white potato

potato pressure cooker nutrition

When a potato is pressure cooked and cooled a large portion of its starch is converted into “resistant starch” – a healthier starch that isn’t fully digested and instead used by the body like fiber – lowering blood cholesterol and fats.

Resistant starch is usually found in beans, whole grains and some fruits (bananas); but, it can also be created by cooking typically starchy foods (such as potatoes, rice, pasta and bread) and then cooling them.  This “retrograded resistant starch” isn’t naturally present in these foods and can only be produced by converting common starch with cooking and cooling.

Scientists in Spain measured pressure cooked potato starch samples at 100°C (boiling),  and with pressure to 120°C (equivalent 15 psi) and 250°C using an autoclave to find out how much of the potato’s own starch would convert into resistant starch.  An autoclave is a pressure vessel used for research and industrial applications that can operate from 1 to 50psi or more (depending on the model) – they can be brought up to pressure using water-generated steam, just like a pressure cooker. Although their paper doesn’t give exact data from their findings, their conclusion was..

…. [Resistant Starch] RS yields obtained in the [High-pressure Autoclave] HPA process were greater than the ones obtained using a boiling water bath as gelatinization system.

Which basically means you can convert more of the potato’s starch into the better-for-you “resistant starch” by pressure cooking compared to boiling.  If eating cold mashed potatoes isn’t appealing, that’s OK. Reheating doesn’t destroy this newly created resistant starch – apparently it can increase it.

A BBC TV Show (Trust Me, I’m A Doctor) conducted a small experiment with cooked, cooled and reheated pasta and found that reheating continues the process of converting a food’s starch to resistant starch.  All 10 volunteers had a 50% lower blood glucose response to the “cooked, cooled & reheated” pasta compared  to the “cooked” or “cooked & cooled.” Evidence, according to the experiment’s author,  that even more resistant starch was converted during reheating.

no acrylamide? no problem!

The potato research continues with Swiss researchers who took a bunch of potatoes to steam, roast, and fry to measure how much acrylamide was produced.  Acrylamide is a carcinogenic compound that forms during high temperature cooking.  The Swiss found that this compound is primarily created during dry cooking methods like roasting or deep frying. It turns out that steaming potatoes under pressure produced almost no acrylamide compared to dry cooking methods where the potatoes reached the same temperatures (25 μg/kg versus 1500 μg/kg ). BUT, if the pressure cooking temperature is raised from the 120°C (equivalent to 15 psi) to 160°C (only achievable with an autoclave) then acrylamide will start  to develop even in the presence of steam and pressure (800 μg/kg).

Don’t worry, most potatoes need only 10 minutes at high pressure (115-120°C) to be fully cooked and these researchers pressure cooked theirs for 20.

bottom line

It is not possible to create carcinogenic acrylamide when cooking potatoes at the high temperatures that can be achieved by household pressure cookers.

Pressure cooking and cooling potatoes produces a nutritional insoluble starch which has a lower glycemic impact. It’s likely that reheating pressure cooked potatoes will increase this resistant starch further for more nutritional benefits.

Aren’t your leftovers starting to look good right about now?!?

potato pressure cooker recipes

Start your quest for resistant starch with one of our pressure cooker potato recipes…

want more?

potato_1V

references:

Andrews, Rayan. “Resistant Starch: What Is It? And Why Is It so Good for You?.” Precision Nutrition Inc, 2011. Web. 25 May 2016.

Escarpa, A., et al. “Resistant starch formation: Standardization of a high-pressure autoclave process.Journal of Agricultural and food chemistry44.3 (1996): 924-928.

van Tulken, Chris, MD. “Is Reheated Pasta Less Fattening?” BBC News Magazine, 16 Oct. 2014. Web. 20 May 2016.

Biedermann, Maurus, et al. “Methods for determining the potential of acrylamide formation and its elimination in raw materials for food preparation, such as potatoes.” Mitteilungen aus Lebensmitteluntersuchung und Hygiene 93.6 (2002): 653-667.

