- Terma N. Temponera str., GR-43100, Karditsa, Greece
- TEI of Thessaly, Department of Food Technology, Post-Docadd
- Dr. Vassilis Athanasiadis has the Bachelor’s degree (BSc) in Food Technology since 2010. Also, has the Master's degre... moreDr. Vassilis Athanasiadis has the Bachelor’s degree (BSc) in Food Technology since 2010. Also, has the Master's degree (MSc) in Applied Public Health and Environmental Hygiene with focus on Food and Water Quality and Safety and Public Health since 2013, and he has the Doctorate degree (PhD) in Food Science and Nutrition since 2018. Dr. Athanasiadis is a Postdoctoral Research Fellow at University of Thessaly and he has experience in recovery, separation and identification of natural product extracts and determination of their antioxidant activity. He has also experience in modern analytical techniques (HPLC, GC-MS, DSC, FT-IR, etc.) and in food processing lines. He participated in 9 national research programs and he has published 14 research articles in international scientific journals with referees (with more than 300 citations) and more than 24 presentations in international and national conferences. Since 2020, Dr. Athanasiadis is an editorial board member in LWT - Food Science and Technology international scientific journal and reviewer in 20 international scientific journals (with more than 160 reviewing). He is also a member of Food InnovaLab research laboratory (at University of Thessaly). Finally, he is a member of Hellenic Association of Food Scientists & Technologists.edit
- Dr. Stavros Lalas, Professor of Food Technology, Department of Food Science and Nutrition, University of Thessaly, Dr. Dimitris P. Makris, Associate Professor of Food Chemistry, Department of Food Science and Nutrition, University of Thessalyedit
Polyphenol-containing extracts from olive (Olea europaea) leaves (OLL) were obtained using a glycerol-based deep eutectic solvent (DES) and a combination of DES with methyl β-cyclodextrin (m-β-CD). The extracts were stored at various... more
Polyphenol-containing extracts from olive (Olea europaea) leaves (OLL) were obtained using a glycerol-based deep eutectic solvent (DES) and a combination of DES with methyl β-cyclodextrin (m-β-CD). The extracts were stored at various temperatures for a period of 20 days and the reducing power (PR) was monitored to trace changes in the antioxidant potency of the extracts. Over the examination period and at every temperature tested, PR displayed a constant decline, which followed pseudo zero-order kinetics. The determination of the decay constants indicated that the presence of m-β-CD acted protectively, slowing down the progression of the PR decline. Examination of the polyphenolic profiles using liquid chromatography–diode array–mass spectrometry showed that after storage for 20 days at 50 °C, some major polyphenols occurring in OLL suffered extended degradation. The formation of a yellow pigment in the extracts stored in DES but not in aqueous ethanol suggested that polyphenol oxidation did occur during storage. It was concluded that the oxidation of some OLL components was rather responsible for the PR decline observed.
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Fruits and vegetables are major sources of antioxidants. These are substances that remove free-radical intermediates by being oxidized themselves and delay or inhibit other oxidation reactions. Recent studies make clear that an... more
Fruits and vegetables are major sources of antioxidants. These are substances that remove free-radical intermediates by being oxidized themselves and delay or inhibit other oxidation reactions. Recent studies make clear that an antioxidant-rich diet acts as a health protecting factor. The antioxidant that was used in this study was 2,5-dimethyl-4-hydroxy-3(2H)-furanone (HDMF). Two frying methods (with and without antioxidant) were used: the first one with no replenishment of oil and the second one with frequent replenishment of oil. As it was proved by the induction period, using the Rancimat method, HDMF increased the resistance against oxidation not only of the frying oils but also of the oil that was absorbed by the chips. The results were in line with those of croissants when they were baked with or without HDMF. Taste panel test confirmed those results as panelists showed a clear preference for those products that were protected against oxidation by HDMF.
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Industrial activity has contributed to potentially toxic metal pollution in various ecosystems throughout the world. In this study, the ability of humic and fulvic acids (isolated from lignite with a simple, rapid, and inexpensive method)... more
Industrial activity has contributed to potentially toxic metal pollution in various ecosystems throughout the world. In this study, the ability of humic and fulvic acids (isolated from lignite with a simple, rapid, and inexpensive method) to reduce toxic metals’ concentration of contaminated water is examined. More specifically, the effect of these compounds is tested on water contaminated (at various concentrations) with Cd, Cr, Cu, Ni, and Pb. The determination is performed by inductively coupled plasma-optical emission spectrometry. The maximum binding capacity is presented by fulvic acids in the following order Cr>Pb>Ni>Cu>Cd (97.8, 96.5, 95.4, 95.1, and 83.3%, respectively), while for humic acids it is Pb>Ni>Cr>Cu>Cd (81.3, 70.7, 68.6, 67.0, and 66.8%, respectively). The binding activity is also tested on water contaminated with two metals simultaneously. In these cases, the existence of two metals in water changes the reduction ability of humic and fulvic acids (positively or negatively).
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Olive leaf (OLL) extracts contain a high load of antioxidant polyphenols with significant pharmacological potency. In this study, the use of a novel natural deep eutectic solvent enabled the effective extraction of OLL polyphenols and... more
Olive leaf (OLL) extracts contain a high load of antioxidant polyphenols with significant pharmacological potency. In this study, the use of a novel natural deep eutectic solvent enabled the effective extraction of OLL polyphenols and their testing as radical scavengers, in the presence or absence of methyl β-cyclodextrin (m-β-CD), using descriptive kinetics. Testing was extended to include interactions with ascorbic acid—a natural powerful antioxidant—by implementing a response surface methodology. The kinetic study showed that m-β-CD may hinder the radical scavenging effect of OLL extracts, yielding lower stoichiometry upon reaction with the radical probe 2,2-diphenyl-1-picrylhydrazy (DPPH). The extension of the reaction time to determine the total stoichiometry confirmed this effect. As a further concurrence, the interactions of OLL extracts with ascorbic acid showed lower radical scavenging performance in the presence of m-β-CD. These results were discussed on the grounds of the role that m-β-CD may play in similar systems.
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A novel deep eutectic solvent (DES) with optimised composition was used to evaluate the effect of methyl β-cyclodextrin (CD) on the efficiency of polyphenol extraction from Olea europaea leaves (OLLs). The process developed was based on a... more
A novel deep eutectic solvent (DES) with optimised composition was used to evaluate the effect of methyl β-cyclodextrin (CD) on the efficiency of polyphenol extraction from Olea europaea leaves (OLLs). The process developed was based on a 2 3 full-factorial design and response surface methodology to assess the simultaneous effect of CD concentration (C CD), liquid-to-solid ratio (R L/S) and temperature (T). Under optimised conditions (C CD = 9%, R L/S = 40 mL g −1 , T = 51 °C), the yield in total polyphenols (Y TP) was 116.65 ± 3.60 mg gallic acid equivalents per g dry weight. This value was significantly higher than that determined for the extraction performed with 60% aqueous etha-nol. The extraction kinetics also showed that the extraction rate was slowed down in the presence of CD, yet the higher extraction capacity of the DES/CD medium was confirmed. Characterisation of the extracts obtained with DES/CD and DES by means of liquid chromatography-mass spectrometry demonstrated that there was no selective extraction of any particular polyphenol, suggesting that CD acted merely as an extraction booster.
