An approach to adapt aroma in fat-free yoghurt systems: Modelling and transfer to pilot scale

Aroma retention and flavour perception of dairy products largely depend on the fat content of their respective varieties. When the milk fat content of model milk solutions was increased from 2% to 12%, a linear increase in the matrix-air partition coefficient K_MG, as determined by the phase ratio variation (PRV) method, was observed for six aroma compounds in the log P range of +1.8 to +4.5, namely ethyl butanoate, ethyl-2-methylbutanoate, (Z)-3-hexenyl acetate, ethyl hexanoate and limonene. (Z)-3-hexenol, the least hydrophobic compound (log P = +1.6), was slightly less retarded at increased fat content. With the exception of limonene, it was observed that the higher the log P, i.e., the hydrophobicity of the aroma compound, the more pronounced was the linear increase of K_MG and hence retention. The successful scale-up from basic laboratory research into pilot plant for the aroma compound retention in fat-free yoghurt is presented.