Determination of β-glukani content in worth and beer

β-glukani so polisaharidi, v katerih so glukozne molekule povezane z (1→3) in (1→4) β glikozidnimi vezmi. Zaradi različnega tipa povezav in razvejanosti, lahko β-glukani varirajo v topnosti, molekulski masi, terciarni strukturi in konformaciji. Vse te karakteristike imajo vpliv na različne imunske efekte. Ječmenovi β-glukani so koncentriran vir vodotopnih prehranskih vlaknin. Njihovi učinki so povezani s povišanjem viskoznosti v tankem črevesju. Zaradi viskoznosti se upočasni vsrkavanje hranil in posledično se zmanjša glikemični indeks. Namen našega eksperimentalnega dela je bil določanje β-glukanov v sladici in pivu s tekočinsko kromatografijo in fluorescentno detekcijo. Metodo smo tudi optimirali in validirali s pomočjo osnovnih parametrov, kot so točnost, natančnost, obnovljivost, ponovljivost. LOD in LOQ nismo določevali, saj so vse koncentracije analita v naših vzorcih nad mejo določljivosti in so v našem merilnem območju. Ugotovili smo, da naša umeritvena krivulja ni linearna temveč je krivulja drugega reda. R2 je 0,9975, kar pomeni, da se krivulja zadovoljivo prilega našim točkam umeritvene krivulje. Meritve smo izvajali v koncentracijskem območju od 25–300 mg/L. Standardne raztopine je bilo potrebno dnevno pripraviti sveže, saj so se tekom tedna umeritvene krivulje standardnih raztopin močno spreminjale. V nekaterih primerih smo morali vzorce redčiti v razmerju 1:9, zaradi previsokega odziva detektorja. Iz posnetih kromatogramov smo odčitali površine pod kromatografskimi vrhovi in s pomočjo enačbe umeritvene krivulje izračunali koncentracijo β-glukanov v pivu. Selektivnost metode smo potrdili s pomočjo specifičnih karakteristik FLD detektorja, ki uporablja specifični valovni dolžini vzbuditve in emisije β-glukanov.β-glucans are polysaccharides in which glucose molecules are linked with (1→3) and (1→4) β glycosidic bonds. Due to different types of links and branching β-glucans may vary in solubility, molecular weight, tertiary structure and conformation. All these characteristics have an impact on different immune effects. Barley β-glucans are a concentrated source of soluble dietary fiber. Their effects are associated with the generation of a greater viscosity in the small intestine. This greater viscosity results in slower absorption of nutrients and consequently reduces glycemic index. The purpose of our experimental work was the determination of β-glucans in wort and beer by liquid chromatography and fluorescence detection. The method was also validated with some basic parameters, such as precision, accuracy, reproducibility, repeatability. We did not analyze LOD and LOQ because, all the concentrations of analyte in the samples were well above the limit of quantification and were, therefore, in our measuring range. We found that our calibration curve is not linear but it is a curve of the second order. R2 is 0.9975, which means that the curve satisfactorily fit our points of the calibration curve. The measurements were carried out in the concentration range between 25 and 300 mg/L. The standard solutions were prepared freshly each day due to the variation of the calibration curve data in the course of the week. In some cases, we diluted samples in the ratio of 1:9 because the detector response was too. The surfaces of the recorded chromatographic peaks were scanned, and the concentrations of β-glucans in the beer were calculated by the use of calibration curve. We have confirmed the selectivity of the method due to the specific characteristic of the FLD detector, which uses only specific wavelengths of excitation and emission of β-glucans