 

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32 Comments

  1. That is very good news! Thanks for keeping us informed. Now, if something could be done alter white rice.

  2. Sharon, there has been some research with rice in the pressure cooker – I haven’t reviewed all of the papers on it thoroughly – the jist of it is that the starch is MORE digestible immediately after pressure cooking which is the opposite of “resistant starch.”

    If you’re trying to lower GI with rice, go for parboiled rice. It’s almost already completely gelatinized and pressure cooking does not “undo” any of this. Like cooked and cooled potatoes and pasta, rice can also produce “retrograded resistant starch.”

    Ciao,

    L

  3. I do believe I read somewhere that adding a teaspoon or so of coconut oil to the water while cooking rice changes the starch.

    1. There’s a case for risotto and pilafs! However, when I follow the links to find out more I’m taken to a Washington Post article saying that this was “preliminary research” – nothing appears to have been actually published about it (I looked because I wanted to know more and see the data : ).

      Ciao,

      L

  4. This is a 20 year old study. I wonder if there are any more recent studies. Also, the conversion to resistant starch is mentioned under autoclave pressure –which pressure cookers never reach. Finally, how much is actually converted is unclear. This article is inflating the science.

    1. The food industry does not change as quickly as computer technology – data collected from potatoes 20 years ago is not going to be significantly different today. Did you know that many of the pressure canning processing times and guidelines are based on research from 1940’s and 50’s? Some USDA guidelines are based on data and research that is even older than that!

      Regarding the RS conversion, the researchers used an Autoclave for both the 120°C and 250°C measurements. They state in the paper that they did not notice any significant difference between the RS yield at both temperatures, so they so they referred to the results of both temperatures in the paper as “High-pressure Autoclave” (HPA).

      Ciao,

      L

    2. P.S. I added the following sentence to the article…

      “An autoclave is a pressure vessel used for research and industrial applications that can operate from 1 to 50psi or more (depending on the model) – they can be brought up to pressure using water-generated steam, just like a pressure cooker. ”

      Thanks for the feedback!

      Ciao,

      L

  5. I think you have the wrong link for the BBC Trust Me I’m a Doctor episode. Try this: http://www.bbc.co.uk/programmes/articles/3LncBcDcCXKgtpFvrDZVnNQ/can-my-leftovers-be-healthier-than-the-original-meal

    1. Victoria, thanks for sharing this link to the BBC site – it has more data and details than the first article I linked-to!

      Ciao,

      L

  6. Very interesting, I consume a product called UCAN Super Starch and your article has me in research mode trying to find out if I can simply use potatoes instead. I’m a obstacle course racer (mud runs, Spartan, Tough Mudder etc) and train on a low carb diet, but when I race I try to carb load without spiking my insulin levels.

    Here’s a great article on the health benefits of resistant starch; http://www.core3training.com/what-you-should-know-about-resistant-starch/

  7. This is great news since we are diabetic.
    I dry roast our rice in a pan before cooking. This also converts the starch in rice but I did not know about potatoes.
    We can now eat rice and it doesn’t make our blood sugar go so high.
    Thanks for this info. I will pressure cook the potatoes from now on. : )

  8. I try to restrict carbs to < 50 gm/day (LCHF diet or lifestyle) and have no eaten many potatoes for 2 years. It is difficult not to take a few off of someone elses plate. After reading the above, I bought some baby new potatoes and cooked the in my new Amazon Prime InstantPot..

    After cooling and reheating in the microwave, They tasted very good eaten with lots of better or sour cream. I read someone's blog about reheating the potatoes reversing starches to original glycemic index and came back here to read the article again.

    Eating fat is good for you. It is carbohydrates and INSULIN that makes you fat and diabetic.

