Comments on: Stretch Today, Gone Tomorrow: Potato Ice Cream 2 The International Culinary Center's Tech 'N Stuff Blog Thu, 09 Jan 2014 18:17:16 +0000 hourly 1 By: Jason McDermott Thu, 22 Jul 2010 08:01:31 +0000 Ok, final post for tonight.

Checked the ice cream again. I noted earlier that it seemed a little grainy and now I can almost taste the starch, albeit almost flavorless in the first place, in the product so I would say that yes retrogradation is definitely happening. It did however take much longer than what I would normally expect for a bowl of ice cream to melt. Once I try again and attain a similar stretchiness to what you were seeing then maybe I can look more into the retrogradation.

By: Jason McDermott Thu, 22 Jul 2010 03:32:14 +0000 Interesting page on National Starch’s website about potato starch:

I’m inquiring about some free samples from them right now, especially a product called “Perfectagel MPT”.

By: Jason McDermott Thu, 22 Jul 2010 00:24:56 +0000 Hey Dave. Thanks.

In regards to submerging in the water I was curious because the potatoes didn’t have that typical “tackiness” that steamed potatoes do. They didn’t feel like boiled potatoes either, but the “tack” was definitely not as prevalent. Note here that the gel created by combining 40 grams potato starch with 200 mL water and cooking creates a gel with surface properties similar to a steamed potato. The gel was quite “tacky” on the surface.

I’m not completely sure what you mean by you let “them flash off steam as they cool…”

I wanted to try the potato starch by itself, but potato starch isn’t made by cooking a potato. Since the cooking is necessary in your recipe I thought I would try that first.

Next set of experiments will be with the potato starch uncooked blended directly into the base. My concern here is it being uncooked.

Then I will try a batch where I cook the potato starch with the base (probably add after the tempering of the eggs and cook for 10 minutes or so with the base). My concern here is that the starches may not gel properly due to over-hydration(?) or fat interference.

I’ve considered also attempting to cook the potato starch in milk (instead of water) in the first place to make a gel. Then shearing it and blending in the base. I’m curious as to the gel properties here and how the fat would interfere with the matrix.

Finally, I would like to just try another version of what I already did but double or triple the amount of potato starch (same amount of water), making thicker more viscous gels. Then shearing these into the base.

I’d be interested to try this with other starches as well. Do you know if any other starches form similar gels when cooked down like the potato starch? I could post a pic or two in the forums at the end of the week of the gels that I’m shearing.

In regards to retrogradation:

1. It is hard to tell with the potato starch ice cream. As I stated before it didn’t quite get the same stretch as you had gotten with potatoes using the potato starch. So, it is hard to tell from a stretch standpoint how much retrogradation has happened. Although, I do find that the mouth-feel of the ice cream doesn’t necessarily feel the same as it did yesterday. It almost feels as if it has become more granular. I’ll check it out again in about 8 hours to see what it is like – that will be around 24 hours post-finished product.

2. I am going to make a simple potato starch gel as I did for the initial experiment and just leave it out overnight to see what happens.

By: davearnold Wed, 21 Jul 2010 14:17:01 +0000 Nice work! I wonder if the submerging had anything to do with it. One more note: when we make the potato ice cream we steam the potatoes and then let them flash off steam as they cool. This is potentially removing a lot of moisture, which may account for the increased stretch when we make it. Have you tried using the potato starch directly in the anglaise base, potentially adding a bit more milk? I eagerly await a recipe. BTW, did the potato starch have retrogradation problems?

By: Jason McDermott Wed, 21 Jul 2010 07:29:17 +0000 Ok, so experimentation time is over. I’d do more tonight, but it is 3:00 AM and nothing is open for me to get more ingredients to bring back to work this late.

For comparison I quadrupled the recipe Dave has listed above minus the potatoes. I also didn’t quadruple the vanilla (didn’t have that many and wasn’t buying them at the grocery store at 2 for $20…!!!). I expected because of this that I would probably taste potato.

First I made just plain ice cream with it. Yes it was a little TOO flavorful.

