Synthesis and characterization of eugenol derivatives: evaluation of antioxidant activity and inhibition of lipid oxidation in mechanically separated poultry meat and mortadella

Abstract

The objectives of the present work were to synthesize eugenyl acetate and bis-eugenol from commercial eugenol and characterize the products; to evaluate the influence of structural modifications on antioxidant activity, oxidative stability and cytotoxicity; to evaluate the effect of the addition of different concentrations of eugenol and its derivatives on the oxidative stability of mechanically separated chicken meat (MSM) stored for 8 days at 0 °C; to evaluate the sensory influence and oxidative stability of cured and uncured bologna processed with sliced MSM containing eugenol and its derivatives during storage for 60 days at 4 °C. Eugenol was acetylated in 81 % yield and oxidized to 57 % bis-eugenol. The products obtained were characterized by FTIR and 1HMN and evaluated for antioxidant activity and cytotoxicity (cellular viability). Chicken MSM was obtained and immediately treated with 250, 500, 1000 and 2000 ppm of eugenol, eugenyl acetate and bis-eugenol. The oxidative quality of MSM (treatments and control) was evaluated after 0, 2, 4, 6 and 8 hours at 0 °C. Chicken MSM containing 250 ppm eugenol and its derivatives was used in the processing of cured and uncured bologna to evaluate the technological, sensory and oxidative stability (TBARS and color) characteristics of sliced products stored for 60 days at 4 °C. No negative effect on the technological characteristics of the product was observed. Greater oxidative stability was observed for the bis-eugenol by the Rancimat method. Antioxidant activities similar to that of the antioxidant BHT were observed for eugenol and bis-eugenol in the DPPH, TBARS and phosphomolybdenum assays. Lower cytotoxicity on eyelid fibroblast cells was observed for the derivatives than for eugenol, and acetylation decreased the in vitro antioxidant effect of eugenyl acetate. Higher peroxide levels were observed in MSM containing bis-eugenol. All the compounds controlled lipid (TBARS and hexanal) and protein oxidation at the concentrations evaluated, with a slight increase in the TBARS index only on the 8th day. No change was observed in hexanal levels during storage. Greater protein oxidation and larger contents of volatile compounds characteristic of oxidative processes during storage were observed for the control MSM. The addition of antioxidants did not change the color (h*), but contributed to an MSM of a lighter tone (L*) than that of the control. Less malondialdehyde (MDA) formation was observed for the bologna cured with MSM containing eugenyl acetate and bis-eugenol than for the control. The same effect was observed for the control of the formation of MDA in uncured bologna containing eugenol and its derivatives as with the control sample. The treatments did not influence the formation and degradation of color in meat that was cured and pigmented by cochineal carmine. The greatest sensory acceptance was observed in cured treatments. Eugenol and its derivatives improved the sensory attributes of the products and only the treatments containing bis-eugenol did not present a clove flavor. All the compounds acted equally as an antioxidant in uncured products, concluding that eugenyl acetate and bis-eugenol can be used in association with sodium nitrite and in cured products.