Person: Fernández Álvarez, Manuela
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First Name
Manuela
Last Name
Fernández Álvarez
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Veterinaria
Department
Farmacia Galénica y Tecnología Alimentaria
Area
Tecnología de los Alimentos
Identifiers
13 results
Search Results
Now showing 1 - 10 of 13
Item Volatile N-nitrosamines in Spanish commercial meat products and in fermented sausages prepared with different ingoing amounts of nitrate and nitrite(Heliyon, 2024) Fernández Hospital, Xavier; Fernández Álvarez, Manuela; Morales Gómez, Paloma; Alba Rubio, Claudio; Haza Duaso, Ana Isabel; Hierro Paredes, EvaSpanish commercial dry fermented sausages and dry hams, manufactured with and without nitrate and/or nitrite have been screened for volatile N-nitrosamine (VNA) content. VNAs have been also quantified in experimental fermented sausages prepared with known ingoing amounts of curing salts. Solid phase microextraction followed by tandem quadrupole gas chromatography/mass spectrometry (GC-QQQ-MS) analysis allowed the identification and quantification of 8 VNAs, 5 of which were detected in the samples. The highest concentration of VNAs found in the commercial products was 5.4 μg/kg. The most frequently detected VNAs were N-nitrosodiphenylamine and N-nitrosopyrrolidine. Principal component analysis and cluster analysis did not show correlation between the content of VNAs and the use of nitrate/nitrite in the formula. In the experimental sausages N-nitrosodiphenylamine and N-nitrosopyrrolidine were only detected (0.55 μg/kg total concentration) when 150 mg/kg of both nitrate and nitrite were added to the formula without any antioxidant. The levels of VNAs detected in this study are similar to those reported in the literature in different fermented meat products and dry hams.Item Differential Apoptotic Effects of Bee Product Mixtures on Normal and Cancer Hepatic Cells(Antioxidants, 2023) Sánchez Martín, Vanesa; Morales Gómez, Paloma; Iriondo De Hond, Amaia; Fernández Hospital, Xavier; Fernández Álvarez, Manuela; Hierro Paredes, Eva; Haza Duaso, Ana Isabel; Gan, Ren-YouMost effective anticancer drugs normally generate considerable cytotoxicity in normal cells; therefore, the preferential activation of apoptosis in cancer cells and the reduction of toxicity in normal cells is a great challenge in cancer research. Natural products with selective anticancer properties used as complementary medicine can help to achieve this goal. The aim of the present study was to analyze the effect of the addition of bee products [propolis (PR) or royal jelly (RJ) or propolis and royal jelly (PR+RJ), 2–10%] to thyme (TH) and chestnut honeys (CH) on the differential anticancer properties, mainly the cytotoxic and pro-apoptotic effects, in normal and cancer hepatic cells. The cytotoxic effects of samples were analyzed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay (0–250 mg/mL) and the effects on apoptosis were analyzed using cell cycle analysis, TdT-dUTP terminal nick-end labeling (TUNEL) assay, DR5 (Death Receptor 5) and BAX (BCL-2-Associated X) activation, and caspases 8, 9, and 3 activities. Both honey samples alone and honey mixtures had no or very little apoptotic effect on normal cells. Antioxidant honey mixtures enhanced the apoptotic capacity of the corresponding honey alone via both extrinsic and intrinsic pathways. Of all the samples, chestnut honey enriched with 10% royal jelly and 10% propolis (sample 14, CH+10RJ+10PR) showed the highest apoptotic effect on tumor liver cells. The enrichment of monofloral honey with bee products could be used together with conventional anticancer treatments as a dietary supplement without side effects. On the other hand, it could be included in the diet as a natural sweetener with high added value.Item Bee products as an alternative for the preservation of nitrate and nitrite-reduced dry fermented sausages(Food Bioscience, 2024) Fernández Hospital, Xavier; Hierro Paredes, Eva; Martín Cabrejas, Izaskun; Caballero, Natalia; Jiménez Begoña; Sánchez Martín, Vanesa; Morales Gómez, Paloma; Haza Duaso, Ana Isabel; Fernández Álvarez, ManuelaFood regulations are becoming increasingly restrictive on the use of nitrate and nitrite as additives in meat products, so different alternatives are being investigated to replace their functions. In this study, we tested the antioxidant activity of mixtures of bee products to partially replace nitrate and nitrite in dry fermented sausages. Two combinations of chestnut honey, propolis and royal jelly were added to sausages at 2% concentration, together with 0 and 75 mg/kg of nitrate and nitrite. TBARs and volatile profile analysis revealed a lower intensity of oxidation phenomena in sausages prepared with bee products, but these differences were not perceived by the tasters in the sensory analysis. Only instrumental differences in the a* colour parameter were observed when nitrate and