A Short Resistant Starch to Popcorn Analogy

Two of the most common questions about resistant starch, particularly in the form of Potato Starch taken as a supplement:

  1. How come you can't cook with it and get the sam effect?
  2. What do you mean it's not digested by us as starch and so doesn't affect blood glucose?

The answer to both questions is basically the same, and the analogy goes like this:

...Suppose you take 1/4 cup of raw popcorn kernels and just swallow them whole, no cooking (popping), no chewing, no broken teeth. What's going to happen? you're going to find them whole, in your poop, right? Now, suppose what would happen if you swallowed those kernels in a fasted state, downed them with water, and tested your glucose readings over a couple of hours? Nothing, right?

Ok, now take the same amount of kernels, pop 'em, eat 'em and see what happens. Measure your glucose.

This is what resistant starch is. Tiny structures of starch with a little moisture locked in. Eat raw, it passes right through, except then becomes food for your gut bacteria, bacteria than can handle upwards of 60g per day of the stuff (the rest ends up whole in your pewp).

But cook it, such as in baked goods or to thicken sauces, and you've just "popped" your resistant starch and transformed it into rapidly digesting starch. Here's a little home science experiment for you in order to better understand the difference. Take 4oz of water, and to that, add 2 heaping teaspoons of potato starch. Watch it immediately sink to the bottom, forming a non-Newtonian fluid. Prod it with your finger. OK, now, pop it in the nuker for a minute.



  1. Dwayne Lunsford says:

    Excellent analogy Richard. And for all of you scratch home brewers out there who adjunct your mash with white rice or other sources of starch, the brewing term for starch hydration and conversion of RS to nonresistant forms is “gelatinization”. Most recipes call for a cooking period where the ground white rice is heated in water for various times before adjusting the temperature and adding in the malt. Assuming a high quality malt with high amylase enzyme content your conversion should be nearly complete in 30 to 40 min (via negative iodine test).

  2. bornagain says:

    A man that does not like bromides seems to like analogies.

  3. Nice analogy Richard.

    I still make a ps crepe from time to time….but not for any benefit…just cuz it tastes so fucking good :-)


  4. And if anybody thinks it’s as simple as ‘a tiny drop of water’ locked inside, read through this: http://www.wipm.ac.cn/jgsz/yjdw/cigongzhenyingyong/bp_swbpjdxz/swbpjdxz_yjcg/201002/W020120525849552050018.pdf

    What goes on inside a tiny granule of starch is unbelievable!

  5. I was successful in making a non Newtonian fluid science-experiment worthy with PS – tough to add so little water though.

    Alton Brown’s popcorn recipe/methodology done with refined coconut oil is a favorite movie snack of mine. (a little heavier on the popcorn salt than he recommends). Cooking in the serving bowl is fun.

  6. The conversion of RS to digestible starch seems clear to me. What I’m sometimes confused about is what happens after it cools. So after you nuke it, will the solution return to RS once it cools down? Not that it would be appetizing, but could you eat it that way for the same benefits? If you then heat it back up again, does it convert back to digestible starch, or does it have to cool again?

    This would sort of emulate the process of using PS as a baking ingredient. If you incorporate it into a bread product like a biscuit or cracker, can you cool it down before you eat it and get any RS benefits from it? I was thinking about this with some tapioca flour based crackers I bought recently. I wondered if the cracker was a good source of RS or not.

  7. @McSack – I was just reading about this! To answer your question about RS in PS crackers–a bit, but not much–just a couple grams per 100g.

    When a potato is heated and eaten, enzymes in our stomach and small intestine attack the ends of the amylose and amylopectin chains. Since the amylopectin starch is so highly branched, with lots of ends—it gets digested very fast. The amylose, with it’s tight bonds and only two ends, gets digested more slowly. This is food for us. A really good food, too. It packs a punch in carbohydrates, protein, and even a bit of fat. it has a full complement of vitamins and minerals. It’s good food…for us, but not our gut bugs. In fact, they go hungry on a meal of freshly cooked potatoes.

    If the cooked potato is allowed to cool, the amylose and amylopectin starches undergo a process called retrogradation where the straight portions of each starch unit rejoin and form crystals. As the temperature drops, the crystals become tighter and tighter and the water which was inside them is expelled. This is why bread goes stale and stored potatoes turn dry. The retrogradation process begins at about 40 degrees F and is fully complete when the temperature drops to 17 degrees F. If you heat this potato back up, the retrograded starch actually gets stronger as more water is expelled. In fact, you can heat and cool it several times and with each cycle, more retrograded starch forms. When eaten, this provides a good meal for you AND your gut bugs. Win-win. This is the way humans cooked and ate for millions of years after we learned to cook food.

