Quality assessment of gluten-free crackers based on buckwheat flour

Formulation and characterization of new products - gluten-free crackers based on two types of buckwheat flour (refined and wholegrain) are presented in this study. Their proximate composition, content of main antioxidant compounds (polyphenols and tocopherols), antioxidant activity (radical scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radicals - DPPH) and sensory quality were analyzed and compared with those of wheat crackers made from refined and wholegrain wheat flours.Protocatechuic acid and ferulic acid were quantified in buckwheat and wheat crackers, while two flavonoids, rutin and quercetin, were quantified only in buckwheat crackers. Content of total phenolics and tocopherols was significantly higher (P < 0.05) in buckwheat crackers in comparison to wheat crackers. Tocopherols in crackers were present in the following order: α- ? γ- > δ-tocopherol. Buckwheat crackers exhibited significantly higher (P < 0.05) radical scavenging activity on DPPH according to their IC₅₀ values.No significant differences were observed in sensory quality of wholegrain buckwheat crackers in comparison to wheat ones. Crackers made from buckwheat flours can broaden the utilization of buckwheat, increase supply of gluten-free products on the market and may be regarded as health-promoting functional foods, especially for celiac disease patients.     

Development of whey-based beverages

This paper considers beverages consisting of whey, fruit components (orange, pear, peach, and apple), citric acid and sucrose. It also offers their optimal composition. The dry matter of the fruit component, the pH of the beverage and its sucrose content were independent variables. Blends were prepared in accordance with the factorial design. After pasteurization, they were exposed to a sensor analysis so that the following characteristics were estimated: flavour, odour, colour, sediment, appearance and total quality (sum of the previous factors). By applying the regression analysis method, a mathematical model of each characteristic was derived. None of the characteristic functions had an extreme, so the maxima lay at the boundaries of the independent variables (6% of dry matter and 4% or 2% of sucrose ). Only the pH changed within a narrow range. The statistical method has shown that the quality of blends with orange and pear mostly depends on the sucrose content, while the quality of blends with peach and apple depends on the dry matter of the fruit. Interaction of dry matter and sucrose is most significant for the blend with pear, while the balance between sucrose and pH strongly depends on the quality of all the other products. The peach–whey beverage containing 6% of dry matter and 2% of sucrose as well as having pH 3.6 proved to be the best.     

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.     

Buckwheat (Fagopyrum esculentum Moench) Grain and Fractions: Antioxidant Compounds and Activities

Abstract: Buckwheat (Fagopyrum esculentum Moench) is an alternative crop belonging to the Polygonaceae family. In comparison to antioxidant activity of frequently used cereals, buckwheat has been reported to possess higher antioxidant activity (AOA), mainly due to high rutin content. The objective of this work was to determine the main antioxidant compounds and AOA of buckwheat grain fractions (whole grain, hull, and groat). Buckwheat grain fractions were extracted with ethanol/water (80/20, v/v), followed by determination of total phenolic and flavonoid content. Quantification of phenolic compounds and tocopherols was performed by high‐performance liquid chromatography (HPLC). The AOA was estimated by 2 direct electron spin resonance (ESR) and 4 indirect (spectrophotometric) tests. Significantly higher contents of total phenolics and total flavonoids were found in buckwheat hull than in whole grain and groat. Protocatechuic, syringic, and sinapic acid, rutin, and quercetin were found in all tested fractions, whereas vanilic acid was found in whole grain and hull. The content of total tocopherols in investigated samples ranged from 23.3 mmol/g for hull to 61.8 mmol/g for groat. Hull was superior in scavenging activity on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH^?), hydroxyl (^?OH), and superoxide anion (O₂^?‐) radicals, reducing activity, AOA by β‐carotene bleaching method, and chelating activity on Fe²⁺ as evidenced by its lower IC₅₀ value. Obtained results can broaden the utilization of buckwheat, especially a share of hull in whole grain flour production. Practical Application: Obtained results suggest possibility to supplement the whole grain buckwheat flour with hull, which leads toward better usage of by‐products in buckwheat production, and enhancement of antioxidant potential of the final product.     

