• egg yolk;
  • spray-dried;
  • cholesterol;
  • oxidation;
  • COPS


A direct-heated spray dryer with an evaporative capacity of up to 7 kg H2O/hr was used to identify processing conditions responsible for formation of cholesterol oxidation products (COPS) in spray-dried egg yolk. Outlet air temperature and nitrogen oxides (NOx) in the combustion gases were the only conditions that affected COPS levels. At outlet temperature 150°C, total COPS concentrations in the spray-dried product were 75 ppm at 5 ppm NOx and 213 ppm at 300 ppm NOx. In products dried at 75°C outlet temperature, total COPS concentrations were 21 ppm at 5 ppm NOx and 58 ppm at 300 ppm NOx. In general, individual COPS responded to outlet temperature and NOx in the same manner as total COPS.