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.
This effect of the concentration on the inhibition of oxidation of meat lipids was reported by Shahidi and Pegg (1998).
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