Organic chemistry behind oil degradation





Reference:
M Mosiewicki et al, European Polymer Journal, 2013
S Basu, Scandinavian Journal of Food and Nutrition, 2007
K E Achyuthan et al, Metabolites, 2017

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Additional experiment:oil viscosity

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Following the success of first experiment, here we advance our story with another experiment by testing the oil viscosity using syringe. Using the well developed model: Poiseuille's Law, we can make use of the fact that viscosity of a fluid is proportional to time taken for it to travel through a given distance. Here we measure the time as the time needed for the oil inside a 10ml syringe to completely drained under the pressure of 50g weight. Since the other parameters such as syringe outlet radius are unobtainable, we measure and compare the time taken as a qualitative comparison as long as control variables are well fixed. Result: Time taken\Oil age t=0 t=5 mins t=10 mins t=15 mins t=20 mins Trial 1 14.2 15.4 16.3 18.1 19.6 Trial 2 14.5 15.3 16.1 18.2 19.8 Trial 3 14.3 15.6 16.3 18.2 20.1 Two sample t-test is used to test significance between t=0 group and t=20 mins group Group\Quantity p-value t-statisitcs stan...
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First experimental result

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In our first experiment we had two different trial sections.  In our trial experiment, we followed the procedure that we had initially made. Using a potato cube of 5mm each side. But we quickly found out that this will not work. Our potato cube size was too small and the heat of oil at 200C was too hot. Before the timer reached 2 minutes, all our potatoes had turned black. First trial Quantity\Drop at t=0 t=5 mins t=10 mins t=15 mins t=20 mins Mass before (g) 20.2 20.4 20.1 20.2 19.9 Mass after (g) 6.6 6.9 6.9 7.1 7.3 Mass drop (%) 67.32 66.17 65.67 64.85 63.31 Normalized water out(%) 67.59 67.59 67.59 67.59 67.59 Attached mass(%) 0.27 1.42 1.92 2.74 4.28 Second trial Quantity\Drop at t=0 t=5 mins t=10 mins ...
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Disgusting oil experiment: effect on oil degradation due to long heating during deep frying process

Backstory Upon seeing the deep dried insects, instead of being disgusted by the insects themselves, we are more shocked by the blackish oil. As we know, degradation of oil can happen under oxygenated environment, heat and light, creating substances with unpleasant smell and taste. Which surely happens in those reused "thousand years" oil for street food. We can already imagine why would they always add excessive spices to cover the rancidity of oil. In fact, we can even see in many restaurant, the usage reused oil can be seen by the weird precipitate on the bubbling oil, which are mostly carcinogenic. Here we want to investigate the effect of long term heating on rancidity of oil in deep frying processes. Theory Oxidative rancidity is associated with the degradation by oxygen in the air. The double bonds of an unsaturated fatty acid can be cleaved by free-radical reactions involving molecular oxygen. This reaction causes the release of malodorous and highly volatile al...
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