    1. Even as diabetics we eat everything but in moderation and not daily. I prefer that we have a lot of variety in order to get enough vitamins and minerals.
      We eat potatoes often because they have a lot of vitamin C and are delicious with most proteins.
      I have been making risotto lately because I can convert the starch before adding the liquid and I still come out with a cream risotto.
      There are many ways we can modify our cooking methods so we can enjoy a variety of foods. : )

    2. “Eating fat is good for you. It is carbohydrates and INSULIN that makes you fat and diabetic.”

      Hi, Brooks:

      Almost two years later, have you realized the above comment is not so black-and-white?

      People routinely comment about “carbohydrates” without clarifying what they mean. [As an aside, few foods are just “Carbs” or “Fat” or “Protein.” Most foods usually contain a mixture.] Is a doughnut a “Carb,” considering they usually have more fat than sugar? Broccoli is a carbohydrate. Can we become diabetic by eating too much broccoli? Of course not. But, many people are not overdosing on vegetables.

      And, as a reminder, the longest-lived people on the planet eat a “High-Carbohydrate” diet — dominated by whole plant foods, and, if any animal products are used, they are in condiment-sized portions.

      There have also been diabetics who have arrested or even reversed their Type 2 Diabetes, using a diet high in vegetables and fruits. Yes, fruits. The WHOLE fruit — fiber, water, and all. It’s high amounts of fat that are contributing to the problem:

      https://medium.com/thrive-global/sugar-does-not-cause-diabetes-did-the-film-what-the-health-get-it-right-3ef441045c01
      https://www.forksoverknives.com/fat-insulin-resistance-blood-sugar
      https://nutritionfacts.org/2016/11/17/fat-is-the-cause-of-type-2-diabetes
      https://ucdintegrativemedicine.com/2016/09/diet-diabetes-saturated-fats-real-enemy

      Now, my intent is not to argue with you (or, anyone), as I’m not a doctor or healthcare professional. But, I do come from a Low-Carb High-Fat (LCHF) background, and, five years later, am still trying to undo the metabolic damage I caused by following that path. I’m well-versed in Paleo, Primal, LCHF, Ketogenesis, Weston A. Price, and many of the popular books, book authors, and diet plans that are either directly related to the above topics or associated with them.

      The only reason I’m bothering to post is so that others will not take your statement “Eating fat is good for you. It is carbohydrates and INSULIN that makes you fat and diabetic” as an absolute, indisputable fact. In my opinion, it isn’t. Plus, in my experience — and, the experience of others that can easily be found online — the matter is not so absolute. In fact, it seems to the contrary.

      Thus, my hope is others will do their own research. And, under the care and guidance of their qualified medical professional, do their own experimentation.

      We DO need fat in our diet. No doubt. But, we don’t need very much of it. And, we need fats in their entire package, as nature provided. For people who have health concerns, I would say: Don’t eat coconut oil, eat coconut. Don’t eat olive oil, eat olives.

      Finally, I should mention that I’m not a vegetarian or vegan. I do eat some animal products, but not much and not dairy. But, that’s my own plan, based on my research and self-experimentation. Even Dr. S. Boyd Eaton — one of the originators of the concept of Paleolithic nutrition who published about it in “The New England Journal of Medicine” in 1985 — has stated that people need to eat less (not necessarily zero) meat.

      “Anybody who eats a whole lot of varied vegetable and plant source foods is getting an acceptable protein and amino acid composition to their meal,” Eaton told the Tribune. “You just have to eat a lot of different plant and vegetable sources.”

      Source: https://www.wellandgood.com/good-food/pegan-paleo-eat-less-meat-boyd-eaton

      So, with all that stated, whatever path anyone selects, I wish you health.