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A number of biological activities have been attributed to polyphenolic substances occurring in the leaves of the olive tree (O. europaea), an olive oil industry waste material, and for this reason several extraction processes have been... more
A number of biological activities have been attributed to polyphenolic substances occurring in the leaves of the olive tree (O. europaea), an olive oil industry waste material, and for this reason several extraction processes have been developed for the efficient recovery of these phytochemicals. The study presented herein describes for the first time the use of an eco-friendly deep eutectic solvent (DES) as a highly effective solvent for the extraction of polyphenols from olive tree leaves. Initially, a central composite design was implemented to optimise solvent composition and liquid-to-solid ratio and then a kinetic assay was performed to investigate diffusivity (De) and temperature effects. The maximum total polyphenol yield was 106.25 mg gallic acid equivalents per g dry weight, achieved at 70 °C. This value was by 18% higher than that achieved with 60% aqueous methanol. Furthermore, the DES extract exhibited significantly higher antiradical activity and reducing power. Temperature increase up to 70 °C was shown to boost De and the activation energy determined for the process was 29.55 kJ mol-1. Characterisation of the extract by means of liquid chromatography-diode array-mass spectrometry showed oleuropein and certain flavone glycosides to be the major polyphenolic constituents.
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Moringa oleifera tree was cultivated for the first time in the mild temperate climate of Greece. Moringa oleifera leaf protein and amino acid content, total phenols and flavonols, lipids, fatty acids, ash and minerals, dietary fiber and... more
Moringa oleifera tree was cultivated for the first time in the mild temperate climate of Greece. Moringa oleifera leaf protein and amino acid content, total phenols and flavonols, lipids, fatty acids, ash and minerals, dietary fiber and carbohydrates, carotenoids, and vitamins C and E were determined. Leaves were high in protein content (26.3%), including all the essential amino acids. They also contained 4512.2 mg GAE.100 g –1 DM of total phenols and were rich in flavonols (myricetin, quercetin, and kaempherol at 649.8, 77.2, and 37.2 mg.
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Mastic is a well-known natural resin from the trunk and branches, of Pistacia lentiscus var. chia (Anacardiaceae), which is grown as endemic only in the Greek island of Chios. During this work, a total mastic gum extract was prepared... more
Mastic is a well-known natural resin from the trunk and branches, of Pistacia lentiscus var. chia (Anacardiaceae), which is grown as endemic only in the Greek island of Chios. During this work, a total mastic gum extract was prepared after removal of the contained insoluble polymer in order to ameliorate solubility and enhance in vivo activity. To overcome the drawbacks (i.e solubility, bioavailability, etc.) of mastic gum extracts (acidic and neutral fraction), the selection of a suitable carrier is crucial. Three different methods of preparation, thin-film evaporation, freezing-thawing, and ethanol injection were used for the preparation of liposomes consisting of Phosphatidylcholine (PC) and Cholesterol (CH). The effect of PC: CH molar ratio on the percentage of mastic extract encapsulated was investigated. Mastic gum extracts components-liposomes interaction was studied using Fourier transform infrared (FT-IR) spectroscopy. The effects of different preparation methods on the physicochemical properties of colloidal systems were evaluated by means of surface morphology, field emission Scanning Electron Microscopy (SEM), and size distribution using a particle size analyzer. For the determination of the antioxidant activity two methods were used: I) The Rancimat method where the protection factor was determined for each sample and compared with known antioxidants. II) Differential Scanning Calorimetry (DSC) where the temperature of oxidation for each sample was determined. Moreover, the crude extract (EtOAc-MeOH) of mastic, as well as, its acidic and neutral fractions was assayed against a panel of 9 human and food pathogenic gram (±) bacteria and fungi.
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This work was dedicated to reporting the full chemical and physical characterisation of Crambe abyssinica Hochst. seed oil. The oil from the seeds was extracted using n-hexane. The seeds contain about 30 % oil. Density, refractive index,... more
This work was dedicated to reporting the full chemical and physical characterisation of Crambe abyssinica Hochst. seed oil. The oil from the seeds was extracted using n-hexane. The seeds contain about 30 % oil. Density, refractive index, colour, smoke point, viscosity, acidity, saponification value, iodine value, fatty acid methyl esters, the relative position of fatty acids in C1 and C3 carbon glycerol, sterols, tocopherols, peroxide value, $ \mathop E\nolimits_{{1{\text{cm}}}}^{1\,\% } $ at 232 nm, and the susceptibility to oxidation measured by the Rancimat method were determined. The oil was found to contain high levels of unsaturated fatty acids, especially C22:1 (63.77 %). The dominant saturated acid was C22:0 (2.14 %). The oil was also found to contain high levels of β-sitosterol (51.93 %), campestanol (21.98 %), and brassicasterol (12.35 %). α-, γ-, and δ-Tocopherols were detected up to levels of 7.67, 125.04, and 3.99 mg/kg, respectively. The induction period (at 110 °C and 20 l/h) of the oil was 8.83 h. The relative position of fatty acids in C1 and C3 position was as follows: linoleic 0.45 %, oleic 8.84 %, and erucic 90.72 %. The thermal profile of the oil presented a single peak at −20.94 °C.
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Natural antioxidants derived from plant sources attract considerable scientific interest. While classic extraction methods consume high volumes of toxic organic solvents, cloud point extraction requires surfactant not exceeding 15% of the... more
Natural antioxidants derived from plant sources attract considerable scientific interest. While classic extraction methods consume high volumes of toxic organic solvents, cloud point extraction requires surfactant not exceeding 15% of the waste volume. In preliminary tests, the suitability of various low hazard surfactants (Span 20, PEG 400, Tween 80 and 20) was explored for separation of phenols and carotenoids from olive mill wastewater and red-flesh orange juice. Tween 80 showed the highest recovery and further applied to the next experiments. The most appropriate surfactant concentrations were 5% (for olive mill wastewater) and 7% (for orange juice) as indicated by recovery % and the rest cloud point extraction parameters (analyte concentration, concentration factor, and phase volume ratio). A double step CPE with 5% + 5% of Tween 80 recovered up to 94.4% of the total phenols from olive mill wastewater, while a 7% + 7% of Tween 80 recovered up to 72.4% of the total carotenoids from orange juice. Evaluation of the final effects and extraction efficiency of single and double step cloud point extraction shows that double step scheme seems to be preferable in both cases. Finally, phenols and carotenoids recovered by Tween 80 maintained high antiradical activity (DPPH test).
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The antimicrobial activity of the oil extracted with n-hexane from the seeds of Moringa peregrina was tested against Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella... more
The antimicrobial activity of the oil extracted with n-hexane from the seeds of Moringa peregrina was tested against Staphylococcus aureus, S. epidermidis, Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae, Candida albicans, C. tropicalis and C. glabrata. The oil proved effective against all of the tested microorganisms. Standard antibiotics (netilmycin, 5-flucytocine, intraconazole and 7-amino-4-methylcoumarin-3-acetic acid) were used for comparison. The resistance to oxidation of the extracted seed oil was also determined.
