Article Highlights• Kinetics of saccharose fermentation by Kombucha was analysed • A saccharose concentration model was defined as a sigmoidal function • Reaction rates were calculated as first derivatives of Boltzmann's functions • Saccharose fermentation by Kombucha occurred according to complex kinetics Abstract The kinetics of saccharose fermentation by Kombucha is not yet well defined due to lack of knowledge of reaction mechanisms taking place during this process. In this study, the kinetics of saccharose fermentation by Kombucha was analysed using the suggested empirical model. The data were obtained on 1.5 g L -1 of black tea, with 66.47 g L -1 of saccharose and using 10 or 15% (V/V) of Kombucha. The total number of viable cells was as follows: approximately 5×10 5 of yeast cells per mL of the inoculum and approximately 2x10 6 of bacteria cells per mL of the inoculum. The samples were analysed after 0, 3, 4, 5, 6, 7 and 10 days. Their pH values and contents of saccharose, glucose, fructose, total acids and ethanol were determined. A saccharose concentration model was defined as a sigmoidal function at 22 and 30 °C, and with 10 and 15% (V/V) of inoculum quantity. The determination coefficients of the functions were very high (R 2 > 0.99). Reaction rates were calculated as first derivatives of Boltzmann's functions. No simple correlation between the rate of reaction and independent variables (temperature and inoculum concentration) was found. Analysis of the empirical model indicated that saccharose fermentation by Kombucha occurred according to very complex kinetics.The consortium of yeasts and acetic acid bacteria known as the Kombucha culture exhibits a metabolic activity on sweetened tea, under batch conditions, giving a pleasant sour beverage containing useful compounds such as some organic acids and certain vitamins. The activity of Kombucha on the traditional carbon source saccharose was investigated by several authors [1-6] and the main pathways of saccharose transformation were determined. It has been proven that the yeast cells are responsible for the extracellular enzymatic hydrolysis of saccharose into glucose and fructose, and transformation of glucose and fructose into ethanol and CO 2 , while acetic acid
It is well known that some of biologically active compounds are chiral molecules. Natural monosaccarides are applicable as chiral precursors. D-arabinose is an appropriate chiral precursor in the synthesis of very important biomolecules such as biotin and its analogues and feromon )-exobrevicomin. Acyclic poly functional D- arabinose derivatives are intermediates in the synthesis of the former biomolecules. This paper deals with the retention behaviour and retention mechanism of acyclic poly functional D-arabinose derivatives. The tested compounds have been chromato graphed on silica gel thin layer using binary organic mobile phases with a different polarity. With increasing polarity of the eluent polar components the solute retention is decreasing. The linear relationship is obtained between the values of retention constant, RM' and the logarithm of the mobile phase polar component volume fraction for all solutes tested and eluents used
A nonmonotone line search method for solving unconstrained optimization problems with the objective function in the form of mathematical expectation is proposed and analyzed. The method works with approximate values of the objective function obtained with increasing sample sizes and improves accuracy gradually. Nonmonotone rule significantly enlarges the set of admissible search directions and prevents unnecessarily small steps at the beginning of the iterative procedure. The convergence is shown for any search direction that approaches the negative gradient in the limit. The convergence results are obtained in the sense of zero upper density. Initial numerical results confirm theoretical results and show efficiency of the proposed approach.
This paper tries to determine how growth of money supply affects inflation in different time-horizons and under different inflation levels in the Czech Republic, Poland, Hungary and Russia. The research is done by using two innovative methodologies -the wavelet approach and Bayesian quantile regression. By observing these four countries, we can assess whether inflation targeting (IT) plays significant role in curbing inflation, because three Visegrad group countries adopted IT almost two decades ago, while Russia started to conduct IT relatively recently. Estimated quantiles suggest that money supply growth does not influence inflation in the Czech Republic and Hungary, whatsoever. We find that money growth impacts inflation in Poland, but very modestly. On the other hand, in the case of Russia, the transmission effect from money to inflation is much higher, and it goes around 40% in low inflation conditions, when M1 aggregate is observed, and around 78% in low inflation conditions, when M3 aggregate is analysed. The overall results clearly indicate that the adoption of the IT framework as a disinflation strategy proved to be successful in the Visegrad group countries, since excessive money growth has little or no effect at all on inflation in these countries.
This paper investigates whether global agricultural futures of corn, wheat, oats, soybean and canola have any influence on the annual agricultural production of these plants in AP Vojvodina. For the estimation purposes, the study applies robust Bayesian quantile regression. Besides, two scenarios are considered-1) current futures prices, and 2) futures prices from the previous year. Estimated results suggest that current futures prices do not affect current agricultural production of corn, wheat, oats and soybean in AP Vojvodina, because the estimated quantile parameters have negative sign or they are very small. However, when futures prices from the previous year are analysed, the majority of estimated QR parameters bear positive sign, which means that Serbian farmers take into account in greater or lesser extent the global agricultural prices when they plan their annual agricultural plantation. According to the findings, canola futures have the greatest effect on the rising Serbian canola production.
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