Open Access
Effects of ozonation on the physicochemical properties and antimicrobial activity of virgin and pomace olive oils
(Wiley, 2025-05-22) Domínguez-Lacueva, Paula; Corella Guillamón, Paula; Cantalejo Díez, María Jesús; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa; Gobierno de Navarra / Nafarroako Gobernua
Ozonated olive oils are recognized for their remarkable antimicrobial properties. The reaction between ozone (O3) and unsaturated fatty acids leads to the formation of bactericidal compounds (ozonides, aldehydes, and peroxides) with valuable applications. This study represents the first comprehensive investigation into the effects of a wide range of ozone exposure durations (from 0 to 48 h) on the physicochemical properties and antimicrobial activity of both virgin olive oil (VOO) and pomace olive oil (POO), along with a thorough statistical analysis of the correlation between ozone dose and these parameters. The physicochemical indicators, including fatty acid methyl ester (FAME) composition, peroxide index, acidity index, iodine value, and viscosity, were measured at ozonation doses ranging from 0 to 1 mol O3. Significant changes were observed with increasing ozonation time, including a 69% and 46% reduction in oleic acid content, as well as increased peroxide values of 1255.2 mEq O₂/kg and 1878.8 mEq O₂/kg for VOO and POO, respectively. Antimicrobial activity was evaluated against Escherichia coli (STCC 45), Pseudomonas aeruginosa (STCC 109), and Staphylococcus aureus (STCC 239), with the highest inhibition observed against S. aureus (22.68 mm with POO at 48 h and 1 mol O3). PCA analysis identified three groups: low ozone doses (0–0.08 mol O₃) associated with higher iodine values; intermediate doses (0.16–0.5 mol O₃) linked to increased peroxide, acidity, viscosity, and antimicrobial activity; while high doses (1 mol O₃) provided no further benefits, suggesting that moderate doses are sufficient for effective antimicrobial activity. These findings highlight the potential of ozonated olive oils for novel applications in the food industry.
Open Access
Excitation-emission matrix spectroscopy coupled with chemometrics for monitoring ozonation of olive oil and olive pomace oil
(Royal Society of Chemistry, 2025-02-07) Domínguez-Lacueva, Paula; Sikorska, Ewa; Cantalejo Díez, María Jesús; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
The effects of ozonation on the Total Polyphenol Content (TPC) of olive oils remain largely unexplored, despite the significant role that polyphenols play in enhancing the health benefits and quality of these oils. Understanding how ozone treatment impacts phenolic compounds is vital, especially considering the documented negative effects of thermal and photochemical oxidation on TPC. The aim of this study was to explore the use of fluorescence spectroscopy combined with chemometrics to develop multivariate models for monitoring the effects of ozonation on TPC and key physicochemical parameters such as the peroxide index (PI), acidity index (AI), iodine value (IV) and viscosity (V) in both, virgin and pomace olive oils. Parallel factor analysis and principal component analysis of fluorescence excitation¿emission matrices (EEMs) of ozonated olive oils revealed that as the ozonation process progressed, TPC and fluorescence emission decreased. And, at the same time, ozonation increased the values of oxidation indicators such as PI, AI, viscosity and intensity of the Rayleigh scattering signal. PLS models based on analysis of unfolded EEMs exhibited good predictive performance for PI (R2 = 0.822; RPD > 2.5), and moderate for TPC and V (R2 = 0.792 and 0.753; RPD > 2). In summary, we demonstrated the feasibility of EEM spectroscopy for monitoring the ozonation process. The use of this method can ease the characterization of ozonated olive oils and, additionally, make the analysis more sustainable.
Open Access
Influence of acid adaptation on the probability of germination of Clostridium sporogenes spores against pH, NaCl and time
(MDPI, 2020) Valero, Antonio; Olagüe Ramos, Elena; Medina Pradas, Eduardo; Garrido Fernández, Antonio; Romero Gil, Verónica; Cantalejo Díez, María Jesús; García Gimeno, Rosa María; Pérez Rodríguez, Fernando; Posada Izquierdo, Guiomar Denisse; Arroyo López, Francisco Noé; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
The Clostridium sp. is a large group of spore-forming, facultative or strictly anaerobic, Gram-positive bacteria that can produce food poisoning. The table olive industry is demanding alternative formulations to respond to market demand for the reduction of acidity and salt contents in final products. while maintaining the appearance of freshness of fruits. In this work, logistic regression models for non-adapted and acid-adapted Clostridium sp. strains were developed in laboratory medium to study the influence of pH, NaCl (%) and time on the probability of germination of their spores. A Clostridium sporogenes cocktail was not able to germinate at pH <5.0, although the adaptation of the strains produced an increase in the probability of germination at 5.0-5.5 pH levels and 6% NaCl concentration. At acidic pH values (5.0), the adapted strains germinated after 10 days of incubation, while those which were non-adapted required 15 days. At pH 5.75 and with 4% NaCl, germination of the adapted strains took place before 7 days, while several replicates of the non-adapted strains did not germinate after 42 days of storage. The model was validated in natural green olive brines with good results (>81.7% correct prediction cases). The information will be useful for the industry and administration to assess the safety risk in the formulation of new processing conditions in table olives and other fermented vegetables.