nitrite were not used in the formulation. The addition of bee products did not affect the typical microbiota (lactic acid bacteria and gram-positive catalase-positive cocci) of sausages. The combination of 2% bee products and 75 mg/kg of nitrate and nitrite may be useful to obtain dry fermented sausages with a sensory quality and oxidation stability similar to a standard product containing the maximum amounts of these additives allowed in the European Union (150 mg/kg each).Item Protective Effect of Thyme and Chestnut Honeys Enriched with Bee Products against Benzo(a)pyrene-Induced DNA Damage(International Journal of Environmental Research and Public Health, 2022) Sánchez Martín, Vanesa; Haza Duaso, Ana Isabel; Iriondo De Hond, Amaia; Del Castillo, María Dolores; Fernández Hospital, Xavier; Fernández Álvarez, Manuela; Hierro Paredes, Eva; Morales Gómez, Paloma; Tchounwou, Paul B.The aim of the present study was to validate the cytotoxicity, genotoxicity, and preventive potential against benzo(a)pyrene (BaP)-induced DNA damage of nine samples of thyme and chestnut honeys enriched with bee products (royal jelly and propolis, 2–10%). Cell viability was determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay (0–250 mg/mL) to select nontoxic concentrations, and DNA damage (0.1–10 μg/mL) was evaluated by the alkaline single-cell gel electrophoresis or comet assay. Treatment with honey samples or royal jelly and propolis did not affect the viability of HepG2 cells up to 100 and 50 mg/mL, respectively. Treatment with 100 μM BaP significantly increased (p ≤ 0.001) the levels of the DNA strand breaks. None of the tested concentrations (0.1–10 μg/mL) of the honey samples (thyme and chestnut), royal jelly, and propolis caused DNA damage per se. All tested samples at all the concentrations used decreased the genotoxic effect of BaP. In addition, all mixtures of thyme or chestnut honeys with royal jelly or propolis showed a greater protective effect against BaP than the samples alone, being the thyme and chestnut honey samples enriched with 10% royal jelly and 10% propolis the most effective (70.4% and 69.4%, respectively). The observed protective effect may be associated with the phenolic content and antioxidant capacity of the studied samples. In conclusion, the thyme and chestnut honey samples enriched with bee products present potential as natural chemoprotective agents against the chemical carcinogen BaP.Item Potential of selected bacteriocinogenic lactic acid bacteria to control Listeria monocytogenes in nitrite-reduced fermented sausages(Food Control, 2023) Caballero, Natalia; Jiménez, Begoña; Haza Duaso, Ana Isabel; Hierro Paredes, Eva; Fernández Hospital, Xavier; Fernández Álvarez, Manuela; Sánchez Martín, Vanesa; Morales Gómez, PalomaThe antilisterial activity of four strains of bacteriocinogenic lactic acid bacteria has been tested in vitro and in a meat model, as an alternative to reduce nitrite added to fermented sausages. Cell-free supernatants were obtained after bacterial growth under monoculture and coculture conditions, both at 32 °C/16 h and 22 °C/72 h. After being adjusted to different pH, supernatants were assayed for inhibition of Listeria monocytogenes inoculated on tryptone soya broth added with 0.8% bacteriological agar. The highest inhibition was observed for Pediococcus acidilactici MP14 and the commercial starter P. acidilactici B-LC-20, especially when they were grown in coculture with Staphylococcus spp. meat starters. Lactococcus lactis MP11 showed lower antilisterial activity, and it was dependant on pH. In a fermented sausage model prepared without and with 50% of the maximum level of sodium nitrite allowed by the European Union (i.e. 75 mg/kg) both pediococci confirmed the activity observed in vitro, and reduced Listeria numbers by 1.3–1.4 log cfu/g in the absence of nitrite and 0.8 log cfu/g in its presence. Therefore P. acidilactici MP14, which had been isolated from an artisanal fermented sausage, has shown potential interest for biopreservation applications that must be confirmed in studies under real sausage manufacture conditions.Item Use of Lactococcus lactis subsp. cremoris NCDO 763 and -ketoglutarate to improve the sensory quality of dry fermented sausages.