    A raw potato (100g in size) has about 17g of RS [20% starch by weight, starch is 75% RS by weight]

    Cook it and it will have about 1g RS

    Cool it, RS grows to 3g

    Reheat it, RS grows to 4g

    Do this 3-4 times and you can get up to maybe 6-8g of RS, but it starts slowing down after the 3rd or 4th cycle.

    So, same with potato starch–raw, lots of RS. Cooked and cooled, minimal RS.

    • Thanks for the response tatertot. That is very helpful. :) These are the crackers we stumbled upon recently: https://www.glutenfreematzo.com/products/matzo/yehuda-gluten-free-matzo It’s too bad the RS is pretty low, but overall still very clean ingredients. I’ve been somewhat haphazardly doing the PS supplementation with homemade kefir but I prefer to generally maximize what I can in the food I eat. But it’s nice to know that reheating it increases the RS, and it now makes sense to me how the parboiled rice retains its RS.

  8. Uwe Nikoley says:

    The question is: at what temperature does the RS break down and at what rate. Another words if I put some in my Lentil soup ( normal hot soup temperature, probably about 160 F), how fast would I have to eat it before a significant portion breaks down?

  9. @Uwe – It happens immediately with potato starch (from a bag). As soon as it starts getting thick, it’s too late. If you put a raw potato in your hot soup it would take a while for it all to come up to temp, but I doubt that is what you are asking.

    Potato starch has one of the lower gelling temps of all starches — about 140 deg F. This low gelling temp makes it desirable to use as a thickening agent, but very touchy for use as an RS source if you want it warmed up.

  10. @Uncle

    I thought I covered that in my email to you yesterday. :)

    Yes, just like the French. Make the soup very flavorful and it will be most tasty very warm, not hot. If very warm is about 130F you can have as much PS as you want.

    To emphasize what Tim said about immediately, consider the cumulative cross section with microscopic particles in suspension. There’s no heat sink, such that each particle is going to have full force immediately.

  11. I have a question that I realize is probably impossible to answer, but I know there are many people on here with much more knowledge than myself who may be capable of shedding some light on the situation. Anyways, I’ve been using potato starch for some time now, and I have been seeing health gains in many seemingly unrelated parts of my body- skin health, fibromyalgia health, mood, and sleep. After using potato starch for about 2 months, however, I still fart like crazy. All day. Every day. Now, I’m 23 years old and I have had an absolutely terrible diet for almost my entire life- at least as long as I can remember. Does anything think that I’m still farting after all this time because I just have so much progress to make with respect to the composition of my gut microbiome and that it hasn’t finished changing yet, or is it possible that I am devoid of a certain Bacteroide that is responsible for keeping the gas to a minimum? I like potato starch so much that I may just consider getting a fecal transplant to keep it without the gas.. :p

    • @Ajmhardy

      I’d say to try periods of zero added PS for 2-3 days to let things settle out. Maybe toss in a fast day. Soon as I did that, once I resumed PS I had less fartage.

  12. @Ajmhardy – What is your diet like now?

    For me, the farting probably lasted close to two months, it would worsen when I ate beans, greens, or fruit. Sugar-free, sugar alcohol stuff (like maltitol) was THE WORST. Now, nearly one year later, I’m at very minimal gas even when eating ‘gassy’ foods, although I haven’t experimented with the sugar alcohols.

    But, yes, everybody starts with a different set of gut bugs. Eat lots of fermented foods and buy a couple different probiotic supplements to try.

    • Ajmhardy says:

      Hey Tim,

      Okay, good to know my fartage isn’t lasting an abnormally long time. My diet is pretty simple- just meats, veggies, berries, and safe starches. Going to try adding kefir on top of the other fermented foods to see if that expedites the process. Thanks for your response!

  13. Thank you. PS! More in shape (bicycling) than at any time in the past four years.

    As I’ve mentioned on this matter previously, I’m a 67 yo male and my bike is a mountain bike. I know every bump and grade within my biking routes, couple in head and tail winds and how my bod typically reacts. I know well when I’m flagging, when I”m average, and when I’m smokin’.

    I have spent months biking to feel in (for me,) top form. This fall and early winter, riding a only a few times a week, not trying to “train” or anything. Started the PS a few months ago. Today, even with a 12mph (per Accuweather) headwind coming at me at 45 degrees, I was fast and powerful and didn’t slow for any reason for two miles.

    Potato starch: Better’n ‘spensive products and cardio.

    Unfortunately, 90 minutes or so after eating .75 cup of beans, my BG is still 143.

  14. Not sure if this has been asked already…Does cooking green bananas (unripe) reduce the RS? How about freezing them — does that increase RS?

  15. @KL – They are just like potatoes in that regard. Cooking destroys RS. Freezing raw bananas, not sure what happens–probably destroys RS. Freezing cooked bananas will form some retrograde RS, but very little.

    • @tatertot so your are saying best way to eat unripe bananas is fresh to get th most RS?

