María Jesús Martín-Mateos

The purpose of this study was to investigate for the first time the effect of the enrichment in white or red grape pomace stabilized by high hydrostatic pressure on the characteristics of dry-cured sausages containing additives (75 mg kg ⁻¹ sodium nitrite and 0.25 g kg ⁻¹ L-ascorbic acid). Both pomace types had no marked effect on the general parameters, microbial counts, and volatile compounds of the sausages. 0.5% of either pomace did not affect the instrumental colour ( p > 0.050), whereas 1.5% increased b* and decreased a* , respectively. At 0.5%, the white pomace did not affect oxidation, but the red pomace increased lipid oxidation similarly to the double additive dosage, as did the white pomace at 1.5%. The red pomace at 1.5% increased lipid and protein oxidation. Despite this increase, the values remained low and hexanal (an oxidation indicator) was not detected. Therefore, the results reveal that the delay in oxidation previously reported in free-additive dry-cured sausages with grape pomace does not occur when additives are also added and oxidation is low. Under those circumstances, the pomace addition (especially the red pomace and the higher dosage) can promote oxidation, as does a high synthetic additive dosage.

High hydrostatic pressure (HHP) can extend the shelf life and ensure safety of meat products such as lamb burgers. Lupinus albus variety Orden Dorado (a low alkaloid content variety) flour, rich in protein and phenolic compounds, offers the potential to enhance the preservation of meat products during storage. Lamb burgers were formulated with Lupinus albus flours (1%, w/w; weight/weight), either conventional or obtained by compression milling, and processed by HHP treatments (untreated, two consecutive cycles at 600 MPa for 1 s; or a single cycle at 600 MPa for 4 min), with the total processing time using the HHP unit being the same for both. Then, they were subsequently stored for 14 days under refrigerated conditions. Proximate composition, microbiological changes, color, and oxidation of burgers during storage were evaluated. Flour obtained by compression milling presented higher phenolic compound content, while its antioxidant activity is similar to that obtained by conventional methods. In lamb burgers, the incorporation of both lupine flours maintained the proximate composition and fatty acids profile. Lipid oxidation after 14 days was significantly lower in burgers with lupine flour obtained by compression milling, whereas protein oxidation responses depended on treatment–formulation interactions. HHP drastically reduced microbial counts, with sustained inactivation of coliforms and Escherichia coli (E. coli) although instrumental color was significantly altered in fresh burgers after processing. However, sensory scores of grilled burgers remained unaffected by either flour type or HHP treatment. Incorporation of Lupinus albus flour into lamb burgers processed by HHP preserved sensory quality while enhancing the microbial and lipid oxidation stability of burgers. Finally, the application of two short (1 s) cycles at 600 MPa was more beneficial than a single 4 min cycle, offering similar microbial inactivation with less impact on the quality changes in burgers. Finally, applying two short (1 s) HHP cycles at 600 MPa was more beneficial than a single 4 min cycle, as it achieved similar microbial inactivation while better preserving the color and oxidative stability of the burgers.

The study evaluated the potential of Thymus mastichina, Lavandula luisiery, and Origanum virens hydrolates—essential oil-rich species found in the Dehesa ecosystem—as natural agents for pork preservation through marination. Hydrolates, the main by-products of essential oil distillation, were characterized by their volatile composition, total phenolic content, antioxidant capacity, and antimicrobial activity against Escherichia coli and Listeria innocua. Pork fillets were marinated (24 h) with increasing hydrolate concentrations (1:1, 1:1.5, 1:2 w/w) and then stored for eight days under refrigeration to assess microbial growth, oxidation, and color changes. All hydrolates exhibited similar antimicrobial effects, though Origanum showed the highest phenolic content and antioxidant activity. Marination had limited antimicrobial impact. Marination with Origanum and Thymus provided significant protection against lipid oxidation during storage, while Lavandula displayed limited or even pro-oxidative behavior at certain doses. Marination did not affect carbonyl formation although it caused slight changes in instrumental color. Overall, the study highlights the potential of Lavandula, Thymus, and Origanum hydrolates as sustainable alternatives to synthetic antioxidants in meat products, emphasizing their antioxidant—rather than antimicrobial—effect.

The growing concern over the presence of polycyclic aromatic hydrocarbons (PAHs) in grilled meats has intensified the search for natural mitigation strategies. This study evaluates the effect of red grape pomace (RGP), a natural by-product with antioxidant properties, on the lipid stability, color, fatty acid profile, volatile compounds, and PAHs formation in barbecued pork burgers. Unlike previous studies focusing on polyphenol extracts, this work investigates, for the first time, the direct incorporation of whole RGP stabilized by high hydrostatic pressure (HHP), a method that preserves its bioactive profile and ensures food safety. Incorporation of RGP at different levels (0.5%, 1%, and 3%) demonstrates its potential as a functional ingredient in meat products. Our results show that RGP effectively inhibits lipid oxidation, as indicated by significantly lower malondialdehyde (MDA) levels (p < 0.001) compared to control batches. It also modified the fatty acid profile by reducing saturated fatty acids and increasing the linoleic acid content (up to 15.56% at the 3% level). As the RPG concentration increased, color parameters (lightness, redness, yellowness, chroma, and hue) decreased significantly (p < 0.001), particularly at higher pomace levels (1% and 3%). The RGP did not significantly affect the PAH concentration, indicating its safe use in barbecued products. However, it selectively influenced volatile compounds, decreasing the hydrocarbon levels at higher concentrations, likely due to its antioxidant properties. These findings suggest that stabilized RGP may serve as a natural additive that enhances the nutritional quality and reduces lipid oxidation, without promoting PAH formation in thermally processed meats.

