Margarita Terziyska

Prof. Dr. Margarita Terziyska

Mathematics, Physics and Information Technologies, University of Food Technologies, Plovdiv, Bulgaria
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Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

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

Representative Publications

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23 February 2021 in Molecules
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Dasha MihaylovaDasha Mihaylova
Dasha Mihaylova
IDIvelina Desseva
Ivelina Desseva
MSMagdalena Stoyanova
Magdalena Stoyanova
Nadezhda PetkovaNadezhda Petkova
Nadezhda Petkova
Margarita TerziyskaMargarita Terziyska
Margarita Terziyska
Anna LanteAnna Lante
Anna Lante
Fruits contain a number of useful substances including antioxidants. Their bio-accessibility after passing through the digestive tract is of primary importance when considering their benefits. In this respect, we investigated the effect of in vitro digestion on the phytochemicals of eight fruit juices. Freshly prepared juices from pomegranate, orange and grapefruit were used as well as commercially available juices from cherry, black grapes and aloe vera, blackberry and chokeberry, and two types of chokeberry and raspberries. Spectrophotometric and HPLC methods were used in order to analyse the sugar content, the total phenolic (TPC) and flavonoid contents (TFC), anthocyanins, phenolic acids and antioxidant activity. Principle component analysis was used to explain the differentiation among the types of fruit juice. Sugar recovery variation was between 4–41%. The bio-accessibility of TPC ranged from 13.52–26.49% and of flavonoids between 24.25–67.00%. The pomegranate juice and the juice of black grapes and aloe vera kept 58.12 and 50.36% of their initial anthocyanins content, while for the other samples less than 1.10% was established. As a result, a maximum of 30% remaining antioxidant activity was measured for some of the samples, but for most this was less than 10%. In conclusion, fruit juices are a rich source of biologically active substances, but a more detailed analysis of food transformation during digestion is needed.

23 October 2022 in Membranes
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Mariya DUSHKOVAMariya DUSHKOVA
Mariya DUSHKOVA
KMKiril Mihalev
Kiril Mihalev
ADAngel Dinchev
Angel Dinchev
KVKiril Vasilev
Kiril Vasilev
DGDiyan Georgiev
Diyan Georgiev
Margarita TerziyskaMargarita Terziyska
Margarita Terziyska
The aim of the present work was to study the potential of ultrafiltration with three polyacrylonitrile membranes (1, 10, and 25 kDa) to concentrate polyphenolic antioxidants in apple juice and extract. The permeate flux, total polyphenols, polyphenolic profile, phenolic acid content, and total antioxidant capacity were determined using the FRAP and DPPH tests, the content of water-soluble proteins during ultrafiltration was established, and the concentration factors and rejections were determined. The permeate flux decreased by increasing the volume reduction ratio and decreasing the molecular weight cut-off of the membranes. The concentration factor and rejection of polyphenolics increased with the increase in the volume reduction ratio (VRR) for all membranes and both liquids. The concentration and rejection effectiveness of the 1 kDa membrane was higher than those observed for 10 and 25 kDa during the ultrafiltration of the apple extract, while these values were comparable for 1 and 10 kDa during the ultrafiltration of the apple juice. The concentration factors and rejections of total polyphenols were higher in the extract than in the juice. Chlorogenic acid was the main compound in the polyphenol profile of apple juice. The total content of phenolic acids, determined by using HPLC, increased by 15–20% as a result of the membrane concentration, but the separation process did not significantly change the ratio between the individual compounds.

10 January 2023 in Applied Sciences
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Zhelyazko TerziyskiZhelyazko Terziyski
Zhelyazko Terziyski
Margarita TerziyskaMargarita Terziyska
Margarita Terziyska
IDIvelina Desseva
Ivelina Desseva
Stanka HadzhikolevaStanka Hadzhikoleva
Stanka Hadzhikoleva
Albert KrastanovAlbert Krastanov
Albert Krastanov
EHEmil Nikolov Hadzhikolev
Emil Nikolov Hadzhikolev
Research on food-derived bioactive peptides is expanding and the need for a convenient online platform that combines a foolproof and intuitive user interface with a reliable database and tools for prediction and analysis is rising. In this regard, this paper presents an open-access web-based platform PepLab (Peptides Laboratory). The database contains 2764 peptide sequence entries, grouped into sixteen classes according to their biological activity and into seven classes according to the source from which they were derived. Moreover, it includes bioinformatic tools for their processing and analysis. The DMpep tool allows extracting information about a number of physicochemical characteristics of a peptide or a set of peptides, including those that are not recorded in the database. The main advantages of PepLab are a user-friendly interface, a responsive design, and optimized search engines for better visibility on the Internet. Prediction of non-reported activity is available based on amino acid sequence analysis. In addition, users can download data and results in a convenient format (text and/or graphic) that was limited in the existing platforms. In this way, the presented PepLab platform will be helpful for researchers from various fields—bioinformatics, pharmaceuticals, food sciences, dietetics, biotechnology, analytical chemistry, etc.

