Solid Fat Content,Pre-Crystallization Conditions,and Sensory Quality of Chocolate with Addition of Cocoa Butter Analogues

The objective of this study was to determine how the addition of two cocoa butter equivalents and cocoa butter improver affect the physical and sensory properties of chocolate. The laboratory-made chocolate samples were tempered at three different pre-crystallization temperatures (25, 27, and 29°C), using different concentrations (3, 5, and 7%) of two commercial cocoa butter equivalents as well as commercial cocoa butter improver of the chocolate. The nucleation time of the chocolate mass primarly depended on pre-crystallization temperature while the value of maximum torque of chocolate mass were influenced by both, pre-crystallization temperature and concentration of fats. Sensory evaluation revealed that cocoa butter equivalents were acceptable in chocolate formulation without producing a negative impact on the sensory quality, while usage of improver required adjustment of raw formulations or process parameters. The results of the instrumentally measured hardness revealed that addition of cocoa butter improver significantly (p > 0.05) increased hardness of chocolate samples.     

Potentiometric sensor for polyethoxylated nonionic surfactant determination

A new liquid membrane surfactant sensor based on a 1,3-didecyl-2-methylimidazolium-tetraphenylborate ion-exchange complex was tested in different ethoxylated nonionic surfactants (EONS) and polyethylene glycols. The sensor also responded to tetraphenylborate (slope = −56.1 ± 0.8 mV/decade of activity) in the 1 × 10⁻⁶ to 2 × 10⁻³ M concentration range.The selectivity performance of the sensor toward alkaline, alkaline earth, and heavy metal cations was investigated. The sensor exhibited a fast response (within a few seconds), when in solution with some metal cations, for a 10-fold concentration change of Triton X-100. Its main application is in indicating the end-point in a potentiometric titration of EONS using sodium tetraphenylborate as the titrant. Several pure and technical grade EONS and polyethylene glycols were successfully titrated. The sensor can be used for titrations within a pH range of 3-11.The resulting potentiometric titration curves revealed an analytically usable inflection for all investigations, enabling reliable equivalence point detection using the first derivative method.The sensor was also applied to the study of barium ion reaction stoichiometry and Triton X-100 pseudoionic complex formation, as well as its reaction with tetraphenylborate.     

Low-frequency noise of thick-film resistors as quality and reliability indicator

The non-linearity and the noise of thick-film resistors are parameters that can be used to make a prediction of resistor reliability. The noise spectroscopy measurements of thick-film resistors are proposed as a diagnostic tool for the prediction of possible types of failure. The correlation between noise spectral density data and the results of accelerated aging of thick-film resistors at high temperature were made for HS80 and 2000 resistor pastes.     

The stability characterization of the pyrotechnic system. The degradation of the nitrate oxidant in the presence of the magnesium under the accelerated aging conditions

The degradation of the nitrate oxidant was followed in the course of the aging process of tracer pyrotechnic mix containing 22.0 % Mg, 46.0 % Sr(NO₃)₂, 22.0 % KCIO₄, 9.0 % Al-Mg alloy and 4.0 % organic binder. The accelerated aging was conducted under the conditions of the increased humidity (98.5 %, 85.0 %, 78.5 %) at the increased temperature (75 °C). Nitrate content as a function of aging time was calculated by substracting nitrite nitrogen from total nitrogen content determined by Devarda's alloy reduction method. The degradation products of the nitrate (nitrite and carbonate) were determined by UV/VlS (Griess reaction) and IR spectroscopy, respectively. Nitrate proved to have a great instability in the presence of the metal, the extent of its conversion to nitrite and carbonate being rather great in comparision to the previously studied alkali metal nitrates in the presence of Mg as well. The loss of the nitrate and the formation of the nitrite and carbonate are governed by the same kinetic laws as fuel degradation to the hydroxide. The rate of the metal oxidation to the hydroxide was faster than the rate of the nitrate degradation process. The failure of the mix is connected to the rather small content of the nitrite (0.4 %) while the texture was significantly destroyed.     

Chemical,rheological and sensory characteristics of sweet spreads made from by-products of soya bean and maize

Sweet maize cob (SMC) and black soya bean seed coat (BSC) were used to prepare a sweet spread. Chemical composition of the prepared spread and its rheological and sensory characteristics were investigated. The results were compared with those of commercial plum and raspberry jams and spreads. Spreads made from SMC and BSC had the highest content of proteins, total fibres, hemicellulose and cellulose. In relation to fruit jams, they are distinguished by the presence and content of p-coumaric, ferulic and 3,4-dihydroxybenzoic acids, as well as of flavonoids such as catechin and quercetin. SMC spread with 3.2% of BSC had the highest content of total anthocyanins (666.75 mg CGE kg⁻¹) (cyanidin 3-glucoside equivalent). Cyanidin-3-glucoside (Cy-3-Glu) was the most abundant anthocyanins in SMC/BSC containing spreads, while in raspberry jam, that was cyanidin-3-sophoroside (Cy-3-Sop). According to chemical, rheological and sensory properties, SMC/BSC containing spreads could be competitive with fruit jams and spreads.     

