Constant Moisture Content Research Articles

Analysis of volatile compounds, α-dicarbonyl compounds, and acetic acid in Robusta coffee by soaking with D-xylose and D-ribose

BackgroundThe study investigated the impact of D-xylose and D-ribose soaking methods (autoclaved and non-autoclaved) on Robusta coffee's volatile compounds, α-dicarbonyl compounds (α-DCs), and acetic acid. Robusta coffees were soaked with D-xylose and D-ribose solutions, and the beans were dried until constant moisture content and lightly roasted.ResultsThe sugar treatment led to an 85.6% reduction in pyrazine levels and a 64.4% decrease in pyridine, while pyrroles and furans increased significantly by 84.4% and 16.4%, respectively (p < 0.05). The total concentration of α-DCs was decreased by 24.6–69.2%, with the autoclaved D-xylose sample exhibiting the lowest among all samples. Acetic acid concentration was lower in non-autoclaved samples compared to autoclaved samples (p < 0.05). Principal component analysis indicated autoclave-treated pentose pretreatment reduced pyrazines and increased in the levels of 1-furfurylpyrrole, methyl furfuryl disulfide, 4-ethyl-2-methoxy-phenol, 2-methoxyphenol, 2-acetylpyrrole, pyridine, furfuryl acetate, and acetic acid.ConclusionThis study, utilizing GC–MS, GC–NPD, and HPLC–UV for compound quantification, offers valuable insights into the changes of volatiles, α-DCs, and acetic acid in Robusta coffee soaking with D-xylose and D-ribose, suggesting potential applications in the coffee industry to modulate flavor profiles.Graphical

Experimental Study on Mechanical Properties of Recycled Aggregate Mixed Soil.

In the context of efforts aimed at reducing carbon emissions, the utilization of recycled aggregate soil mixes for soil stabilization has garnered considerable interest. This study examines the mechanical properties of mixed soil samples, varying by dosage of a soft soil curing agent C, recycled aggregate R content, and curing duration. Mechanical evaluations were conducted using unconfined compressive strength tests (UCS), field emission scanning electron microscopy (FESEM), and laser diffraction particle size meter tests (PSD). The results indicate that the strength of the mixed soil samples first increases and then decreases with higher dosages of recycled aggregate, reaching optimal strength at a 20% dosage. Similarly, an increase in curing agent dosage enhances the strength, peaking at 20%. The maximum strength of the mixed soils is achieved at 28 days under various proportions. The introduction of the curing agent leads to the formation of a flocculent structure, as observed in FESEM, which contributes to the enhanced strength of the soil mixes. Specimens prepared with a combination of 20% R and 20% C, maintained at a constant moisture content of 20%, and cured for 28 days exhibit a balance between economic, environmental, and engineering performance.

Effect of free vibration on mechanical characteristics of Bi-directional functionally graded beams under hygrothermal effect

ABSTRACT The effect of free vibration on mechanical characteristics of bi-directional functionally graded material (BDFGM) beams under the influence of hygrothermal effects involves the application of the harmonic differential quadrature method (HDQM). The material parameters are supposed to vary in both axial and thickness directions. The temperature distribution is employed along the length direction of the BDFGM beams while maintaining a constant moisture concentration. An exponential law with axial thermal variation under moisture effect is investigated to analyse vibration behaviour in the BDFGM beams using the HDQM. Hamilton’s principle is used to obtain governing equations. Three kinds of temperature distribution profile were considered i.e. uniform (UTR), linear (LTR) and nonlinear temperature rise (NLTR). Free vibration analysis is performed using the HDQM. The precision of the HDQM is validated by comparing it with prior studies. Various configurations of boundary conditions, including supported, clamped, and free, are considered. Parametric results are investigated to explore the effect of the exponent parameters, temperature profile and constant humidity content. Results indicate that temperature, constant moisture content, material properties, and different end conditions significantly influence natural frequency. The outcomes can be applied to designing two or more directional FGM structures for different environmental conditions.

