11 replies to this topic

[DocDougherty]

I have been successfully making idli for a few years but have had problems lately that I don't fully understand. My recipe uses 64g of urad gota (decorticated whole black matpe beans), 192g of parboiled rice, 1-1/4t salt, and 1/4t guar gum (as a tasteless, colorless substitute for the methi seeds which according to a researcher at University of Mumbai act only as a thixotropic agent). The beans and rice are soaked separately for 6 hrs (the rice is washed the urad not) in RO filtered water (no chlorine, mineral content< 10ppm). The soaked beans are then ground (with water to make a total dry beans + water weight of 256g) plus salt and guar gum for 5 min in a stone grinder, producing a very smooth paste. The soaked rice (dry rice plus water to make 550 gm) is added and ground for 11 min until the particle size is like coarse sand or idli rava. The batter is then covered with plastic and fermented at 30°C (86°F) until it at least doubles in volume.

When it works, it works fine, taking about 13 to 15 hrs to double. The batter is then steamed in greased idli pans for 13-15 min, cooled slightly and served or cooled fully and frozen.

The problem I have been seeing is that the batter does not ferment (after 48 hrs it just picks up a pink bacterial growth on the top surface that stinks but does not get foamy or rise). I have an active hypothesis that the beans I have bought were treated with heat or radiation to kill insects before they were imported and that the process also killed off the leuconostoc mesenteroides bacteria that is the active agent for the fermentation.

Does anybody have any insights that support or refute the hypotheses? Or is there something I don't yet fully grasp that is essential to the making of these wonderful fluffy little steamed dumplings?

[Jenni]

What you are doing sounds right...the only thing I can think of is the guar gum is affecting it somehow. I don't really understand why you are using it....why not use methi?

All the times I have made idli (which is many many), I have never had batter not ferment at all. Sometimes it takes longer, especially in Winter in the UK, but it does get there.

My only difference in your method is I add a handful of poha to the rice when it is being ground, I grind the rice and urad separately and then combine them, and also I use methi seeds. My rice:urad proportion is 3:1

I hope someone else will come here and let us know about why your idlis are going funky!

[DocDougherty]

Thanks Jenni. I am consistent with your 3:1 ratio of rice to urad though I recognize that lots of people insist on less rice, and your addition of poha is actually going the other way. The amount of water has to match the grinding time to get the right viscosity in the finished batter. I have accidentally let the grinder run too long and had to add a little water to thin it out. I suspect that the poha would act to suck up some additional water and smooth out the final product.

The guar gum is a good functional substitute for methi without adding any color so I get nice white idli and don't experience significant syneresis during what might be 12 hrs of refrigeration between when the batter is sufficiently fermented and when I steam the idli. You can also use xanthan gum which has no flavor but costs a bit more (I can't taste the guar at the concentration in which it is used here, though in more delicate applications I do switch over and use xanthan). I suppose I could try a batch without the guar just to see if is affecting anything but I am still using the same batch of guar gum that I got two years ago and it has worked just fine for all that time.

I did have difficulty getting reasonable fermentation times with some early batches when I was using urad dhal (split beans) so, on a suggestion that I found on-line, I switched over to urad gota. I also have run tests where I washed the gota in one batch and did not wash the gota used for another batch and verified that the unwashed beans ferment more quickly, but the washed beans will still make a nice idli after a few more doubling times. I even ran one case where I sterilized the surface of the urad gota in 3% hydrogen peroxide for a couple of hours and I still got a good result (which convinces me that the bacteria are actually in the bean itself and not just on the surface).

It is in part this persistent presence of the leuconostoc bacteria that makes me suspect that I have managed to get a supply of well-sterilized urad gota (and I have little confidence that

Doc

PS - I am a big fan of yours.

[Jenni]

Well you seem to have wonderful scientific knowledge of the subject and it's great to see housewives' tips (use whole skinned urad instead of split, wash it little or not at all, etc.) being verified. Another tip is that when you combine the two battered (i know you grind them both together but many people say you shouldn't) you should use (clean) hands instead of a spoon or whatever as the warmth from your hand is supposed to help. I always do this.

I mentioned my ratio but forgot to say I do measure that by volume, weight may be very subtly different. The poha is such a small amount that it doesn't really change the ratio, but it is supposed to make the idli soft and fluffy.

As for methi making them less white, it is a long time since I made idli with 100% white rice so I cannot say. I use some parboiled red as well as white so my idli are very subtly not pure white. I heard that methi seeds have similar properties to the urad in that they are supposed to be a good source for the...would you call it wild yeasts?

All I can recommend is that you try changing one thing at a time to try to figure out what may be causing the issue. I did this when I started to get rust coloured patches after the idli were steamed. I made idli again and again and just did one thing differently each time, even down to changing the steaming pan and mixing bowl. In the end it turned out that the paticular brand/type of rice I was using seemed to be the cause. I switched brands and have had no probs since.

Btw when I posted about my problem on a different forum one person very politely suggested that perhaps some other unwanted bacteria may have affected the batter...maybe due to not keeping things clean and so on. This is something you may want to consider as it seems some other bacteria is growing in your batter.

