Elderberry (Sambucus nigra L.) Encapsulated Extracts as Meat Extenders against Lipid and Protein Oxidation during the Shelf-Life of Beef Burgers

Abstract

In this work, we studied the impact of encapsulated elderberry extracts as natural meat extenders to preserve both the quality and the oxidative stability of beef burgers. In particular, the comprehensive chemical changes of beef burgers treated with different antioxidants, namely, (a) a control without antioxidants, (b) 0.5 g/kg sodium erythorbate (ERY), (c) 2.5 g/kg encapsulated elderberry extract (EE 2.5), and (d) 5 g/kg encapsulated elderberry extract (EE 5), each one packaged under modified atmosphere (80% O2 and 20% CO2) for 13 days storage at 2 ± 1 °C, were deeply evaluated. Overall, EEs showed a wide array of antioxidant compounds, namely polyphenols like anthocyanins, flavonols, and phenolic acids. Multivariate statistics provided marked chemical differences between burgers manufactured with EEs and synthetic antioxidants (ERY) during 13-days storage in terms of both metabolomic profiles and typical lipid/protein oxidation markers (such as malondialdehyde and total carbonyls). Most of the differences could be attributed to some discriminant compounds, namely glutathione, 4-hydroxy-2-nonenal, hydroxy/peroxy-derivatives of fatty acids, carbonyl compounds (such as 5-nonen-2-one and 1,5-octadien-3-one), and cholesterol. Interestingly, significant correlations (p < 0.01) were observed between malondialdehyde, total carbonyls, and these discriminant metabolites. The combination of spectrophotometric approaches and a high-throughput untargeted metabolomics analysis outlined a strong modulation of both lipid and protein oxidations, likely promoted by the encapsulated meat extender (elderberry), thus confirming its ability to delay oxidative phenomena during the shelf-life of beef burgers.

Keywords: foodomics; functional foods; healthy meat; natural additives; oxidative degradation; polyphenols; storage.

Figure 1

Visual aspect of the beef burgers formulated after the preparation (T0) and considering the four treatments, namely CON, ERY, EE 2.5, and EE 5.

Figure 2

Unsupervised hierarchical cluster analysis (HCA), carried out from the fold-change distribution of each compound detected in CON, EE 2.5, EE 5, and ERY beef burgers during storage (i.e., at 1, 5, and 13 days) by using untargeted metabolomics.

Figure 3

Orthogonal projections to latent structures discriminant analysis (OPLS-DA) considering the different beef burgers (CON, EE 2-5, EE 5, and ERY) during the entire storage period.

Figure 4

Orthogonal projections to latent structures discriminant analysis (OPLS-DA) considering the different beef burgers (CON, EE 2-5, EE 5, and ERY) at the final time-point of the storage period (13 days).