Abstract
We have been researching ways to decrease the amount of wasted oil. According to our previous investigations, we have found that consumers use the excess oil when frying and throw away the waste oil after one or two uses. Our goal is to see whether or not it is possible to fry in smaller pans using less oil without adding any fresh oil.
It was found that the oxidation rancidity of frying oil after being used 4 times did not proceed. But the fatty acids composition between the fried sample and the frying oil differed significantly. We also found that the percentage of saturated fatty acids in the fried sample decreased after frying and conversely the percentage of unsaturated fatty acids increased. We determined that fatty acid formation moves back and forth between the fried samples and the frying oil. The change in the composition of fatty acids and the turbidity and viscosity of the frying and extracted oil are related to the number of frying times the same oil is used.
The sensory evaluation results of sample fried food using oil already used for 3 times were higher compared to that using fresh oil, for overall evaluation and crispness.
It appears that the better sensory evaluation of the sample fried in oil used for the 4 th time is a result of the variation of fatty acid composition. The sensory evaluation of the color of the fried sample had little to do with the number of times the oil had been used. But 65% of the panel said they throw away frying oil after using it for the 4 th time.
As the result of research we determine that it isn't important to use a lot of oil for frying. We shouldn't judge the life span of oil only by the number of times it is used, but rather consider whether the quality of the fried food is affected.
