Search Results (7)

Rye flour is a commonly used filler in plywood production, made from finely ground rye grains. It enhances glue viscosity, ensuring even distribution and better adhesion, which improves the plywood’s mechanical properties, dimensional stability, and resistance to warping. Additionally, rye flour increases the plywood’s strength and durability, making it more resistant to mechanical damage and external factors. Its affordability and availability further support its widespread use in plywood production. However, the growing availability of new raw materials has sparked interest in alternative fillers, especially considering food waste challenges caused by low demand or poor household management. This study explores the potential of spirulina, bamboo flour, lupine flour, and coconut flour as alternative fillers to rye flour, being part of the food chain, in three-layer plywood production. Plywood panels were manufactured using birch and pine veneers, urea-formaldehyde resin, and varying filler contents (10, 15, and 20 parts by weight/pbw). Key mechanical properties were evaluated, including modulus of elasticity (MOE), modulus of rupture (MOR), shear strength, density profile, and filler water absorption. The highest MOE for hardwood plywood was observed with coconut flour (20 pbw, 17,228 N mm⁻²). Conversely, the lowest MOE values were recorded for coniferous plywood with spirulina (8440 N mm⁻²). For MOR, the best performance in softwood was achieved using lupine flour (10 pbw, 113 N mm⁻²), while coconut flour yielded the highest MOR in hardwood plywood (20 pbw, 177 N mm⁻²). Spirulina exhibited the lowest MOR (72 N mm⁻², 15 pbw). Shear strength peaked with lupine and coconut flour. The filler composition determines adhesive properties and bond performance through water absorption, structural interactions, and filler content optimization. These findings emphasize the potential for fine-tuning alternative fillers to achieve desired mechanical performance, ensuring sustainable and efficient plywood production. These also demonstrate the potential of certain alternative fillers, particularly coconut and lupine flours, excluded from the food value chain, in improving specific properties of plywood. Full article

This study evaluated the refinement of sorghum, corn, and cowpea grains using the processing steps and equipment originally designed for wheat milling that consists of a conventional gradual reduction system. The need to mill these grains resulted from a desire to produce alternative ingredients for developing new fortified blended extruded foods used for food aid programming. Milling of white sorghum grain resulted in a crude protein content of 7.4% (wb) for both whole and coarse-milled flour. The crude protein content in whole fine-milled sorghum was 6.8% (wb), which was significantly lower than that of whole coarse flour at 9.3% (wb). A decrease in the ash content of sorghum flour correlates with the decortication process. However, degermed corn, fine and coarse, had significantly different crude protein content of 6.0 ± 0.2% (wb) and 7.7 ± 0.06% (wb), respectively. Degerming of corn improved the quality of corn flour (fine and coarse) by reducing the crude fat content from 3.3 ± 0.18% (wb) to 1.2 ± 0.02% (wb) and 0.6 ± 0.13% (wb), respectively. This helped increase the starch content from 60.1 ± 0.28% (wb) in raw corn to 74.7 ± 0.93% (wb) and 71.8 ± 0.00% (wb) in degermed fine and coarse corn flour, respectively. Cowpea milling did not produce differences in the milling stream outputs when the crude fat and crude protein were compared. Whole flour from the grains had higher milling yields than decorticated flour. This study demonstrated that a mill dedicated to wheat size reduction can be adapted to refine other grains to high quality. Full article

Two rice varieties were used to study the effect of freezing and grinding processes on rice flour properties. The freezing and grinding processes followed by sieving mainly affected the particle size distribution, starch damage, and amylose content of flours. In case of both rice varieties, the percentage of fine particles increased in the flours obtained from frozen rice. Freezing caused the increase of the flour yields from 45.5–50.9% to 54.6–56.5% and the decrease of the flour fineness modules. Moreover, the amylose content and starch damage registered changes when grinding frozen rice, but in case of those parameters, the values are influenced additionally by the native starch properties of variety and most probably by the texture of the endosperm. The swelling power, water solubility index, and gelatinization temperature were higher in flour from frozen rice compared to the flour from non-frozen rice. The modifications generated by rice freezing prior to grinding resulted in increased mechanical properties and decreased thermo-mechanical weakening of proteins. The hardness of the gel was directly correlated with the amylose content, while the freezing process led to the increase of the dough breakdown and starch retrogradation. Full article