Locust bean gum as an adhesive for wood particleboards

Locust bean gum, derived from the carob tree, was evaluated as a biobased adhesive in particleboard manufacturing, investigating the effect of adhesive amount, mat moisture content, and process parameters such as temperature and time. Single-layer particleboards prepared with locust bean gum showed that effective hydration of the polymer chains is necessary to achieve satisfactory interactions with wood and thus yield a sufficient particleboard strength. A mat moisture content below 30 % resulted in weak particleboards, which easily broke immediately after pressing. With increasing mat moisture content, while keeping the adhesive amount constant, the internal bond strength was increased. Moreover, with constant mat moisture contents (40 %), the internal bond strength increased when the adhesive amount was increased, even though not proportionally. With an increase from 9 % to 18 % adhesive, the internal bond strength was increased by more than 100 %. However, with a further increase in adhesive content from 18 % to 36 %, the increase in internal bond strength was statistically insignificant. Even with high mat moisture contents (35–45 %), larger lab-scale particleboards had internal bond strength that fulfilled standard requirements for P2 boards, commonly used for furniture in dry conditions (SS EN 312), when the pressing time was long enough (75 s/mm) to allow for water and vapors to be removed before releasing the pressure. Using biopolymers as adhesives, without extensive chemical modification and hazardous crosslinkers, could lead to a more benign and sustainable particleboard production. Since the chemistry and setting/curing processes of biopolymer-based adhesives differ from those of the fossil-based adhesives used today, increased understanding of how production parameters affect the properties of the particleboards prepared with biopolymers may pave the way for their better utilization in this field.

Process Parameters Optimization for Continuous Infrared Rice Bran Stabilizer and Assessment of Their Impact on Quality and Shelf Life

Background: Rice bran is the most valuable by-product of the rice milling operation. The FFA level rises immediately after milling and bran oil becomes hazardous for consumption owing to its lower pH, rancid flavor and soapy taste. Methods: A continuous-type infrared rice bran stabilizer was designed and process parameters such as moisture content, thickness, power density and treatment time were optimized for their impact on FFA content of bran, capacity and energy demand of the stabilizer using response surface methodologies. Under constant power density and moisture content, it has been confirmed that the capacity decreases with infrared exposure time. Result: The capacity was minimum (6.7 kg/h) at 0.5 cm thickness and 5 min exposer times, whereas it was maximum (40.2 kg/h) at 1 cm bed thickness and 3 min exposer time. The energy demand rose as the power density and time of exposure increased while the bed thickness and moisture content remained constant, whereas the FFA lowered nonlinearly as the power density and exposure time increased. FFA content was shown to be low at lower bed thickness and moisture content and to increase slowly as thickness and moisture content increased to 0.8 cm and 15% (w.b), respectively. However, when bed thickness and moisture level increase further, FFA content raised dramatically.

Harmonizing Drying Time, Layer Thickness, and Drier Zones for Drying Kinetics: Quality and Safety of Solar Tunnel-Dried Wet-Processed Parchment Coffee (Coffea arabica L.).

