Under oven test and Rancimat test conditions, the fatty acids changes, the aldehyde formation, and the inhibitory effect of rosemary extract on rapeseed oil (RO) oxidation had been comparatively analyzed in this work. Results demonstrated that the aldehyde compounds generated from RO were (E)-2-decenal, (E)-2-undecenal, and (E,E)-2,4-decadienal both in oven test and Rancimat test, however, nonanal is generated in not Rancimat test but oven test. Meantime, rosemary-derived antioxidants effectively inhibited the formation of (E)-2-decenal, (E)-2-undecenal, and (E,E)-2,4-decadienal both in oven tests and Rancimat tests, while, it promoted the production of nonanal only in the oven test. The mechanism whereby nonanal is generated exclusively in oven test may be attributed to the higher likelihood of β-cleavage occurring at the proximal end of peroxide double bonds compared to the Rancimat test. Meanwhile, the effective inhibition of alkenal/alkadienal formation by rosemary antioxidants is primarily due to their selective suppression of β-cleavage at the distal end of peroxide double bonds both in test of oven and Rancimat. All results indicated that rosemary-derived antioxidants promoting the double bond-proximal β-scission exhibited differences in test of between oven and Rancimat, and provide a theoretical basis for evaluating the selection of lipid oxidation detection methods. • Rosemary antioxidants have a good inhibitory effect on the degradation of monounsaturated fatty acids in Rancimat test, and inhibit the degradation of all fatty acids in high-temperature oven test. • Double bond-distal β-scission is the main cleavage site of rapeseed oil in the Rancimat test, while the probability of double bond-proximal β-scission has been greatly increased during high-temperature oven test. • Rosemary antioxidants inhibit double bond-distal β-scission during Rancimat and high-temperature oven test, but promote the proximal site during oven test.
Xiong et al. (2026) studied this question.