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Walnuts of five cultivars (Sampion, Jupiter, Sejnovo, Elit, and Geisenheim 139) of Juglans regia were collected during the 2008 harvest in Cacak, Central Serbia. Two techniques of oil extraction were implemented - cold pressing and organic solvent extraction. The influence of the implemented methods on the fatty acid composition, tocopherol level as well as oxidative stability was examined. Predominant fatty acids were palmitic, oleic, linoleic, and linolenic acids. The oleic acid concentration ranged from 15.9_23.7% of the total fatty acids, while the linoleic acid concentration ranged from 57.2-65.1% and that of linolenic acid from 9.1-13.6%. The process of oil extraction had no significant effect on the concentration and composition of fatty acids in the oil. The total concentration of tocopherols ranged from 28.40 mg/100 g to 42.40 mg/100 g of the extracted oil. The most common tocopherol in all samples was gamma-tocopherol. The oil extracted using the Soxhlet method contained higher amounts of total tocopherols while the stability of the oil samples (expressed as induction period) ranged from 5.0 h to 7.1 hours. Reduced stability of the oil samples as measured by the Rancimat method was negatively correlated with the level of linolenic acid and total content of tocopherols.

This article is focused on the determination of the mechanical behaviour of several layers of plant seeds (Pisum sativum, Phaseolus vulgaris, Helianthus annuus and Jatropha curcas) under compression loading. The results from the experiment showed that during compression plant seeds may change their mechanical behaviour. Deformation characteristic ceases to be a function of growing and begins to resemble that of trigonometric functions (this behaviour is called the wave effect). Limit deformation, strain energy and volume energy were determined for all the seeds tested. From the calculated amounts of the volume energy, garden pea had the best resistance to change in the mechanical behaviour due to the fact that its change in the mechanical behaviour was not discovered. The other plant seeds (common beans, common sunflower and jatropha) with respect to resistance to change in the mechanical behaviour followed in that order of magnitude.

This article is focused on the utilization of tangent curve for description of mechanical behaviour of pressed mixture under compression loading. The aim of this experiment was to determine the general equation describing deformation characteristics of pressed mixtures under compression loading and to verify this equation. The experiment was carried out using mixtures of seeds of Helianthus annuus, Jatropha curcas, Pisum sativum, Phaseolus vulgaris, and also mixtures of spruce wood chips and waste paper chips. The results from the experiment showed that mechanical behaviour of the pressed mixtures under compression loading can be described by tangent curve function. From the determined coefficients of determination R2 it was clear that fitted tangent curve functions described the measured amounts exactly for all pressed mixtures. It can be therefore assumed that this tangent curve function is appropriate for use in pressing any pressed mixtures during linear compression.

An aqueous solution of phenolic resin was impregnated through drilled holes in wood, and we manufactured compressed wood with the deformation fixed by the phenolic resin. The methods of impregnation used in this study were an in-liquid platen-pressing method and a vacuum treatment. The effect of the drilled holes on solution retention was examined. Moreover, the control of solution retention was examined under the application of compression drying. The impregnation of resin into the specimens without drilled holes was insufficient, and the deformation could not be fixed. On the other hand, sufficient impregnation was possible in the specimen with drilled holes, and the deformation fixation was observed. At the stage of compression when the solution was squeezed out of the specimen, the solution retention of each specimen was accurately controlled in the specimens with drilled holes. At the stage of compressive deformation and deformation fixation using a hot press, the specimens without drilled holes could not be processed normally because swelling occurred. However, swelling did not occur in the specimens with drilled holes.

Binderless fiberboards with densities of 0.3 and 0.5 g/cm3 were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8 MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10 min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a density of 0.5 g/cm3, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions.

In this research, the fracture resistance of barley grain was measured in terms of the grain rupture force and energy. Eight treatments were performed as a randomised complete block design with 10 replications. The barley grains were quasi-statically loaded in horizontal and vertical orientations with the moisture content at four levels: 7.34, 12.11, 16.82, and 21.58% dry basis, and loading rates at two levels: 5 and 10 mm/min. Based on the results obtained, the force required for initiating the grain rupture decreased from 161.97 to 93.94 N, and from 75.37 to 50.16 N, and the energy absorbed at the grain rupture increased from 36.42 to 74.70 mJ and from 27.34 to 62.65 mJ, for horizontal and vertical orientations, respectively, with the increase in the moisture content from 7.34 to 21.58% dry basis. This showed that seeds are more flexible in the horizontal orientation.

