Maria Katsouli

Dr. Maria Katsouli

National Technical University of Athens (NTUA), School of Chemical Engineering
orcid

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 March 2021 in Molecules
Verified
Journal Article
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SCSofia Chanioti
Sofia Chanioti
MKMaria Katsouli
Maria Katsouli
CTConstantina Tzia
Constantina Tzia
Olive pomace, the solid by-product derived from olive oil production consists of a high concentration of bioactive compounds with antioxidant activity, such as phenolic compounds, and their recovery by applying innovative techniques is a great opportunity and challenge for the olive oil industry. This study aimed to point out a new approach for the integrated valorization of olive pomace by extracting the phenolic compounds and protecting them by encapsulation or incorporation in nanoemulsions. Innovative assisted extraction methods were evaluated such as microwave (MAE), homogenization (HAE), ultrasound (UAE), and high hydrostatic pressure (HHPAE) using various solvent systems including ethanol, methanol, and natural deep eutectic solvents (NADESs). The best extraction efficiency of phenolic compounds was achieved by using NADES as extraction solvent and in particular the mixture choline chloride-caffeic acid (CCA) and choline chloride-lactic acid (CLA); by HAE at 60 °C/12,000 rpm and UAE at 60 °C, the total phenolic content (TPC) of extracts was 34.08 mg gallic acid (GA)/g dw and 20.14 mg GA/g dw for CCA, and by MAE at 60 °C and HHPAE at 600 MPa/10 min, the TPC was 29.57 mg GA/g dw and 25.96 mg GA/g dw for CLA. HAE proved to be the best method for the extraction of phenolic compounds from olive pomace. Microencapsulation and nanoemulsion formulations were also reviewed for the protection of the phenolic compounds extracted from olive pomace. Both encapsulation techniques exhibited satisfactory results in terms of encapsulation stability. Thus, they can be proposed as an excellent technique to incorporate phenolic compounds into food products in order to enhance both their antioxidative stability and nutritional value.

14 May 2024 in Molecules
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Journal Article
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MARIA TSEVDOUMARIA TSEVDOU
MARIA TSEVDOU
ANAthina G. Ntzimani
Athina G. Ntzimani
MKMaria Katsouli
Maria Katsouli
GDGeorge Dimopoulos
George Dimopoulos
Dimitrios TsimogiannisDimitrios Tsimogiannis
Dimitrios Tsimogiannis
PTPetros Taoukis
Petros Taoukis
Olive oil production is characterized by large amounts of waste, and yet is considerably highly valued. Olive pomace can serve as a cheap source of bioactive compounds (BACs) with important antioxidant activity. Novel technologies like Pulsed Electric Fields (PEF) and High Pressure (HP) and microwave (MW) processing are considered green alternatives for the recovery of BACs. Different microwave (150–600 W), PEF (1–5 kV/cm field strength, 100–1500 pulses/15 µs width), and HP (250–650 MPa) conditions, in various product/solvent ratios, methanol concentrations, extraction temperatures, and processing times were investigated. Results indicated that the optimal MW extraction conditions were 300 W at 50 °C for 5 min using 60% v/v methanol with a product/solvent ratio of 1:10 g/mL. Similarly, the mix of 40% v/v methanol with olive pomace, treated at 650 MPa for the time needed for pressure build-up (1 min) were considered as optimal extraction conditions in the case of HP, while for PEF the optimal conditions were 60% v/v methanol with a product/solvent ratio of 1:10 g/mL, treated at 5000 pulses, followed by 1 h extraction under stirring conditions. Therefore, these alternative extraction technologies could assist the conventional practice in minimizing waste production and simultaneously align with the requirements of the circular bioeconomy concept.


3 January 2024 in Foods
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MKMaria Katsouli
Maria Katsouli
EDEfimia Dermesonlouoglou
Efimia Dermesonlouoglou
GDGeorge Dimopoulos
George Dimopoulos
EKEleftheria Karafantalou
Eleftheria Karafantalou
MGMaria Giannakourou
Maria Giannakourou
PTPetros Taoukis
Petros Taoukis
From a quality standpoint, it is desirable to preserve the characteristics of fresh-cut potatoes at their peak. However, due to the mechanical tissue damage during the cutting process, potatoes are susceptible to enzymatic browning. This study pertains to the selection of the appropriate osmotic dehydration (OD), high pressure (HP), and pulsed electric fields (PEF) processing conditions leading to effective quality retention of potato cuts. PEF (0.5 kV/cm, 200 pulses) or HP (400 MPa, 1 min) treatments prior to OD (35 °C, 120 min) were found to promote the retention of the overall quality (texture and color) of the samples. The incorporation of anti-browning agents (ascorbic acid and papain) into the osmotic solution improved the color retention, especially when combined with PEF or HP due to increased solid uptake (during OD) as indicated by DEI index (2.30, 1.93, and 2.10 for OD treated 120 min, non-pre-treated, HP pre-treated, and PEF pre-treated samples, respectively). PEF and HP combined with OD and anti-browning agent enrichment are sought to improve the quality and microbial stability of fresh-cut potatoes during refrigerator storage. Untreated fresh-cut potatoes were characterized by color degradation from the 2nd day of storage at 4 °C, and presented microbial growth (total viable counts: 6 log (CFU)/g) at day 6, whereas pre-treated potato samples retained their color and microbiologically stability after 6 days of cold storage (total viable counts, <4 log(CFU)/g).