(Meat Science, 2004) Bruna, Jose María; Ordóñez, Juan Antonio; de la Hoz, Lorenzo; Herranz Hernández, María Beatriz; Fernández Álvarez, Manuela; Hierro Paredes, EvaThe aim of the present work was to enhance the degradation of free amino acids in dry fermented sausages as precursors of volatile compounds responsible for the ripened flavour. For this purpose, Lactococcus lactis subsp. cremoris NCDO 763, its intracellular cell free extract (ICFE) and α-ketoglutarate were added to sausages. Papain was also used to increase the amount of free amino acids. When L. lactis was inoculated in sausages, an increase in the proteolytic phenomena was observed. The addition of α-ketoglutarate increased transamination phenomena in batches where it was added. The enhancement of these phenomena determined a noticeable rise in the content of glutamic acid (the main final product in transamination reactions) and a decrease, among other amino acids, of valine and leucine, with the formation of high amounts of their derivatives 2-methylpropanal and 3-methylbutanal. These aldehydes are responsible for the ripened flavour of dry fermented sausages. Sensory analysis showed an improvement of odour and flavour when L. lactis and α-ketoglutarate were combined. On the other hand, the intracellular cell free extract of L. lactis did not show any important activity in relation to amino acid breakdown even when used together with α-ketoglutarate and/or papain.Item Formation of Listeria monocytogenes persister cells in the produce-processing environment(International Journal of Food Microbiology, 2023) Li, Xiran; Fernández Hospital, Xavier; Hierro Paredes, Eva; Fernández Álvarez, Manuela; Sheng, Lina; Wang, LuxinPersisters are a subpopulation of growth-arrested cells that possess transient tolerance to lethal doses of antibiotics and can revert to an active state under the right conditions. Persister cells are considered as a public health concern. This study examined the formation of persisters by Listeria monocytogenes (LM) in an environment simulating a processing plant for leafy green production. Three LM strains isolated from California produce-processing plants and packinghouses with the strongest adherence abilities were used for this study. The impact of the cells' physiological status, density, and nutrient availability on the formation of persisters was also determined. Gentamicin at a dose of 100 mg/L was used for the isolation and screening of LM persisters. Results showed that the physiological status differences brought by culture preparation methods (plate-grown vs. broth-grown) did not impact persister formation (P > 0.05). Instead, higher persister ratios were found when cell density increased (P < 0.05). The formation of LM persister cells under simulated packinghouse conditions was tested by artificially inoculating stainless steel coupons with LM suspending in media with decreasing nutrient levels: brain heart infusion broth (1366 mg/L O2), produce-washing water with various organic loads (1332 mg/L O2 and 652 mg/L O2, respectively), as well as sterile Milli-Q water. LM survived in all suspensions at 4 °C with 85 % relative humidity for 7 days, with strain 483 producing the most persister cells (4.36 ± 0.294 Log CFU/coupon) on average. Although persister cell levels of LM 480 and 485 were reasonably steady in nutrient-rich media (i.e., BHI and HCOD), they declined in nutrient-poor media (i.e., LCOD and sterile Milli-Q water) over time. Persister populations decreased along with total viable cells, demonstrating the impact of available nutrients on the formation of persisters. The chlorine sensitivity of LM persister cells was evaluated and compared with regular LM cells. Results showed that, despite their increased tolerance to the antibiotic gentamicin, LM persisters were more susceptible to chlorine treatments (100 mg/L for 2 min) than regular cells.Item Improvement of the sensory properties of dry-fermented sausages by the addition of free amino acids(Food Chemistry,, 2005) Ordóñez, Juan Antonio; Hoz Perales, Lorenzo De La; Fernández Álvarez, Manuela; Hierro Paredes, Eva; Herranz Hernández, María Beatriz; Ordóñez Pereda, Juan AntonioThe addition of free amino acids in the manufacture of dry-fermented sausages, as a method to enhance their flavour, was evaluated.For this purpose, three batches of dry-fermented sausages were manufactured: a control batch (C), and the same formula treated with 0.159% (g/100 g sausage) of a mixture of valine, isoleucine and leucine (58/35/66) (w/w) (batch L1) or treated with 1.01% of a ‘‘pool’’ of free amino acids (batch L2) (gly/asn/his/arg/thr/ala/pro/tyr/val/met/ile/leu/phe/trp/lys/asp/glu/ser /gln/cys) (19/19/105/41/55/ 69/90/10/58/27/35/66/35/62/110/56/106/18/19/10) (w/w). The pH values, dry matters and water activities of experimental sausages did not show significant differences (p < 0.05) among different batches. However, an increase in the microbial counts (lactic acid bacteria and micrococci) and in the level of free amino acids and ammonia was observed in batches L1 and L2. A higher amount of volatile compounds was also detected in both experimental batches (L1 and L2), particularly those compounds derived from amino acid breakdown, such as branched aldehydes and their corresponding alcohols. In the sensory analysis, bach L1 showed a better overall quality than the control and batch L2. The addition of free amino acids in the manufacture of dry-fermented sausages, as a method to enhance their flavour, was evaluated. For this purpose, three batches of dry-fermented sausages were manufactured: a control batch (C), and the same formula treated with 0.159% (g/100 