Treatment with 0.1% oregano inhibited lipid oxidation to the same extent as rosemary (alone or with ascorbic acid).
However,when oregano was used at a lower concentration (0.02%), the antioxidant effect was significantly lower (p < 0.01); therefore, there was a concentration-dependent effect.
Oregano, which belongs to the same family as rosemary, contains also a number of phenolic compounds, rosmarinic acid being the most abundant.
Regarding the addition of ascorbic acid, a small but significant(p < 0.05) prooxidant effect was evident starting from d 12 of storage.
Yildiz-Turp and Serdalroglu (1998) already reported that the addition of 500 ppm ascorbic acid was completely ineffective in preventing lipid oxidation, and even exerted a prooxidant effect.
However, it has been reported that the addition of ascorbic acid to ground meat in combination with such antioxidants as rosemary or a-tocopherol, exerted a synergistic effect