If I use two or three cups of rice to prepare rice in a pressure cooker, I have to add plenty of water, pressure-cook it until one whistle and wait for around 1.5 hours until I open the pressure cooker. However, for idli or dosa, the raw rice + urad dal is ground to form a paste and allowed to ferment. Then it's either steamed (for idli) for 10 minutes or poured onto a surface or flat pan, and cooked for just a few minutes.

The primary questions:

  • I don't understand how this gives the batter enough time to get cooked fully. Compared to how much time and extra water it took to cook rice grains in the pressure cooker.
  • Also, won't such a process prevent a lot of the bacteria and yeast from getting killed?
  • Does it make more sense to partially or fully cook the majority of the rice grains in a pressure cooker, before mixing it with the raw urad dal and a tiny bit of raw rice ground in a mixie or stone grinder (to bring in the bacteria and yeast)?

Reason for asking:
I used a mixie to prepare the batter (so had a slightly coarser texture). Fermentation only began a little, since the ambient temperature here is 21 degree Celsius. The idli and the dosa I prepared with this batter, didn't seem to get cooked fully. It still had a bit of rawness to it.

Some initial searching I did revealed:

  • Bacteria: Leuconostoc mesenteroides, Streptococcus faecalis, Lactobacillus fermentum and Bacillus amyloliquefaciens help in souring and leavening. Yeast: Saccharomyces cerevisiae, Debaryomyces hansenii and Trichosporon beigelli produce flavour, enzymes and helped in the saccharification of starch. source
  • Batter ferments best at 28 degree Celsius and an initial pH of 4.5. source
  • Mixie has a lesser chance of causing starch damage, compared to a stone grinder. source
  • The aerobic bacterial count increases in 16 hours. source

2 Answers 2


I'm going to address another part of your question, which is rice cooking time.

Normal cooking time for rice via the absorption method is about 20 minutes. I'm not at all clear on what you're doing with the pressure cooker; presure cooker rice should require only about the same amount of time -- 10 minutes cooking time plus 10 minutes cooling time. So your 90 minute rice cooking time is way outside of the normal range.*

So, given that the time required to fully cook whole rice grains is about 20 minutes at a simmer, you can see where cooking finely ground rice at a slightly higher (hot steam) temperature would take less time -- around 10 minutes.

(* there are rice techniques that require an hour to cook, but those use very little water and are slow-steaming the rice)

  • 3
    There are a great number of methods for cooking rice, each with its advantages, and I would never criticize someone’s rice cooking method unless they were unhappy with the result. But yeah, I would not have the patience to wait for rice for the better part of two hours, even if the result were really good rice.
    – Sneftel
    Commented Aug 7, 2022 at 19:36
  • I agree with Sneftel. In my experiments, contrary to the popular belief of using 1 cup rice and 2 cups water, I have needed 4 or 5 cups water (and drain the excess water). It's not about presentation or keeping cooked grains separate, the way chefs are taught. It's about cooking it upto the point that it gets fully cooked. I know nobody will agree, but this is from a decade of experience of improperly cooked food resulting in sleep loss and uneasiness (due to a weakened digestive system, which can also happen with elderly people). I know the health angle isnt encouraged here so I'll stop.
    – Nav
    Commented Aug 8, 2022 at 1:32
  • 1
    I'm just pointing out that your personal definition of "fully cooked rice" is way longer cooked than most people's. So using your definition, Idly probably aren't fully cooked either, even if most people would consider them so.
    – FuzzyChef
    Commented Aug 8, 2022 at 16:25
  • 1
    @Sneftel given that one of his questions is "rice takes 90 minutes to cook, how can idly be cooked in 10 minutes", the fact that 90 min rice is unusual is relevant.
    – FuzzyChef
    Commented Aug 8, 2022 at 16:26
  • 1
    @FuzzyChef: the 90 min is because I wait for the pressure cooker's pressure to reduce on its own. If the cooker can be opened before that because rice takes 10min to get cooked, I'm willing to correct myself. I've eaten idlis that have caused me no issues. Fully cooked, in my definition. The ones I tried making, ended up a bit uncooked. But that batter had barely begun fermenting. So I also wondered if aeration during fermenting helps the steam's heat reach inside the idlis & cook it fully. And whether more moisture in the batter helps the dosas get cooked better.
    – Nav
    Commented Aug 8, 2022 at 19:14

You're using multiple inconsistent definitions of "fully cooked".

Both idli and rice are safe to eat once they've been heated to around 65 degrees celsius for a few minutes. At that temperature, all the microorganisms which are found in dry ingredients and normally contribute to food-borne infections have been killed; remaining ones pose no threat if the food is served promptly.

Of course, heating rice to 65 degrees for a few minutes is not going produce good rice. You can safely eat it, but you wouldn't want to do so, because there won't have been enough time/temperature for the grains to fully hydrate and gelatinize. And you wouldn't want to eat idli batter which had only been cooked to 65 degrees. It wouldn't be firm, and the bits of rice in it would still be hard. But once idli is up to cooking temperature, it cooks quickly because the rice in it is in little bits which hydrate quickly.

So for both idli and rice, the cooking time is not selected to ensure food safety. With the time and temperatures used, it's just not going to be an issue (again, assuming the food is eaten promptly after cooking). Cooking times are selected to make the result taste good.

It's not clear what you mean by "rawness", but I'm assuming you meant "hard bits", like with the undercooked rice. The larger the bits of rice in your batter, the longer the idli will take to cook. And that means you're at risk of overcooking the idli, by getting it too hot.

As for including precooked rice: Sure, if you like. That's murmura idli, after all. But the solution to your problem is to grind the rice more finely, or to start with idli mix instead of rice grains.

  • The original question is confusing, but for idli or dosa there is a fermentation step that helps clear a food safety hurdle. I think this is more about fermentation than cooking, but certainly could be clarified by the OP
    – moscafj
    Commented Aug 7, 2022 at 12:03
  • @moscafj: I was asking about how to ensure that it gets fully cooked. But as you guessed correctly, I was also wondering if fermentation helps in "pre-cooking" the starches in any way.
    – Nav
    Commented Aug 7, 2022 at 12:41
  • No, it does not.
    – Sneftel
    Commented Aug 7, 2022 at 12:55
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    @moscafj Fair enough. But by the time idli gets enough botulism to make you blink, it’s got enough aureus to kill your whole cricket team.
    – Sneftel
    Commented Aug 7, 2022 at 13:32
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    @Nav it takes very little time at those kinds of temperatures to kill pretty much all bacteria. 10 minutes is definitely more time than that. And since you are defining "fully cooked" differently than most chefs (which define "fully cooked" as safe and tasty to eat), you will have to be a lot more specific about what that means if you expect people to be able to answer that.
    – Esther
    Commented Aug 8, 2022 at 14:27

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