Ústav chemie potravin a biotechnologií

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EXPLORING THE IMPACT OF DIFFERENT PACKAGING TYPES AND REPEATED PACKAGE OPENING ON VOLATILE COMPOUND CHANGES IN GROUND ROASTED COFFEE
(SLOVAK UNIV AGRICULTURE NITRA, 2024-08-02) Trenzová, Kristina; Gross, Michal; Vítová, Eva; Pořízka, Jaromír; Diviš, Pavel
In this study, the dynamics of volatile compound alterations during the storage of ground roasted coffee in various packaging were investigated using solid -phase microextraction-gas chromatography -mass spectrometry. Each type of packaging underwent repeated opening and closing, simulating the gradual consumption behavior of the consumer who consumes ground coffee in smaller doses over time. The experimental results revealed that after 30 days of storage, 35 to 45% of the volatile substances originally present in the coffee were lost regardless of the type of packaging used. Notably, storing coffee in a paper sachet proved to be the least effective method, resulting in a loss of over 80% of all volatile coffee substances during this storage period.
A Comparison of the Effects of Continuous Illumination and Day/Night Regimes on PHB Accumulation in Synechocystis Cells
(MDPI, 2024-07-20) Fleischhacker-Daffert, Christina; Zerobin, Antonia; Hummel, Ferdinand; Slaninová, Eva; Kroupová, Zuzana; Obruča, Stanislav; Mrázová, Kateřina; Hrubanová, Kamila; Krzyžánek, Vladislav; Nebesářová, Jana; Ludwig, Katharina; Fritz, Ines
Poly(3-hydroxybutyrate) (PHB) is a biobased and biodegradable polymer with properties comparable to polypropylene and therefore has the potential to replace conventional plastics. PHB is intracellularly accumulated by prokaryotic organisms. For the cells PHB functions manly as carbon and energy source, but all possible functions of PHB are still not known. Synechocystis (cyanobacteria) accumulates PHB using light as energy and CO2 as carbon source. The main trigger for PHB accumulation in cyanobacteria is nitrogen and phosphorous depletion with simultaneous surplus of carbon and energy. For the above reasons, obtaining knowledge about external factors influencing PHB accumulation is of highest interest. This study compares the effect of continuous light exposure and day/night (16/8 h) cycles on selected physiology parameters of three Synechocystis strains. We show that continuous illumination at moderate light intensities leads to an increased PHB accumulation in Synechocystis salina CCALA 192 (max. 14.2% CDW - cell dry weight) compared to day/night cycles (3.7% CDW). In addition to PHB content, glycogen and cell size increased, while cell density and cell viability decreased. The results offer new approaches for further studies to gain deeper insights into the role of PHB in cyanobacteria to obtain bioplastics in a more sustainable and environmentally friendly way.
The study of relationship between taste and wheat bran protein isolate fortification during high-protein yogurt manufacturing
(ELSEVIER, 2024-05-03) Slavíková, Zuzana; Diviš, Pavel; Bialas, Wojciech; Montowska, Magdalena; Adamczyková, Michaela; Pořízka, Jaromír
High-protein (HP) food is becoming a popular and nutritionally valuable commodity. The most common protein fortifiers are milk whey or soy protein isolates. However, one of the potentially promising sources of quality protein isolate is wheat bran, the secondary product of wheat milling. Wheat bran protein isolate (WBPI) can be obtained using a sustainable and environmentally friendly pH shift method. Considering its nutritional properties, incorporating WBPI into people's diet is convenient. This work focuses on protein fortification of plain yogurt using WBPI while maintaining sensory acceptability. Direct fortification of yogurts with WBPI to achieve 5 % and 10 % protein content revealed two main sensory defects - bitterness and sandiness. Several approaches, such as grinding WBPI, protein blending, and WBPI encapsulation, were applied to improve the overall impression score of HP yogurts. It was found that eliminating the sandiness of WBPI-fortified yogurt is not possible by reducing WBPI particle size. Blending WBPI with dried milk decreased bitterness, but the products lacked amino acid diversity. The most effective procedure to mask the sensory defects was WBPI encapsulation using alginate, revealing an appropriate way to incorporate natural plant proteins into HP food.
G-quadruplex propensity in H. neanderthalensis, H. sapiens and Denisovans mitochondrial genomes
(Oxford University Press, 2024-05-30) Brázda, Václav; Šislerová, Lucie; Cucchiarini, Anne; Mergny, Jean-Louis
Current methods of processing archaeological samples combined with advances in sequencing methods lead to disclosure of a large part of H. neanderthalensis and Denisovans genetic information. It is hardly surprising that the genome variability between modern humans, Denisovans and H. neanderthalensis is relatively limited. Genomic studies may provide insight on the metabolism of extinct human species or lineages. Detailed analysis of G-quadruplex sequences in H. neanderthalensis and Denisovans mitochondrial DNA showed us interesting features. Relatively similar patterns in mitochondrial DNA are found compared to modern humans, with one notable exception for H. neanderthalensis. An interesting difference between H. neanderthalensis and H. sapiens corresponds to a motif found in the D-loop region of mtDNA, which is responsible for mitochondrial DNA replication. This area is directly responsible for the number of mitochondria and consequently for the efficient energy metabolism of cell. H. neanderthalensis harbor a long uninterrupted run of guanines in this region, which may cause problems for replication, in contrast with H. sapiens, for which this run is generally shorter and interrupted. One may propose that the predominant H. sapiens motif provided a selective advantage for modern humans regarding mtDNA replication and function.
Simultaneous determination of sweeteners and preservatives in beverages by HPLC-DAD-ELSD
(HACCP Consulting, 2020-10-28) Diviš, Pavel; Jurečková, Zuzana; Vespalcová, Milena; Pořízka, Jaromír; Punčochářová, Lenka
People suffering from diabetes or being overweight must severely reduce their sugar use, often seeking food with sweeteners. Often, sugar is replaced by non-nutritious sweeteners in beverages, which also contain several other substances like vitamins, caffeine, amino acids, phenolic compounds and thus increasing the shelf life of the beverages is additionally treated with the addition of preservatives. As the concentration of additives in food (including beverages) is determined by the legislation in force, it is necessary to have an appropriate analytical method for food control. Since artificial sweeteners and preservatives are very different substances, they are determined separately using different HPLC methods. In this work HPLC method combining the advantages of specific (diode array detector, DAD) and universal (evaporative light scattering detector, ELSD) detector was validated and used for simultaneous determination of benzoic acid, sorbic acid, aspartame, acesulfame K, saccharin, sucralose and steviol glycosides in sugar-free beverages. The proposed analytical method showed good linearity, precision, and accuracy. Measured limits of detection (0.6 – 11.8 mg.dm-3 depending on the analyte) were sufficient to analyze 5-times diluted beverage samples. The validated method has been successfully used for the simultaneous analysis of artificial sweeteners and preservatives in beverage samples (energy drinks, ice teas, carbonated drinks). Except for steviol glycosides, the concentration of monitored substances in beverages did not exceed the maximum permitted concentrations given in the valid legislation.

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