Sensitive Colorimetric Determination of Cholesterol in Dairy Products

Abstract

Abstract Cholesterol can be determined colorimetrically in dairy products at levels of ≥10 μg (coefficient of variation = 5.3%) with an o-phthalaldehyde reagent when non-cholesterol lipids arc eliminated prior to color development. Absorbance for 2 mg tripalmitin was found to be equivalent to about 20 μg cholesterol. Saponification followed by hexane extraction removed interfering lipids. Using the described procedure, 238 individual raw milk samples were found to contain 144.4±37.9 μg cholesterol/ml, while their skim milk portions had 26.5±6.4 μg cholesterol/ml (mean ± standard deviation). The o-phthalaldehyde cholesterol estimates agreed with those obtained by a gas-liquid chromatographic procedure when cheese and ice cream were analyzed by the colorimetric procedure with and without prior fat extraction.