Design and applications of a neural networks assisted portable liquid surface tensiometer

In this paper, a portable instrument for surface tension measurements, characterization and applications is described. The instrumentation is operated wirelessly, and samples can be measured in situ. The instrument has changeable different size probes; therefore, it is possible to measure samples from 1 ml up to 10 ml. The response of the measured retraction force and the concentrations of measured surfactant is complex. Therefore, two calibration methods were proposed: (i) the conditional calibration using polynomial and logarithmic fitting and (ii) the neural network trained model prediction of the surfactant concentration in samples. Calibrating the instrument, the neural network trained model showed a superior coefficient of determination (0.999), comparing it to the conditional calibration using polynomial (0.992) and logarithmic (0.991) fit equations

Bee products for food and human health

OP23The diversity of the products produced by the bees are unique. Apis mellifera are the most popular domesticated bee species used among beekeepers. Probably there are not animal or insect species in the nature producing such a variety of products suitable for human consumption. Honey, bee pollen, bee bread, propolis, royal jelly, wax and bee venom are the whole family of the products produced by the bees. However, some products are more suitable for food (such as honey), others - for health. Because of possible allergic reactions, bee venom is not recommended to use for self-treatment. The diversity of the bee products' biological activities are described in the literature: antioxidant, antibacterial, antifungal, antiviral, anti-inflammatory, antitumor, antiproliferative, antimetastatic, immunomodulatory, antiseptic, antistress, antiulcer, antihyperlipidemic, antidiabetic, anticancer and etc. The activities list is not final, as various bee products or their mixtures are highly investigated nowadays. It is difficult to distinguish what has the highest impact to their biological activity. Probably the activity depends on a complex set of factors, such as botanical origin, related to phytochemicals in the bee products, secretion of the honey bees, containing proteins, amino acids, fatty acids, enzymes, pheromones, vitamins and minerals, which are secreted from different glands of the bees, varying the proportions of these compounds among the different bee products, or interaction of these factorsInstrumentinės analizės APCVytauto Didžiojo universiteta

The application of chemometric techniques for the classification of bee products : a review

The chemometric techniques are used for the classification of the samples to the groups. The classification may be unpredictable (when samples are grouped according to some specific parameters) and predictable (when the dependence of the sample to some specific (already known) group is tested). The hierarchical cluster analysis, principal component analysis, linear discriminant analysis are the most popular in classification of food samples, including bee products. However other tests, like artificial neural networks, partial least squares or partial least squares discriminant analysis, canonical variate analysis, soft independent modelling class analogy, and etc., are applied. As composition of bee products is enough rich in diversity of chemical compounds, the various factors are used for the classification of the samples: carbohydrates composition, amino acids content and composition, volatile compounds composition, phenolic compounds and flavonoids content and composition, mineral composition. Chemometric classification of bee products can be based not only chemical composition, but also on other characteristics, like antiradical activity, DNR composition, electrical conductivity, optical rotation, antibacterial activity, and etcBiochemijos katedraVytauto Didžiojo universiteta

Analysis of bee products using chromatographic techniques : a review

Bee products are very valuable for consumers due to their unique properties, which cover the “power” of plants and bees itself. Bee products are used as food or are introduced in the folk medicine from the ancient times. Honey is the most favourable out of all bee products due to it sweet taste and characteristic aroma. Bee bread, bee pollen, propolis, bee wax, royal jelly and bee venom are also very valuable bee products with a wide spectrum of biological activity. The latter two are not so easily available for the consumers and mainly are used in pharmacy products. However the use of bee products as food or as medicine, requires determination of their composition, evaluation of quality and biological activities or verifying the authenticity. The variety of chromatographic techniques allows to evaluate many parameters concerning to the bee products composition or impurities. Sugar composition can be determined by different methods, e.g. HPLC with refractometric detection, HPLC with pulsed amperometric detection, ion exchange chromatography with pulsed amperometric detection. GC-FID and GC-MS also can be applied for sugar analysis; just in this case the derivatization of carbohydrates must be performed to make them volatile. Aroma of bee product can be analyzed by GC with various detectors, after different sample preparation techniques, i.e. direct headspace analysis, solid phase microextraction (SPME), solvent extraction (SE), Likens-Nickerson, purge-and-trap or hydrodistillation. The residues of pesticides, fungicides and antibiotics in bee products can be determined using HPLC or GC after a proper sample preparation. [...]Biochemijos katedraVytauto Didžiojo universiteta

