7 replies to this topic

[cteavin]

Hi everyone,

My friend came back from Singapore with a wonderful present -- an idle pan. I'd love to make idli often but don't want to go through the process of grinding and fermenting daily. I was wondering if I could save some of the fermented batter in the fridge and feed it like a culture. My idea is to have the unfermented batter in a separate container so that each evening I could pour off what I need, add some culture and let it rest on the kitchen countertop (where it's warm) until morning.

Is that doable? Is it done?

[indianfoodandy]

Hi

yes this is done in India. They put the mixture in the fridge unfermented (as soon as you have ground the rice and urad) and then take what they need out to ferment.

You can keep the fermented batter in the fridge for about 2-3 days - just take what you need off the top.

Andy

[Chris Amirault]

Welcome, indianfoodandy! I'm hoping we can sort this out, as I have the same question.

If I read correctly, cteavin was asking whether fermented batter can be kept indefinitely in the fridge and "fed" like a sourdough starter is fed, regularly giving it a bit of something to prevent it from over-fermenting. Your response suggests that the answer is no: that once batter is fermented, you've only got 2-3 days before it over-ferments.

However, I think your response suggests a solution, namely, keeping unfermented batter in the fridge and taking it out in small quantities to ferment when needed.

So, two questions. Is the information above correct? And how long does the unfermented batter last?

[indianfoodandy]

Sorry took so long to reply - been a bit busy

The fermentation process is driven by 'wild' yeast - basically yeast that floats about in the air - it also won't happen at the temperature in the fridge . So feeding the fermented mixture and expecting it to keep fermenting won't work. However other process do still occur in the fermented mixture even at 3 deg C so the fermented mixture will slowly go off even in a fridge.

I have heard stories of unfermented mixture lasting up to a month as long as it doesn't dry out, but I have never confirmed this myself.

Hope this helps

Andy

[Jenni]

I have never kept idli batter for more than two days, the idlis just get eaten in my house! I don't know if you can keep it longer, but a good way of using up leftover idli batter is to make utthappam.

[DocDougherty]

There is an excellent (award winning) paper on idli fermentation by an 8th grader at

http://www.usc.edu/C...jects/J0405.pdf

which lays out the fermentation regimen and identifies the two principal components of the active culture as lactic acid bacteria from the Leuconostoc and Lactococcus families.

These are not "yeasts" per se, and probably exist in the native urad dal (speculation on my part but a fairly short series of experiments would nail down the source) rather than the rice. The fenugreek seems to be important in guiding the evolution of the bacterial population to enhance both flavor and texture (speculation on the part of Ms. Guhan).

I have demonstrated to my own satisfaction that you can innoculate a new batch (250cc) with a little(25cc)active culture from a prior batch and dramatically speed up the fermentation (down from 20 hr to 4 hr), so the native concentration of bacteria, while reliable, is quite low irrespective of the source.

I ferment at about 100F for 16 - 20 hrs when I start from scratch, but there are still many variables to play with (ingredients and their ratios, times, temperatures, process steps, ...). I am pretty sure that you could ferment small batches (5cc) starting at 24 hrs intervals and have an adequate supply to speed up a larger batch when you need it.

In a pinch (assuming you live in or near an appropriatly diverse neighborhood) you can buy refrigerated idli batter from your local Indian grocery for use as either innoculant or final product.

Cheers,
Doc

[patcholi1961]

I routinely re-start idli batter using my unwashed batter container from the previous batch.

The batch before last, I also added too much water by mistake, I drained the excess liquid and kept it in the fridge.

I used this as you would sourdough starter for the current batch. They are fluffier than usual.

[DocDougherty]

As an amendment to the post above (two up): my practice has evolved to use less batter from the prior batch and a lower fermentation temperature; I now add 1/4 teaspoon of the prior batch to the dal soaking water, the fermentation temperature is 30°C (86°F), and I use the dal soaking water to fluidize the batter in the grinder. With six hours of soaking, 30 min of preparation time (7 min to grind the dal, 12 additional minutes to grind the rice) and 12 hrs of fermentation, they come out just fine.

Edited by DocDougherty, 01 June 2011 - 07:30 AM.