Ústav chemie potravin a biotechnologií

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Impact of Cultivar and Season on the Flavor of Red, White, and Black Currants: Integrated Instrumental and Sensory Analysis
(MDPI, 2025-05-06) Vítová, Eva; Diviš, Pavel; Pořízka, Jaromír; Zemanová, Jana
Currants are highly valued nutritionally and are traditionally grown in the Czech Republic. This study investigated 15 cultivars of red, white, and black currants to better understand their positive sensory properties and their relationship to consumer preference. Red and white cultivars, in particular, have received little attention from this perspective. Sensory quality, primarily flavor, was evaluated in conjunction with volatile compound profiling to identify the sensorially superior cultivars. The results confirmed clear differences between black currants and red/white variants. Red and white currants, belonging to the same species (Ribes rubrum), exhibited similar volatile compound content and composition, as well as similar sensory characteristics, distinguishing them significantly from black currants (Ribes nigrum). The flavor of black currants, characterized by strong astringency and distinct blackcurrant notes, was generally perceived less favorably by the evaluators. A total of 54 volatile compounds were identified across the analyzed cultivars. Alcohols (contributing flowery and fruity aromas), aldehydes (grassy aromas), and esters (fruity aromas) were the most abundant in most cultivars. Using the odor activity value (OAV) concept, 15 of these compounds were identified as likely contributors to currant flavor (OAV >= 1). Principal component analysis (PCA) identified the top cultivars within each variant: 'Victoria' (white), 'Rubigo' (red), and 'Demon' (black). These are proposed for potential practical applications.
Analysis of quadruplex propensity of aptamer sequences
(OXFORD UNIV PRESS, 2025-05-26) Cucchiarini, Anne; Dobrovolná, Michaela; Brázda, Václav; Mergny, Jean-Louis
Aptamers are short DNA or RNA sequences that can fold into unique three-dimensional structures, enabling them to bind specifically to target molecules with high affinity, similar to antibodies. A distinctive feature of many aptamers is their ability to adopt a G-quadruplex (G4) fold, a four-stranded structure formed by guanine-rich sequences. While G4 formation has been proposed or demonstrated for some aptamers, we aimed to investigate how frequently quadruplex-prone motifs emerge from the SELEX process. To achieve this, we examined quadruplex candidate sequences from the UTexas Aptamer Database, which contains over 1400 aptamer sequences extracted from 400 publications spanning several decades. We analyzed the G4 and i-motif propensity of these sequences. While no likely i-motif forming candidates were found, nearly 1/4 of DNA aptamers and 1/6 of RNA aptamers were predicted to form G4 structures. Interestingly, many motifs capable of forming G4 structures were not previously reported or suspected. Out of 311 sequences containing a potential stable G4 motif, only 53 of them (17%) reported the word "quadruplex" in the corresponding article. We experimentally tested G4 formation for 30 aptamer sequences and were able to confirm G4 formation for all the sequences with a G4Hunter score of 1.31 or more. These observations suggest the need to reevaluate G4 propensity among aptamer sequences.
Polyhydroxyalkanoate involvement in stress-survival of two psychrophilic bacterial strains from the High Arctic
(Springer, 2024-05-04) Grzesiak, Jakub; Rogala, Małgorzata Marta; Gawor, Jan; Kouřilová, Xenie; Obruča, Stanislav
An ever-growing body of literature evidences the protective role of polyhydroxyalkanoates (PHAs) against a plethora of mostly physical stressors in prokaryotic cells. To date, most of the research done involved bacterial strains isolated from habitats not considered to be life-challenging or extremely impacted by abiotic environmental factors. Polar region microorganisms experience a multitude of damaging factors in combinations rarely seen in other of Earth's environments. Therefore, the main objective of this investigation was to examine the role of PHAs in the adaptation of psychrophilic, Arctic-derived bacteria to stress conditions. Arctic PHA producers: Acidovorax sp. A1169 and Collimonas sp. A2191, were chosen and their genes involved in PHB metabolism were deactivated making them unable to accumulate PHAs (Delta phaC) or to utilize them (Delta i-phaZ) as a carbon source. Varying stressors were applied to the wild-type and the prepared mutant strains and their survival rates were assessed based on CFU count. Wild-type strains with a functional PHA metabolism were best suited to survive the freeze-thaw cycle - a common feature of polar region habitats. However, the majority of stresses were best survived by the Delta phaC