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The possibility to increase the nutritional value of table olives using polyphenols extracted from olive leaves was studied. Leaves were subjected to extraction using water with proportions of 1%, 5% and 10% of leaves and various... more
The possibility to increase the nutritional value of table olives using polyphenols extracted from olive leaves was studied. Leaves were subjected to extraction using water with proportions of 1%, 5% and 10% of leaves and various temperatures and times (room temperature/24 h, 40 °C/10 min and 70 °C/5 min). The antioxidant activity of extracts was determined using the Rancimat method and their content in oleuropein and hydroxytyrosol was determined by HPLC. The extract with the highest antioxidant activity and polyphenol content (10% ratio of olive leaves extracted at room temperature for 24 h) was used for the treatment of debittered table olives. The treated and untreated olives were subjected to determination of their α-tocopherol, oleuropein and hydroxytyrosol content. A 457% increase was observed for oleuropein and 109% for hydroxytyrosol content after treatment. Sensory evaluation of treated table olives showed an increase in bitterness. However, treated and untreated table olives showed equal overall acceptability and overall preference.
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Lentils are known to be an integral part of a nutritionally balanced diet. Their sprouts are considered even more nutritional since they contain phytonutrients that confer health benefits. As such, incorporating them into a human diet can... more
Lentils are known to be an integral part of a nutritionally balanced diet. Their sprouts are considered even more nutritional since they contain phytonutrients that confer health benefits. As such, incorporating them into a human diet can be advantageous. In this study, seeds from brown and black lentils were germinated aiming to study the changes in their nutritional value after they were grown for different amount of days to different lengths. Since the sprouts can be consumed at various stages of their growth, four growth stages were studied. For each stage, three batches were grown, and one sample of each batch was randomly picked and analyzed in triplicates. The sprouts were examined for their nutritional value. To this end, their content of proteins and carbohydrates was determined, as well as their content in carotenoids and vitamin C. Moreover, emphasis was placed on the phytochemical compounds contained in the sprouts. As results indicate, lentil sprouts not only exhibit hi...
Apricot kernels are known to be rich in bioactive compounds such as polyphenols, which have applications in various fields such as cosmetology and the food industry. However, the extraction of these compounds has not been extensively... more
Apricot kernels are known to be rich in bioactive compounds such as polyphenols, which have applications in various fields such as cosmetology and the food industry. However, the extraction of these compounds has not been extensively studied. In this study, we aimed to extract oil from apricot kernels and investigate its composition and antioxidant properties. Samples from two years of apricot cannery by-products were used in the study. We employed a common extraction procedure using hexane as a solvent, followed by an analysis of the oil’s fatty acid composition and determination of its antioxidant properties using several methods. Our results indicated that the oil extracted from apricot kernels is rich in oleic and palmitoleic acids, which exhibit health benefits. As regards the volatile compounds of the oil, 2-methyl propanal, benzaldehyde, and benzyl alcohol were detected as the main compounds. Benzaldehyde was also found to be the main component of the essential oil of the ker...
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Quinces are well known for their multiple health benefits, including antioxidant, hypoglycemic, antimicrobial, anti-inflammatory, anticarcinogenic, etc., properties. Despite the widespread utilization of various plant parts, the peel has... more
Quinces are well known for their multiple health benefits, including antioxidant, hypoglycemic, antimicrobial, anti-inflammatory, anticarcinogenic, etc., properties. Despite the widespread utilization of various plant parts, the peel has been largely ignored in the industry. In this study, we explored the effects of different extraction parameters, such as temperature, time, and composition of the extraction solvent, and techniques such as ultrasound (US) and a pulsed electric field (PEF), either alone or in combination, and optimized these parameters using a response surface methodology (RSM) to enhance the extraction of bioactive compounds such as chlorogenic acid, total polyphenols, flavonoids, and ascorbic acid from waste quince peels. From our results, it was apparent that quince peels are a great source of many bioactive compounds with high antioxidant activity. More specifically, after principal component analysis (PCA) and partial least squares (PLS) analysis, quince peels c...
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The objective of this study was to investigate the feasibility of using Cloud Point Extraction (CPE) to isolate natural antioxidants (polyphenols) from apricot cannery waste (ACW). Four different food-grade surfactants (Genapol X-080, PEG... more
The objective of this study was to investigate the feasibility of using Cloud Point Extraction (CPE) to isolate natural antioxidants (polyphenols) from apricot cannery waste (ACW). Four different food-grade surfactants (Genapol X-080, PEG 8000, Tween 80, and Lecithin) were tested at varying concentrations to evaluate the effectiveness of the technique. It was observed that low concentrations of surfactants in one-step CPE resulted in less than 65% polyphenol recovery, which necessitated further extraction steps. However, high concentrations of surfactants were found to significantly improve polyphenol extraction from ACW for all surfactants tested. Among the four surfactants, PEG 8000 was found to be the most effective in most circumstances; specifically, adding only 2% of the surfactant per step in a two-step CPE was enough to effectively extract polyphenols with recovery rates better than 99%. When 10% w/v of PEG 8000 was used, recoveries greater than 92% were obtained. Since PEG ...
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Oxidative damages are responsible for many adverse health effects and food deterioration. The use of antioxidant substances is well renowned, and as such, much emphasis is placed on their use. Since synthetic antioxidants exhibit... more
Oxidative damages are responsible for many adverse health effects and food deterioration. The use of antioxidant substances is well renowned, and as such, much emphasis is placed on their use. Since synthetic antioxidants exhibit potential adverse effects, plant-derived antioxidants are a preferable solution. Despite the myriads of plants that exist and the fact that numerous studies have been carried out so far, there are many species that have not been examined so far. Many plants under research exist in Greece. Trying to fill this research gap, the total phenolics content and antioxidant activity of seventy methanolic extracts from parts of Greek plants were evaluated. The total phenolics content was measured by the Folin–Ciocalteau assay. Their antioxidant capacity was calculated by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging test, the Rancimat method based on conductometric measurements, and the thermoanalytical method DSC (Differential Scanning Calorimetry). The tested...
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Due to the worldwide consumption of coffee, many tons of spent coffee grounds (SCGs) are discarded each year, as a by-product of coffee preparation. Not only their disposal is costly, but also it may cause the release of compounds that... more
Due to the worldwide consumption of coffee, many tons of spent coffee grounds (SCGs) are discarded each year, as a by-product of coffee preparation. Not only their disposal is costly, but also it may cause the release of compounds that can endanger the environment. However, there are valuable chemical compounds that can be extracted from SCGs and used in the food industry. The aim of this study was to investigate the main parameters affecting the extraction of caffeine and polyphenols (i.e., chlorogenic acid, neochlorogenic acid, and caffeic acid) and to evaluate the antioxidant properties of the extracts. To this end, extraction solvent, temperature, time, and liquid-to-solid ratio were studied. A response surface methodology was used to optimize the extraction process. According to the results, the caffeine content of the optimum extract was found to be 6.14 mg/g in dry SCGs, the total polyphenol content was 19.85 mg gallic acid equivalents/g, while the ferric reducing antioxidant...
