Efeito protetor do fruto da aroeira (Schinus terebinthifolius Raddi) sobre a foto-oxidação do colesterol e ácidos graxos poli-insaturados em sistemas modelo contendo óleo de sardinhas (Sardinella brasilliensis)

Abstract

Sardines are constantly characterized as food of high nutritional value due to the high content of polyunsaturated fatty acids EPA and DHA, however, they contain appreciable concentrations of cholesterol. Ultraviolet radiation, derived from the exposure of these compounds to fluorescent light, promotes their degradation and formation of oxidized compounds, compromising the nutritional quality and safety of these foods. Thus, it is essential to search for alternative sources of natural antioxidants that minimize photo-oxidative processes and meet consumer demand for foods that are free of synthetic additives. The objective of this study was to evaluate the protective effect of aroeira fruits (Schinus terebinthifolius Raddi) at three levels of addition (1%, 2% and 3%) against lipid oxidation in model systems containing sardine oil exposed to ultraviolet radiation for 15, 30, 45 and 60 days, beyond control. The fruits were previously characterized, where the presence of essential fatty acids and bioactive compounds was determined. Bioactive compounds such as total phenolics (5.05 ± 0.19 mg GAE / g), total flavonoids (4.16 ± 0.11 mg EQ / g) and total carotenoids (25.42 ± 0.48 μg / g) were determined and composed as masticadienic acid (m/z 453), tetrahydroamentoflavone (m/z 541), agathisflavone (m/z 537), hikinoflavone (m/z 539) and 7-O-methylpelargonidin 3-O-galactoside (m/z 447) were identified by liquid chromatography coupled to mass spectrometry. The antioxidant activity of aroeira fruits was verified in in vitro analyzes. Free radical scavenging test (DPPH) determined 84.45 ± 1.61% of oxidative inhibition for the fruit extract, while the determination of the iron reduction power (FRAP) presented a value of 121.54 ± 1.31 μmol Fe2+/g. To determine lipid oxidation, the formation of thiobarbituric acid reactive substances (TBARS) and changes in the composition of fatty acids and cholesterol were identified, quantifying the formation of cholesterol oxidation products (COPs). Exposure to fluorescent light led to a constant drop in the content of polyunsaturated fatty acids (PUFAs) and an increase in the content of substances reactive to thiobarbituric acid (TBA) and COPs during the 60 days of exposure. The content of PUFAs decreased between 65.60 and 89.10% in the control samples (without the addition of antioxidants) over the 60 days of exposure to fluorescent light. However, the addition of aroeira fruits minimized the degradation of PUFAs, indicating a variation in the percentage of degradation between 58.36 and 80.93% over the 60 days of exposure. Exposure of oil without antioxidants to fluorescent light for 60 days reduced the cholesterol content by 61.86%, with an increase in the total COP content of 61.54 ± 0.04 for 2013.84 ± 12.86 μg/g of oil. However, the treatment with aroeira fruits showed a protective effect of 21.55, 25.94 and 34.77% for the additions of 1, 2 and 3%, respectively. The synthetic antioxidant showed a greater protective action against the photo-oxidation of sardine oils, although the protective effect of aroeira fruits did not show significant differences in relation to BHT, suggesting that their use as natural antioxidants may be an alternative to the detriment of synthetics, helping to preserve the nutritional aspects of sardine oil and ensuring that the product is safe.