Tunnel solar dryer is the recently used drying method for better quality and safety of parchment coffee. However, the higher variation of drying temperature and RH along the long tunnel solar dryer results in a heterogeneous environment in the tunnel, which could make parchment coffee dried at different times or with different moisture contents. This study is aimed at investigating the effect of solar tunnel dryer zones at different zones of the dryer, divided into three zones from the inlet to the exit side of the drier and drying layer thicknesses on the drying time, drying kinetics, physicochemical, sensory, and fungal growth loads of parchment coffee. Furthermore, seven mathematical models were evaluated to select the best-fitting model for a specific zone to predict drying time. Results showed that dryer zones significantly (p < 0.05) interacted with layer thickness for most of the measured parameters except titratable acidity and sensory properties. The dryer zone, coupled with the reduction in drying layer thickness, caused an increase in effective diffusivity and moisture removal rate and reduced drying time. The drying time to reach constant moisture content varied from 14 to 17 hours. Overall raw bean, cup, and total quality varied from 36.3 to 37, 48 to 51, and 84.3 to 87.3%, respectively. Values for physicochemical parameters ranged from 5.3 to 6.9 (pH), 2.1 to 2.6% (titratable acidity), 2.3 to 4.3°Brix TSS, 10.9 to 15.2% (ether extract), 39.2 to 53.5GAE/g (total phenolic content), and 38.5 to 59.2 (DPPH scavenging capacity). The fungal infection percentage at the end of drying varied from 4 to 93.3%, which could be associated with potential mycotoxin formation if recommended conditions were not maintained. In general, for better quality, similar drying times, and a lesser fungal load, it is recommended to use 4, 5, and 6 cm layer thickness in zones one, two, and three, respectively. The drying kinetics of parchment coffee in different dryer zones with different drying layer thicknesses showed variation. Zone one at 2 and 4 cm layer thicknesses is best described by the Verma model. Four- and six-centimetre layer thicknesses in zones 2 and 3 are best described by the modified Midilli model.

Effects of different pressures and veneer moisture content in adjacent layers on properties of PUF bonded plywood

In practice, for the manufacture of plywood, the veneer is usually dried to a moisture level suitable for bonding. However, anatomical differences within and between veneer sheets are a significant factor and some of them may contribute to significant differences in moisture content (MC). The novelty of this work was to study the possibility of using wood veneers of different MC in adjacent layers in one structure of plywood panels and how this affects the physical and mechanical properties of the panels. The Norway spruce (Picea abies L. Karst) wood veneers with mean MC approximately of 2%, 5% and 7% and phenol-urea-formaldehyde (PUF) resin were used in the experiments. The five-layers plywood panels were manufactured at the two pressing pressures of 0.8 MPa and 1.2 MPa. There was no significant difference in the bending and bonding properties, but only wood failure as measured on bonding specimens which showed higher average values on specimens manufactured with high pressure during hot pressing. Higher differences in MC of each veneer with constant MC of the veneer stack didn’t worse bending and bonding properties of plywood.

Large scale land reclamation and the effects on hydro-mechanical behavior in loess and loess-derived fill

To discover the complex hydro-mechanical evolution on Loess Plateau that accompany large-scale land reclamation project, we tracked changes of moisture, matric suction, anisotropic displacements and stresses in geological interfaces of natural loess and deep man-made fill during a comprehensive process of construction and the subsequent three years rest period. Results indicate that vertical stress increases during emplacement of thick fill, while the lateral earth pressure first increases and then gradually decreases with elapsed time. There was a non-linear increase in lateral earth pressure with depth of infill during construction. Whereas lateral earth pressure decreased with depth in lengthy rest period. The fill vertically compressesed and laterally extended during construction, while the geological interface of fill and loess laterally rebounded during construction pause. The primary vertical displacement occurred at the contact zone between the original loess slope and fill. The lateral earth pressure coefficient of infill is influenced by lateral compression and extension of contact zone during land reclamation process. It mirrors the observation that variations in lateral earth pressure with depth are dependent on deformation of natural slope materials. Interestingly, vertical stress and lateral earth pressure periodically fluctuated during rest period, correlating to creeping and shrinkage in loess influenced by moisture content change under different environmental relative humidity. The volumetric moisture contents in fill and contact zone significantly increased during construction. The moisture content of contact zone is 10% higher than the overlying higher density fill after construction, which is attribute to the process of matric suction equilibrium. Considering a constant moisture content, the ratio of historical mean principal stress to deviatoric stress in fill and interface are under the principal stress failure line during construction. However, water diffusion potentially threats the stability of this man-made geological structure.