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Lately, additional attention is being placed on edible insects, since they constitute an excellent, cost-efficient source of proteins with a low ecological footprint. Tenebrio molitor was the first insect that was considered edible by... more
Lately, additional attention is being placed on edible insects, since they constitute an excellent, cost-efficient source of proteins with a low ecological footprint. Tenebrio molitor was the first insect that was considered edible by EFSA in 2021. This species can replace conventional protein sources and thus, it has the potential to be used in many different food products. In the present study, a food by-product that is commonly produced (i.e., albedo orange peel waste) was used as a feed additive for T. molitor larvae, in an effort to further improve the circular economy and enhance the nutritional value of the insects. To this end, bran, which is commonly used as feed for T. molitor larvae, was fortified with the albedo orange peel waste (up to 25% w/w). Larval performance, in terms of larval survival and growth, as well as the larval nutritional value, i.e., the content of protein, fat, carbohydrates, ash, carotenoids, vitamins A and C, and polyphenols, was evaluated. Based on ...
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The present study examines, compares, and documents the environmental impact of five extraction techniques through Life Cycle Assessment (LCA). The material used was Moringa oleifera freeze-dried leaves and the assessment was based on... more
The present study examines, compares, and documents the environmental impact of five extraction techniques through Life Cycle Assessment (LCA). The material used was Moringa oleifera freeze-dried leaves and the assessment was based on their polyphenol content Three out of the five examined techniques are referred to in the literature as “green” techniques, namely Pulsed Electric Field (PEF), Microwave-Assisted Extraction (MAE), and Ultrasound-Assisted Extraction (UAE). The other two examined were conventional extraction techniques and, specifically, boiling water and maceration; the latter served as a control in this study. The analysis utilized special software (SimaPro ecoinvent) for the “cradle to gate” LCA, along with a sensitivity analysis of the model examining the variation in the environmental impact based on the origin of the source of electricity (renewable sources such as photovoltaic arcs), aiming to highlight the optimal technology choice. This LCA study’s Functional Un...
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Tocopherols are natural bioactive compounds with several health benefits. This study evaluated the effect of different ratios of α- and δ- tocopherol homologs to protect sunflower oil (SO) and olive pomace oil (OPO) against oxidation. A... more
Tocopherols are natural bioactive compounds with several health benefits. This study evaluated the effect of different ratios of α- and δ- tocopherol homologs to protect sunflower oil (SO) and olive pomace oil (OPO) against oxidation. A synergistic effect was recorded when the two tocopherols were combined at a ratio of 7:1 (α-T/δ-T). The oil samples were exposed to accelerated oxidation conditions using a Rancimat (90 °C and airflow of 15 L/h for 24 h) and protection from tocopherols was compared with that from butylated hydroxytoluene (BHT). Assessment of oil stability was examined using well-known parameters such as peroxide value (PV), thiobarbituric acid reactive substances (TBARS), p-anisidine value (p-AV), conjugated dienes (CD) and trienes (CT), and total oxidation (Totox) value, which were all significantly reduced when tocopherols were added at a ratio of 7:1 α-T/δ-T. Primary oxidative compounds measured according to PV were only reduced in SO samples (6.11%). Off-flavor c...
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In this study, an alternative debittering technique for olives, invented and patented by Prof. Vassilis Dourtoglou, was employed. Olive fruits (Olea europaea cv. Megaritiki) were stored under CO2 atmosphere immediately after harvest for a... more
In this study, an alternative debittering technique for olives, invented and patented by Prof. Vassilis Dourtoglou, was employed. Olive fruits (Olea europaea cv. Megaritiki) were stored under CO2 atmosphere immediately after harvest for a period of 15 days. After the treatment, a sensory evaluation between the olives stored under CO2 and those stored under regular atmospheric conditions (control) was performed. Additionally, the CO2-treated olives were used for the cold press of olive oil production. The volatile profile of the olive oil produced was analyzed using headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC-MS). A total of thirty different volatile compounds were detected. The volatile characteristics of olive oil are attributed, among others, to aldehydes, alcohols, esters, hydrocarbons, alkanes, and terpenes. The volatile compounds’ analysis showed many differences between the two treatments. In order to compare the vola...
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Apricots are one of the most important fruits in the Mediterranean region for both their nutritional and economic value. They are widely cultivated and consumed fresh or dried or are used in the food industry for the production of jams,... more
Apricots are one of the most important fruits in the Mediterranean region for both their nutritional and economic value. They are widely cultivated and consumed fresh or dried or are used in the food industry for the production of jams, juices, etc. In any case, the seeds they contain constitute waste. The kernels are very rich in bioactive compounds such as polyphenols, a fact that makes them very appealing in cosmetology. However, the extraction of the bioactive compounds of apricot kernels is poorly examined. In this study, the preparation of polyphenol-rich extracts from apricot kernel biomass is discussed. To this end, a common extraction procedure with water as a solvent was employed. To enhance the extraction yield, the use of a deep eutectic solvent (DES) was examined. In addition, the use of pulsed electric field (PEF) either as a standalone extraction method or as a complementary step was also examined. According to the results, it was evident that when PEF was applied bef...
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The traditional extraction methods used to recover natural antioxidants from food industry wastes involve significant amounts of hazardous solvents. A viable alternative is the use of non-toxic surfactants to remove organic compounds from... more
The traditional extraction methods used to recover natural antioxidants from food industry wastes involve significant amounts of hazardous solvents. A viable alternative is the use of non-toxic surfactants to remove organic compounds from wastes at temperatures above the cloud point. Cloud point extraction has only recently begun to be used to recover high-value added compounds from food industry wastes. In the current work, a method for the isolation of high-value added components from liquid tomato wastewater using a cloud point extraction method was developed and optimized. Food-grade lecithin was examined for its potential to be used as a surfactant in the developed procedure. Moreover, parameters affecting the extraction (ionic strength, sample pH, temperature of extraction, and surfactant concentration) were examined and optimized. According to the results, the maximum recovery of carotenoids from the sample could be achieved with the developed procedure, by simply adjusting t...
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Waste orange peels (WOP) are a food processing residue rich in bioactive polyphenols. However, data on aqueous extraction processes for efficient polyphenol recovery are rather limited. The present study dealt with the optimization of WOP... more
Waste orange peels (WOP) are a food processing residue rich in bioactive polyphenols. However, data on aqueous extraction processes for efficient polyphenol recovery are rather limited. The present study dealt with the optimization of WOP polyphenols, using a batch stirred-tank mode and water as solvent. After a preliminary single-factor examination, the implementation of response surface methodology revealed that optimum extraction time and temperature were 60 min and 55 °C, respectively. Under these conditions, the extraction afforded a total polyphenol yield of 26.13 ± 0.78 mg gallic acid equivalents per g dry mass. The use of aqueous solutions of citric, tartaric and lactic acid showed that total polyphenol yield may be significantly increased with 1% tartaric acid or equally with 2.5% citric acid. However, the effect on individual polyphenolic constituents was rather negligible, as determined by high-performance liquid chromatography. The discrepancies observed in the antioxida...