Relationship of Physicochemical Characteristics with Sensory Profile of Cookies Enriched with Medicinal Herbs

In this work, a range of model cookies enriched with different quantities of medicinal herbs, applied in two forms (pulverized mixture and extract), were studied to compare and describe relationships between physicochemical and sensory data. Multivariate statistical methods were applied to estimate relationships in the analyzed data. Analysis of variance showed that the majority of analyzed parameters were highly significant in discriminating among the samples (p < 0.05), which supported the usefulness of their application in characterizing the quality profile of enriched cookies. Principal component analysis on physicochemical data revealed that cookies at the same enrichment level showed more similarities. Principal component analysis on sensory data exhibited a larger separation between the samples with increasing enrichment levels, especially in the case of pulverized herbal mixture. According to partial least squares regression, two significant partial least squares components explained 92.7% and predicted 78.0% variation in the data. The most important parameters in discriminating between the cookies enriched with medicinal herbs were lightness, red tonality, and hardness. The selected physicochemical parameters could be used in future studies to evaluate variously enriched cookies by establishing models and investigating the predictability of sensory quality.     

Chemical characteristics of oils from naked and husk seeds of Cucurbita pepo L.

Pumpkin seed oils from naked and husk pumpkin seeds, produced by an industrial process and by laboratory extraction, were evaluated for fatty acid composition, tocopherol, sterol and squalene content. The major fatty acids in the oils from both varieties were oleic, linoleic and palmitic acid, followed by stearic acid. The ratios of monounsaturated to polyunsaturated fatty acids for husk and naked seed oils were about 0.60 and 0.75, respectively. Analysis of tocopherols in industrially pressed and laboratory‐extracted oils showed that husk seed oils had higher amounts of total tocopherols than naked seed oils. Oils extracted in the laboratory had higher amounts of tocopherols than industrial oils. Pumpkin seed oil, in general, had a high level of squalene, which was higher in husk seed oils than in naked seed oils and in extracted than in pressed oils. The total amount of sterols was higher in husk than in naked seed oils and in extracted oil samples. The main sterols were Δ7‐sterols and their content was similar in all samples, but the content of Δ5‐sterols was higher in oil samples of husk pumpkin seed and in extracted than in pressed oils.     

Irradiation Effects on Phenolic Content,Lipid and Protein Oxidation and Scavenger Ability of Soybean Seeds

The effect of medium doses of γ-irradiation (1–10 kGy) on total phenolic and tannin contents, lipid peroxidation, protein oxidation intensity and soluble protein content of soybean seeds, (genotype Ana), was investigated. Screening for antioxidant ability was performed using FRAP and DPPH methods. Total phenolic and tannin contents and DPPH scavenger activity were increased, while protein oxidation intensity was decreased by applied doses of γ-irradiation. Gamma irradiation provoked insignificant changes in lipid peroxidation and soluble protein content, while protein oxidation intensity was significantly decreased when dose of 10 kGy was applied. Presented results implicated that increased antioxidant capacity and protein stability of soybean seeds were increased after application of γ-irradiation.     

Toughness testing of ultra high performance fibre reinforced concrete

In this paper an investigation is made of the applicability of the ASTM C 1609 procedure for testing toughness of ultra high performance fibre reinforced concretes containing a large amount of fibre (≥2% by volume) and exhibiting deflection hardening behaviour. All mixtures exhibited deflection hardening behaviour, and the parameters varied included (1) the amount of steel fibres, (2) the type of steel fibres, (3) the size of the longest fibre, (4) the addition of polypropylene fibres, and (5) the size of the maximum aggregate grain in the concrete matrix. Based on comparison of the curves obtained from flexural toughness tests with the evaluation of the test results obtained according to ASTM C 1609 and with the statistical analysis, the authors recommended additional toughness parameters (P_100,3.00, P_100,4.00, P_100,6.00, T_100,3.00, T_100,4.00, and T_100,6.00) for the evaluation of toughness results. Such additional toughness parameters are calculated using a similar procedure as that specified in ASTM C 1609.     

Utilisation of steel slag as an aggregate in concrete

This paper aims to investigate the possibility of utilizing steel slags produced in Croatian plants as a concrete aggregate. Aggregate properties were determined on coarse slag fractions (4–8, 8–16 mm) according to the relevant European Standards. Considering the obtained results, slags were specified in accordance with the classes as given in the main European standard for aggregates, whereupon these classes were compared to the Croatian regulation requirements. The obtained results proved that coarse slag fractions can be suitable for concrete application. Therefore, concrete mixtures were prepared with coarse slag fractions whose hardened state properties (compressive and flexural strength, static modulus of elasticity, volume changes and corrosion susceptibility) were then compared with the properties of reference concrete made of commonly used natural aggregate materials, namely dolomite. According to the obtained test results it can be concluded that the observed slags can be a good substitute for natural aggregate materials.