Extração e microencapsulação de polifenóis do bagaço da uva (Vitis labrusca. Var. Isabel): ação das microcápsulas sobre a estabilidade oxidativa de hambúrguer bovino

Abstract

The reuse of agro-industrial residues to obtain bioactive molecules gives antioxidant components with potential application in the meat industry since the oxidative processes are among the main causes of loss of quality in meat products. In this sense, the objective was to evaluate the effects of the application of microencapsulated phenolic extract, composed from grape pomace, on the oxidative stability of pre-cooked bovine hamburger. The extract was used using grape pomace used in the production of frozen juices and pulps. After obtaining, the extract was microencapsulated by the lyophilization technique, using maltodextrin as a wall material. The microcapsules were characterized for moisture, water activity (Aa), hygroscopicity, color, morphology, phenolic content, anthocyanin content and antioxidant capacity. For the effect of microcapsules on the oxidative stability of hamburgers, 3 treatments were formulated: hamburger added with 100 ppm of sodium erythorbate (SEB), hamburger added with 1% lyophilized grape extract (LEB) and hamburger added with 6.7 % microencapsulated grape extract (MEB). The definition of the lyophilized and microencapsulated extract options was based on the concentration of total phenolics, maintaining the concentration of 100 ppm in all treatments. The hamburgers were processed in a pre-cooking process and stored under refrigeration (4°C) for 15 days. Throughout the experiment, the hamburgers were prevented from changes in color and levels of lipid and protein oxidation. The encapsulated material presented high antioxidant potential with values of 377.44 ± 0.01 μmol TEAC.100g-1, 1768.12 ± 0.2 μmol TEAC.100g-1 and 1185 ± 0.2 μmol TEAC.100g-1 for the DPPH, ABTS and FRAP tests respectively, corroborating the high content of phenolic compounds (14.7 ± 0.04 mg GAE.g-1) and anthocyanins (94.84 ± 0.02 mg cyanidin-3-glucoside.100g -1) no encapsulated material. Morphological analysis of microcapsules information crystal structures, characteristics of microencapsulated materials by lyophilization. The pre-cooking process did not show results in the oxidation levels of the hamburgers evaluated by the TBARS and carbonyl compounds methods. The refrigerated storage period had a significant effect on the instrumental color, so that the SEB treatment was darker at the end of storage, and with a lower red intensity than the other groups, indicating an oxidation of the meat pigment. The MEB treatment shows the best results for both lipid and protein oxidation inhibition, these lower values of malonaldehyde and total carbonyls during refrigerated storage. The highest oxidation indexes were observed for the SEB treatment, indicating that the freeze-dried and microencapsulated phenolic extracts were efficient in controlling lipid and protein oxidation. The results obtained show that a microencapsulation protected the phenolic extracts. Although the oxidation of lipids and proteins is a natural process, the MEB treatment offered greater oxidative stability to the hamburgers, followed by the LEB and SEB treatments.