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The interest in extracting bioactive compounds from food processing waste is growing unabated. Apricots are widely consumed worldwide, and many tons of waste are produced annually. Therefore, apricot pulp waste (APW) may serve as a rich... more
The interest in extracting bioactive compounds from food processing waste is growing unabated. Apricots are widely consumed worldwide, and many tons of waste are produced annually. Therefore, apricot pulp waste (APW) may serve as a rich source of bioactive compounds. In the present study, we investigated the extraction of antioxidant polyphenols and carotenoid pigments from APW. In both cases, a response surface methodology was employed, so as to optimize the extraction parameters. As regards polyphenols, it was found that optimum extraction yield (i.e., 28.6 mg gallic acid equivalents per g of dry weight) was achieved using a deep eutectic solvent (comprised of glycerol, citric acid, and L-proline at a molar ratio of 2:1:1), a liquid-to-solid ratio of 100 mL/g, and heating at 80 °C for 155 min. Similarly, optimum extraction of carotenoids (171.2 mg β-carotene equivalents per 100 g of dry weight) was achieved by extracting APW with an n-hexane: acetone: ethanol (2:1:1, v/v/v) mixtur...
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To date, many studies have been published, aiming to extract bioactive compounds from plants. Lately, research focuses on maximizing the extraction yield, using environmentally friendly techniques and solvents. In this study, the... more
To date, many studies have been published, aiming to extract bioactive compounds from plants. Lately, research focuses on maximizing the extraction yield, using environmentally friendly techniques and solvents. In this study, the extraction of polyphenolic compounds from Cistus creticus is discussed. Extraction of the compounds has been carried out with water and ethanol, employing the most common approach. To further enhance the extraction yield, the usage of four deep eutectic solvents (DESs) has also been examined. In an effort to further enhance the extraction yield, pulsed electric fields have also been employed. According to the results, it was evident that the use of DESs made of glycerol: choline chloride (2:1) increased the extraction yield by 75%, compared to extraction with water. Moreover, the use of pulsed electric fields enhanced the extraction yield of the common approach, by up to 70%. When pulsed electric fields and DESs were combined, the extraction yield increased...
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More and more research is being focused on the production of value-adding products from waste materials. Food waste is not only a major global issue, but also an excellent source of bioactive compounds. In this study, the parameters that... more
More and more research is being focused on the production of value-adding products from waste materials. Food waste is not only a major global issue, but also an excellent source of bioactive compounds. In this study, the parameters that affect the extraction of the bioactive compounds (polyphenols, ascorbic acid, hesperidin, carotenoids) from orange peels, and their antioxidant properties, were optimized, using a response surface methodology (RSM) (examining the extraction temperature, time, and composition of the extraction solvent). In addition, the effect of two more techniques was examined [ultrasound (US) and pulsed electric field (PEF)], either separately or combined, so as to determine whether they can enhance the extraction of the compounds. From our results, it was apparent that orange peels are an excellent source of many bioactive compounds since the extracts contained hesperidin (16.26 mg/g dw), total polyphenols (34.71 mg GAE/g dw), ascorbic acid (1228.93 mg/100 g dw) ...
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In this study, the use of pulsed electric field (PEF) for the extraction of polyphenols from mature Elaeagnus pungens ‘Limelight’ leaves is discussed. Optimization of the main parameters that affect the extraction process was carried out.... more
In this study, the use of pulsed electric field (PEF) for the extraction of polyphenols from mature Elaeagnus pungens ‘Limelight’ leaves is discussed. Optimization of the main parameters that affect the extraction process was carried out. More specifically, the composition of the solvent (ethanol, water, and mixtures of the two at a 25% v/v step gradient) and the main PEF-related parameters (i.e., pulse duration, pulse period, and electric field intensity) was optimized. The obtained extracts were examined for their polyphenol content with the Folin–Ciocalteu assay and individual polyphenols were also assessed with high-performance liquid chromatography. The extracts obtained with PEF were compared to the extract compared without PEF, in terms of total polyphenols. According to the results, the optimum extraction parameters were found to be a pulse duration of 10 μs, a pulse period of 1000 μs, and an electric field intensity of 0.85 kV cm−1 after 20 min of extraction. The optimum so...
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Humic acids (HAs) and fulvic acids (FAs) are naturally occurring compounds that influence the fate and transportation of various compounds in the soil. Although HAs and FAs have multiple uses, the reports about their sorbent potential for... more
Humic acids (HAs) and fulvic acids (FAs) are naturally occurring compounds that influence the fate and transportation of various compounds in the soil. Although HAs and FAs have multiple uses, the reports about their sorbent potential for environmental pollutants are scanty and sparse. In this study, HA and FA, isolated from lignite samples from two mines in Greece, were studied as sorbent materials for three active compounds of plant protection products, namely glyphosate (herbicide), cypermethrin (pyrethroid insecticide), and azoxystrobin (fungicide). According to the results, both HA and FA are promising sorbent materials for these active compounds, with HA achieving better sorption for cypermethrin and azoxystrobin, while FA was found to be more efficient for glyphosate. Moreover, their performance was not compromised by other components commonly found in commercially available herbicides/insecticides/fungicides. In addition, no significant leaching of the sorbed compounds was r...
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Wood-related procedures, such as lumberjacking and pruning, inevitably result in big piles of leaves, which are considered a major by-product. Extracting valuable compounds from natural by-products is an ongoing trend. In this work, the... more
Wood-related procedures, such as lumberjacking and pruning, inevitably result in big piles of leaves, which are considered a major by-product. Extracting valuable compounds from natural by-products is an ongoing trend. In this work, the use of Pulsed Electric Field (PEF) was evaluated as a pretreatment step, prior to the ultrasound-assisted extraction of phenolic compounds from Aesculus carnea leaves. In addition, various solvent systems were examined, as well as the time of pretreatment with PEF. According to the results, up to 33% more phenolic compounds can be extracted, under optimum conditions (30% ethanol in water as solvent and PEF pretreatment for 30 min, compared to the same solvent, without PEF). Moreover, PEF treatment time was not (i.e., 30 and 60 min) and no differences were recorded, suggesting that a lower treatment time can yield the same extraction of phenolic compounds. As such, the use of PEF is highly recommended in combination with ultrasound extraction, to maxi...
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Tzatziki is a deli salad widely consumed in the Eastern Mediterranean and Balkan countries, and it is acknowledged for its health benefits. So far, it is proved to exhibit extreme resistance to microbial spoilage by (pathogenic)... more
Tzatziki is a deli salad widely consumed in the Eastern Mediterranean and Balkan countries, and it is acknowledged for its health benefits. So far, it is proved to exhibit extreme resistance to microbial spoilage by (pathogenic) microorganisms and microbial self-stabilization, but no research was carried out regarding its oxidative stability despite the fact that it contains a large amount of lipids. In this study, the factor that affects the oxidative stability of tzatziki was exploited. Different samples of tzatziki salad were prepared and stored for 16 or 27 days, depending on the conducted experiment. They varied in the type of yogurt (set yogurt or traditional Greek-style yogurt), the type of oil (olive oil or soybean oil), and the addition or not of preservatives, garlic, and cucumber. Samples were analyzed in terms of oxidative stability (by the Rancimat method), colony-forming units, and tocopherol content throughout the storage period. Among the examined parameters, no corr...
