George Ntourtoglou

In recent years, consumers have been turning to natural products. Following this trend, the European Union has now recognized natural rosemary extract as a natural preservative (E392) in various foods. Considering this, the current study aimed to extract antioxidant compounds from rosemary leaves employing green techniques. More specifically, non-toxic solvents (water-ethanol) and green extraction techniques, such as Atmospheric Room Temperature Plasma (ARTP) for pretreatment of rosemary leaves and subsequently Pressurized Liquid Extraction (PLE) for the recovery of the antioxidant compounds, were used. Response Surface Methodology (RSM) was applied to optimize ARTP operating parameters, and the optimized ARTP + PLE extract was evaluated using spectrophotometric assays and HPLC-DAD. Under optimal conditions, the extract yielded a total polyphenol content (TPC) of ~72 mg gallic acid equivalents per g and an ascorbic-acid-associated reducing capacity (AACRC) of ~19 mg/g, while the extract exhibited relatively high antioxidant capacity as assessed by the FRAP (ferric-reducing antioxidant power) assay (~924 μmol ascorbic acid equivalents per g) and DPPH radical scavenging activity (~467 μmol ascorbic acid equivalents per g). Compared with the untreated PLE control, the ARTP-PLE extract showed increases of 3.1% in TPC, 2.03% in FRAP, 5.61% in DPPH and 25.86% in AACRC. Four commercial rosemary antioxidant preparations (E392) of different formulation types were also analyzed to contextualize the composition of the optimized extract. The commercial products, analyzed in their native form, displayed compositional patterns characteristic of oil-based formulations, whereas the ARTP + PLE extract reflected the profile of hydroethanolic rosemary extracts. These differences arise from extraction conditions and solvent systems. The comparison is descriptive and does not imply quality ranking or stability differences. Overall, the study provides insight into how plasma pretreatment can influence the composition of rosemary extracts within hydroethanolic systems.

Laurel (Laurus nobilis L.) is a characteristic species of the Mediterranean flora, valued for its medicinal, aromatic, and culinary uses. Many of these properties are attributed to its volatile constituents. In this study, the effect of Atmospheric Room Temperature Plasma (ARTP) pretreatment on laurel powder was evaluated, with emphasis on volatile recovery and food application. Volatile extraction was optimized using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS), investigating key parameters such as salt concentration, extraction temperature, equilibration time, extraction time, and fiber type. Subsequently, critical ARTP variables (nitrogen flow, treatment duration, treatment distance, substrate thickness, and plasma power) were optimized. Response Surface Methodology was applied in both optimization processes. The results demonstrated that fiber type was the most influential factor for volatile recovery, with extraction temperature also exerting a significant effect. A more nuanced pattern emerged during ARTP pretreatment, where moderate plasma intensities enhanced the recovery of several key volatiles. This trend was not uniform across compounds, indicating that plasma-induced microstructural changes interact with the physicochemical properties of individual analytes. To demonstrate food relevance, a ready-to-use broth model prepared with laurel powder confirmed improved headspace transfer of characteristic volatiles following ARTP treatment. Taken together, these findings suggest that ARTP can serve as a practical, non-thermal pretreatment for improving volatile release, supporting its potential use in the food, pharmaceutical, and cosmetic industries.

Over the past few years, naturally sourced bioactive molecules have drawn increased attention for their antioxidant capacity and wide-ranging health effects. At the same time, interest in eco-friendly extraction approaches has risen sharply. Atmospheric Room Temperature Plasma (ARTP), a novel non-thermal pretreatment method, has emerged as a promising green technology due to its minimal environmental impact, cost-effectiveness, and superior extraction efficiency compared to conventional methods. In this study, ARTP pretreatment—optimized across variables such as treatment distance, substrate thickness, power, nitrogen flow, and duration—was combined with ultrasonic-assisted extraction to enhance the recovery of bioactive compounds from Moringa oleifera leaves. Both techniques were optimized using Response Surface Methodology (RSM). Under optimal conditions, the extract yielded a total polyphenol content of approximately 40 mg gallic acid equivalents per gram of dry weight. Antioxidant activity, assessed via ferric-reducing antioxidant power (FRAP) and DPPH radical scavenging assays, reached ~280 and ~113 μmol ascorbic acid equivalents per gram dry weight, respectively, and the ascorbic acid content was ~5.3 mg/g. These findings highlight the potential of ARTP as an effective and sustainable pretreatment method for producing high-value phytochemical extracts, with promising applications in the food, pharmaceutical, and cosmetic industries.

This study explores the chemical and sensory differentiation of Greek white wines produced from five indigenous grape varieties—Savvatiano, Vidiano, Moschofilero, Assyrtiko, and Malagouzia—across diverse terroirs in Greece. A targeted analytical approach was employed to quantify 12 key volatile aroma compounds derived primarily from amino acid metabolism and lipid degradation, using GC-MS and GC-FID. The selected volatiles, including isoamyl alcohol, phenylethyl alcohol, tyrosol, and hexanoic acid ethyl ester, were chosen for their sensory relevance and their biosynthetic linkage to nitrogenous precursors. Principal Component Analysis (PCA) of wines from the 2019 and 2020 vintages revealed clear varietal clustering, under standardized winemaking conditions. Malagouzia wines were characterized by rich and diverse volatile profiles, particularly long-chain fatty acids and esters, while Vidiano exhibited a consistently restrained aromatic expression. Sensory analysis using sorting and ultra-flash profiling confirmed the chemical clustering, with Moschofilero, Vidiano and Malagouzia wines forming distinct sensory groups. The findings demonstrate that key amino acid-derived volatiles can serve as biochemical markers of varietal typicity and support the use of volatile profiling as a tool for terroir-driven wine classification and quality assessment in Greek white wines.

