Inherent and process-induced hydrophobicity influences aroma retention in fat-free dairy matrices

It was shown that both inherent and process-induced hydrophobicity can influence the aroma retention in fat-free dairy matrices. The extent and direction to which these parameters take effect depends on the composition of the dairy matrix as well as on the hydrophobicity (log P) of the aroma compounds. The phase ratio variation (PRV) method was used to determine the matrix–air partition coefficient K MG. For the hydrophobic aroma compound limonene, K MG increased when the ratio of casein protein to whey protein was increased in model milk, while the less hydrophobic ethyl hexanoate and the hydrophilic diacetyl remained unaffected. This was attributed to the hydrophobic character of the casein micelle. Upon acidification with glucono-δ-lactone, K MG of diacetyl decreased significantly while K MG of ethyl hexanoate and limonene slightly increased. This was attributed to the predominance of hydrophobic interactions in acidified dairy matrices, which were analysed via bonds analysis using destabilising buffer solutions.