The effect of common duckweed (Lemna minor L.) extract on the shelf-life of beef burgers stored in modified atmosphere packs: A metabolomics approach.

The impact of duckweed extracts (DEs) on the shelf-life of packaged beef burgers was evaluated through classical assays and untargeted metabolomics. Beef burgers were formulated with an antioxidants-free control (CON), 1 g/kg sodium ascorbate (ASC), and increasing levels of a DEs, namely 1 (DE1), 5 (DE5), and 10 (DE10) g/kg, packaged under modified atmosphere and stored at 4 °C for 19 days. The DEs, abundant in phytochemicals, determined no issues with the hygienic status of the product. DEs modulated the redox status, being ineffective in preserving linolenic acid from peroxidation. However, the oxidation marker 2-nonenoic acid was down-accumulated in the DE10 sample following 19 days of storage, recording a lower glutathione:glutathione disulfide ratio. The accumulation of adipate semialdehyde revealed the inefficiency of DEs in coping with protein oxidation, while DEs prevented the accumulation of biogenic amines. Therefore, this work suggests a potential pro-oxidant role of the formulated DEs.

Impact of axenic and mixed starter cultures on metabolomic and sensory profiles of ripened Italian salami.

In this work, the synergistic/antagonistic impact of glucose and mixed starter cultures, namely Latilactobacillus sakei, Pediococcus pentosaceus, and Staphylococcus xylosus, was evaluated in Italian salami in terms of metabolomics and sensory profiles. As expected, Salami manufactured with 0.5 % glucose exhibited a substantial pH drop, showing values close to 5 at 12 days of ripening. Metabolomics revealed 1841 metabolites, mainly belonging to amino acids, peptides, glycerolipids, and nucleic acids, showing a greater hierarchical role of glucose addition when compared with inoculated microbial starters. Distinct metabolomic fingerprints could be observed across treatments, mainly concerning glutamyl peptides like gamma-glutamyl-glutamate (related to the kokumi taste), biogenic amines (spermine), and lipid oxidation products (i.e., the oxylipin 13S-hydroperoxylinolenic acid). Such differences may drive the differences in sensory profiles recorded among treatments. These findings indicate the need to select ad-hoc starter cultures to improve the safety, quality, and sensory traits of salami.

Changes in the chemical and sensory profile of ripened Italian salami following the addition of different microbial starters.

In this work, Italian salami were produced using microbial starters (Pediococcus pentosaceus, Lactobacillus sakei, and Staphylococcus xylosus) and compared to a control sample (without starter). Metabolomics in combination with microbiological and sensory analyses were used to investigate the overall quality. Samples were analyzed immediately after stuffing, following 7, 30, and 45 days of ripening. Each microbial starter imposed distinctive metabolomic signatures at the end of ripening. The accumulated discriminant compounds were mainly related to lipid oxidation (including hydroxy- and epoxy derivatives of fatty acids) following the inoculation with L. sakei. However, the inoculation with P. pentosaceus resulted in the accumulation of γ-glutamyl peptides, compounds driving a kokumi-related taste. Noteworthy, our findings supported the involvement of the chemical compounds profiled in the definition of final taste and aroma. This information paves the way towards the definition of more objective and tailored starters-related flavours enhancement approaches in the sector of cured meat.