Also, you might look for others with the same problem on the net. If it is a problem with the urad as you suspect then I would have thought many others would also have the same problem as you. Try indus ladies website, they surely would be talking about it.

Btw I am nervous about your last comment. I have a big mouth but deserve no admiration. My knowledge is very very small, it's just that those with more knowledge do not post on this particular forum.

Sent from my HTC Wildfire S A510e using Tapatalk

[Yajna Patni]

I make my idli similar to you. I have no scientific knowledge. I don't use methi because i cant stand the taste. I have heard it helps the wild yeasts. It definitely sounds like you are picking up mold instead of yeast. I have had this happen with sourdough though not Idli. Would using a different spot to ferment help? I think somewhere buried on the India forum is a long thread on idli, where Gautam, who does know everything from a scientific point of view has posted a lot on using methi to help the yeasts, and also on different kinds of rice.
I am not nearly as much of a purist as jenni, and I often do not have par boiled rice around so I use basmati, I have also used jasmine. It has all fermented, although when it is damp and cold it takes a while longer.

[DocDougherty]

Jenni,
Yes - 30°C is about optimum temperature for incubating bacteria of many varieties and of course the humidity and available nutrients further encourage them. But for the good guys as well as the bad it is always a race to see who wins, and doubling times at that temperature for many species is on the order of 90 min, so a 15 hr fermentation extended to 48 hrs provides for additional growth of opportunistic contaminants by a factor of about a 1,000,000:1. After 15 hrs it is usually clear whether the idli are progressing and the question becomes "is there something else growing here that is suppressing the leuconostoc. I have tried using a starter from a prior batch to speed things up (successfully) but I also discovered that you can't do that on a continuing basis for exactly the reason you point out - you are providing the absolute optimum conditions for the contaminants. In sourdough bread starters the pH drops below 4.5 and suppresses many competitors (including the notorious and pesky leuconostoc mesenteroides), but idli starts at around pH 6 and seems to rarely go below pH 5.

I am looking for other sources of urad gota - just to see if I observe the same behavior in a different batch while trying to find the the government-mandated protocols for processing imported legumes. When I find a new source that works, I will run some thermal tolerance tests to see how long and how hot I have to heat the urad to get the behavior I am currently seeing. I have tried this with rice - subjecting it to dry heat at 80°C for 24 hrs produces no growth on agar.

[DocDougherty]

Thank you Yajna. I am flying this afternoon so I will have some time at the airport to look into the India forum for the idli posts. There is much literature that provides guidance on the importance of amylose/amylopectin ratios to good quality idli. I have tried different varieties of rice and found that parboiled rice was consistent, and per Jenni's guidance, and following the principle that "if it ain't broke don't fix it" have kept that part of the equation constant.

[Jenni]

I wouldn't necessarily describe myself as a purist...Partly I feel that decent basmati is an expensive waste in idli. But mostly, it's because I have achieved better results with rices other than basmati. It's the length of the grain that is a visual clue for amylose/amylopectin ratios and short and medium grain rices have the correct ratio.

[DocDougherty]

A dramatic turnaround! I made two small changes to the process and this morning I have batch of idli that has doubled after 13 hrs of fermentation.

I used the same batch of urad gota that failed previously, but made a small change in the soaking/washing protocol; I soaked them in filtered water for ~3 hrs without washing them, then stirred and poured off the excess cloudy liquid, replacing it with more filtered water and continuing to soak for another ~3 hrs.

The second change was to replace the 1/4t of guar gum with 1/4t of xanthan gum.

Now I will have to go back and repeat the experiment twice, once with the modified soak/wash but using guar gum, and once using xanthan gum but not washing the urad gota.

Happiness is a refreshed supply of idli, but I am more curious than ever about the underlying phenomenology that resulted in three sequential failed batches.

[DocDougherty]

After steaming, cooling and eating some, I thought I would post a photo of the finished product.
This is a close up of the cut face of 1/4 of an idli.
It is a good batch - pure white, very soft and fluffy, great flavor:

[DocDougherty]

After some further experimentation I have observed that I get a more reliable fermentation if I soak the urad gota in warm water, covered with plastic wrap, and left in the sun (so that the soaking temperature is perhaps 100°F or higher). Less washing is probably better, but I generally wash once in warm water. When the soaking is done in a warm place, I observe patches of very small bubbles collecting on the surface of the water, and the more small bubbles I see, the better the fermentation after grinding. So perhaps the lesson is that for those who live in cool climates, you still need a warm place (in the kitchen or elsewhere) to both soak the dal and ferment the idli. Another advantage of a warm soak has been that four or five hours is sufficient soaking time to fully hydrate the dal.

Attached Images

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[DocDougherty]

The photo above is of the micro-bubbles that form on the surface accompanied by a few larger bubbles at the edge of the bowl that are not related to the accelerated fermentation. (I ran out of editing time before I could get this into the revised post though the photo was added)

The photo was taken after soaking for ~2 hrs @ 93°F. The dal had been washed once in warm, chlorine-free water.

Edited by DocDougherty, 18 March 2012 - 03:26 PM.