Abstract Binderless boards were prepared from kenaf core under various manufacturing conditions and their water resistance properties were evaluated. The board properties evaluated were retention ratios of modulus of rupture (MOR) and modulus of elasticity (MOE), internal bonding strength after water treatment (IB), thickness swelling (TS), water absorption (WA), and linear expansion (LE). These values were then compared with those of boards bonded with urea-formaldehyde (UF), urea melamine formaldehyde (UMF), and phenol-formaldehyde (PF) resins, and their water resistance properties were assessed. We found that pressing temperature was one of the most important conditions for the improvement of water resistance properties. The retention ratios of MOR, MOE, and IB of kenaf core chip binderless boards (pressing temperature 200°C, target density 0.8g/cm³, and the three-step pressing of 6MPa for 10min, then 4MPa for 3min, and 2MPa for 3min) were 37.1%, 49.9%, and 55.7%, respectively, compared with values for UMF-bonded boards of 22.5%, 27.1%, and 40.7%, and values for PF-bonded boards of 42.8%, 41.8%, and 54.1%, respectively. The results showed that the water resistance properties of binderless boards were higher than those of UMF-bonded boards and almost as high as those of PF-bonded boards.

Sweet corn has a very short period of optimum harvest maturity, and its quality changes rapidly close to and following the peak. The aim of this study was to determine the sweet corn quality on the ground of some physicochemical properties of intact kernels (moisture content, compression, shear and puncture force, bulk density, sugar and starch contents) and cut kernels (processing recovery, cut corn yield) at four subsequent harvesting dates. The moisture and sugar levels, and ear yield decreased. The starch level, bulk density (intact and cut kernels), compression force, shear force and puncture force, processing recovery and cut corn yield increased. The first harvesting date showed a greater advantage in the higher sweet corn quality for processing than the second harvesting date. The moisture decreased from 77.41% to 69.83% with delayed harvesting date. A decline was observed in quality characteristics (increase of force in compression, shear and puncture tests, raise in the starch level). However, the second harvesting date had an advantage in a higher processing recovery and cut corn yield.

The effects of the pressing technology and clarification of white grape musts on concentrations of phenolic compounds and their antioxidative capacity were investigated. Four different varieties were processed by hydraulic or pneumatic pressing technologies. In the individual stages of pressing and after the application of different doses of the clarification agent, must samples were analysed for the content of polyphenols and the antioxidative capacity. The highest concentrations of caftaric acid were estimated in the musts made by hydraulic pressing from grapes of Welschriesling variety. On the other hand, musts made from grapes of Gruener Veltliner showed the highest contents of trans-piceid in both variants of pressing. The values of antioxidative capacity of the must samples analysed were not significantly different. The influence of clarification on the changes of phenolic substances in young red wines of Saint Laurent variety was also studied. Six various clarifiers were tested as applied in two different doses. Polyvinylpolypyrrolidone caused the highest losses of trans-resveratrol in the course of red wine clarification. The concentrations of catechin, epicatechin, and total anthocyanins as well as the colour parameters of red wines were influenced at most by the application of egg white.

Quarter-sawn and plain-sawn specimens of Scots pine were semi-isostatically compressed at 5, 15, 50, and 140 MPa in a Quintus press. Elastic strain was measured using a telescope device that was pushed together when wood was compressed and remained in this position at release of pressure. Delayed elastic and plastic strains were assessed through repeated callipering during 5 years after densification. At 140 MPa, wood reached an almost compact structure (ρ ≈ 1450 kg/m3) but as a result of elastic springback the density decreased to just below 1000 kg/m3. At 140 MPa, the elastic and delayed elastic strains were 14.6% and 1.8%, respectively, in quarter-sawn specimens, and were 13.1% and 0.8%, respectively, in plain-sawn specimens. The higher elastic strains in quarter-sawn specimens can be attributed to elastic springback in the tangentially deformed latewood bands.