Open Access
Modeling the growth of six Listeria monocytogenes strains in smoked salmon pâté
(MDPI, 2023) Bolívar, Araceli; Garrote Achou, Chajira Camila; Tarlak, Fatih; Cantalejo Díez, María Jesús; Correia Peres Costa, Jean Carlos; Pérez Rodríguez, Fernando; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
In this study, the growth of six L. monocytogenes strains isolated from different fish products was quantified and modeled in smoked salmon pâté at a temperature ranging from 2 to 20 °C. The experimental data obtained for each strain was fitted to the primary growth model of Baranyi and Roberts to estimate the following kinetic parameters: lag phase (λ), maximum specific growth rate (μmax), and maximum cell density (Nmax). Then, the effect of storage temperature on the obtained μmax values was modeled by the Ratkowsky secondary model. In general, the six L. monocytogenes strains showed rapid growth in salmon pâté at all storage temperatures, with a relatively short lag phase λ, even at 2 °C. The growth behavior among the tested strains was similar at the same storage temperature, although significant differences were found for the parameters λ and μmax. Besides, the growth variations among the strains did not follow a regular pattern. The estimated secondary model parameter Tmin ranged from −4.25 to −3.19 °C. This study provides accurate predictive models for the growth of L. monocytogenes in fish pâtés that can be used in shelf life and microbial risk assessment studies. In addition, the models generated in this work can be implemented in predictive modeling tools and repositories that can be reliably and easily used by the fish industry and end-users to establish measures aimed at controlling the growth of L. monocytogenes in fish-based pâtés.
Open Access
Changes in the quality parameters and antimicrobial activity of ozonated virgin and pomace olive oils under different storage conditions
(MDPI, 2025-03-15) Domínguez-Lacueva, Paula; Corella Guillamón, Paula; Cantalejo Díez, María Jesús; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
Ozonated olive oils have emerged as a promising alternative for natural antimicrobial agents in the food industry due to their potential to inhibit microbial growth. However, the stability and effectiveness of these oils under different storage conditions has not been thoroughly explored. This study examines the changes in the physicochemical properties and antimicrobial activity of ozonated virgin olive oil (VOO) and pomace olive oil (POO), stored at 4 ◦C and 20 ◦C for 6 months. The peroxide index (PI), acidity index (AI), iodine value (IV), and viscosity (V) were analyzed, along with their antimicrobial activity against Escherichia coli (STCC 45), Pseudomonas aeruginosa (STCC109), and Staphylococcus aureus (STCC 239). The results showed that both oils underwent changes in their physicochemical properties and antimicrobial activity over time. The PI initially increased up to day 30, with VOO reaching a peak value of 741.44 ± 32.16 meq O2/kg and POO reaching 1067.23 ± 56.56 meq O2/kg, but after this point, it began to decrease in both oils and at both temperatures (4 ◦C and 20 ◦C). The acidity index (AI) increased over time, particularly in POO, which reached a final value of 6.32 ± 0.14 mg KOH/g. Both oils showed a reduction in iodine value (IV), and an increase in viscosity (V) over time. In terms of antimicrobial activity, P. aeruginosa remained stable with an average inhibition zone of 9.41 ± 0.23 mm, while E. coli showed the greatest increase in activity over time, reaching 21.31 ± 4.01 mm in POO at 20 ◦C. On the other hand, S. aureus exhibited the highest average antimicrobial activity, with a mean inhibition diameter of 14.49 ± 0.36 mm, and the largest inhibition zone of Ø = 18.97 ± 1.46 mm observed after 180 days of storage. A Spearman correlation analysis revealed a strong positive relationship (ρ > 0.85, p < 0.05) among PI, AI, and the antimicrobial activity with storage duration. This study provides novel insights into the stability of ozonated oils, offering valuable perspectives for their application in the food industry, especially using pomace olive oil, a key by-product in olive oil production.