The valorization of wine lees, a major by-product of winemaking, is gaining attention as part of broader initiatives to promote circular economy and sustainable resource use in the agri-food sector. This study assessed ultrasound (US), pulsed electric fields (PEF), and their combination (PEF + US) as non-thermal technologies for promoting yeast autolysis and recovering intracellular proteins from wine lees. All treatments effectively reduced yeast viability, with populations decreasing from ~7.0 to ~4.7 log CFU/mL within 5 min. PEF alone achieved this microbial inactivation with a low energy input of 25–100 kJ/kg. In contrast, US yielded the highest protein release (~5700 μg/mL after 20 min), although it required a substantial energy input (~19,800 kJ/kg). The combined PEF + US method provided comparable protein yields (~5400 μg/mL) while reducing energy consumption by more than 50%. These results demonstrate that PEF is the optimal method for low-energy microbial inactivation, whereas US and PEF + US are more effective for protein recovery. The synergy of the combined approach offers a balanced and scalable solution for sustainable bioprocessing, reinforcing the potential of hybrid technologies in the green extraction of wine industry by-products and their integration into circular bioeconomy strategies.

Rose hips are rich in polyphenols, making them a promising ingredient for the development of functional fruit-based beverages. This study aimed to evaluate the effect of Pulsed Electric Field (PEF) extraction treatment on rose hip (RH) pulp to enhance the extraction of polyphenols, carotenoids, and volatile compounds. Additionally, this study examined the impact of adding rose hip berries during different stages of carbohydrate fermentation on the resulting phenolic and aroma profiles. A control wort and four experimental formulations were prepared. Rose hip pulp—treated or untreated with PEF—was added either during fermentation or beforehand, and the volatiles produced were analyzed using GC-MS (in triplicate). Fermentation was carried out over 10 days at 20 °C using Saccharomyces cerevisiae and Torulaspora delbrueckii. At a 10:1 ratio, all beverage samples were subjected to physicochemical testing and HPLC analysis for polyphenols, organic acids, and carotenoids, as well as GC-MS analysis for aroma compounds. The results demonstrated that the use of PEF-treated rose hips significantly improved phenolic compound extraction. Moreover, the PEF treatment enhanced the aroma profile of the beverage, contributing to a more complex and appealing sensory experience. This research highlights the rich polyphenol content of rose hips and the potential of PEF-treated fruit as a natural ingredient to improve both the functional and sensory qualities of fruit-based beverages. Their application opens new possibilities for the development of innovative, health-promoting drinks in the brewing industry.

Grape marc spirits, such as the Greek tsipouro/tsikoudia, reflect the cultural heritage of winemaking traditions worldwide. This study explored the application of Attenuated Total Reflectance–Fourier Transform Infrared (ATR-FTIR) spectroscopy combined with chemometrics for its potential as a fast classification methodology for spirit characterization. ATR-FTIR spectra from thirty-nine products revealed distinctive bands corresponding to various chemical constituents, such as alcohols, organic acids, water, carbohydrates, and phenols. Principal Component Analysis (PCA) was performed on all acquired ATR-FTIR data and 78.50% of the total variance in the data was explained. Also, partial least squares–discriminant analysis (PLS-DA), used for the classification of products based on their major geographic origin, gave a correct classification of 89.5% for the north and 83.3% for the south of Greece. Classification of the type of distillations used was with 74.36% accuracy. Significant markers were identified through analysis, such as those associated with the O-H bending vibrations of phenols or alcohols, contributing to the discrimination of grape marc spirits from Crete when compared with the other four main geographical origin designations. By combining ATR-FTIR spectroscopy with chemometrics, this research gave insights into the origins and compositional variations of the spirits, providing an opportunity for a quality control assessment tool.

Six wild-type non-Saccharomyces strains, belonging to the species Zygosaccharomyces bailii, Priceomyces carsonii, Trigonopsis californica, and Pichia manshurica, were evaluated for white wine production using Assyrtiko grapes from Santorini in Greece. Fermentation kinetics, in terms of glucose and fructose consumption and sensory analysis, was first employed to test the enological potential of the yeast strains. Based on their performance, two strains of Z. bailii (Zb-A19Y5 and Zb-K29Y2) and one strain of T. californica (Tc-A9Y1) selected for further analysis. The selected strains were tested in larger fermentation volumes for sugar consumption, while the produced wines were assessed for classical enological parameters, volatile compounds (GC/MS), and sensory analysis. Tc-A9Y1 could lead to dry wine (1 g/L of residual sugars) with 1.6 vol (12%) less alcohol than the other experimental wines. The wines that were fermented with the strain Zb-K29Y2 exhibited very high concentrations of isoamyl alcohol (604.33 ± 76.8 mg/L), but at the same time, they were characterized by low fruity notes. None of the produced wines presented any off-flavor aromas. Exploiting non-Saccharomyces strains with great fermentation capacity, which are able to produce high-quality wines and adapted to global warming conditions, is a new challenge for the wine industry.

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 maximize the yield of phenolic compounds extracted from the leaves of Aesculus carnea.

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), but also that the solvent used during PEF pretreatment can affect the process. Furthermore, a 234% increase in the total content of volatile compounds was recorded, when PEF was used as a pretreatment step. Therefore, the combination of PEF and ultrasound-assisted extraction is highly promising to obtain grape stem extracts with a higher content of bioactive compounds.