Rheological and Pipe Flow Properties of Chocolate Masses at Different Temperatures.

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.

Texture, color, and sensory changes occurring in chocolate bars with filling during storage.

The impact of storage temperature (6, 12, 20, 30℃) and period (2, 6, 10, 18, 26 weeks) on the texture, color, and sensory characteristics of dark and milk-filled chocolate bars was studied. Temperatures of 6 and 12℃ were the most suitable for bar storage; these samples were evaluated not to be significantly deteriorated by the storage period. The condition of samples stored at 20℃ started to deteriorate after 10 weeks in storage; the decline was observed mainly in meltdown rate and off-flavors, resulting in low overall acceptability. This effect was more evident in dark chocolate bars. Keeping the bars at 24℃ for 24h immediately after production (retemperation) improved the bar resistance to fat bloom, even if the decrease in the sensory quality was observed at the beginning of the storage period.

The Use of Unconventional Malts in Beer Production and Their Effect on the Wort Viscosity.

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.

Identification of Alleles of Puroindoline Genes and Their Effect on Wheat (Triticum aestivum L.) Grain Texture.

Grain hardness is one of the most important quality characteristics of wheat (Triticum aestivum L.). It is a significant property of wheat grains and relates to milling quality and end product quality. Grain hardness is caused by the presence of puroindoline genes (Pina and Pinb). A collection of 25 genotypes of wheat with unusual grain colour (blue aleurone, purple and white pericarp, yellow endosperm) was studied by polymerase chain reaction (PCR) for the diversity within Pina and Pinb (alleles: Pina-D1a, Pina-D1b, Pinb-D1a, Pinb- -D1b, Pinb-D1c and Pinb-D1d). The endosperm structure was determined by a non-destructive method using light transflectance meter and grain hardness by a texture analyser. Genotype Novosibirskaya 67 and isogenic ANK lines revealed hitherto unknown alleles at the locus for the annealing of primers of Pinb-D1. Allele Pinb-D1c was found to be absent from each genotype. The mealy endosperm ranged from 0 to 100% and grain hardness from 15.10 to 26.87 N per sample.