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I’m curious whether starting a rice cooker with hot or cold tap water has an effect on the resulting hydration of the rice. I’m unsure of whether I would need to add more or less water to reach the same result, compared to cold. I don’t expect there to be that much of a difference, but it would be nice to know which way to tweak things.

One reason I ask is because I sometimes consider adding hot water to my rice cooker so that it’ll cook a smidge faster (since it’s starting closer to boiling), even though I know that’s not that large of an effect.

It shouldn’t matter, but for full disclosure I usually do a 1.5:1 ratio for my long-grain basmati rice (which I know is a bit on the low side for many). Since it’s close to the level of “too little water” I’d like to know if changing the temperature of the water will push it further over the line or go the opposite way.

General assumptions:

  • Both sets of rice have been prepared the same way (rinsed or not, etc)
  • Using a rice cooker, specifically a basic temperature sensor (like a bimetallic strip)
  • Using tap water, so say 50°F/10°C vs 120°F/50°C
fyrepenguin
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  • Not an answer: I doubt it will many any difference (other than time) if it's the same amount of water. The rice cooker will do its thing and the amount of water you put in will be in the rice at the end-point. – Ecnerwal Mar 29 '25 at 13:04
  • I've never specifically done a side-by-side test, but I know I've seen mention that a fast heating rice cooker makes for better sushi rice... but they also pre-soak the rice, which could play a major factor in this. There's also what your desired result is and the variety of rice (abborio always stays a little firm in the middle, while sushi rices don't; basmati will lengthen significantly when cooked correctly, etc). Washing might also become more significant with hot water – Joe Mar 29 '25 at 13:27
  • @Joe yeah, the prior steps will definitely have an impact, but assuming I have two pots of rice prepared the same way, I’m curious if the initial water temp will have any difference in the result. One hypothesis I had is “hot water will reach boiling quicker so less time for water to evaporate as it heats, so it’ll be more moist”, but I can also imagine “reaching boiling quicker results in the risk of undercooking the rice slightly” or something like that – fyrepenguin Mar 29 '25 at 17:51
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    May also matter if the cooker is "fuzzy logic" or not. https://cooking.stackexchange.com/q/42301 – Ecnerwal Mar 29 '25 at 19:01
  • @Ecnerwal that’s some interesting reading. I’ve clarified the question to exclude such fuzzy logic cookers, as I’m using a dead simple type of cooker. I hadn’t even considered those – fyrepenguin Mar 29 '25 at 19:49

1 Answers1

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In general, my understanding is most rice cookers are designed with cold or cool water as the starting point. Likely because the water temperature impacts the rate it is absorbed into the rice. Rice cookers are designed to bring the water to a boil and then automatically reduce heat once the water is absorbed or evaporated.

However, your instinct is correct. Hot water to start will speed the process. This might, in fact, impact the final texture of your rice. The only way to tell how much and whether or not it matters to you is to do a side-by-side comparison (actually a triangle test would be best). For what it is worth, I done exactly what you propose (hoping to speed the process) from time to time. I've never perceived a difference, but also have never done a comparison.

One commenter mentioned "fuzzy logic". If your rice cooker has fuzzy logic, initial water temperature might not matter much at all, since these systems are monitoring and adjusting time and temperature throughout the process.

moscafj
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