robbarron Posted July 30, 2009 Posted July 30, 2009 Sorry if this is in the wrong section, I am new to hear and do not know much about science. I would appreciate as much help as possible and for you to treat me like an idiot in your explanations please. My problem: When you cook potatoes by boiling them, they take a while, i presume it is something to do with the break down of the proteins or something like that? I am just wondering is there a scientific process you can do to speed up this reaction? Sorry i have not explained very well and if any one needs any more infomation or a better explanation to give me answers then please state and i will try and explain in more detail. Thanks very much for all your help in advance and i look forward to hearing the replies. Thanks.
insane_alien Posted July 30, 2009 Posted July 30, 2009 yes, it is quite easy to speed up the process of boiling potatoes. you use a pressure cooker. unlike boiling the potatoes in an open pot, the pressure cooker prevents the steam from escaping into the atmosphere. this causes the pressure to build up although it does have a relief valve to prevent too much pressure which could turn it into a bomb. the reason more pressure allows for faster cooking is that when you increase the pressure, the boiling point of water will increase. when the pressure is twice that of the atmosphere water boils at ~120*C. because the temperature is higher, the cooking process proceeds at greater rate. a rule of thumb is that a reaction doubles in rate for every 10*C i'm not sure how well this applies to boiling potatoes but if we assume this holds true then an increase of 20*C causes the time required to boil them to be only a quarter of the time needed under the usual conditions. if you need anymore clarification i'll be happy to expand on this.
robbarron Posted July 30, 2009 Author Posted July 30, 2009 Ok, thanks. I will get back to you if I need any further help. Thanks very much.
iNow Posted July 30, 2009 Posted July 30, 2009 +1 on IAs response. Pressure cooking potatoes whips them out in no time at all... You can make homeade mashed in almost the same amount of time as instant mashed.
robbarron Posted July 30, 2009 Author Posted July 30, 2009 is there a pressure cooker out there which is for sale or do i have to make my own little contraption up for it to work? Thanks again for all info, much appreciated.
GDG Posted July 30, 2009 Posted July 30, 2009 Cutting them into smaller pieces helps too. Potatoes are pretty dense globs of carbohydrate, and it takes a while for heat to transfer from the water through the potato all the way to the center. If you cut the potato into chunks, you can substantially reduce the distance the heat must travel, and thus reduce the cooking time. The smaller the piece, the quicker it should cook. Heat transfer is also a function of the temperature difference, which is why raising the boiling temperature (in a pressure cooker) makes it cook faster. You can buy pressure cookers at many cooking supply outlets, including Amazon.com.
insane_alien Posted July 30, 2009 Posted July 30, 2009 (edited) its not so much to do with heat transfer as the temperature remains pretty constant throughout the process(the heat has plenty of time to transfer to the center). although it will play a role, just not as significant as raising the temperature to get faster denaturing of the proteins.(See EDIT2:) i'd advise against making your own pressure cooker as without a relief valve there is nothing to stop it rupturing and causing horrible steam burns or embedding shrapnel in you. go for one of the commercial models (i've seen them in asda which is the british branch of wal-mart so try there). EDIT: oh and read the instruction before you use it. but they're basically don't open it straight away. it'll either have to be left to cool for a few minutes or have a valve to release the pressure first. opening a pressure cooker while it is pressurise is a bad idea as the force on the lid could potentially be enough to send you flying. EDIT2: just thinking more about this(need to get life). the heat transfer through the potato isn't as important if you boil them the way i do, put the potatoes in while the water is cold and then heat it to boiling. BUT it would be much more important if you added the potatoes to already boiling water. Edited July 30, 2009 by insane_alien
UC Posted July 31, 2009 Posted July 31, 2009 its not so much to do with heat transfer as the temperature remains pretty constant throughout the process(the heat has plenty of time to transfer to the center). although it will play a role, just not as significant as raising the temperature to get faster denaturing of the proteins. Very little protein to speak of Perhaps gelatinization of starches is what you're looking for.
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