      Best,
      Walt

      1. Walt,
        I agree and disagree with your points. I bought a Walmart glucose meter and per Dr. William Davis’ recommendation checked my blood sugar before and 45 min. (peak) after eating pressure cooked, refrigerated and microwave re-heated potatoes (123 sec.). Results—FBS 100mg./dl to 175mg./dl. I considered the “experiment” a failure as the renal threshold is about 180 mg./dl. Above that level and sugar will be spilled in the urine. The potatoes tasted great though—so sad. The ADA takes the position that the diabetic has the “right” to eat a relatively normal diet with obvious exceptions, covering glucose spikes with bolus insulin doses, if necessary. Dr. William Bernstein, a long lived type 1 diabetic, disagrees and recommends minimizing carbohydrates. There is now a group of over 1000 type 1 children who maintain a HbA1C= 5.0% following his principles (Typeonegrit.com). I suggest Bernstein’s DIABETIC SOLUTIONS. Also read Dr. Jason Fung’s OBESITY CODE and Drs. Phinney and Volek’s The Art and Science of LOW CARBOHYDRATE LIVING. High insulin levels are bad for you. It is suspected cause of the inflammation of coronary heart disease and essential hypertension too. Cigarettes are worse. I am a retired M.Diety too, which doesn’t make me an expert but I have read a lot.
        Best wishes,
        Brooks

        1. Dr. Brooks,

          It took me a second to get the “M.Diety” comment. I’d never heard that before. Very funny.

          I sincerely appreciate your thoughtful reply and I value your education, professional experience, and personal experimentation. Obviously, you’ve given a lot of time and attention to the subject — far more than a layperson like me.

          While I’m familiar with Drs. Phinney and Volek, it’s only via podcasts and YouTube videos. I will see if I can locate their book in audio format. Funny you mention Dr. Fung, too, as I was just reading an article on his https://idmprogram.com website. He’s enjoying a lot of popularity, at the moment. He’s helping a lot of people, so it’s well-deserved attention.

          So, for people that follow a program like Dr. McDougall’s “Starch Solution” and have success in losing weight and reversing chronic conditions, how does that work? That is, if “carbs drive sugar drives fat storage” as Gary Taubes has said, then why do many people see improvements in body composition and biomarkers?

          This is what’s currently flummoxing me, in the ongoing “Carb Wars.”

          You’ve likely heard about the gentleman in Australia that ate nothing but potatoes for an entire year and lost around 115 lbs. Similarly, here in the U.S., Penn Jillette (of ‘Penn & Teller’) dropped over 100 lbs. in about three months, by eating mostly potatoes. We can, of course, go back to the early 1940s and Dr. Walter Kempner’s “Rice Diet” at Duke University that consisted of white rice, fruit, fruit juice, and white sugar and helped many people lose weight and reverse chronic conditions. Now, the “Rice Diet” is not a healthy long-term strategy, of course, but the point is that the diet was nothing but refined carbohydrates. Yet, people lost weight and reversed disease.

          These days, I know some folks are going to the opposite extreme and eating sticks of butter (Dr. Fung’s co-author Jimmy Moore), adding butter and MCT/coconut oil to their coffee, and some are even eating meat-and-water-only diets. That just seems like insanity. Perhaps we humans just have trouble with moderation. I’m not really sure.

          When I followed a low-carb diet for about four years, I remember people stating “the human body has no dietary requirement for carbohydrate.” While they point to gluconeogenesis to support their case, I look at it the opposite way — that carbohydrates are so important, that the body has a backup method of generating glucose, should we not get any in our diet.

          I felt pretty good on a low-carbohydrate diet — for a few years. But, eventually, I crashed. My personal, unscientific opinion is that, in the extended absence of sufficient dietary carbohydrates, out adrenal system is on overdrive and keeps us going with stress hormones. I think this is what makes us feel good. But, it only lasts for so long — and, it comes at a price.

          But, again, I don’t really know. More importantly, I’m always open to being corrected and educated. Thus, I will look into the resources you were kind enough to mention.

          Again, thank you for the discussion.

