Fig. 4.

The expanded regions of primary oxidation products (conjugated diene groups) in the ¹H NMR spectra of 10% O/W emulsions added with different antioxidants. O/W emulsions were prepared with 200 ppm of ferulic acid (FA), 4-vinylguaiacol (4-VG), and catechin, respectively. Oxidation study was performed for 50 days at 37 °C in the dark. Conjugated diene groups were Z,E-conjugated form [multiplet, E = 6.55 ppm (CH = CH − CH = CH), H = 6.00 ppm, J = 5.55 ppm, K = 5.50 ppm] and E,E-conjugated form [multiplet, F = 6.25 ppm (CH = CH − CH = CH), G = 6.05 ppm, I = 5.75 ppm, L = 5.45 ppm), respectively