Effect of milk composition upon the partition coefficients of diacetyl, acetaldehyde, and ethanol in acidified milk products

Abstract

Acidified milk samples were prepared with fat concentrations from 0 to 20% and solids-not-fat concentrations from 6 to 12%. The partition coefficients of acetaldehyde, ethanol, and diacetyl were determined in acidified samples at pH 4.4 and 4.6, and at 30 and 500C using gas chromatographic headspace analysis (IGCHS). Concentration, SNF x concentration and the SNF x fat x concentration interaction affected the partition coefficients of acetaldehyde at both 30 and 50'C. At 50'C, the milk fat x concentration interaction significantly affected the partition coefficient. The partition coefficient of acetaldehyde increased with increasing concentrations of milk fat. Partition coefficients decreased as concentration of acetaldehyde increased. The partition coefficients for ethanol at 300C were affected only by concentration of ethanol. At 500C, concentration of ethanol, pH, milk fat, milk fat x concentration interaction, and SNF x milk fat x pH interaction affected the partition coefficients of ethanol. The partition coefficients for ethanol increased with increasing concentration of ethanol at both temperatures. At 500C, partition coefficients increased as concentration of milk fat increased at 12 % SNF and pH did not have an effect on partition coefficients. Concentration of diacetyl, pH, and milk fat x concentration interaction affected the partition coefficients of diacetyl at both temperatures. At 300C, milk fat affected the partition coefficients of diacetyl and at 500C, pH x concentration of diacetyl interaction affected the partition coefficients of diacetyl. Partition coefficients increased with increasing concentration of diacetyl at both temperatures. At 300C, as concentration of milk fat increased so did the partition coefficients. The highest partition coefficients were observed for acetaldehyde compared to diacetyl and ethanol at both temperatures and at the lowest concentration.