Applying the Porosity-to-Cement Index for Estimating the Mechanical Strength, Durability, and Microstructure of Artificially Cemented Soil

Fine, expansive, and problematic soils cannot be used in fills or paving layers. Through additions to these soils, they can be converted into technically usable materials in civil construction. One methodology to make them viable for construction is through a stabilization process. Nevertheless, current methodologies regarding dosage based on compaction effort and the volumetric amount of binder used are unclear. Thus, this research describes cement-stabilized sedimentary silt's strength and durability properties from Curitiba (Brazil) for future application in paving. Splitting tensile strength, unconfined compressive strength, and loss of mass against wetting and drying cycles (W-D) were investigated in the laboratory utilizing greenish-gray silt (originating from one of the Guabirotuba Formation layers, Paraná) and high-early strength Portland cement- ARI (CPV). Utilized were cement concentrations (C) of 3, 5, 7, and 9%, molding dry unit weights (d) of 14, 15, and 16 kN/m3, curing periods (t) of 7, 14, and 28 days, and constant moisture content (w) of 23%. With an increase in cement concentration and curing time, the compacted mixes demonstrate an increase in strength, an improvement in microstructure, and a decrease in accumulated mass loss (ALM) and initial porosity (η). Using the porosity/volumetric cement content ratio (η/Civ), the lowest amount of cement required to stabilize the soil in terms of strength and durability was determined. The porosity/cement index provided an appropriate parameter for modeling the mechanical and durability properties, and a unique equation between the strength/accumulated loss of mass and the porosity/binder index was obtained for the curing times studied. Lastly, C = 5% by weight is the minimum acceptable amount for prospective subbase soil application. Doi: 10.28991/CEJ-2023-09-05-02 Full Text: PDF

Effect of oil exposure stages on the heat resistance of Salmonella enterica serovar Enteritidis phage type 30 in peanut flour

The oil in low-moisture foods (LMFs) shows protective effects on bacteria during thermal processing. However, the circumstances under which this protective effect strengthens remain unclear. This study aimed to understand which step of the oil exposure to bacterial cells (inoculation, isothermal inactivation, or recovery and enumeration step) in LMFs can enhance their heat resistance. Peanut flour (PF) and defatted PF (DPF) were selected as the oil-rich and oil-free LMF models. Salmonella enterica Enteritidis Phage Type 30 (S. Enteritidis) was inoculated into four designated PF groups representing different oil exposure stages. It was isothermally treated to obtain heat resistance parameters. At a constant moisture content (aw,25°C = 0.32 ± 0.02) and controlled aw,85°C (0.32 ± 0.02), S. Enteritidis exhibited significantly high (p < 0.05) D values in oil-rich sample groups. For instance, the heat resistance values of S. Enteritidis in the PF-DPF and DPF-PF groups were D80°C of 138.22 ± 7.45 min and 101.89 ± 7.82 min; however, the D80°C in the DPF-DPF group was 34.54 ± 2.07 min. The oil addition after the thermal treatment also helped injured bacterial recovery in the enumeration. For instance, the D80°C, D85°C, and D90°C values in the DFF-DPF oil groups were 36.86 ± 2.30, 20.65 ± 1.23, and 7.91 ± 0.52 min, respectively, which were higher than those in the DPF-DPF group at 34.54 ± 2.07, 17.87 ± 0.78, and 7.10 ± 0.52 min. We confirmed that the oil protected S. Enteritidis in PF in all three stages: desiccation process, heat treatment, and recovery of bacterial cells in plates.

Diurnal Monitoring of Moisture Content of Scots Pine and Small-Leaved Lime Trunks Using Ground Penetrating Radar (GPR) and Increment Cores

Ground penetrating radar is non-invasive technology suitable for mapping moisture content variations since it shows high sensitivity to changes in water saturation. In this work we used a GPR tomography approach to estimate moisture content within two small-leaved lime (Tilia cordata) and two Scots pine (Pinus sylvestris) trunks. Additional information was derived using the method of GPR zero-offset. GPR data was collected in Moscow (diurnal monitoring in September 2021) using a shielded GPR antenna working at 1500 MHz. Moisture values derived from GPR data were compared with the values obtained directly by measuring sampled wood cores gravimetrically. A good agreement was observed between GPR-derived moisture content and core sample-derived values. Notwithstanding GPR-derived moisture content is about two times higher than core sample-derived values, a strong linear relation with a determination coefficient more than 0.8 is observed. Diurnal monitoring did not reveal any significant changes in moisture content inside the trunks. It can be concluded that the period of early autumn in the Moscow region is characterized by a constant moisture content of the small-leaved lime trunk during the day.