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The valorization of red grape pomace is significant as grape is one of the most cultivated fruits worldwide and generated by-product quantities are enormous. For this purpose, numerous encapsulation techniques have been developed.... more
The valorization of red grape pomace is significant as grape is one of the most cultivated fruits worldwide and generated by-product quantities are enormous. For this purpose, numerous encapsulation techniques have been developed. However, the studies on microemulsions composed with deep eutectic solvent extracts are very limited. In this study, red grape pomace extract (RGPE) was first prepared by deep eutectic solvent extraction and characterized by HPLC analysis. Rutin, quercetin, catechin and caftaric acid were identified as the main non-pigment phenolic compounds. The RGPE was further encapsulated in microemulsions (MEs) following a low-energy approach using a mixture of low molecular weight surfactants, and the pseudo-ternary phase diagram was constructed. The physical and antioxidant stability of MEs containing 3–15 wt% RGPE was investigated for a period of 30 days. MEs were stable at an ambient temperature of 25 or 37 °C. The radical scavenging activity of encapsulated RGPE ...
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The present work aimed to identify, for the first time, the traditional manufacturing process and the physicochemical properties of the Kariki cheese originated from the Island of Tinos, Greece. Various physicochemical parameters... more
The present work aimed to identify, for the first time, the traditional manufacturing process and the physicochemical properties of the Kariki cheese originated from the Island of Tinos, Greece. Various physicochemical parameters (moisture, protein, fat and NaCl content, pH, acidity, fatty acid profile, and pigments) were determined on cheese samples (matured for three months in a dried calabash). The samples were obtained from the only dairy company in Tinos Island that produces this type of cheese using traditional methods. The results showed that Kariki is a yellow cheese, hard on the outside but soft on the inside, with low moisture and acidity content, and high proportion of fat comparable to similar types of cheese products. These characteristics are probably derived from the maturation process in the calabash. Kariki also showed much higher content in saturated fatty acids and lower content in monounsaturated fatty acids and polyunsaturated fatty acids than the other cheeses ...
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An eggplant-based salad, called aubergine salad (AS), is a traditional appetizer and as such, is quite popular in the Mediterranean area. It is widely produced either on a home scale or on an industrial scale and widely consumed. However,... more
An eggplant-based salad, called aubergine salad (AS), is a traditional appetizer and as such, is quite popular in the Mediterranean area. It is widely produced either on a home scale or on an industrial scale and widely consumed. However, there are cases where preservatives (such as sodium benzoate and potassium sorbate) are added in order to extend the shelf life of the product. In the present study, the stability of this delicatessen against oxidation and microbial spoilage was evaluated, with or without preservatives. The physicochemical properties of the salad were evaluated, along with the tocopherol content, resistance to oxidation, and microbial count. According to the results, it is evident that the induction period of AS is 16% (in the case that preservatives were used) and 26% (in the case without preservatives) increased, compared to a control sample (plain soybean oil). This can be attributed to the increased content in tocopherols, and more specifically to α-tocopherol....
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On behalf of the open access journal Sustainability (ISSN 2071-1050, IF 3.251), I am pleased to announce a new Special Issue entitled "Exploring Natural Product Extracts, Food Technology and Functional Foods on the Sustainable... more
On behalf of the open access journal Sustainability (ISSN 2071-1050, IF 3.251), I am pleased to announce a new Special Issue entitled "Exploring Natural Product Extracts, Food Technology and Functional Foods on the Sustainable Health Perspective". Prof. Dr. Stavros I. Lalas (Department of Food Science & Nutrition, University of Thessaly, Greece) and I are serving as Guest Editors for this issue. The submission deadline is 30 September 2022 and papers may be submitted immediately or at any point until 30 September 2022, as papers will be published on an ongoing basis. For more information on this Special Issue and submission guidelines, please visit the following page: https://www.mdpi.com/journal/sustainability/special_issues/natural_product_extracts
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Increasing the yield of extraction of bioactive compounds from plants is of high importance. Grape stems are widely discarded during the wine-making process, despite their high content in many valuable compounds. The aim of this work was... more
Increasing the yield of extraction of bioactive compounds from plants is of high importance. Grape stems are widely discarded during the wine-making process, despite their high content in many valuable compounds. The aim of this work was to examine whether the use of pulsed electric field (PEF) treatment of the stems could increase the yield of polyphenol and volatile compounds in the extracts. For this reason, a relatively low-energy consuming PEF process was employed (low-electric field strength, 1 kV/cm) for a short time (30 min) at the grape stems. In addition, the effect of different solvents during this pretreatment step was examined. With the use of Folin–Ciocalteu assay, the extracts were compared with the respective control samples (not pretreated with PEF). Moreover, extracts were prepared to assess whether changes occur to the volatile profile of the extracts. The results were conclusive that not only PEF can increase the yield of polyphenols (up to 35% increase recorded)...
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Polyphenols are an important class of compounds, due to their excellent antioxidant properties. Lately, much effort has been placed into developing new extraction techniques and optimizing them, so that polyphenols can be retrieved more... more
Polyphenols are an important class of compounds, due to their excellent antioxidant properties. Lately, much effort has been placed into developing new extraction techniques and optimizing them, so that polyphenols can be retrieved more efficiently from the plant materials. One of the most recent advances in extraction techniques is pulsed electric field extraction (PEF). This new technique is environmentally friendly and has the potential to maximize the recovery of compounds from plant tissues. Although the efficiency of PEF depends, among others, on the nature of the solvent used, up to date, there are no reports on the optimization of the PEF extraction of polyphenols, using hydroethanolic solutions of varying content in ethanol. In this study, three hydroethanolic solutions, water, and ethanol were used for the PEF-based extraction of total polyphenols from Sideritis raiseri. Results were conclusive that the 1:1 mixture of ethanol and water can increase by up to 146% the yield ...
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Research Interests:
Industrial activity has contributed to potentially toxic metal pollution in various ecosystems throughout the world. In this study, the ability of humic and fulvic acids (isolated from lignite with a simple, rapid, and inexpensive method)... more
Industrial activity has contributed to potentially toxic metal pollution in various ecosystems throughout the world. In this study, the ability of humic and fulvic acids (isolated from lignite with a simple, rapid, and inexpensive method) to reduce toxic metals’ concentration of contaminated water is examined. More specifically, the effect of these compounds is tested on water contaminated (at various concentrations) with Cd, Cr, Cu, Ni, and Pb. The determination is performed by inductively coupled plasma-optical emission spectrometry. The maximum binding capacity is presented by fulvic acids in the following order Cr>Pb>Ni>Cu>Cd (97.8, 96.5, 95.4, 95.1, and 83.3%, respectively), while for humic acids it is Pb>Ni>Cr>Cu>Cd (81.3, 70.7, 68.6, 67.0, and 66.8%, respectively). The binding activity is also tested on water contaminated with two metals simultaneously. In these cases, the existence of two metals in water changes the reduction ability of humic and fulvic acids (positively or negatively).
