The aim of this study was to use unconventional malts in beer production and observe their effect on the wort viscosity. Six malts were analysed in this study-barley, black barley, oat, wheat, rye, and corn. Firstly, the parameters of cereals were measured after the malting process in an experimental malting house and wort production. Samples were analysed in each phase of the mashing process. Carbohydrate contents and viscosities were analytically determined from the samples. The resulting values of the dynamic viscosity were significantly higher than the values obtained by other authors, ranging from 3.4 up to 35.5 mPa·s-1. This study also confirmed the hypothesis that states that the breakdown of carbohydrates leads to a decrease in viscosity. Values measured in the black barley malt sample were higher when compared with light barley malt. Unconventional malts had a higher viscosity and were thus more difficult to filter. If these types of malts are used it is recommended to add barley malts or malts with a higher enzyme activity to them.

• Klíčová slova
• beer, beer production phases, malt, viscosity, wort,
• Publikační typ
• časopisecké články MeSH

Liquid egg products are one of the basic raw materials for the food industry. Knowledge of their rheological and flow behaviour in real technical elements is absolutely necessary for the selection of suitable technological equipment for their processing. In this article, the rheological properties of liquid egg products were determined. Eggs from six different species of poultry are used: domestic hen (Gallus gallus domesticus) hybrid Hisex Brown; Japanese quail (Coturnix japonica); German carrier goose (Anser anser f. domestica); domestic ducks (Anas platyrhynchos f. domestica); domestic guinea fowl (Numida meleagris f. domestica); and domestic turkeys (Meleagris gallopavo f. domestica). Liquid egg products showed pseudoplastic behaviour in range of shear strain rates from 0.2 up to 200 s-1 and at the temperature of 18 °C. Thus, the flow curves were constructed using the Ostwald-de Waele rheological model, with respect to the pseudoplastic behaviour of liquid egg products. According to the values of the coefficients of determination (R2), the sum of squared estimate of errors (SSE) and the root mean square error (RMSE), this model was appropriately chosen. Using the consistency coefficient K, the flow index n and the adjusted equations for the flow rate of technical and biological fluids in standard pipelines, the 3D velocity profiles of liquid egg products were successfully modelled. The values of the Reynolds number of the individual liquid egg products were calculated, and the type of flow was also determined. A turbulent flow has been detected for some liquid egg products.

• Klíčová slova
• egg, flow, poultry species, rheology, velocity,
• Publikační typ
• časopisecké články MeSH

Chocolate masses are one of the basic raw materials for the production of confectionery. Knowledge of their rheological and flow behaviour at different temperatures is absolutely necessary for the selection of a suitable technological process in their production and subsequent processing. In this article, the rheological properties (the effect of the shear strain rate on the shear stress or viscosity) of five different chocolate masses were determined-extra dark chocolate (EDC), dark chocolate (DC), milk chocolate (MC), white chocolate (WC), and ruby chocolate (RC). These chocolate masses showed thixotropic and plastic behaviour in the selected range of shear rates from 1 to 500 s-1 and at the specified temperatures of 36, 38, 40, 42, and 44 °C. The degree of thixotropic behaviour was evaluated by the size of the hysteresis area, and flow curves were constructed using the Bingham, Herschel-Bulkley and Casson models with respect to the plastic behaviour of the chocolate masses. According to the values of the coefficients of determination R2 and the sum of the squared estimate of errors (SSE), the models were chosen appropriately. The most suitable models are the Herschel-Bulkley and Casson models, which also model the shear thinning property of the liquids (pseudoplastic with a yield stress value). Using the coefficients of the rheological models and modified equations for the flow velocity of technical and biological fluids in standard piping, the 2D and 3D velocity profiles of the chocolate masses were further successfully modelled. The obtained values of coefficients and models can be used in conventional technical practice in the design of technological equipment structures and in current trends in the food industry, such as 3D food printing.

• Klíčová slova
• 2D and 3D flow profiles, chocolate masses, mathematical models, pipe flow velocity, rheology, temperature, thixotropy,
• Publikační typ
• časopisecké články MeSH

In this study, we investigated whether the mathematical formulas, which generally reveal the external quality characteristics of living organisms, yield the correct results in goose eggs. For this purpose, three genotypes and 555 eggs were studied that were grouped into Native (n = 356), Chinese (n = 163) and Linda (n = 36), which were raised in Aksaray province. The averages in the Native, Chinese and Linda geese were 5.43, 5.38 and 5.7 cm, respectively, in breadth; were 8.12, 8.03 and 8.67 cm in length, respectively; the shape index was 66.9, 67.2 and 66.7 cm, respectively; the egg volume was 142.8, 138.8 and 172.5 cm3, respectively; the egg surface area was 136.9, 134.3 and 155.4 cm2, respectively; the egg weight was 159.1, 154.5 and 192.3 g, respectively; the specific gravity of the eggs was 1.11, 1.11 and 1.12 g/cm3, respectively; the shell thickness was 0.510, 0.504 and 0.555 mm, respectively; the shell weight was 14.79, 14.32 and 18.26 g, respectively; the shell volume was 70.06, 67.82 and 86.41 cm3, respectively; the shell specific gravity was 2.111 3, 2.111 0 and 2.113 5 g/cm3, respectively; and the shell ratio was 9.29, 9.26 and 9.49 g, respectively. The number of pores is calculated as 14 828, 14 502 and 17 152, respectively. Although the formulas used give compatible results, there is a need for formulas that calculate closer to the truth rather than formulas that calculate the egg weight and egg shell weight.

• Klíčová slova
• egg measurements, equations, geese, shape index,
• Publikační typ
• časopisecké články MeSH

Heather honey is a valuable and rheologically special type of honey. Its above-average selling price may motivate its intentional violation with a mixture of honey from another botanical origin, the price of which is lower on the market. This work deals with the rheological properties of such devalued heather honey in order to determine the changes in the individual rheological parameters depending on the degree of dilution of the heather honey. For this purpose, a differently diluted heather honey sample series was created and the following rheological parameters were determined: hysteresis area, n-value, yield stress (τ0), parameter B (Weltman model), parameter ϕ, or parameter C (model describing the logarithmic dependence of the complex viscosity on the angular frequency). Part of the work was research into whether the set parameters can be used as comparative parameters. It was found that the hysteresis area does not appear to be a suitable relative comparison parameter due to the high variability. The parameters that appear to be suitable are the relative parameters n-value and the parameter ϕ, which showed the greatest stability. The change in the determined rheological parameters is, depending on the degree of dilution, non-linear with a step change between the samples containing 40% (w/w) and 60% (w/w) of a heather honey.

• Klíčová slova
• comparison rheological parameter, dilution, heather honey, mathematical modelling, rheology, time-dependent behaviour,
• Publikační typ
• časopisecké články MeSH