/library/oar/handle/123456789/18429 2025-12-25T14:52:26Z 2025-12-25T14:52:26Z Psakis, Georgios Lia, Frederick Valdramidis, Vasilis P. Gatt, Ruben /library/oar/handle/123456789/141213 2025-11-12T14:30:55Z 2024-01-01T00:00:00Z

Title: Exploring hydrodynamic cavitation for citrus waste valorisation in Malta : from beverage enhancement to potato sprouting suppression and water remediation Authors: Psakis, Georgios; Lia, Frederick; Valdramidis, Vasilis P.; Gatt, Ruben Abstract: Introduction: The endorsement of circular economy, zero-waste, and sustainable development by the EU and UN has promoted non-thermal technologies in agro-food and health industries. While northern European countries rapidly integrate these technologies, their implementation in Mediterranean food-supply chains remains uncertain. Aims: We evaluated the usefulness of hydrodynamic cavitation (HC) for valorizing orange peel waste in the fresh orange juice supply chain of the Maltese Islands. Method: We assessed: a) the effectiveness of HC in extracting bioactive compounds from orange peels (Citrus sinensis) in water (35°C) and 70% (v/v) ethanol (−10°C) over time, compared to conventional maceration, and b) the potato sprouting-suppression and biosorbent potential of the processed peel for copper, nitrate, and nitrite binding. Results: Prolonged HC-assisted extractions in water (high cavitation numbers), damaged and/or oxidized bioactive compounds, with flavonoids and ascorbic acid being more sensitive, whereas cold ethanolic extractions preserved the compounds involved in radical scavenging. HC-processing adequately modified the peel, enabling its use as a potato suppressant and biosorbent for copper, nitrate, and nitrite. Conclusion: Coupling HC-assisted bioactive compound extractions with using leftover peel for potato-sprouting prevention and as biosorbent for water pollutant removal offers a straightforward approach to promoting circular economic practices and sustainable agriculture in Malta.

2024-01-01T00:00:00Z Psakis, Georgios Griffin, Sholeem Dimopoulou, Maria Angelis-Dimakis, Athanasios Lorenzo, Jose Manuel /library/oar/handle/123456789/139265 2025-09-26T10:40:23Z 2024-01-01T00:00:00Z

Title: Editorial : Greening the way : emerging green technologies in process intensification Authors: Psakis, Georgios; Griffin, Sholeem; Dimopoulou, Maria; Angelis-Dimakis, Athanasios; Lorenzo, Jose Manuel Abstract: In 2022, 229.5 million metric tons of municipal solid waste (MSW; inclusive of electronic waste (e-waste), food waste, and healthcare waste) were generated in the European Union, amounting to 513 kg per person (European Commission, 2024). With the accumulation of MSW contributing to pollution, resource depletion, and greenhouse gas emissions (methane, carbon dioxide and nitrous oxide), further exacerbating climate change, effective waste management becomes essential for safeguarding environmental sustainability, public health and global resource security. The MSW management challenge has set in motion European plans (Circular Economy Action Plan (European Commission, 2020) and Green Deal (European Commission, 2021)) and global strategies (Sustainable Development Goal 12; Responsible Consumption and Production (United Nations Development Programme, 2021)), aiming at waste reduction, efficient/systematic recycling and resource recovery through green-valorisation (eco-friendly technologies with use of green-chemistry). Execution of these plans requires the adoption of innovative practices by multiple-stakeholders, planting seeds for the development of sustainable circular economies. Thus, application of Innovative tools and methods, and integration of time-, energy- and cost-effective technologies in process intensification, are now more critical than ever for attaining sustainability goals. [excerpt]

2024-01-01T00:00:00Z de Oliveira Mallia, Jefferson Griffin, Sholeem Buttigieg, Clara Gatt, Ruben /library/oar/handle/123456789/138631 2025-09-03T05:39:23Z 2024-01-01T00:00:00Z

Title: A rapid prototyped atmospheric non-thermal plasma-activated aerosol device and anti-bacterial characterisation Authors: de Oliveira Mallia, Jefferson; Griffin, Sholeem; Buttigieg, Clara; Gatt, Ruben Abstract: Non-plasma technologies are being extensively investigated for their potential to mitigate microbial growth through the production of various reactive species. Predominantly, studies utilise atmospheric non-thermal plasma to produce plasma-activated liquids. The advancement of plasma-liquid applications has led to the investigation of plasma-activated aerosols (PAAs). This study aimed to produce a rapid-prototyped plasma-activated aerosol setup and perform chemical and anti-bacterial characterisation on the resultant activated aerosols. The setup was produced using stereolithography 3D printing, and air was used as the carrier gas. The novel design of the device allowed for the direct production of PAAs without the prior generation of plasma-activated water and subsequent aerosolisation. The generated PAAs were assessed for nitrite, hydrogen peroxide and ozone content using colourimetric assays. Anti-bacterial efficacy was tested against three human pathogenic strains: Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Salmonella enterica. It was observed that nitrite and ozone contact concentration increased with exposure time, yet no hydrogen peroxide was detected. The generated PAAs showed significant zones of no growth for all bacterial strains. These devices, therefore, show potential to be used as anti-bacterial disinfection technologies.

2024-01-01T00:00:00Z Lytras, Fotios Psakis, Georgios Gatt, Ruben Hummerjohann, Joerg Raso, Javier Valdramidis, Vasilis /library/oar/handle/123456789/138616 2025-09-02T10:28:42Z 2024-01-01T00:00:00Z

Title: Evaluation of strain variability of food microorganisms in response to decontamination by pulsed electric fields and thermal treatments Authors: Lytras, Fotios; Psakis, Georgios; Gatt, Ruben; Hummerjohann, Joerg; Raso, Javier; Valdramidis, Vasilis Abstract: The effect of pulsed electric fields (PEF) and thermal treatments on the inactivation of the population of 40 strains of 4 model microorganisms (Escherichia coli, Listeria monocytogenes, Lactiplantibacillus plantarum, Saccharomyces cerevisiae) were investigated. Microbial samples of McIlvaine buffer pH 7.0 were subjected to pulses with electric field strength 20 kV/cm and total specific energies (88, 136, and 184 kJ/kg). Depending on the species and strain, microorganisms exhibited various resistances. PEF microbial resistance and strain variability data were correlated to the total specific energy used. E. coli strains showed statistical log10 inactivation differences under the 88 and 136 kJ/kg but not under the 184 kJ/kg PEF treatment. In contrast, L. monocytogenes strains showed statistical log10 inactivation differences only under the 184 kJ/kg treatment. L. monocytogenes L6 strain was identified as the most resistant strain at PEF treatment (184 kJ/kg). This result was in accordance with the resistance under thermal treatment (62.8 °C, 30 min).

2024-01-01T00:00:00Z