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Fruits and vegetables are major sources of antioxidants. These are substances that remove free-radical intermediates by being oxidized themselves and delay or inhibit other oxidation reactions. Recent studies make clear that an... more
Fruits and vegetables are major sources of antioxidants. These are substances that remove free-radical intermediates by being oxidized themselves and delay or inhibit other oxidation reactions. Recent studies make clear that an antioxidant-rich diet acts as a health protecting factor. The antioxidant that was used in this study was 2,5-dimethyl-4-hydroxy-3(2H)-furanone (HDMF). Two frying methods (with and without antioxidant) were used: the first one with no replenishment of oil and the second one with frequent replenishment of oil. As it was proved by the induction period, using the Rancimat method, HDMF increased the resistance against oxidation not only of the frying oils but also of the oil that was absorbed by the chips. The results were in line with those of croissants when they were baked with or without HDMF. Taste panel test confirmed those results as panelists showed a clear preference for those products that were protected against oxidation by HDMF.
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Polyphenol-containing extracts from olive (Olea europaea) leaves (OLL) were obtained using a glycerol-based deep eutectic solvent (DES) and a combination of DES with methyl β-cyclodextrin (m-β-CD). The extracts were stored at various... more
Polyphenol-containing extracts from olive (Olea europaea) leaves (OLL) were obtained using a glycerol-based deep eutectic solvent (DES) and a combination of DES with methyl β-cyclodextrin (m-β-CD). The extracts were stored at various temperatures for a period of 20 days and the reducing power (PR) was monitored to trace changes in the antioxidant potency of the extracts. Over the examination period and at every temperature tested, PR displayed a constant decline, which followed pseudo zero-order kinetics. The determination of the decay constants indicated that the presence of m-β-CD acted protectively, slowing down the progression of the PR decline. Examination of the polyphenolic profiles using liquid chromatography–diode array–mass spectrometry showed that after storage for 20 days at 50 °C, some major polyphenols occurring in OLL suffered extended degradation. The formation of a yellow pigment in the extracts stored in DES but not in aqueous ethanol suggested that polyphenol oxidation did occur during storage. It was concluded that the oxidation of some OLL components was rather responsible for the PR decline observed.
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ABSTRACT Moringa oleifera tree was cultivated for the first time in the mild temperate climate of Greece. Moringa oleifera leaf protein and amino acid content, total phenols and flavonols, lipids, fatty acids, ash and minerals, dietary... more
ABSTRACT Moringa oleifera tree was cultivated for the first time in the mild temperate climate of Greece. Moringa oleifera leaf protein and amino acid content, total phenols and flavonols, lipids, fatty acids, ash and minerals, dietary fiber and carbohydrates, carotenoids, and vitamins C and E were determined. Leaves were high in protein content (26.3%), including all the essential amino acids. They also contained 4512.2 mg GAE.100 g–1 DM of total phenols and were rich in flavonols (myricetin, quercetin, and kaempherol at 649.8, 77.2, and 37.2 mg.100 g–1 DM, respectively). Their lipid content was 5.6% (saturated fatty acids 28.33%, mono-unsaturated fatty acids 8.54%, and polyunsaturated fatty acids 61.27%). Leaves were rich in Ca, K, Mg, and P (1712.6, 1002.9, 460.4, and 194.2mg .100 g–1 DM, respectively), while other minerals (Mn, Na, Fe, Zn, Cu, and Se) were found in lower concentrations. The dietary fiber content of dried leaves was 34.1%, while the nonstructural carbohydrate content was 22.0%. They also had high carotenoid content (lutein, zeaxanthin, and β-carotene at 10.03, 1.52, and 2.02 mg.100 g–1 DM, respectively). The vitamins C and E concentrations were 203.1 and 104 mg.100 g–1 DM, respectively. The herbal tea was high in total phenols (736.9 mg GAE.L–1) and flavonols (myricetin, quercetin, and kaempherol at 203.7, 17.4, and 10.6 mg.L–1, respectively), and had antioxidant activity (protection factor: 4.2).
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Research Interests:
A novel deep eutectic solvent (DES) with optimised composition was used to evaluate the effect of methyl β-cyclodextrin (CD) on the efficiency of polyphenol extraction from Olea europaea leaves (OLLs). The process developed was based on a... more
A novel deep eutectic solvent (DES) with optimised composition was used to evaluate the effect of methyl β-cyclodextrin (CD) on the efficiency of polyphenol extraction from Olea europaea leaves (OLLs). The process developed was based on a 23 full-factorial design and response surface methodology to assess the simultaneous effect of CD concentration (CCD), liquid-to-solid ratio (RL/S) and temperature (T). Under optimised conditions (CCD = 9%, RL/S = 40 mL g−1, T = 51 °C), the yield in total polyphenols (YTP) was 116.65 ± 3.60 mg gallic acid equivalents per g dry weight. This value was significantly higher than that determined for the extraction performed with 60% aqueous ethanol. The extraction kinetics also showed that the extraction rate was slowed down in the presence of CD, yet the higher extraction capacity of the DES/CD medium was confirmed. Characterisation of the extracts obtained with DES/CD and DES by means of liquid chromatography-mass spectrometry demonstrated that there was no selective extraction of any particular polyphenol, suggesting that CD acted merely as an extraction booster.
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Research Interests: Organic Chemistry, Biology, Medicine, Candida, Antimicrobial activity, and 15 moreBacteria, Enterobacteriaceae, Pseudomonas aeruginosa, Moringa, Molecules, Seeds, Staphylococcus, Antifungal Agents, Microbial Sensitivity Tests, Pseudomonas Aeruginosa, Drug Stability, Seed oil, Plant Oils, Moringa peregrina, and resistance to oxidation
Fοllow up with our previous study on the extraction of saffron processing waste polyphenols using deep eutectic solvents, the objective of this examination was a comparative evaluation of pressurized liquid extraction (PLE), stirred-tank... more
Fοllow up with our previous study on the extraction of saffron processing waste polyphenols using deep eutectic solvents, the objective of this examination was a comparative evaluation of pressurized liquid extraction (PLE), stirred-tank extraction (STE) and stirred-tank extraction with ultrasonication pretreatment (STE/UP) with respect to the recovery of pigments and antioxidant polyphenols from saffron processing waste. Aqueous solutions of citric and lactic acids at two different concentrations were used as green solvents. The extracts obtained under the specified conditions were analyzed for total pigment and total polyphenol yields as well as for their ferric-reducing power and antiradical activity. Furthermore, each produced extract was analyzed with liquid chromatography–mass spectrometry to profile its analytical polyphenolic composition. In all cases, PLE provided inferior results compared to the two other techniques, producing extracts with lower polyphenolic concentration...
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The current study evaluates the Pulsed Electric Field (PEF) technique for the extraction of polyphenols from the plants Rosa canina, Calendulaofficinalis and Castanea sativa. These plants are traditionally used both for the preparation of... more
The current study evaluates the Pulsed Electric Field (PEF) technique for the extraction of polyphenols from the plants Rosa canina, Calendulaofficinalis and Castanea sativa. These plants are traditionally used both for the preparation of therapeutic decoctions and the aromatization of beverages (alcoholic or not). Pulses of 10 μs duration were used to apply electric field intensities ranging from 1.2 to 2.0 kV cm−1. The period of the phenomenon was set to 1 ms, with a total extraction time of 20 min. The total polyphenol content as well as the identified polyphenolic compounds of the extracts were determined for monitoring and evaluation. To estimate the PEF effect, control extracts were prepared using the same process as PEF extracts but without the application of electric field. For all the three plant materials studied, the PEF technique appeared to be successful in increasing polyphenols extraction. The application of a moderate to high electric field, up to 1.4 kV cm−1, result...
