Efeito protetor da salsa (Petroselinum crispum) (Mill.) Nym. e cebolinha (Allium schoenoprasum L) como antioxidantes naturais sobre a oxidação lipídica em sardinhas preparadas termicamente

Abstract

Among the diversity of marine fish present in the Southeastern and Southern regions of Brazil, the Brazilian sardine (Sardinella brasiliensis) is the most important fishing resource due to its nutritional value and low cost. In addition to the high biological value of the proteins, this fish also stands out due to the significant concentrations of n-3 polyunsaturated fatty acids, which confer significant nutritional and functional characteristics with several beneficial effects on health. Despite these desirable characteristics, sardines also contain high levels of cholesterol, which together with polyunsaturated fatty acids are highly susceptible to lipid oxidation, when exposed to thermal processing at high temperatures, inducing thermo-oxidation of cholesterol, forming the products of oxidation of cholesterol (COPs). COPs have been associated with the development of coronary diseases, atherosclerosis, and other chronic and degenerative diseases. Thus, studies on alternative techniques in the thermal preparation of fish, in combination with alternative sources of natural antioxidants are necessary to guarantee the quality and safety in the ingestion of these foods The objective of this research was to evaluate the chemical composition, to identify the phenolic compounds, to evaluate the in vitro antioxidant capacity and the in vivo free radical scavenging capacity, organic aromatic herbs, parsley and chives and their mixture, called cheiro-verde. As well as evaluating the efficacy of the additions of these culinary herbs as natural antioxidants, reducing lipid degradation and the formation of oxidation products during the heat treatment of fillets of sardines processed thermally by air-fryer pan and electric grill, thus justifying the accomplishment of this work. The results of the chemical characterization of the studied herbs indicate that they can be considered as a source of fibers and minerals. The main fatty acids were identified (g/100 g of oil); (C 18:2 n-6) and (C 18:3 n-3), and as the main phytosterols the compounds brassicasterol, β-sitosterol, stigmasterol, campesterol, and 7-ketoestigmasterol. Samples of the culinary herbs presented significant phenolic contents (mg GAE/g), flavonoids (mg of quercetin equivalent (Q E)/g) and total carotenoids (μg/g). In this study, 24 phenolic compounds in the extracts (80:20) methanol/water were also identified by UPLC-ESI-MS in the parsley, chives and green-odor samples, among which were protocatecuic acid, luteolin, kaempferol, quercetin and ferulic acid. Aromatic herbs also presented good values of antioxidant properties in vitro; DPPH ranged from 51.59 to 54.92%; ABTS from 5.12 to 8.29 (μmol TE/g) and FRAP from 6.33 to 8.32 (μmol TE/g). The tests of the bioactive compounds of the aromatic herbs the extracts presented antioxidant action in the yeasts (Saccharomyces cerevisiae), reducing the effects of the oxidative stress caused by the hydrogen peroxide. This study was the first to evaluate the formation of cholesterol oxides products (COPs) in sardine fillets thermally processed using air-fryer, oil-free. The results of the two thermal processes, air-fryer and electric grill, showed a significant impact on the levels of n-3 PUFAs, losses in cholesterol levels and increase of COP levels in control sardine samples. On the other hand, were tested the addition of fresh herbs, parsley, chives and cheiro-verde at 2 and 4% levels in sardines submitted to heat, proving to be effective as natural antioxidants in the preservation of cholesterol levels and PUFAs, eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, and in reducing the total levels of POCs. The additions of 4% of parsley and 4% of cheiro-verde were the most effective against the lipid oxidation of the sardines treated thermally. This suggests a probable synergistic effect between the antioxidant compounds found in parsley and chives. Thus, it is concluded that the culinary herbs evaluated in this study can be considered as alternatives sources of natural antioxidants to be used in the inhibition of lipid oxidation during the thermal preparation of sardines.