EFFECTS OF ADDED COPPER ON CONCENTRATIONS OF VOLATILE MATERIALS PRODUCED IN MILK

Analyzing the steam distillate from milk enabled measurement of increases in concentrations of n-hexanal, n-pentanal, propanal, acetaldehyde in raw, laboratory-pasteurized and plant-pasteurized-homogenized milk exposed to 0 and 5 ppm added Cu. Greatest changes were in the Cu-treated laboratory-pasteurized milk and the least in Vacu-Therm pasteurized-homogenized milk. The 2-thiobarbituric acid values (TBA) in the exposed milk, laboratory pasteurized, 0.90; raw, .078; plant pasteurized, .056, reflected changes in volatile materials. Acetaldehyde concentrations increased about the same in whole pasteurized-homogenized milk as in skim milk exposed to 1 or 2 ppm Cu. The other carbonyl compounds increased consistently in whole milk, but little or none in skim milk. Increases in concentration of the carbonyl compounds (other than acetaldehyde, acetone and butanone) produced in pasteurized-homogenized milk exposed to 4 ppm Cu for 44 h were reduced by adding 150 mg of ascorbic acid/l of milk. The concentrations was greater in ascorbic acid-Cu-treated milk than in milk not treated with Cu. Adding the steam distillate from Cu-oxidized milk produced the typical Cu-oxidized flavor in good-flavored milk.