatoes in the 90's and it was to toss the cooked potato in a collander a few times to get the outsides fluffy before putting into the oven - it's the potato fluff that makes the crispy. Baking soda may be doing that in the pan but it's not required. Just toss the taters a few times while hot and steaming before adding the seasoning.

I've been cooking for 50 years but my roast veges: potatoes, pumpkin, sweet potato etc are always crisp because I dust them with Corn Starch while they're in the oven. Corn Starch works by soaking up the moisture as it does when you use to thicken gravy & sauces etc & when sprinkled on roast vege. in the oven, it does the same. Couple teaspoons max. is all it takes. crunchy outside, soft & fluffy inside.

Thing is: the maillard reaction is base-catalyzed. Not so much acid-catalyzed. Put the baking soda in the oven first; might come out even better. The bicarbonate should change to carbonate which is more basic.

I do this all the time with just salt in the water - works great. Give them a good shake in the colander after draining so they get a really good thicks starchy layer happening. Then I just roast on a high temperature until they turn super golden and crispy looking. It works phenomenally well to air fry them afterwards, 200C for 20 minutes in ours! Always a massive hit.

I'm happy you did this test! The only bias from the original test restraints was that the two acid-additive potatoes received 10 extra minutes at 400. I wonder if the baking soda potatoes went longer they may have caramelized more adding more crunch? Or, if oil was added to coat the potatoes on the flip at 20 minutes, would the potatoes all have been crispier?

For par boiling. Acid holds the spud together, alkaline blows it apart. But, spuds are either waxy or starchy. Alkaline might be be better for waxy spuds, to make em more starchy/pillowy but will turn a starchy spud to moosh. Fast food chains par boil in vinegar, then freeze and fry. Saves time and makes the best fries.

I used to work at Mc Donald's in 1988 and they made us rinse the (already cut) potatos at least SEVEN TIMES or until water becomes transparent. The idea is to get rid of all the STARCH. BTW, GREAT VIDEO as usual, dear Mark.

I know it would have been additional work but you really needed a control potato - even just a small batch of just parboiled and roasted potato (singular) with just butter. I have a feeling the scores might have played differently.

I did a test of my own with some interesting results. I made up a solution of sodium hydroxide and another one of sulphuric acid and popped both in their own spray bottles. I ran two simultaneous tests in the same kitchen at the same time, using equal amounts of potatoes with ovens set to gas mark 7. Rather than boiling them in the solutions I chose to boil first, toss in oil and then spray the potatoes periodically (roughly every 5 minutes) whilst I'm the oven. The sulphuric potatoes has a sort of caustic aroma, which quite frankly made my eyes bleed a little, whilst the sodium potatoes took on a soapy look. Again, a little sting to the eyes. After finishing the test I was rushed to the hospital and I have been able to clos my eyes a little. I'm not sure how the potatoes turned out but I'm pretty sure they must have looked great because the paramedics said they couldn't believe what they were looking at. Next time, I'm going to try boiling the potatoes in natural seawater. I don't want to shock the potatoes with conventional heating, so I will try gently raising the temperature through a process I've read about called hydrolysis. This should keep all the flavour whilst getting rid of any volatiles.

Today's my lucky day, I just got a pound of potatoes at the grocery store

I never boil my roasted potatoes, I soak em for a while, dry them , toss in olive oil and a few seasonings…always very crispy

This is very useful because potatoes are among the few vegetables that are still reasonably priced right now, ha! Thanks for doing the research and thanks for posting!

I think the baking soda ones cooked faster because they’re on a darker pan. It’s very common in baking to adjust cooking times based on light vs dark pan. Great video! 😊

The pH of an acid solution depends on the acid and the concentration of the acid. Citric acid is a bit stronger than acetic acid in a molecule to molecule comparison. In these example the citric acid pot has a much higher concentration (8 times more acid molecules) than the vinegar pot (1/2 tsp solid citric acid vs 1/2 tsp vinegar which is 5% acetic acid). The difference in pH will be greater than shown in the chart for lemon juice and vinegar. Rough calculations say the citric acid pot was pH=2.67 and the vinegar pot was pH=3.88. Vinegar straight from the bottle is pH=2.41 Kenji uses 2 tablespoons (6 teaspoons) of vinegar when boiling potatoes for potato salad or blanching potatoes for french fries. The acid (lower pH) slows the breakdown of pectin that holds the potato cell together giving a smoother, firmer exterior to the cooked potato pieces. Baking soda (higher pH) speeds up the breakdown of pectin giving a softer more crumbly cooked exterior. Two tablespoons of 5% vinegar in 2 quarts of water is pH=3.47. To get the equivalent pH=2.67 found in citric acid pot with vinegar, you would have to mix about 5.5 cups water with 2.5 cups (120 tsp) vinegar.

