Natural antioxidants (rosemary and parsley) in microwaved ground meat patties: effects of in vitro digestion

BACKGROUND Minimizing food oxidation remains a challenge in several environments. The addition of rosemary extract (150 mg kg(-1)) and lyophilized parsley (7.1 g kg(-1)) at equivalent antioxidant activity (5550 mu g Trolox equivalents kg(-1)) to meat patties was assessed in terms of their effect during microwave cooking and after being subjected to an in vitro digestion process. RESULTS Regardless of the use of antioxidants, cooking caused a decrease of the fat content as compared to raw samples, without noticing statistical differences in the fatty acid distribution between raw and cooked samples [44%, 47% and 6.8%, of saturated fatty acid (SFA), monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA), respectively]. However, the bioaccessible lipid fraction obtained after digestion was less saturated (around 34% SFA) and more unsaturated (35% MUFA +30% PUFA). Cooking caused, in all types of samples, an increased lipid [thiobarbituric acid reactive substances (TBARS)] and protein (carbonyls) oxidation values. The increase of TBARS during in vitro digestion was around 7 mg malondialdehyde (MDA) kg(-1) for control and samples with parsley and 4.8 mg MDA kg(-1) with rosemary. The addition of parsley, and particularly of rosemary, significantly increased the antioxidant activity (DPPH) of cooked and digested microwaved meat patties. CONCLUSION Whereas rosemary was effective in minimizing protein oxidation during cooking and digestion as compared to control samples, parsley could only limit it during digestion. Lipid oxidation was only limited by rosemary during in vitro digestion.