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The effect of storage conditions on the oxidative stability of cholesterol in butter was studied by quantifying cholesterol oxides by GC-MS. Experimental variables for storage conditions were packaging, storage temperature, light source, and storage period. No cholesterol oxides were detected from packaged butter under all storage conditions. When unpackaged butter was stored under ultraviolet light at ambient temperature, 7α-hydroxycholesterol, 7β-hydroxycholesterol, cholesterol β-epoxide, cholesterol α-epoxide, cholestane-triol were detected after 2, 4, 6 and 8 weeks of storage. The amounts of cholesterol oxide species produced were different depending on the storage periods. The amounts of each cholesterol oxides, 7α-hydroxycholesterol, 7β-hydroxycholesterol, cholesterol p-epoxide, cholesterol α-epoxide, and cholestane-triol, produced after 2 weeks of storage were 34.2, 14.0, 12.1, 1.30, and 0.50 ppm , respectively, and after 8 weeks of storage were 68.1, 29.1, 56.3, 8.50, and 4.00 ppm, respectively with trace amounts of 3, 5-cholestadien-7-one. When fluorescent light was used instead of ultraviolet light with other conditions remained the same, the same species of cholesterol oxides were detected but with lesser amounts.
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