The baking soda method is so good. Having parboiled potatoes with roasted brussel sprouts is heavenly

The quickest way to my heart is crispy roasted potatoes

My Mom was using the baking soda method when I was a kid in the 70s. She learned it from her Mom, who learned it from working in a diner in the 40s and 50s.

Here in Argentina there is a very traditional recipe for pumpkins in syrup (Zapallo en almíbar). In this recipe, the first step is to leave the pumpkin pieces in lime (calcium oxide) for 8 hours to form a crunchy outer layer. I wonder if the effect of the lime would be the same over the patato starches.

thanks for the breakdown, love the multiple type test

The secret is in `throwing `them on the baking paper, as opposed to laying them!! They also say that the potato variety has a bearing on the tast. Belgians always use the Bintje variety when frying French-fries. And funny enough, French-fries have their origin from Belgium.

The reason your potatoes didn't get as crispy as you would like is that your heat wasn't high enough. After learning the white vinegar in the water potato trick, I never do my oven potatoes any other way. I boil them for at least 10 minutes after the water's come to a boil, then I drain them, toss the oil on them while they're still in that pan and hot, throw them in the baking tray, and cook them for 35 minutes at 425°. They come out so crunchy that your neighbor can hear you eat your potato and yet, the insides are still pillowy and soft

Thanks I am always making roasted potatoes but never thought to boil in anything except water but I normally use oil and butter to get the crust, but now I know a better way, thanks.

this works really good for shallow pan fried fries i used to do it all the time, i use vinegar for skinny cut fries works great to get that perfect crisp

Another technique, is to shake the potatoes after you par boil them in the colander. Aggressively! It'll give it rustic, roughed up, exterior.

I boil them, let them fully dry, next coat with avocado oil & last put them in an air cooker.

Baking soda was a known diner secret way before 2007 to make crispy home fries. Use more baking soda, though.

Thank you so much! I work with paper and I really struggle with cutting a straight line!

Those came out awesome! Definitely gonna try ‘em. Also Id be curious to see how the experiment would turn out with 3 different bases instead of 2 acids and a base. Like I’ve had pretzels made with either baking soda or lye and there’s a difference.

1/2 teaspoon of pure citric acid powder is prabably a LOT more acidic than 1/2 teaspoon of vinager (which is basically acetic acid dissolved in water), hence the difference maybe?. Beyond that it's probably very 'chemistry' stuff like minimoles, and I failed chemistry spectacularly, so take this with a pinch of sodium chloride. Great that you are doing open research on such an important topic. Watching this to see if you and your subscribers can come up with a genuinely definitive answer. Agree with atrotsiuk - high quality research needs proper control measures. Double-blind with placebo is the 'gold standard'. The world deserves the best answer to this. Keep it coming please!

Par boil. Strain and toss 3 or 4 times in a plastic colander. Place in baking tray of hot oil. Add a couple os spoons of flour, some Paprika, salt and pepper. Easy peasy lemon squeasy.

That really is s great method for roasting potatoes, I've done it a few times and it's hard to put them down

The % of acid between water based vinegar and a powder of citric acid might result in a large difference between the two for acid percentages.

Love this - thanks. Potatoes are LIFE!

Thanks for doing the comparisons.

Nice experiment; I will definitely try the baking soda variant! I think you should also try using baked baking soda (i.e. sodium carbonate, what you get from roasting baking soda in the oven) in one batch (I think I may try that too).

I will have to give this a try, but Gaz Oakley's method and recipe is by far the best roasted potatoes I've ever made.

ooh - I wonder if bicarb par-poiled could have vinegar added to the olive oil before baking .... I'm gonna have to try!

I don't parboil. I just cut them into chunks, coat them with salt, pepper, garlic powder and oil. Then roast.

