Avaliação da capacidade antioxidante de extratos naturais no controle da oxidação de linguiças frescais

Abstract

Lipid oxidation is a critical process for the quality of meat products. It is a determinant factor for consumer’s acceptance and shelf life of these products. The use of natural antioxidants is an alternative to delay the oxidative deterioration of food and it is in line with the growing demand for more natural products, without the use of synthetic additives. The objective of this study was to determine the antioxidant activity of natural extracts and evaluate their efficiency in the oxidative stability of fresh sausage. The phenolic compounds of rosemary extract, tocopherol mixture, grape seed extract and BHA were 4.1; 30.48; 27.40 and 72.68 mg EAG/g sample, respectively. The tocopherol mixture and grape seed extract showed antioxidant activity similar to BHA also by the DPPH (472.89; 275.71 and 1271.0 μmol ET/g sample) and FRAP (1065.25; 665.87 and 1446.11 μmol EFeSO4/g sample) methods. The efficacy of these natural antioxidants applied to fresh sausage was evaluated through the acidity content, peroxide value, thiobarbituric acid reactive substances and qualitative rancidity, thermogravimetry and fatty acids profile, during the 15 days of storage at 4.0 ºC, under light incidence. The results demonstrated a pro-oxidant effect of grape seed extract (6.74% acidity and TBARS 2.74 mg MDA/kg sample) compared to control (4.85% acidity) and BHA (0.053 mg MDA/kg sample). The result of the peroxide value for the sample containing the mixture of tocopherols (3.07 mE O2/kg) was significantly lower than the control (11.40 mE O2/kg) and the TBARS values for the samples treated with BHA (0.473 mg MDA/kg) and the mixture of tocopherols (0.441 mg MDA/kg) at 11 days were similar, proving the potential of this natural antioxidant to replace the synthetic one. The main fatty acids found in fresh sausages were C16:0 (palmitic acid), C18:0 (stearic acid), C18:1 (oleic acid) and C18:2 (linoleic acid). The thermogravimetric charts showed that lipid degradation in the sample containing grape seeds extract began at a lower temperature than the other samples (190.0 ºC). On the other hand, tocopherol was able to delay this process, reaching the highest rate of mass loss only at 338.0 ºC. The analyzes confirmed the greatest loss of total mass for the control sample, with 28.45% loss. All samples with antioxidants in the formulations performed better than the control in this assay, having shown total mass loss percentages of 22.99%, 18.22% and 21.05% for BHA, mixture of tocopherols and grape seed extract, respectively. Thus, this study demonstrated the viability of replacing the BHA by a natural source, the mixture of tocopherols, and revealed the pro-oxidant effect of the grape seed extract when applied to a meat matrix.