mutants, suggesting that the biochemical imbalance caused by the lack of PHAs induced a permanent cell-wide stress response thus causing them to better withstand the stressor application. Delta i-phaZ mutants were superior in surviving UV irradiation, hinting that PHA granule presence in bacterial cells is beneficial despite it being biologically inaccessible. Obtained data suggests that the ability to metabolize PHA although important for survival, probably is not the most crucial mechanism in the stress-resistance strategies arsenal of cold-loving bacteria. Key points PHA metabolism helps psychrophiles survive freezing PHA-lacking psychrophile mutants cope better with oxidative and heat stresses PHA granule presence enhances the UV resistance of psychrophiles
AUTHENTICITY OF WINES PRODUCED FROM 'FRANKOVKA' GRAPE VARIETY ORIGINATING IN THE MODRÉ HORY REGION (CZECH REPUBLIC)
(POZNAN UNIV LIFE SCIENCES, 2024-11-29) Diviš, Pavel; Pořízka, Jaromír; Gross, Michal; Fojt, Lukáš; Vítová, Eva
Background. The geographical authenticity of wine, often referred to as terroir, is crucial in determining its unique characteristics and quality. Terroir encompasses the environmental factors where the grapes are grown, including soil composition, climate, and topography. These factors influence the flavor, aroma, and overall profile of the wine, giving it characteristics that are unique to its region of origin. Establishing geographical authenticity helps protect wine heritage, ensures quality control, and enhances market value. This study analyzed the phenolic, volatile, and elemental composition of wines with original certification (WOC) from the Modr & eacute; Hory region (MH) and compared them with wines from other Morava wine regions. Materials and methods. The study analyzed 24 wines of the 'Frankovka' variety from the Morava wine region, with 12 of these wines originating from the MH region with WOC certification. The researchers used Solid-Phase Microextraction coupled with Gas Chromatography-Mass Spectrometry, High-Performance Liquid Chromatography, Inductively Coupled Plasma Optical Emission Spectroscopy, and Inductively Coupled Plasma Mass Spectrometry techniques for the analysis. Results. Phenolic analysis revealed that MHWOC wines had significantly lower resveratrol levels, likely because of lower rainfall in the MH region. Volatile compound analysis reliably identified 38 substances, with MHWOC wines showing significant differences in the levels of ethyl octanoate, ethyl hexanoate, ethyl decanoate, and ethyl butyrate, attributed to unique production practices. Elemental analysis indicated higher Mg concentrations in MHWOC wines which were related to the region's clay and loess soils, whereas other wines from the Morava wine region exhibited higher levels of Sc, Ti, Fe, K, V, and Y due to different soil compositions. Conclusion. This study highlights the influence of regional soil and climate on wine composition and the potential of these parameters for the geographical authentication of wine. Based on the analysis, principal component analysis (PCA) reliably distinguished MHWOC wines from other wines originating from the
Comparative Study of Water and Milk Kefir Grains as Biopolymeric Adsorbents for Copper(II) and Arsenic(V) Removal from Aqueous Solutions
(MDPI, 2024-11-28) György, Balázs; Bujdoš, Marek; Vojtková, Hana; Diviš, Pavel; Slaný, Michal; Matúš, Peter; Urík, Martin
This study investigates the biosorption capabilities of kefir grains, a polysaccharide-based byproduct of the fermentation process, for removing copper(II) and arsenic(V) from contaminated water. Unlike traditional heavy-metal removal methods, which are typically expensive and involve environmentally harmful chemicals, biopolymeric materials such as kefir grains provide a sustainable and cost-effective alternative for adsorbing hazardous inorganic pollutants from aqueous solutions. Our experimental results revealed significant differences in the sorption capacities of two types of kefir grains. Grains of milk kefir outperformed water kefir, particularly in copper(II) removal, achieving up to 95% efficiency at low copper concentrations (0.16 mmolL-1) and demonstrating a maximum sorption capacity of 49 mu molg-1. In contrast, water kefir grains achieved only 35.5% maximum removal efficiency and exhibited lower sorption capacity. For arsenic(V) removal, milk kefir grains also showed superior performance, removing up to 56% of arsenic in diluted solution with experimental sorption capacities reaching up to 20 mu molg-1, whereas water kefir grains achieved a maximum removal efficiency of 34.5%. However, these findings also suggest that while kefir grains show potential as low-cost biosorbents, further modifications are needed to enhance their competitiveness for large-scale water treatment applications.

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