Skirtingos botaninės kilmės medaus sudėties ypatumai ir savybės

Bibliogr.: p. 105-113Kauno technologijos universiteta

Vaistinių augalų antrinių metabolitų analizė panaudojant dujų ir skysčių chromatografijos metodus su masių spektrometrija

The research on bioactive compounds of natural origin has gained much interest in the last two decades. The aim of the present study was the analysis of secondary metabolites of three medicinal plants (Bidens tripartita L., Calendula officinalis L. and Silybum marianum L.) cultivated in Lithuania and collected at different phenological stages. Supercritical CO2 extraction was applied for the extraction of essential oils from B. tripartita and C. officinalis. Identification of volatile compounds was produced using gas chromatographic-mass spectrometric analysis. Non-volatile compounds from all plants were extracted with methanol/water solution. The total content of phenolic compounds was tested by the Folin–Ciocalteu method, and the total content of flavonoids was also determined by AlCl3 colorimetric method. Radical scavenging activity was determined in model system with DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical. The qualitative analysis of phenolic compounds was performed by high performance liquid chromatography (HPLC). The study showed that both qualitative and quantitative composition of volatile and non-volatile compounds were strongly dependent on the plant phenological stageBiochemijos katedraVytauto Didžiojo universiteta

Ežiuolė : nuo empirinio naudojimo iki modernių fitoterapijos priemonių

Biochemijos katedraBotanikos sodasVytauto Didžiojo universiteta

Characterization of essential oils composition of two medicinal plants (Bidens triparita and Calendula officinalis) at different phonological stages

Biochemijos katedraVytauto Didžiojo universiteta

The impact of lactic acid bacteria fermentation on phytochemical composition of bee pollen

Bee bread is the bee pollen with added honey and bee secretions and stored in the comb. Natural fermentation of pollen in beehive lasts for a few months. The biological value of some medicinal plants increases after lactic acid fermentation, but there is no literature data about the artificially fermented pollen collected by bees. The aim of this study was to get product similar to the bee bread, which has higher biological value compared to the natural bee pollen. Fermentation of bee pollen was performed by lactic acid bacteria, namely Lactobacillus rhamnosus and Lactobacillus delbruleckii. The influence of different parameters (medium composition, pH, temperature, duration) to fermentation process was determined. Free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and total amounts of phenolic compounds and flavonoids were evaluated using spectrophotometric methodsBiochemijos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta

The impact of different fermentation parameters on antioxidant activity of bee pollen

The aim of this study was to get product similar to the bee bread, which has higher biological value compared to the natural bee pollen. The influence of different parameters, such as temperature, pH, fermentation term, to fermentation process was determined. Free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity, total amounts of phenolic compounds and flavonoids were evaluated by spectrophotometric methods. Fermentation of bee pollen was performed by lactic acid bacteria, namely Lactobacillus rhamnosus. Results showed that temperature range from 32°C to 37°C had no impact to fermentation and had no influence to total amount of phenolic compounds or radical scavenging activity. Changes of pH in the samples resulted the decrease of radical scavenging activity by an average of 0.8 times, but increased total amount of flavonoids by 1.7 times. Alkaline fermentation mixture resulted an increase of total phenolic compounds almost twice, but acidification had less impact and resulted an increase of total phenolic compounds by an average of 1.1 times. Control samples were not affected by changes of pH. Fermentation term had impact only on the total amount of flavonoids, which after fermentation increased significantly in all samples by 1.7 times, except samples, that were fermented only 3 days, where increase of total amount of flavonoids was only by 1.1 timesGamtos mokslų fakultetasInstrumentinės analizės APCVytauto Didžiojo universiteta