Next, I tried to add the potato. This didn’t quite work as well as it did for you guys at the FCI. It did appear to gain some stretchiness, but nowhere near as much as the pictures you have posted. I didn’t have an appropriate steaming vessel with me at work so I utilized a pasta pot with strainer and attempted this. The potatoes may have submerged in the water for a short period of time while I was out of the room. Could this have been the downfall here? And obviously it tasted like potato since there wasn’t enough vanilla in it.

I also tried to just utilize a large quantity of Resistant Corn Starch 260 from No luck. No stretch and it tasted, well like corn starch. It also left you feeling like you had a hairy tongue, which is absolutely gross! I tried to cook this in some water (brought to simmer), but it just dissolved and once it cooled it began to separate out of the water.

Finally, I’ve been playing with potato starch a lot lately in the forums attempting with KennethT to make an edible biodegradable potato plastic (something he had at El Bulli). We are on the right track there, but it got me thinking about the cooking process of the potato starch. It becomes very gelatinous when heated with just water. The addition of an acid and glycerin makes it plastic.

So, I took 40 grams of Bob’s Red Mill potato starch and added it to 200 mL of distilled water and cooked it until just before a boil. At this point the solution thickens quickly. I then cooled this solution in a styrofoam cup. Once cooled it came out of the cup in a large jiggly mound of opaque gelatinous weirdness! I figured if I could shear it in the blender back into a liquid state then I could add the anglaise and try it. It sheared wonderfully and incorporated into the anglaise great. This was by far the closest I got to making stretchy ice cream as you did.

It didn’t have “enough” stretch though. But, the flavor profile was spot on. The potato starch gel added no additional flavors as did the steamed potato and corn starch. The final consistency was more palatable as well.

Next week or the week after (when time and money permits) I will attempt another round of trials unless you guys beat me to it. I want to double the amount of potato starch to 80 grams/200 mL water and try that and possibly move up from there.

**Click my name for new gastronomic alchemy videos!**

By: Jason McDermott Mon, 19 Jul 2010 23:29:01 +0000 Ok, I finally have some time at work. Tonight I’m going to make up the anglaise base and cook some potatoes. Then tomorrow night we are going to just make regular LN2 ice cream followed by stretchy with potatoes followed by a trial on the RS260 resistant corn starch as well as a trial with some cooked and cooled potato starch.

Will post results over the next week or so.

By: Jason McDermott Mon, 12 Jul 2010 19:16:58 +0000 Cesar – from what I’ve read it would be better for colon health and your diet to eat your mashed potatoes cold the next day. Crazy right?

Using pregelatinized starch may also be the way to go. It is worth a shot.

Let me know about those articles as well.

I just got my resistant corn starch 260 in the mail today. It was really cheap ($3/lb – $8/lb shipped – ordered only 1 lb). It is a large amount of powder.

First try with this will be based on the idea that potatoes, when cooked and cooled, increase in resistant starch to about 10%. I will use Dave’s stretchy potato ice cream recipe and based on the resistant starch being 10% I’ll use 22.5 g of Resistant Corn Starch 260.

By: Cesar V Fri, 09 Jul 2010 17:26:58 +0000 Hi all, I’m requesting the papers Jason suggested – an interesting second thoughts is that it would be better then to eat your mashed potatoes the day after you make them :-)

Jason, do you mean making your own pre-gelatinized starch?

I might have missed it from the above, but instead of using a modified or resistant starch, why not use a pregelatinized starch that is added to the cooled mix and let hydrate for 5-10 min before freezing?

By: Jason McDermott Fri, 09 Jul 2010 11:43:43 +0000 Not yet. I’ve got some Resistant Corn Starch 260 on order and being shipped. It is a RS2 type resistant starch so it may not work properly. But, I’m having some issues finding RS3 type starch without making it myself (i.e. cooked and cooled potatoes…). Although it does state that RS3 is also found in legumes and breakfast cereals. I don’t know about the beans… but, it might be fun to make some breakfast cereal flour and see what happens.

It will be a few days before I have any LN2 access as well (possibly up to a week). I will definitely get back to you on my results.

Also, what about just utilizing potato starch or making a slurry of potato starch and water, heating it and then cooling it…?

By: davearnold Thu, 08 Jul 2010 15:46:49 +0000 Have you tried it with RS starch yet?