The Roles of Fat and pH on the Detection Thresholds and Partition Coefficients of Three Compounds: Diacetyl, Delta-Decalactone, and Furaneol in Water, Oil, and Emulsions.

Abstract

The effect of fat and pH on the best estimate threshold (BET) of 3 prominent dairy product flavor compounds with varying physicochemical properties: diacetyl, delta-decalactone, and furaneol, in water, oil and oil-in-water model emulsions (at 10 and 20 % fat at neutral and acidified pH 5.5) were investigated. The headspace-matrix partition coefficients (KHS/matrix) of each compound in the different matrixes were established. The rheology and particle size of the emulsions used in this study were also investigated. The particle size and the viscosity of the emulsions did not affect the BET or the partition coefficients. Reducing fat from 20 to 0 % did not affect the BET value or partition coefficient of diacetyl (P>0.05). Increasing fat content increased the BET value and decreased the partition coefficient (P<0.05) of the most lipophilic compound in the study, delta-decalactone. Fat did not affect the BET of furaneol (P>0.05) but did have an effect on the partition coefficient (P<0.05). At pH 7, addition of fat decreased the partition coefficient of furaneol whereas at pH 5.5, addition of fat increased the partition coefficient of furaneol. Adjustment of pH from 7.0 to 5.5 did not impact the BET values of delta-decalactone, but did affect the partition coefficients of furaneol at all fat levels and impacted diacetyl at 0 % fat. The partition coefficient results generally agreed with the BET values on the effect of fat and pH, although, the partition coefficient test was more sensitive to the differences in the matrix composition than a threshold test.