This study investigated the use of grape/wine pomace as a potential substitute for nitrifying salts in the production and preservation of frankfurters. Red wine pomace (RWP) from Tempranillo and white wine pomace (WWP) from Cayetana grapes were added to frankfurters made with Iberian pig backfat—an underutilized fat rich in oleic acid—at two levels (0.5% and 3% w/w). These new formulations were compared with a control (containing only meat, salt, and spices) and a commercial formulation containing nitrites and ascorbic acid. Analyses were conducted immediately after production and following 45 days of refrigerated storage to evaluate microbiological, color, physicochemical, and textural changes in the frankfurters. The addition of pomace slightly reduced the pH of the frankfurters but did not affect microbial counts during the manufacturing process. Frankfurters with pomace displayed a similar color to the control but showed lower redness compared to the commercial formulation with nitrites. Importantly, pomace reduced lipid and protein oxidation during production and storage. The reduction in lipid oxidation due to the pomace was comparable to the effect of nitrites and ascorbic acid. Furthermore, pomace effectively reduced protein oxidation, unlike nitrites and ascorbic acid, which primarily targeted lipid oxidation. Significant differences in texture were observed between commercial frankfurters and those containing pomace. Despite these variations in the appearance and the texture, the strong protective effect of pomace against oxidative reactions highlights its potential as a natural alternative to synthetic additives, offering a promising solution for the meat industry.

The inclusion of an ingredient made from red grape pomace (RGP) var. Tempranillo was evaluated for the preservation of a traditional dry-cured sausages (salchichón). The pomace was valorized through thermal blanching (103 °C for 1 min) and hydrostatic high-pressure treatment (600 MPa/5 min) before the addition to salchichón. Four formulations of salchichón were evaluated, including a negative control (NC—without red grape pomace or synthetic additives), positive control (PC—with ascorbic acid and nitrites), low level (LL—0.5%), and high level (HL—1%) of RGP. Physicochemical, microbiological, and sensorial effects were analyzed. RGP reduced the final pH of salchichón and favored the growth of lactic acid bacteria at similar levels as PC. The addition of ascorbic acid and nitrites resulted in a final product with a redder and less yellow color than the other formulations. This cured color was not reached with the addition of RGP. However, its inclusion slightly reduced lipid and protein oxidation in salchichón. PC showed high levels of sulfur and terpene levels in a volatile profile, although at a sensory level, only differences in spicy taste were not noticed by panelists. The incorporation of the ingredient could enable the substitution of nitrites with valorized red grape pomace in sausages, although the desirable color achieved with nitrifying salts was not fully attained.

White grape pomace (winery by-product) stabilized by blanching and high hydrostatic pressure has recently been successful at delaying lipid oxidation in burgers. The aim of this study was to investigate whether it can also delay lipid oxidation in dry-cured sausages, and to compare its effect when added at 0.5 and 3% with those of synthetic additives (sodium nitrite and ascorbic acid) and no additives (Control) in lipid and protein oxidation, the instrumental color, the sensory characteristics, and the volatile compounds. The pomace (68.7 ± 7.4 mmol Trolox g⁻¹) was as effective as the additives at preventing lipid oxidation, resulting in values 3.2–3.8 times lower than the Control sausages. However, the pomace was not effective at decreasing the microbial counts, improving the instrumental and sensory color and the volatile compound profile, and decreasing the off-odor and off-flavor developed in the Control sausages. The lack of a detrimental effect of the pomace at 0.5% on the volatile compounds and the sensory characteristics and its benefits to delay lipid oxidation suggest that it might be useful to improve the oxidative stability. Conversely, at 3%, with a detrimental effect on some sensory characteristics and no benefits over the lower dosage, is not advisable.

White wine pomace, a by-product from winemaking, was stabilized after the application of thermal blanching (with the aim of deactivating the polyphenoloxidase enzyme), milling, and processing by hydrostatic high-pressure treatment (with the aim of reducing initial microbial loads while preserving phenolic compounds content). The valorized pomace (VP) ingredient was added at different proportions to pork burgers (0.5%, 1%, and 3% w/w) to improve their preservation, and the effect was compared to those produced by sulfites and with a control (without sulfites or VP). Burgers were vacuum-packed and refrigerated for 7 days. Microbiological, color, oxidation, and sensory parameters were analyzed. Neither sulfites nor VP reduced the microbial development of most microorganism groups evaluated (p > 0.05); however, both prevented coliform growth during storage (p < 0.01). The use of sulfites prevented the discoloration of burgers during storage, while VP had no effect (p < 0.001). On the contrary, VP limited lipid and protein oxidation development during storage (p > 0.05), while sulfites had no effect. Therefore, the use of VP from white wine production could have an antioxidant effect but a limited antimicrobial or color-protective effect for the preservation of pork burgers.