          Respectfully,

          Walt

          1. Walt,
            I am IMPRESSED with the depth of your study! I have covered everything you mentioned, including McDougal, Penn, the Duke rice diet + the fellow who ate potatoes for a year. Obviously there is more than one program that works. I can’t explain why Dr. McDougal’s program works. A fellow ate nothing but bacon for a month and lost weight too, his labs also looked better.
            I believe Dr. William Davis is right about most things and have read WHEATBELLY and may get UNDOCTORED. I bought a glucose meter on his recommendation. My “experiment” with cold potatoes has not been done yet. Consider getting a $30 Walmart glucose meter kit plus strips. Eat 3-4 eggs for breakfast and check your blood sugar fasting in 45 min. Repeat with potatoes, etc. The lower you keep your blood sugar (HbA1c< 5.5%) the better will be your health and the lower will be you risk for developing degenerative disease. That's my opinion anyway.

            Best wishes,

            Brooks

            1. Dr. Brooks,

              Thank you for the encouragement in my studies. It seems we both have a great interest in trying to discover the best plan for ourselves.

              In addition to the aforementioned resources, I’ve also listened to many old recordings of Nathan Pritikin and watched his YouTube video wherein he is being interviewed by Dr. McDougall. I’ve also some limited familiarity with Broda Barnes and the Banting Diet.

              In more recent times, there’s also the main plant-based Medical Doctors like Caldwell Esselstyn, Neal Barnard, Michael Klaper, Michael Greger, and Thomas Lodi. Also, Alan Goldhamer, Pam Popper, Doug Lisle, T. Colin Campbell, and Jeff Novick.

              And, of course, the main folks in Paleo/Primal circles: S. Boyd Eaton, Art De Vany, Loren Cordain, Robb Wolf, Mark Sisson, Mat Lalonde, Paul Jaminet, Colin Champ, and David Perlmutter. Then, many others: Chris Masterjohn, Denise Minger, Mary Enig, Stephan Guyenet, Nina Teicholz, Diana Schwarzbein, etc., ad infinitum.

              It’s a long list that’s about eight years in the making. (Well, really, it started in 1999 with Bill Phillips’ book “Body-for-Life” then Andrew Weil and Dr. Mercola.) Sadly, while I’ve learned many things, I still feel like I’m chasing my tail. Lately, I’ve been thinking it’s time to move on to other things.

              Perhaps the best way for me to get answers for my specific situation is to follow your advice about a glucose meter kit + strips to measure. I thank you for the suggestion.

              My last HbA1c was 5.4%, but that was three years ago and I’ve changed my diet many times. I’ll soon be meeting with my GP and he’s usually very accommodating in ordering basic labs (CBC, CMP) for me. The last time, I paid about $75 for an advanced lipid panel to look at additional parameters. Perhaps it’s time to do all that again, get a baseline, then start monkeying-around.

              Sometimes, I have to laugh at us humans. In many ways, we’re quite clever and able to accomplish great technical feats. However, we cannot seem to do what all other species can do — instinctively eat food without intellectual interference.

              Again, my thanks for your valuable insights.

              Wishing you Health and Happiness,

              Walt

              1. Walt,
                We share a Hb A1c=5.4%. I was hoping it would be lower.
                Mark Sisson attended a Dr. McDougall event with a significant other. He was not impressed with the food or the shape of the attendees. He probably has high standards. I would not worry about LDLp but would try to get triglyceride/HDL < 2.0 and CRP as low as possible.
                Just so we can die healthy without needing diapers or a bib!

                Good luck,
                Brooks

  9. Question about the “cooling” portion of this process – anything special here? Does it need to be rapidly cooled or is allowed to cool naturally ok? Cooled for a particular length of time? What temp equals “cool”? (Cool to the touch or needs to be below 40 degrees F?).

    Would I get RS by pressure cooking my pasta, rinsing with cold water until cool and then dropping back into some boiling water to reheat for serving in order to use “same day”? Or do I need to make my pasta/potatoes/rice a day or more ahead?

