[baxter001]

Is the whole whistle counting thing typically an Indian usage of a pressure cooker?

I often see whistle counts mentioned in recipes from the country but all of the more local recipes I have seen relied more upon strict timings.

[tomkinstinch]

American here. I've never heard of this usage of pressure cookers, and I'm not sure I really understand it. Can anyone explain why whistle counting works?

Does the pressure-temperature relation of the combined gas law hold in the steam regime, considering the weight clamps the cooker to a maximum pressure? It seems like the whistle frequency would be a function of heat input to the system (or rather heat lost) while temperature would mostly be determined by the letoff pressure value. You'd think a longer time or higher temperature would shorten cooking time, not the amount of heat escaping the system. Below the letoff pressure, temperature is a great proxy for pressure (via the combined gas law), and indeed this is how many of the electric pressure cookers "sense" pressure; they have thermistors thermally coupled to the cook pot. Could it be that pressure recovers to the letoff value more quickly at higher temp? That would make whistle counting for temperature roughly similar to the light measurement method of the modulo camera that was discussed a couple days ago[2]. It seems like the diameter of the pot might impact pressure recovery time though.

All that said, it is GREAT to see more cooking tech, OP. Anything that helps people to cook more (or better) can only be a good thing.

Perhaps worth knowing is that there are three types[1] of pressure cookers, and it seems like OP's product could only potentially work for one (?) of them: old-school weight-clamped. Fagor-type pressure cookers release steam constantly, old-school weight-on-top pressure cookers release steam intermittently, and Kuhn Rikon pressure cookers release no steam at all (best for flavor since no volatiles are lost to the kitchen with escaping steam).

1. http://www.cookingissues.com/index.html%3Fp=2561.html

2. https://news.ycombinator.com/item?id=10053691

[baxter001]

By that reasoning determining cooking time by the number of whistles would be a very coarse and inaccurate measure of "time spent at optimal cooking temprature" very sensitive to heating temperature.

If the weighted valve and letoff system is succeeding in staying close to a constant pressure/temperature surely a simple timer would be a better solution.

[flarg]

Yes it is, I think primarily because of the design of popular makes of pressure cooker in Indian (Butterfly, etc.) which have not advanced as much as in Europe. After a lifetime of the old whistle style of pressure cooker I finally convinced my wife to try a new style with a pop-up pressure indicator (Fissler Vitaquick - highly rated by America's Test Kitchen) and she finds it miles better, and quicker, than the old style. Not only that, no risk of exploding pressure cookers (as is common in Indian households). I'm still struggling to convince friends and family - who still go to the local Indian store to buy pressure cookers made "back home" when their own "explodes".

[septerr]

Yes, the whistle counting thing is typical in usage of pressure cookers in Indian cooking (I am an Indian).