Potatoes FOR THE WIN!!! But seriously, thank you 😋🥔

The vinegar thing reminds me of the trick where you basically pickle brine french fries and they apparently come out super crispy. Joshua Weissman just recently made a video on viral TikTok recipes and that was one of them (spoiler alert: it was the only recipe they labeled S tier).

Yay Monica’s back! Potatoes all looked bomb

I needed this. I made some really bad roasted potatoes recently.

Good episode! It would be interesting to see if any tops baking soda (something more basic).

Great test. Would have liked to know the pH of the water once each ingredient was added. Sure we can look at the chart but with your water source what impact did it have. I’m just being a science geek-wondering where the optimum pH level really is. Of course the type of potato also influences the outcome. I understand baking potatoes like russets are better than using a waxy boiling potato.

Its possible the difference between vinegar and citric acid is, in fact, the pH. You note they have similar pH levels, but pH is not an intrinsic property of an acid. It is concentration dependent, and also depends on the strength of the individual acid. Citric acid and acetic acid (the acid found in vinegar) are both weak acids, but rough estimates: ½ teaspoon of citric acid is ~2,5 grams. With a molar mass of 192 g/mol that is 0,013 moles, dissolved in 1,9 liters of water for a concentration of 0,007 moles per liter. The pH will be roughly 2,7. ½ teaspoon of vinegar, which is typically 5% acetid acid, will be 2,5*0,05 grams = 0,125 grams of acetid acid. Molar mass is 44 g/mol, so that gives us 0,0028 moles of acetic acid to 1,9 liters of water, or 0,0015 moles per liter. The pH of such a solution will be 3,8. Keeping in mind each step on the pH scale is a factor of 10 in the relative strength of acid present, this is quite a significant difference.

Choice of potato variety matters. King Edwards and Maris Piper are the best I know.

I wonder if you could take it a step further and use hydrated Lime for an even more basic solution.

A vital part is letting them steam till cool. I use the soda, add tumeric(color) and thyme to the boiling water, drain them off, shake them with the lid on to get that mush all over them, on tray till cold and firm. Melt some beef tallow(by far the best) in a bowl, and roll them in that, place onto a hot oven tray. Add your herbs/garlic after 30 mins when you flip them. Serve immediately. These are great bringing for dinner at family gatherings because you can arrive on the tray and just shove in the oven.

In my experience it has less to do with altering the PH of the water and more to do with agitating the potatoes enough that you break up the starchy surface and create a lot of surface area after you've drained the water

It seems that acids did not do too well. you could try Sodium Carbonate (used for Ramen) and / or Sodium Hydroxide (used in Pretzels)

I wonder if the amount of every ingredient was optimal. You could easily double the vinegar or citric acid but you can't really put in too much baking soda before it starts to adversely affect flavor.

As a heads up, you may know, but Kenji worked at ATK/Cook's; so he may have even developed the ATK recipe. ;)

I rather like the trying different recipes/products videos you've done lately. The vegan cream cheese one and this one have been fun and informative. (And I'm not even plant based). You're just a great content creator.

It is not surprising that Maillard reactions occur faster at higher pH values!

Would you get better crispier home fries pretreating with the soda/ vinegar and parboiling before deep frying?

To account for difference between citric acid and vinegar, in addition to the aforementioned pH is a log scale so citric acid is 10x more acidic; you did not use equivalent amounts with vinegar being a 5% solution of acetic acid and the powder citric acid presumably 100% citric acid.

Grandma's in Germany cook with natron which is an essential component of baking soda . nothing new about that. still love to see crispy potatoes being the new standard in the world's kitchens.

Dang rabbit holes😂. I’ll be down this one for a while because it looks delicious!

I wonder if this would work with other root vegetables.

Most of the recipes I've seen tell you to shake them around a bunch after the parboiling step to kinda fluff up the exterior. I wonder if that would make them more crispy? Buuuuuutttt, I've never successfully made them crispy so what do I know😂

I’ve been using the baking soda method for years (a bit too much of a potato fan 😆). Russets are not my favorite for this method though. I’ve had great success with the baby gold potatoes from Publix just sliced in half. Also have had good success with the smaller red potatoes. Both seem to crisp up way better.

