Comparison of antioxidants to prevent oxidation of sulphur flavour compound in sunflower oil

The objective of this study was to compare the effectiveness of various antioxidants in slowing sulphur flavour compound oxidation in oil matrix. A model aroma compound mixture was prepared in sunflower oil and stored for 8 weeks. Six systems were studied, in which samples contained: 0.01% δ-tocopherol; 0.05% rosemary extract or a mixture of 0.02 % (ratio 1: 1) δ-tocopherol and ascorbyl palmitate; or of butylated hydroxy anisole (BHA) and butylated hydroxy toluene (BHT); and lastly with no antioxidant added, with low-Oxygen level or with ambient air oxygen level. Aroma volatiles were analysed by static headspace-GC-FID to determine stability over time. The effect of each antioxidant system on their stability was generally compound-dependent: BHA/BHT and systems containing tocopherol did not provide any significant protection (p > 0.05) to furfuryl mercaptan (FMCP), dimethyl sulphide (DMS) and propane thiol (1-PSH), but did protect 2-butanethiol (2-BSH) over 8 weeks of storage. In contrast, adding rosemary extract did not improve the stability of 2-BSH but substantially protected the three other compounds. Overall, less reactive sulphur compounds were better protected by the presence of antioxidants. While all antioxidants systems reduced oxidation of the oil matrix over time, they were not as effective in reducing the losses of flavour compounds.