Antioxidant, antimicrobial, and anticancer activity of 3 Umbilicaria species

Abstract: The aim of this study is to investigate in vitro antioxidant, antimicrobial, and anticancer activity of the acetone extracts of the lichens Umbilicaria crustulosa, U. cylindrica, and U. polyphylla. Antioxidant activity was evaluated by 5 separate methods: free radical scavenging, superoxide anion radical scavenging, reducing power, determination of total phenolic compounds, and determination of total flavonoid content. Of the lichens tested, U. polyphylla had largest free radical scavenging activity (72.79% inhibition at a concentration of 1 mg/mL), which was similar as standard antioxidants in the same concentration. Moreover, the tested extracts had effective reducing power and superoxide anion radical scavenging. Total content of phenol and flavonoid in extracts was determined as pyrocatechol equivalent, and as rutin equivalent, respectively. The strong relationships between total phenolic and flavonoid contents and the antioxidant effect of tested extracts were observed. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration by the broth microdilution method. The most active was extract of U. polyphylla with minimum inhibitory concentration values ranging from 1.56 to 12.5 mg/mL. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using MTT method. All extracts were found to be strong anticancer activity toward both cell lines with IC₅₀ values ranging from 28.45 to 97.82 μg/mL. The present study shows that tested lichen extracts demonstrated a strong antioxidant, antimicrobial, and anticancer effects. That suggests that lichens may be used as possible natural antioxidant, antimicrobial, and anticancer agents.     

Quantification of the thaumatin-like kiwi allergen by a monoclonal antibody-based ELISA

Thaumatin-like proteins (TLPs) have been established as a new family of fruit and pollen allergens. The aim of this study was to develop a two-site ELISA for the quantification of the thaumatin-like kiwi allergen (Act d 2) in kiwifruit extracts and kiwifruit-containing food products. Genomic DNA (gDNA) of Act d 2 was amplified and the deduced amino acid sequence was determined to obtain a primary structure. Act d 2 purified from kiwifruit extract by HPLC was identified by Edman degradation and MS. Balb/c mice were immunized with Act d 2 for the production of mAbs by hybridoma technology. The optimized ELISA measured Act d 2 concentrations ranging from 0.2 to 9.0 ng/mL, with intra- and interassay coefficients of variation of 3.65 and 10.44%, respectively. The developed ELISA is a useful method for the quantification of the thaumatin-like kiwi allergen in kiwifruit extracts as well as the allergen level in kiwifruit-containing food products. It may be a helpful analytical tool for the evaluation of the stability (integrity) of fruit allergen extracts for in vitro diagnosis.     

Effects of a first-order chemical reaction on turbulent mass transfer

The effects of a first-order chemical reaction on turbulent mass transfer from a wall are investigated using a Lagrangian method that involves the numerical solution for the flow field in conjunction with the tracking of mass markers released from the wall. The markers react according to a Poisson distribution that is correlated to the reaction rate constant. The method allows studying a range of Schmidt number fluids and a range of Damköhler numbers. The behavior of a continuous line source of the reactant, and the behavior of the dissolution of the reactant from the wall are examined. It is found that the mass transfer coefficient increases dramatically when a first-order reaction occurs. A correlation between the mass transfer coefficient and the Damköhler number is proposed for both low and high Schmidt numbers. The fundamental reason for the change in the mass transfer properties is that each marker is affected by different parts of the turbulence velocity field depending on the Schmidt and Damköhler numbers.     

Formation of a liquid jet after detachment of a vapour bubble

Originated by the action of Laplace-pressure at the moment of break-off of a vapour bubble, a liquid jet can form, penetrate the bubble and pierce the bubble vertex at a relatively high velocity. The prehistory of the jet formation, including the detachment process of a single vapour bubble are described in the paper. Photographs of a vapour bubble, generated on a horizontal heated surface, show clearly the process of bubble detachment, the formation and the development of a liquid jet immediately after the bubble break-off. Refrigerant R113 containing 1% (mass) of oil was used as the test liquid.     

Fifteen years of constraint-based tutors: what we have achieved and where we are going

Fifteen years ago, research started on SQL-Tutor, the first constraint-based tutor. The initial efforts were focused on evaluating Constraint-Based Modeling (CBM), its effectiveness and applicability to various instructional domains. Since then, we extended CBM in a number of ways, and developed many constraint-based tutors. Our tutors teach both well- and ill-defined domains and tasks, and deal with domain- and meta-level skills. We have supported mainly individual learning, but also the acquisition of collaborative skills. Authoring support for constraint-based tutors is now available, as well as mature, well-tested deployment environments. Our current research focuses on building affect-sensitive and motivational tutors. Over the period of fifteen years, CBM has progressed from a theoretical idea to a mature, reliable and effective methodology for developing effective tutors.