Browsing by Author "Estevinho, Letícia M."
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- Antioxidant Properties and Microbiological Stability of Yogurt Enriched with Elderberry ExtractPublication . Pascariu, Oana-Elena; Estevinho, Letícia M.; Seixas, Natália; Dopcea, Ioan; Boiu-Sicuia, Oana A.; Geicu-Cristea, Mihaela; Israel-Roming, FlorentinaThis study examines the impact of added elderberry (EDB) extract on the physico-chemical, microbiological, and sensory properties of yogurt over a 21-day storage period. Two separate experiments were conducted: the first focused on testing concentrations of 0.05%, 0.1%, 0.2%, and 0.5% (w/w) EDB extract for impoving antioxidant properties and replacing potassium sorbate, a chemical preservative commonly used in dairy products, while the second aimed to enhance the bioactive compounds’ concentration by adding 0.5% EDB extract, and to assess the effect of a sweetener (agave syrup) on the sensory profile. Both experimental approaches demonstrated a significant increase (p < 0.01) in total phenolic content. In the first experiment, there was approximately 2.6 times more total phenolic content compared to the control (with a maximum of 11.71 mg GAE/100 g for the sample with 0.2% EDB extract), and about 6 times more with the addition of 0.5% EDB extract and agave syrup (with a maximum of 25.29 mg GAE/100 g). Additionally, the IC50 value decreased for all samples with EDB extract, suggesting enhanced antioxidant activity. Specifically, the antioxidant activity was approximately 3.3 times higher for the control for samples obtained from homemade yogurt with EDB extract, and about 8 times higher for samples obtained by adding EDB extract to commercial yogurt, compared to their respective controls. The high stability of bioactive compounds during the storage period highlights the potential of EDB extract as a functional antioxidant ingredient. Microbiological analysis confirmed the safety of the yogurt, with lactic acid and mesophilic bacteria showing stable counts and minimal declines over time. In the first experiment, a reduction of about 2.3 CFU/g was observed from day 0 to day 21 in samples with 0.1% and 0.2% EDB extract, while the control sample showed a reduction of 1.84 CFU/g. However, the control sample recorded the growth of psychrophilic bacteria, yeasts, and molds. In the second experiment, the samples with 0.5% EDB extract showed an average reduction of approximately 0.35 CFU/g, while the control showed a reduction of 0.51 CFU/g, maintaining stable counts and no detectable growth of psychrophilic bacteria, yeasts, molds, or coliforms. Additionally, the inclusion of different concentrations of EDB extract, along with the combination of a higher concentration of EDB extract and agave syrup, improved the yogurt’s sensory attributes, thereby enhancing consumer acceptance. For the first experiment, 68% of the panelists expressed their preference for the samples with EDB extract, and 10% preferred the control sample. In the second experiment, 49% preferred the sample with 0.5% EDB extract and agave syrup, while 23% preferred the control sample. These findings support the integration of EDB extract into yogurt formulations to boost antioxidant properties while preserving microbiological stability. Future research should explore the potential health benefits and long-term effects of these functional dairy products.
- The Effect of Incorporating Fermented Elderberries (Sambucus nigra) into Bread: Quality, Shelf Life, and Biological EnhancementPublication . Seixas, Natália; Paula, Vanessa B.; Dias, Teresa; Dias, Luís G.; Estevinho, Letícia M.Elderberries, known for their antioxidant, anti-inflammatory, and antiviral properties, have traditionally been used to prevent and treat infections and boost the immune system. By increasing the quantity and quality of certain compounds, fermentation can potentially make them more effective as food additives. The aim of this study was to evaluate the effect of incorporating fermented elderberries on the bioactivity and shelf life of a traditional bread. The elderberry fermentation process was optimised using Saccharomyces cerevisiae, guided by a Plackett–Burman experimental design. The aim was to assess the impact of incorporating fermented elderberries into bread on its bioactive properties and shelf life. The fermentation of the elderberries was found to enhance their bioactive compounds and antioxidant activity. The total phenolic content ranged from 8.63 to 20.56 mg GAE/g (in samples without and with 2% extract, respectively). The antioxidant capacity, measured using the FRAP method, also showed a significant increase with the addition of the extract (from 9.16 to 26.66 mg Fe (II) E/g of the sample). Furthermore, bread enriched with fermented elderberry extracts demonstrated an extended shelf life during the study period.
- Quantifying the Impact of High‐Pressure Processing on the Phenolic Profile, Antioxidant Activity, and Pollen Morphology in HoneyPublication . Scepankova, Hana; Majtan, Juraj; Pospiech, Matej; Moreira, Manuela M.; Pinto, Carlos A.; Dias, Luís G.; Estevinho, Letícia M.; Delerue‐Matos, Cristina; Saraiva, Jorge A.Honey can benefit from non‐thermal processing techniques such as high‐pressure processing (HPP) to improve its quality and bioactivity. This study investigated the impact of HPP (600 MPa for 5, 10, and 15 min) on honey's quality, including the levels of hydroxymethylfurfural (HMF), antioxidant activity, total phenolic content (TPC), and phenolic profile. HPP treatment did not significantly affect HMF or TPC levels but led to selective changes in the phenolic profile. Despite a reduction in certain phenolic compound content, HPP for 5 and 15 min caused a significant increase in the antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl [DPPH]) of honey from the mean value of 41.8% to values of 45.4% and 49.6%, respectively. On the other hand, HPP for 10 min did not change the antioxidant activity of tested honey. A 27.5% reduction in the equatorial diameter of pollen grains was observed after HPP combined with temperature at 75°C, suggesting an improved release of bioactive compounds. The content of specific phenolic compounds, including caffeic acid, p‐coumaric acid, sinapic acid, naringin, kaempferol, and the TPC, significantly affected the DPPH activity. The increment in the antioxidant activity of HPP honey may be attributed to selective changes in the content of certain phenolic compounds and improved their extraction from pollen grains.
- Use of Black Pepper Essential Oil to Produce a Healthier Chicken PâtéPublication . Rodrigues, Sandra; Leite, Ana; Vasconcelos, Lia; Pereira, Etelvina; Seixas, Natália; Estevinho, Letícia M.; Teixeira, AlfredoThis study aims to explore the effect of using black pepper essential oil (BPEO) to produce a healthier chicken pâté. Four different formulations were produced: a control formulation without back pepper and three with increasing BPEO contents. To test the effect of using BPEO, physiochemical analyses were performed at two different moments, 8 and 21 days after production. Microbiological analyses were performed 2, 9, 16, and 23 days after production. Sensory analysis to evaluate the pleasantness of the pâtés to consumers was performed 21 days after production. Finally, total phenol and flavonoid content and antioxidant activity were evaluated. Results show no significant physicochemical differences. Pâtés with no BPEO or black garlic were the most pleasant, but 0.3 or 0.5% of BPEO were not significantly less appreciated, while 1% of the EO caused a decrease in taste and global appreciation. The higher the BPEO content, the higher the phenol content, antioxidant (with an increase from 1.58 to 2.27 mg eq. Fe II/g of sample, in the Control at T23 and V3 at T23, respectively), and microbial activity (with total mesophiles count reduction from 5.91 to 5.21 log CFU/g sample in V3 from T9 to T16). The use of 1% of BPEO showed a significant effect on the reduction in mesophile counts for at least two weeks. These results highlight the potential for optimizing BPEO or black garlic content to ensure both consumer acceptance and enhanced functional properties. While further analysis will help pinpoint the best formulation, the current findings are a promising step towards achieving an optimal balance.