    Thank you!

  10. Aurora,

    I am almost to the point of buying a glucose meter to help answer that question although I am not diabetic. In looking up other articles on resistant starch, they imply that reheating loses the benefits. Insulin is the fat storage hormone and it is eating carbohydrates that make you fat. The healthiest thing you can do for you and your family is to minimize carbohydrate intake and throw away “vegetable” seed oils (PUFAs) polyunsaturated omega 6 fatty acids.

  11. IFortuna, vit C is destroyed by heat, so unless you are eating your potato raw, you aren’t getting C from it. Sorry to burst your bubble.

  12. So, as a newbie to pressure cooking in general my question is: How do I cook these in a pressure cooker; in liquid or a steamer basket?
    Thank you.

    1. Alan, it depends on the recipe you use. For example, mashed potatoes are boiled, while making a potato salad the slices are steamed (to keep them from falling apart). Here are all of the hip potato recipes, just choose one and follow the steps.
      https://www.hippressurecooking.com/category/ingredient/vegetables/potato/
      Welcome!

      Ciao,

      L

    2. I don’t eat many but pressure cooked a pot full of small potatoes yesterday for a large group. I use 1 cup of water and the trivet and used 14 min. It probably makes no difference whether the rack is used.

  13. Very glad to hear that reheating doesn’t reverse the effect!

  14. I bought a Walmart glucose meter to check out the theory of resistant starch in pressure cooked and refigerated potatoes. I cooked some medium gold potatos in my Instant Pot for 13 min. and refrigerated them for several days. This morning, I reheated 3 small to medium potatoes for 123 sec. in the microwave. I checked my blood glucose before and at 30 min after starting to eat. My blood glucose went from 105 mg/dl to 175 mg/dl.

    IMHO the resistant starch theory failed this n=1 experiment. I may try the experiment again and eat the potates cold.
    I have tried to eat LCHF (low carb high fat) for 3 years and won’t be buying any potatoes real soon.

    1. This is an interesting experiment. But, to make a conclusion you would also need to test your sugar levels after eating a warm freshly-cooked potato and then compare. I bet Greg, a retired science teacher, would have more suggestions on how to make this experiment more solid. ; )

      Ciao,

      L

    2. The article indicates that the cookling/cooling/reheating method forms resistant starch and that the absorbable starch is reduced by this percentage of resistant starch, not that all absorbable starch is eliminated. I would totally expect you to still have a glycemic response to the remaining normal starch. Your experiment should be to see what your numbers are eating normally cooked potatoes and then compare the number to the resistant starch potatoes. You would need to either consume the exact same things each meal or only eat potatoes each time in order to maintain control in your experiment (i.e. same amount of butter, same drink, etc.).

  15. Laura,

    I am a retired MD and have studied nutrition for the last 3+ years. The key to health and longivity is to minimize blood insulin levels by minimizing carbohydrate ingestion and replacing with good fats.
    The kidney can resorb glucose up to 180-200 mg./dl. Any higher and glucose is spilled into the urine. The pancreas will try to keep up by putting by increasing insulin secretion. Insulin is the fat storage hormone and chronic demand for more and more insulin is the cause of many dieaseses. In fact, it is the #1 health problem in the world. Cholesterol is not the problem. Excessive carbs are the problem.

  16. Aurora,
    I intended to continue self experimentation as you have outlined had my glucose been in the130-150 mg/dl at 30 min.however 175 is close to the renal threshold and is too high for me and my belief system. I enjoyed the potatoes too. My hemoglobin A1c was normal earlier this year @ 5.4% (I had hoped it to be < 5.0%). That is a test for your blood sugar level over 3 months. You don't catch obesity and diabetes type 2 like the flu. You earn them by eating too much sugar and carbohydrates too often. That is my understanding and I have studied the subject for 3 years.
    Insulin is the fat storage hormone and you can't burn fat with an elevated insulin level.

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