Open Access
Transfering sustainability competences through green pedagogies and service-learning in higher education
(European Center of Sustainable Development, 2025-02-01) Cantalejo Díez, María Jesús; Martínez Aldaya, Maite; Navarlaz Fernández, Isabel; Ciencias; Zientziak; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura
Sustainability competences are reflected in the ability to look ahead to change and shape the future of the societies in which they live through active participation in the sense of sustainable development. Through service-learning, students take responsibility for their actions. The complex nature of sustainability issues makes it useful to explore problems and their solutions holistically. In the framework of the NEMOS project (A New Educational Model for Acquiring Sustainability Competences through Service-Learning), a collaborative process was initiated to pool the knowledge and experience of five Higher Education Institutions working together to implement new educational models for effectively acquiring sustainability competences through service-learning in food-related degrees. This EU-funded project was launched and aimed to advance the transition to sustainability education through practical and innovative educational approaches and interventions. Green pedagogy can support transformative learning through the exploration and clarification of learners
Open Access
Prevalence, identification and antimicrobial resistance of Listeria monocytogenes and Listeria spp. isolated from poultry and pork meat
(Wiley, 2024) Martínez-Laorden, Alba; Arraiz-Fernández, Celia; Cantalejo Díez, María Jesús; González-Fandos, Elena; Agronomía, Biotecnología y Alimentación; Agronomia, Bioteknologia eta Elikadura; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD
The aim of this work was to evaluate the prevalence of Listeria monocytogenes and other Listeria spp. in chicken, duck, quail, turkey and pork meat, including the antibiotic resistance of isolated strains. A total of 184 meat samples were collected from different retailers in La Rioja (Spain). The presence of Listeria spp. and L. monocytogenes were detected in 24.46% and 10.32% of the meat samples respectively. L. monocytogenes was the predominant Listeria spp. found in chicken, quail and pork meat, while L. innocua and L. welshimeri were the predominant species in duck and turkey meat respectively. A total of thirty-three strains (55.93%) of Listeria spp. were found to be multi-resistant (resistant to ≥3 families of antibiotics). The highest multi-resistant rates were observed in L. monocytogenes (73.68%) and L. innocua (70.59%), followed by L. ivanovii (50%). Resistance to ampicillin and trimethoprim-sulfamethoxazole were found in L. monocytogenes strains isolated from chicken, being of special concern, since these antibiotics are used in the treatment of listeriosis. Special measures should be taken to reduce meat contamination such as adequate handling, correct preparation (cooking) and cleaning and disinfection in order to avoid cross-contamination.
Open Access
Evaluation of different nutritional sources in lactic acid bacteria fermentation for sustainable postbiotic production
(MDPI, 2025-02-14) Garrote Achou, Chajira Camila; Cantalejo Díez, María Jesús; Díaz Cano, Jesús; Molinos Equiza, Xabier ; Institute on Innovation and Sustainable Development in Food Chain - ISFOOD; Gobierno de Navarra / Nafarroako Gobernua
In recent years, interest in postbiotics has grown due to their potential health benefits and applications in food systems. This study evaluated various nutritional sources for lactic acid bacteria (LAB) fermentation to enhance postbiotic production. Three LAB strains were tested: Pediococcus acidilactici CECT 9879 (PA), Weissella cibaria CECT 30731 (WC), and Lactococcus lactis CECT 30734 (LL). Fermentation experiments assessed bacterial growth, pH levels, and antibacterial activity against E. coli using different carbon and nitrogen sources. Fructose and xylose significantly improved growth in WC (9.39 ± 0.16 log CFU/mL) and LL (9.37 ± 0.22 log CFU/mL) compared to glucose. Ribose enhanced antimicrobial activity in PA (41.67 ± 2.89%) and WC (50.00 ± 0.00%) relative to glucose. Additionally, plant-based nitrogen sources, such as soy (LL: 8.93 ± 0.12 log CFU/mL and 81.67 ± 2.89%) and wheat (WC: 9.40 ± 0.17 log CFU/mL and 65.00 ± 0.00%), along with microbial sources like yeast (PA: 9.57 ± 0.12 log CFU/mL and 40.00 ± 0.00%), effectively supported growth and antibacterial activity. These findings highlight the potential of developing animal-free fermentation media that meet nutritional, safety, and sustainability criteria while making a significant contribution to the optimization of postbiotic production.