Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: FredL on 30/12/2015 01:04:38
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Does the process of frying in oil affect the carbohydrate content of potatoes?
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The carbohydrate content of a potato is mainly starch. Raw starch is difficult to digest and cooking breaks down the starch into a more digestible form. So although the carb content is the same, the accessible calories will increase. This is true for all cooking methods.
When deep frying 2 additional things happen, firstly you will get fat absorbed into the surface which will increase the calorie content, but not the carb content. Secondly, the sugars released by cooking the starch will be caramelised by the hot fat at the surface giving a brown colour and a rather delicious taste. Although the caramel is slightly harder to digest it doesn't make much difference to the overall calorie content.
Hope that helps.
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Okay. Does the answer remain the same when you leave the potato in the hot oil until it is a small dark brown lump?
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At some point, given enough time and temperature, it would no longer be food. There has been some question as to the safety of frying from the health standpoint, in that there has been a link to increased incidence of cancer to people exposed frequently to hot oils. This includes both cooks and, I believe, auto mechanics. So I would say definitely you don't want to cook them beyond a certain point, or heat the oil beyond a certain temperature nor for an excessive period of time. Oxidation of the oil may play a role in its deterioration.
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Okay. Does the answer remain the same when you leave the potato in the hot oil until it is a small dark brown lump?
Mmmm, not going to ask who does the cooking in your household [:)]
However, been there, done that, got the faded tee shirt.
Heat of oil will firstly dehydrate the potatoe, then I suspect the starches and sugars will begin to polymerise - like plastic. You could look up British Gum which is burnt starch but in hot oil there is no unlimited supply of oxygen as when something is burnt in the atmosphere (not unlimited I know, but lots available). Some chemists eg ChiralSPO might know the full mechanisms.
As Atomic-S says, be careful with overheating oils, dangerous transfats are produced. Still, I don't suppose you will be eating the potatoe you describe.