Correlating Volatile Lipid Oxidation Compounds with Consumer Sensory Data in Dairy Based Powders During Storage

Abstract

Lipid oxidation (LO) is a recognised problem in dairy powders due to the formation of volatile odour compounds that can negatively impact sensory perception. Three commercial dairy powders, fat-filled whole milk powder (FFWMP), skim milk powder (SMP), and infant milk formula (IMF), stored under different conditions (21 °C, 37 °C, or 25 °C with 50% humidity), were evaluated by consumer acceptance studies, ranked descriptive sensory analysis, and LO volatile profiling using headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME GCMS) over 16 weeks. Significant (p = 0.001) differences in the concentration of LO compounds and sensory perception were evident between sample types in the different storage conditions. The sensory acceptance scores for FFWMP and SMP remained stable throughout storage in all conditions, despite the increased perception of some LO products. The IMF sample was perceived negatively in each storage condition and at each time point. Overall increases in hexanal, heptanal, and pentanal correlated with "painty", "oxidised", "cooked", and "caramelised" attributes in all samples. The concentration of some LO volatiles in the IMF was far in excess of those in FFWMP and SMP. High levels of LO volatiles in IMF were presumably due to the addition of polyunsaturated fatty acids (PUFA) in the formulation.

Keywords: dairy powder; fatty acid; flavour; infant milk formula; lipid oxidation; sensory; volatile profile.

Figure 1

Radar plot illustrating the ranked descriptive analysis (RDA) scores for the sensory attributes evaluated at T16 for samples stored at 21 °C (AM) and 37 °C (ACC).

Figure 2

Principle component analysis (PCA) biplot of fat-filled whole milk powder (FFWMP), skim milk powder (SMP), and infant milk formula (IMF) samples at T8 demonstrating the trends observed throughout the study for the ranked descriptive analysis (RDA) and volatile analyses. AM: ambient, 21 °C; ACC: accelerated, 37 °C.

Figure 3

Principle component analysis (PCA) biplot demonstrating the correlations between the sensory perception and volatile compounds for fat-filled whole milk powder (FFWMP) at T4, T8, T12, and T16 of storage. AM: ambient, 21 °C; ACC: accelerated, 37 °C.

Figure 4

PCA biplot demonstrating the correlations between the sensory perception and volatile compounds for skim milk powder (SMP) at T4, T8, T12, and T16 of storage. AM: ambient, 21 °C; ACC: accelerated, 37 °C.

Figure 5

Principle component analysis (PCA) biplot demonstrating the correlations between the sensory perception and volatile compounds for infant milk formula (IMF) samples at T4, T8, T12, and T16 of storage. AM: ambient, 21 °C; ACC: accelerated, 37 °C.