Abstract:

Objective: To establish a valid method to discriminate waste cooking oil. Methods: This study used refractive
index, cholesterol, fatty acid composition, Na+ content as indicator components to establish an integrated evaluation system
for discriminant analysis of waste. Results: When oil samples had refractive index lower than 1.4750, cholesterol content
more than 0.1 mg/g, fatty acid U/R value significantly lower than edible oil or with characteristic fatty acids, and Na+ content
more than 3 mg/kg, they could be considered as not safe with respect to one or combinations of these parameters. At least
five characteristic fatty acids for waste cooking oil were identified by GC-MS analysis. Conclusion: The accuracy of the
method was 100% by using these four parameters and hence could discriminate waste cooking oil from edible vegetable oil.

Key words: waste cooking oil, refraction rate, cholesterol, fatty acid, Na+ content