Cholesterol oxidation products (COPS) were estimated in a variety of foods by gas chromatography. Substantial quantities of α- and β-epoxide (2 to 46 and 0 to 111 ppm, respectively) and lesser quantities of 7β-hydroxy- and 7-ketocholesterol were found in powdered egg products. Other foods found to contain COPS included dehydrated chicken, turkey and beef (0 to 43 ppm); and Cheddar, Blue, Romano and Parmesan cheese powders (0 to 17 ppm). Powdered infant formulas and dehydrated baby foods displayed several peaks coinciding to COPS but none were confirmed by mass spectroscopy. COPS were either not detected or noted at < 15 ppm in fresh dairy products.

The effects of normal and adverse environmental holding conditions on the formation of cholesterol oxidation products (COPS) in powdercd cheeses and salted and unsalted butteroil were invcstigatcd. Little or no change in COPS levels was noted in a variety of powdcrcd dairy products stored at 4, 21, or 38°C for up to 6 months. Storage for 18 mo at 4°C resulted in a three-fold increase in the levels of COPS. Cheddar cheese powder continuously exposed to light (1611 lx) displayed increases in a-epoxide and 7-ketocholesterol through week 3, thereafter declining to a level at week 9 of about one-half of that seen at week 3. Continuous heating of buttcroil (110°C) cduscd large increases in COPS' levels, with unsalted buttcroil exceeding levels found in salted buttcroil by 2-to 3-fold.

A capillary gas chromatography (GC) method was studied for direct analysis for cyclopropenoid fatty acids (CPEFAs) as methyl esters. No thermal alterations were indicated in CPEFA methyl esters on a Supelcowax IO or a DB-5 capillary column like other fatty acid methyl esters (FAMES), which obviated a second derivatization. GC conditions are described for a complete separation and quantitation of CPEFAs in cottonseed oils. CPEFAs of cottonseed oils from various refining steps were analyzed by the method. The reliability of the method was demonstrated with over 95% recoveries of CPEFA methyl esters diluted in corn oil FAMES at various levels as low as 0.017%.