7 January 2026 in Sci
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Margarita TerziyskaMargarita Terziyska
Margarita Terziyska
IIIliana Ilieva
Iliana Ilieva
Zhelyazko TerziyskiZhelyazko Terziyski
Zhelyazko Terziyski
NKNikolay Komitov
Nikolay Komitov
The integration of artificial intelligence into the Industrial Internet of Things (IIoT), supported by edge computing architectures, marks a new paradigm of intelligent automation. Tiny Machine Learning (TinyML) is emerging as a key technology that enables the deployment of machine learning models on ultra-low-power devices. This study presents a systematic review of 110 peer-reviewed publications (2020–2025) identified from Scopus, Web of Science, and IEEE Xplore following the PRISMA protocol. Bibliometric and thematic analyses were conducted using Biblioshiny and VOSviewer to identify major trends, architectural approaches, and industrial applications of TinyML. The results reveal four principal research clusters: edge intelligence and energy efficiency, federated and explainable learning, human-centric systems, and sustainable resource management. Importantly, the surveyed industrial implementations report measurable gains—typically reducing inference latency to the millisecond range, lowering on-device energy cost to the sub-milliwatt regime, and sustaining high task accuracy, thereby substantiating the practical feasibility of TinyML in real IIoT settings. The analysis indicates a conceptual shift from engineering- and energy-focused studies toward cognitive, ethical, and security-oriented perspectives aligned with the principles of Industry 5.0. TinyML is positioned as a catalyst for the transition from automation to cognitive autonomy and as a technological foundation for building energy-efficient, ethical, and sustainable industrial ecosystems.

28 February 2024 in Applied Sciences
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SDSvetla Maksimova Dyankova
Svetla Maksimova Dyankova
MDMaria Doneva
Maria Doneva
Margarita TerziyskaMargarita Terziyska
Margarita Terziyska
PMPetya Metodieva
Petya Metodieva
INIliana Nacheva
Iliana Nacheva
Pumpkin seed cake, a byproduct of cold-pressed oil production, represents a food waste material with a great potential for valorization. The objective of the present study is to optimize the papain enzymatic hydrolysis process of pumpkin seed cold-pressed oil cake (CPC) to obtain protein hydrolysates with the highest antioxidant activity. Box–Behnken Response Surface Methodology (RSM) was used to optimize the simultaneous effects of an enzyme concentration of papain, a temperature, and a reaction time on the process of enzymatic hydrolysis on pumpkin seed cold-pressed oil cake (CPC). For these three input factors, different values are used—1, 2, and 3% for papain concentration, 20, 30, and 40 °C for temperature, and 60, 120, and 180 min for hydrolysis time. Thus, the design generated a total of 21 experimental runs. The aim is to obtain protein hydrolysates with the highest antioxidant activity. The responses DPPH and ABTS were calculated and the determined regression models were statistically analyzed and validated. The results revealed that optimal conditions included a papain concentration of 1.0%, a temperature of 40 °C, and a hydrolysis time of 60 min to retrieve the highest level of bioactive compounds.

28 September 2023 in Membranes
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Mariya DUSHKOVAMariya DUSHKOVA
Mariya DUSHKOVA
Alexios VardakasAlexios Vardakas
Alexios Vardakas
VSVasil Shikov
Vasil Shikov
KMKiril Mihalev
Kiril Mihalev
Margarita TerziyskaMargarita Terziyska
Margarita Terziyska
One main objective of this study was to increase the utilization of raw material in the rose (Rosa damascena Mill.) essential oil industry by the application of membrane technologies. In this research, distilled (dearomatized) rose petals, the primary byproduct in essential oil production, were subjected to an enzyme-assisted extraction and subsequent membrane separation for partial concentration at different levels using UF1-PAN and UF10-PAN membranes. The results show that the permeate flux decreased with a rise in volume reduction ratio and increased with a rise in transmembrane pressure and feed flow rate. At the beginning of the process, the highest flux was with the UF1-PAN membrane, but at the end of the process, it was with the UF10-PAN membrane. Total polyphenols of the retentates increased by 27–39% and 26–67% during ultrafiltration with the UF1-PAN and UF10-PAN membranes, respectively, with the highest value obtained for the UF10-PAN membrane at VRR 6. The highest concentration factor and rejection of total solids, total polyphenols, redox-active antioxidants, and radical scavenging antioxidants were obtained at VRR 6 with the UF10-PAN membrane. The use of green technology based on enzyme-assisted extraction and ultrafiltration for recovery and concentration of polyphenols from rose petal byproduct solves practical environmental problems for the treatment and utilization of byproducts from the rose oil industry. The retentate obtained could be used in the food production, cosmetic, and pharmaceutical industries.