g sausage) of a mixture of valine, isoleucine and leucine (58/35/66) (w/w) (batch L1) or treated with 1.01% of a ‘‘pool’’ of free amino acids (batch L2) (gly/asn/his/arg/thr/ala/pro/tyr/val/met/ile/leu/phe/trp/lys/asp/glu/ser /gln/cys) (19/19/105/41/55/ 69/90/10/58/27/35/66/35/62/110/56/106/18/19/10) (w/w). The pH values, dry matters and water activities of experimental sausages did not show significant differences (p < 0.05) among different batches. However, an increase in the microbial counts (lactic acid bacteria and micrococci) and in the level of free amino acids and ammonia was observed in batches L1 and L2. A higher amount of volatile compounds was also detected in both experimental batches (L1 and L2), particularly those compounds derived from amino acid breakdown, such as branched aldehydes and their corresponding alcohols. In the sensory analysis, bach L1 showed a better overall quality than the control and batch L2.Item Enhancement of the Antioxidant Capacity of Thyme and Chestnut Honey by Addition of Bee Products(Foods, 2022) Sánchez Martín, Vanesa; Morales Gómez, Paloma; Gonzalez-Porto, Amelia V.; Iriondo De Hond, Amaia; Lopez-Parra, Marta B.; Del Castillo, Maria Dolores; Fernández Hospital, Xavier; Fernández Álvarez, Manuela; Hierro Paredes, Eva; Haza Duaso, Ana IsabelHoney consumption and imports have increased in recent years, and it is considered by consumers to be a healthy alternative to more commonly used sweeteners. Honey contains a mixture of polyphenols and antioxidant compounds, and the botanical origin and geographical area of collection play an important role in its chemical composition. The present study investigated the physicochemical properties, total phenolic content, and antioxidant capacity of Spanish thyme honey and chestnut honey, and their mixtures with royal jelly (2% and 10%) and propolis (2% and 10%). The analysis of the physicochemical parameters of both honey samples showed values within the established limits. Propolis showed the highest value of total phenolic content (17.21–266.83 mg GAE/100 g) and antioxidant capacity (DPPH, ORAC, and ABTS assays; 0.63–24.10 µg eq. Tx/g, 1.61–40.82 µg eq. Tx/g, and 1.89–68.54 µg eq. Tx/g, respectively), and significantly reduced ROS production in human hepatoma cells. In addition, mixtures of honey with 10% of propolis improved the results obtained with natural honey, increasing the value of total phenolic content and antioxidant capacity. A significant positive correlation was observed between total phenolic compounds and antioxidant capacity. Therefore, the antioxidant capacity could be attributed to the phenolic compounds present in the samples, at least partially. In conclusion, our results indicated that thyme and chestnut honey supplemented with propolis can be an excellent natural source of antioxidants and could be incorporated as a potential food ingredient with biological properties of technological interest, added as a preservative. Moreover, these mixtures could be used as natural sweeteners enriched in antioxidants and other bioactive compounds.Item Impact of voltage and pulse delivery mode on the efficacy of pulsed light for the inactivation of Listeria(Innovative Food Science and Emerging Technologies, 2022) Hierro Paredes, Eva; Fernández Hospital, Xavier; Fernández León, María Fernanda; Caballero, Natalia; Cerdán, Beatriz; Fernández Álvarez, ManuelaListeria innocua inactivation by pulsed light (PL) was evaluated at different settings and voltages to establish the best treatment conditions and post-treatment handling for further implementation of PL in the food industry. Fluences up to 0.2 J/cm2 were applied to superficially inoculated TSA agar plates (4.5–5 log cfu/cm2). Inactivation was calculated, and log-linear and Weibull models were applied. A fluence of 0.2 J/cm2 applied in a single pulse inactivated 3.8 log cfu/cm2, while sequential application of this fluence yielded an inactivation between 1.5 and 2.5 log cfu/cm2 depending on the delivery mode (consecutive flashing or with 5 min-holding times under ambient light or in the dark). Data from consecutive PL treatment were fitted with the Weibull model. No photoreactivation following PL was observed after 120-min exposure to ambient light in any of the conditions assayed. This study showed that flashing with a single pulse at higher voltage would offer the highest inactivation of Listeria. Industrial relevance: This study offered information of practical interest to establish pulsed light processing and post-processing conditions for the control of Listeria spp. in the food industry, for instance in ready-to-eat (RTE) products. The use of higher voltages provided higher inactivation and allowed minimizing the number of flashes. If sequential treatments are to be applied, the treatment is more effective if short holding times are kept between pulses. The post-processing illumination conditions do not influence the efficacy of PL treatment.