    • tatertot says:

      Yep, that’s the best way to eat anything for the most RS.

      I get bananas so green you need to peel them with a knife and wash them down with coffee. An acquired taste for sure.

      I kind of figured with bananas, for an average sized one, 30-40g when super green, 15g when you can peel it, 0g when it’s ripe and fully yellow. And an even continuum in between those phases.

  16. Spanish Caravan says:

    @Tatertot, I’ve been buying these 5 lb. bags of frozen Goya yuca slices. I defreeze them by leaving them in room temperature, then refreeze them, then repeat. I’ve done that for about a week and these yuca slices are rock hard and devoid of moisture. They’re actually fairly edible, just like dried plantains are. They taste just like crackers, too.

    How much RS3 do you think is in repeatedly freeze-dried then melted yuca? I’m thinking about doing the same with potatoes (after skinning), making chunos in the process. These chunos are not similar to PS, right? PS has RS2 whereas chunos has RS3. But both should not move your BG much, right?

  17. Hey, Spanish! Happy New Year!

    In that paper I linked up above about water inside starch, it indicates that it is so purified, it won’t freeze until it hits like -30 degrees. If that’s the case, then freezing and thawing potatoes or whatever, should leave the RS2, raw starch granules, intact. The freezing would probably disrupt the outer cell walls and proteins, freeing up and preserving the starch.

    Have you read how they make chuno in a traditional way?

    “It is a five-day process, obtained by exposing a frost-resistant variety of potatoes to the very low night temperatures of the Andean Altiplano, freezing them, and subsequently exposing them to the intense sunlight of the day.”

    I’ve never given it much thought, and I am not 100% positive it works for all starches, but it would make sense that freezing and then thawing/drying, would preserve the RS2.

    So, your freeze-dried yuca may be chock-full of RS2.

    Yuca is cassava, correct? It’s supposed to have a lot of RS.

  18. Tradeit says:

    I’ve phoned Frontier & Bob’s for ps processing info but they only confirm “heated” in processing. Anyone have more precise heating info ? Tatertot- how important is temperature over 140 in manufacturing ps ?

  19. tatertot says:

    Tradeit – They blast the potatoes with hot water to clean and peel them, after that it’s all cold water.

  20. So what do you think about Buckwheat groats? I read that it is OK for gluten sensitive and has a 7-37% RS (depending how it is a prepared I guess)?

  21. the_whizzer says:

    I have two questions.

    1: What qualities are we looking for in a potato starch re the manufacturing process? There’s a local supplier here in the UK called Encona who do a brand called Farina. I’ve sent them a query, but I was curious as to what response I should be looking for? TLDR: what in the manufacturing process of BRM has made it the recommended brand (so I can look for that in other brands)?

    2: Is BRM tapioca flour acceptable for the tapioca starch side of things? It says flour in large lettering but below that it says ‘also known as tapioca starch’. Is it starch or flour? Does anyone know?


    • tatertot says:

      @the whizzer –

      1. About the only quality I care about is that it is indeed starch and not flour. And it must be food-grade, unmodified starch. Drilling in deeper, you could look for organic, certified GMO free stuff. Nothing special about Bob’s except we know it works and is unmodified and food grade.

      2. BRM tapioca starch/flour – Not recommended. May have RS, but nobody can confirm. BrazilBrad is checking for alternative tapioca starch suppliers and may have news soon.

    • the_whizzer says:

      Thanks, Tatertot. Your enthusiasm and dedication to the subject and this blog is much appreciated.

  22. the_whizzer says:

    Oh, one more thing for now: some people had mentioned what enables you to be sure what is starch and what is flour based on a reading of the nutritional info – what was that? Was it just that it should be just carbs with no other nutritional stats at all?

    Thanks again.

    • tatertot says:

      The nutrition label means nothing. Ignore it.

      There are a few ways to tell starch from flour. Mix with water is easiest, if it turns into biscuit dough–it’s flour, if it mixes, then separates back out, it’s starch.

  23. Ok, I have been reading for awhile. I prefer the Bobs Mill Potato Starch. So do I just wash it down raw by the TBSP with water?


  24. If I use Bobs Red Mill Potato flakes, do I just wash it down raw with water?

  25. tatertot says:

    I hope you are joking about potato flakes–don’t use them, they are way different than starch.

    To take starch, mix it with anything you like as long as it’s not hot (over 120 degrees to be safe). Some use water, yogurt, milk, kefir, applesauce, sour cream, or just spoon it in your mouth and mix with saliva. It’s all good.

  26. tatertot says:

    That’s the right stuff. There is also potato flour and flakes–those are the wrong stuff–pre-cooked, no RS.

  27. And how do you recommend we dose this? Dry with water? Urghhhh


  1. […] bring the starch above 140 degrees Fahrenheit lest you want to turn your resistant starch into tiny, non-resistant starch popcorns. […]

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