Size of methyl ricinoleate droplets during biotransformation into γ-decalactone by Yarrowia lipolytica was measured in both homogenized and non-homogenized media. In non-homogenized but shaken medium, droplets had an average volume surface diameter d 32 of 2.5 μm whereas it was 0.7 μm in homogenized and shaken medium. But as soon as yeast cells were inoculated, both diameters became similar at about 0.7 μm and did not vary significantly until the end of the culture. The growth of Y. lipolytica in both media was very similar except for the lag phase which was lowered in homogenized medium conditions. ; Peer reviewed