Coffee husk, a major lignocellulosic waste derived from the coffee industry, was first ground into flour of fine particles of approximately 90 µm and then torrefied at 250 °C to make it more thermally stable and compatible with biopolymers. The resultant torrefied coffee husk flour (TCHF) was thereafter melt-compounded with polylactide (PLA) in contents from 20 to 50 wt% and the extruded green composite pellets were shaped by injection molding into pieces and characterized. Although the incorporation of TCHF reduced the ductility and toughness of PLA, filler contents of 20 wt% successfully yielded pieces with balanced mechanical properties in both tensile and flexural conditions and improved hardness. Contents of up to 30 wt% of TCHF also induced a nucleating effect that favored the formation of crystals of PLA, whereas the thermal degradation of the biopolyester was delayed by more than 7 °C. Furthermore, the PLA/TCHF pieces showed higher thermomechanical resistance and their softening point increased up to nearly 60 °C. Therefore, highly sustainable pieces were developed through the valorization of large amounts of coffee waste subjected to torrefaction. In the Circular Bioeconomy framework, these novel green composites can be used in the design of compostable rigid packaging and food contact disposables. Full article

The aim of the study was to compare the physical and sensory properties of gluten-free bread with the addition of whole and ground flax seeds. The grinding process of flax seeds was carried out using a knife grinder and ball mill. After short-knife grinding (20 s) (GM-200, Retsch), the seeds were divided into whole (average particle size 0.634 mm), coarse (769 mm) and fine (0.328 mm) flour, and these flours were additionally ground with ball milling (60 s) (Pulverisette 6, Fritsh). The grinding energy of seeds was evaluated. Baking of gluten-free bread was performed with 10% addition of different forms of whole and ground flaxseeds. The colour, volume, texture and sensory parameters of bread were evaluated. In addition, the crumbling index of bread was developed and defined as the percentage share of crumbed pieces of the bread slice in relation to the mass of the entire crumb sample cut out together with crumbs. Specific grinding energy of flaxseeds during short (20 s) knife grinding was equal to 109.5 J·g⁻¹, and additional ball milling (60 s) caused significantly (α = 0.05) more than 4 times higher energy consumption, but more reduced particles of whole (0.497 mm), coarse (0.621 mm) and fine flour (0.308 mm) were obtained. After adding ground seeds, it was necessary to add more water to the dough, which increased dough yield from 220% to 240% and even to 260% when ball milling of coarse flax flour was applied. The most significant increase in the volume of bread and the most reduced crumbling was observed for breads with addition of coarse fractions of flaxseeds ground with ball milling. In comparison with the control sample of gluten-free bread; significant improvement in bread volume, textureand sensory evaluation was observed after using both whole and ground flaxseeds. Furthermore, the crumbling index was related to an organoleptic evaluation and can be used in bread quality assessment as a complement to instrumental texture measurements. Full article

The size distribution of wheat-grain starch granules has an impact on the yield of fine flour. The aim of the study was to compare the impact of conventional (mineral fertilizers, pesticides) and organic farming treatments (cover crops, composted cattle manure) on (i) the size distribution of starch granules, (ii) the level of the first break whole and fine flour yield. The grain samples of winter wheat cv Fredis were taken from a long-term field crop rotation experiment established in 2008 at the Estonian University of Life Sciences in Tartu County (58°22′ N, 26°40′ E) on Stagnic Luvisol soil. The weather conditions during the grain filling period of winter wheat had a strong impact (p < 0.001) on the grain starch granule size distribution. The proportion of starch granules with a smaller diameter (C-type granules) was higher in years with a longer grain filling period. The size distribution of starch granules was not influenced by farming system. The increased proportion of C-type granules increased the fine flour yield significantly. Fertilisation with organic manure and twice with mineral nitrogen increased significantly the mean diameter value of different starch granules. Full article

The use of defatted soybean flour (DSF) in food as a source of dietary fiber has been limited due to its rough texture and bitter taste. Our previous work indicates that superfine DSF prepared by jet milling could overcome these problems, as it positively affected physical and sensory properties. Therefore, differently sized DSFs were incorporated in tofu, and their impacts on physical and sensory properties were investigated in this study. Coarse DSF (Dv₅₀ = 341.0 µm), fine DSF (Dv₅₀ = 105.3 µm), and superfine DSF (Dv₅₀ = 5.1 µm) were prepared by conventional sifting and jet milling. Tofu was made with a 5% addition of differently sized DSFs and without DSF (control tofu). The quality of tofu was evaluated by scanning electron microscopy, color measurement, texture profile analysis, and quantitative descriptive analysis. The tofu made with coarse and fine DSF showed negative changes in its physical and organoleptic qualities, such as reduced yields, a less pure color, a harder texture, and a rougher mouthfeel. However, the tofu made with superfine DSF showed only minimal changes in its qualities compared to the control. Therefore, superfine DSF is a promising fiber supplement that does not change the physical and sensory properties in the making of high-quality tofu. Full article