The citric acid is 100% pure acid, the Vinegar is likely to be around 5%, so using the same volume means citric got a lot more acid.

The high pH (baking soda) makes the food soften and consequently dissolve more easily. This soft texture becomes fluffy and crispy when fried/baked. On the contrary, the citric acid and vinegar that you used in the test, because of the low pH, tightens the texture.

Maybe an apple cider vinegar would be a good marriage between the acids.

I'd like to see the baking powder potatoes coated in flour to increase the crispiness. I'm certainly going to give it a go.

I always thought the secret was to dry them off really good and put them in the freezer for a little bit to get rid of the excess moisture but heck i cut up potatoes and fry them straight away just turn up the temperature of your oil really high to force the moisture out but as far as roasting goes I don't know.

Ok, no: coat in olive oil and a bit of coarse salt; spread on a baking sheet, add a few garlic cloves and a few springs of fresh rosemary.

Finally a RU-vid video worth watching! :O :D

Thank you… just what I was looking for

I just add semolina to the parboiled potatoes to get my crunch. Shake them up to get some broken edges and they’re great.

Nice experiment, solid proces throughout. For the experiments sake i wonder though if using the same half a tea spoon for each variable ingredient might mess up the comparison, each ingredient requires its own measure for a better outcome. Im sticking with baking soda though 😅

Thank you for using vegan butter and providing a vegan recipe!😊🥔

Chem. E. in me coming out. More vinegar, it's only 5% maybe acetic acid.

@2:00 It’s cool to see you and Monica just lounging.

Looks yummy

I wonder how lye (used for commercially made pretzels) would compare to the baking soda (often used as a lye substitute in homemade pretzels).

I love a good potato taste test.

i've used Kenji's recipe ever since he put it out there. it's the best, for sure. maybe if you had given it 10 extra mins like the other two (instead of the original recipe target time), it would've hit the level of crispiness you were hoping for?

And if you had baked the baking soda potatoes 10 minutes longer like the other two? Well then you would have been a REAL scientist.

I'm going to cook mine in the air fryer to see how it goes.😊

1/2 tsp of vinegar is much less than the other two, since it’s only about 5% acetic acid, vs 100% of the other two. Not a fair shake for the vinegar, vs citric acid.

A roast potato may loose crispness from the heat dissipating from the centre, it depends on the size of the potato, you can achieve a superior result by dispensing with the additions and roughing up the outside of the potatoes after boiling, then coating them in oil/butter

Any thoughts to blending with both citric acid and baking soda?

I parboil mine but just enough that they are still firm on the interior but the exterior has gellified because of the starch. I'll drain them and toss them in a bowl to break up the exterior and expose more surface area in the air fryer.

Aside from a control group there is one other method you should include. Threat your sounds like a German grandmother treats her pretzels. Instead of a boil in baking soda try a 60 second dip in a water solution with food grade lye. It's what makes the best pretzels brown. Here in the USA we are afraid of lye so most boil their dough in baking soda water. Once you have tried lye you will never go back. No cooking required and ready to go in a minute. The lye completely converts at oven temps into a food safe residue with no odor or flavor. It's the bomb on taters!

No one ever uses phosphoric acid. I just hear complaints about it being deadly and corrosive.

TBH vinegar is the way to do it. Cuz if you overdo it, that's the flavor that belongs on the potatoes. It's no risk.

Thanks for this presentation. Good info.

I think Heston was the first for baking soda.

Potatoes are life, and they are good.

Since the vinegar and citric acid are both acidic and the baking soda is a base but produced the best result I wonder if making the water more alkaline by adding more baking soda or as I've seen for some ramen cheats baking the baking soda would improve it further or if it would become to bitter.

What is the baking soda got subbed with washing soda or caustic soda, like with pretzels?

Wish Recipe reviewers had benchmarks or at least let us know what your taste buds like compared to things ive already eaten. Like say rate McD's, BK, Wendys, Rallys etc.. because if you tell me your favorite is BK and hate Rallys then i might not agree with your overall opinion what taste good etc.. Like i use to love McD's fries now meh, id rather Wendys.. Either way good video thank you i look forward to trying it out

Wondering about shio koji potatoes. Or does that only work its magic on proteins?

I wonder if you could use washing soda or lye like people do for pretzels? Both of those are more basic than baking soda.