Preferred skin tones on mobile displays under illuminants having different correlated colour temperatures.

A psychophysical experiment was conducted to investigate preferred skin tones of 4 skin types under 5 illuminants varying in correlated colour temperatures. The experiments were performed on calibrated mobile display devices. Four facial skin tone images representing each skin type were captured and were rendered to 25 skin tone images to cover a large colour region. The facial skin tone images were assessed by a panel of 28 Chinese observers using an alternative forced choice psychophysical method. The ellipses based on observer preference rate were derived, and the preferred skin tone centres and 50% tolerance ellipse of different skin types under each test illuminants were obtained. According to the colour appearance shift of preferred skin tones under illuminants with varying CCTs, all data were transformed and compared in the a*b* plane under D65 and CIE 1931 Standard Colorimetric Observer condition. The results on the impact of illuminants on preferred skin tones were reported here. All types of skin tones had a good agreement under different illuminants.

Homogenization and lipase treatment of milk and resulting methyl ketone generation in blue cheese.

A specific range of methyl ketones contribute to the distinctive flavor of traditional blue cheeses. These ketones are metabolites of lipid metabolism by Penicillium mold added to cheese for this purpose. Two processes, namely, the homogenization of milk fat and the addition of exogenous lipase enzymes, are traditionally applied measures to control the formation of methyl ketones in blue cheese. There exists little scientific validation of the actual effects of these treatments on methyl ketone development. The present study evaluated the effects of milk fat homogenization and lipase treatments on methyl ketone and free fatty acid development using sensory methods and the comparison of selected volatile quantities using gas chromatography. Initial work was conducted using a blue cheese system model; subsequent work was conducted with manufactured blue cheese. In general, there were modest effects of homogenization and lipase treatments on free fatty acid (FFA) and methyl ketone concentrations in blue cheese. Blue cheese treatments involving Penicillium roqueforti lipase with homogenized milk yielded higher FFA and methyl ketone levels, for example, a ∼20-fold increase for hexanoic acid and a 3-fold increase in 2-pentanone.