2.8. Lipid hydroperoxides in O/W emulsion

Concentration of lipid hydroperoxides were determined using a modified method of Yi et al [15]. Sample (0.3 mL) was mixed with 1.5 mL isooctane/2-propanol (3:2, v:v), vortex-mixed three times, and centrifuged for 3 min at 2000 g. The upper layer of 0.2 mL was collected and mixed with 2.8 mL methanol/1-butanol (2:1, v:v). Thiocyanate/Fe²⁺ solution (30 μL) was added to the mixture and the mixture was vortex-mixed for 10 s. The samples were incubated for 30 min at room temperature and the absorbance at 510 nm was measured using an UV/VIS-spectrometer (Model UV-1650PC; Shimadzu, Kyoto, Japan). The concentration of lipid hydroperoxide was calculated using a cumene hydroperoxide standard curve.