14 November 2024 in Applied Sciences
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Journal Article
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MKMaria Katsouli
Maria Katsouli
ITIoanna Thanou
Ioanna Thanou
EREvgenia Raftopoulou
Evgenia Raftopoulou
ANAthina G. Ntzimani
Athina G. Ntzimani
PTPetros Taoukis
Petros Taoukis
MGMaria Giannakourou
Maria Giannakourou
This study pertains the encapsulation of bioactive compounds, specifically phenolic compounds and lycopene, extracted from olive and tomato by-products via oil-in-water (O/W) nanoemulsions and their potential application in functional beverages. The effect of various edible oils (olive pomace oil (OPO), sunflower oil (SFO), corn oil (CO), fish oil (FO), and canola oil (CLA)) in the lipid phase and antioxidants (ascorbic acid and phenolic extracts) in the aqueous phase on the physicochemical properties of oil-in-water (O/W) nanoemulsions enriched with lycopene was evaluated, along with the bioaccessibility of the encapsulated bioactive compounds using the static INFOGEST in vitro simulation protocol for gastrointestinal food digestion. All examined edible oils led to nanoemulsions with uniform droplet sizes (droplet size < 300 nm, droplet distribution < 0.3) and high stability during storage at 4 °C, with FO being the smallest, at 259.3 ± 9.1 nm, and OPO the largest, at 286.6 ± 10.0 nm. Ascorbic acid increased the droplet size by 5–8%, improved droplet distribution, and led to a lower deterioration rate (−0.014 d−1) when compared to the “control” counterparts (−0.037 d−1). Lycopene bioaccessibility was significantly affected by the lipid phase, with OPO exhibiting the highest percentage (53.8 ± 2.6%) and FO the lowest (40.1 ± 2.1%). The OPO nanoemulsion was selected for the development of a functional beverage, showing excellent long-term stability. The phenolic compound concentration remained consistent during storage, and the lycopene degradation rate was minimal, at −0.0088 d−1, resulting in an estimated shelf life of 165 days at 4 °C, based on a 50% reduction in lycopene content. Similarly, phenolic compounds demonstrated high bioaccessibility, without a significant dependence on the lipid phase, and stability during shelf life, enhancing the beverage’s overall antioxidant profile. These results indicate that O/W nanoemulsions are effective delivery systems for functional beverages, offering improved stability and bioaccessibility of lycopene.

27 July 2022 in Foods
Verified
Journal Article
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MKMaria Katsouli
Maria Katsouli
ISIoanna Semenoglou
Ioanna Semenoglou
MKManto Kotsiri
Manto Kotsiri
EGEleni Gogou
Eleni Gogou
TTTheofania Tsironi
Theofania Tsironi
PTPetros Taoukis
Petros Taoukis
The study investigated the effect of active modified atmosphere packaging (20% CO2–60% N2–20% O2) with CO2 emitters (MAP-PAD) and conventional MAP (MAP) on the quality and shelf-life of gilthead seabream fillets during chill storage, while the most appropriate enzymatic Time Temperature Integrators (TTI) were selected for monitoring their shelf-life at isothermal and variable temperature storage conditions (Teff = 4.8 °C). The concentration of CO2 and O2 in the headspace of the package, volatile compounds and of the microbial population were monitored during storage. The kinetic parameters for bacterial growth were estimated at 0–10 °C using the Baranyi growth model. The MAP-PAD samples presented significantly lower microbial growth rates and longer lag phases compared to the MAP samples, leading to significant shelf-life extension: 2 days of extension at 2.5 °C and 5 °C, while 50% extension at variable conditions (Teff = 4.8 °C). CO2 emitters in the package improved the chemical freshness (K-values) and volatile compounds (characterizing freshness). The responses of different enzymatic TTI were modeled as the function of enzyme concentration, temperature and storage time. The activation energy (Ea) ranged from 97 to 148 kJ mol−1, allowing the selection of appropriate TTIs for the shelf-life monitoring of each fish product: LP-150U for the MAP and M-25U for the MAP-PAD samples. The validation experiment at Teff = 4.8 °C confirmed the applicability of Arrhenius-type models, as well as the use of TTIs as effective chill chain management tools during distribution and storage.