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Olive leaves (OLL) are reported as a source of valuable antioxidants and as an agricultural by-product/waste. Thus, a twofold objective with multi-level cost and environmental benefits arises for a “green” standalone extraction... more
Olive leaves (OLL) are reported as a source of valuable antioxidants and as an agricultural by-product/waste. Thus, a twofold objective with multi-level cost and environmental benefits arises for a “green” standalone extraction technology. This study evaluates the OLL waste valorization through maximizing OLL extracts polyphenol concentration utilizing an emerging “green” non-thermal technology, Pulsed Electric Field (PEF). It also provides further insight into the PEF assistance span for static solid-liquid extraction of OLL by choosing and fine-tuning important PEF parameters such as the extraction chamber geometry, electric field strength, pulse duration, pulse period (and frequency), and extraction duration. The produced extracts were evaluated via comparison amongst them and against extracts obtained without the application of PEF. The Folin-Ciocalteu method, high-performance liquid chromatography, and differential scanning calorimetry were used to determine the extraction effi...
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Research Interests:
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Olive leaves (OLL), an agricultural waste by-product, are considered a significant bioresource of polyphenols, known as bioactive compounds. This study evaluates the pulsed electric field (PEF) technique for the extraction of polyphenols... more
Olive leaves (OLL), an agricultural waste by-product, are considered a significant bioresource of polyphenols, known as bioactive compounds. This study evaluates the pulsed electric field (PEF) technique for the extraction of polyphenols from OLL. The study parameters included a series of “green” solvents (ethanol, water as well as mixtures of them at a 25% step gradient) and different input values for the pulse duration of PEF. The phytochemical extraction degree was evaluated using total phenol concentration (Folin–Ciocalteu method) and high-performance liquid chromatography (HPLC) analyses, while the antioxidant activity was assessed using differential scanning calorimetry (DSC). The results obtained from the PEF extracts were compared with those of the extracts produced without the PEF application. The highest PEF effect was observed for aqueous ethanol, 25% v/v, using a pulse duration of 10 μs. The increase in the total polyphenols reached 31.85%, while the increase in the spec...
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The present study aimed to evaluate the pulsed electric field (PEF)-assisted extraction of phytochemicals from Salvia officinalis L. leaves. The study parameters included a PEF pulse duration of 10 or 100 μs for 30 min, using different... more
The present study aimed to evaluate the pulsed electric field (PEF)-assisted extraction of phytochemicals from Salvia officinalis L. leaves. The study parameters included a PEF pulse duration of 10 or 100 μs for 30 min, using different “green” extraction solvents: pure ethanol, pure water, and their mixtures at 25, 50, and 75% v/v concentrations. The resulting extracts were evaluated against reference extracts obtained without PEF. For estimation of the extraction efficiency, the content in total polyphenols, individual polyphenols, and volatile compounds, as well as the resistance to oxidation, were determined. The optimal PEF contribution on the total and individual polyphenols, rosmarinic acid, extractability (up to 73.2% and 403.1% increase, respectively) was obtained by 25% v/v aqueous ethanol solvent using a pulse duration of 100 μs. PEF was proven to also affect the final concentration and composition of volatile compounds of the extracts obtained.
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Research Interests:
A number of biological activities have been attributed to polyphenolic substances occurring in the leaves of the olive tree (O. europaea), an olive oil industry waste material, and for this reason several extraction processes have been... more
A number of biological activities have been attributed to polyphenolic substances occurring in the leaves of the olive tree (O. europaea), an olive oil industry waste material, and for this reason several extraction processes have been developed for the efficient recovery of these phytochemicals. The study presented herein describes for the first time the use of an eco-friendly deep eutectic solvent (DES) as a highly effective solvent for the extraction of polyphenols from olive tree leaves. Initially, a central composite design was implemented to optimise solvent composition and liquid-to-solid ratio and then a kinetic assay was performed to investigate diffusivity (De) and temperature effects. The maximum total polyphenol yield was 106.25 mg gallic acid equivalents per g dry weight, achieved at 70 °C. This value was by 18% higher than that achieved with 60% aqueous methanol. Furthermore, the DES extract exhibited significantly higher antiradical activity and reducing power. Temperature increase up to 70 °C was shown to boost De and the activation energy determined for the process was 29.55 kJ mol-1. Characterisation of the extract by means of liquid chromatography-diode array-mass spectrometry showed oleuropein and certain flavone glycosides to be the major polyphenolic constituents.
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A number of biological activities have been attributed to polyphenolic substances occurring in the leaves of the olive tree (O. europaea), an olive oil industry waste material, and for this reason several extraction processes have been... more
A number of biological activities have been attributed to polyphenolic substances occurring in the leaves of the olive tree (O. europaea), an olive oil industry waste material, and for this reason several extraction processes have been developed for the efficient recovery of these phytochemicals. The study presented herein describes for the first time the use of an eco-friendly deep eutectic solvent (DES) as a highly effective solvent for the extraction of polyphenols from olive tree leaves. Initially, a central composite design was implemented to optimise solvent composition and liquid-to-solid ratio and then a kinetic assay was performed to investigate diffusivity (De) and temperature effects. The maximum total polyphenol yield was 106.25 mg gallic acid equivalents per g dry weight, achieved at 70 °C. This value was by 18% higher than that achieved with 60% aqueous methanol. Furthermore, the DES extract exhibited significantly higher antiradical activity and reducing power. Temperature increase up to 70 °C was shown to boost De and the activation energy determined for the process was 29.55 kJ mol-1. Characterisation of the extract by means of liquid chromatography-diode array-mass spectrometry showed oleuropein and certain flavone glycosides to be the major polyphenolic constituents.
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On behalf of the open access journal Sustainability (ISSN 2071-1050, IF 3.251), I am pleased to announce a new Special Issue entitled "Exploring Natural Product Extracts, Food Technology and Functional Foods on the Sustainable Health... more
On behalf of the open access journal Sustainability (ISSN 2071-1050, IF 3.251), I am pleased to announce a new Special Issue entitled "Exploring Natural Product Extracts, Food Technology and Functional Foods on the Sustainable Health Perspective". Prof. Dr. Stavros I. Lalas (Department of Food Science & Nutrition, University of Thessaly, Greece) and I are serving as Guest Editors for this issue.
The submission deadline is 30 September 2022 and papers may be submitted immediately or at any point until 30 September 2022, as papers will be published on an ongoing basis. For more information on this Special Issue and submission guidelines, please visit the following page:
https://www.mdpi.com/journal/sustainability/special_issues/natural_product_extracts
The submission deadline is 30 September 2022 and papers may be submitted immediately or at any point until 30 September 2022, as papers will be published on an ongoing basis. For more information on this Special Issue and submission guidelines, please visit the following page:
https://www.mdpi.com/journal/sustainability/special_issues/natural_product_extracts