Graphic Analytical Methods for Determining Moist Air Characteristics in Multistage Compressors

The purpose of the study is a comparative analysis of methods for graphic analytical determination of the characteristics of moist air in multistage compressors. Two methods are compared, which differ in the used I-d-diagrams: unified in terms of pressure and atmospheric. I-d-diagrams unified in terms of pressure differ from atmospheric ones by diagrams of saturated air relative humidity () only at various pressures. For multistage compressors, curves are plotted on unified I-d-diagrams at atmospheric pressure and compressed air pressure in intercoolers and receivers. It is assumed that the isobaric cooling of compressed air and condensation of its water vapor occurs in coolers and receivers at the final compression pressure in the previous compressor stages. The method, which uses I-d-diagrams unified by pressure, involves the diagram plotting of air compression and cooling on a grid of curves. An example of plotting such diagrams for a two-stage compressor with an intercooler and a receiver is given. A detailed description of the thermodynamic state of moist air in such a compressor is given. The nodal points of the processes in the compressor are plotted on a pressure-unified I-d-diagram according to the known values of moisture content and air temperature. The pressure and temperature at the end points of compression are calculated by the equations of the polytropic process at n = 1.26. The dew points in the cooler and receiver are graphically defined as the intersection of the curves for the final compression pressures with the corresponding straight lines for constant air moisture content in the compressor stages. The technique using atmospheric (barometric) I-d-diagrams is used in the absence of unified I-d-diagrams suitable for pressure. The essence of the developed technique is to determine the curves on the atmospheric I-d-diagrams, graphically coinciding with the curves A numerical example of the application of such a technique is given. The advantages and disadvantages of both methods are evaluated.

Evaluation of Split-Type Air Conditioner Performance under Constant Outdoor Moisture Content and Varied Dry-Bulb Temperature

An experimental investigation on the performance of an air conditioner and its operating conditions under constant outdoor moisture content and varied dry-bulb temperature has been accomplished. The test was conducted on an air conditioner using R32 with a nominal cooling capacity of 2.6 kW and the test was carried out in a controlled and standardized test room. During the test, the outdoor temperature was varied from 24 to 36℃ while maintaining the humidity ratio at 14.9 kg vapor per 1 kg of dry air. The indoor compartment was maintained at 27℃ dry-bulb temperature and 19℃ wet-bulb temperature. Generally, as the temperature of outdoor air increases by 1℃, the input power increases by 1.4%, the cooling capacity decreases by 0.9%, and the coefficient of performance decreases by 1.95%. In addition, the outdoor air temperature has a more significant effect on the refrigerant discharge and liquid line temperature than that of refrigerant suction temperature.

Energy consumption computing of cold plasma‐assisted drying of apple slices (Yellow Delicious) by numerical simulation

AbstractEnergy consumption is a great challenge during fruit drying. New techniques such as cold plasma are used as pretreatment or the main treatment for food drying. In this work, apple drying with cold plasma was investigated with COMSOL simulation. Two treatments were designed: (a) traditional air drying at 60°C and 0.5 m/s airflow, and (b) cold plasma treatment at 100 W, and 60 Hz with laminar airflow at 60°C and 0.5 m/s. The samples were two apple slices with a 6 cm diameter and 0.3 cm thickness. Results show that plasma technology without airflow does not have an effective role in drying. But the combination of plasma and airflow drying reduced the drying time from the 9,600 s to 3,600 s. The plasma‐treated samples reached a constant moisture content faster than the air‐dried samples. The energy consumption of drying with plasma was 85‐fold lower than a traditional air‐drying method. The shrinkage of plasma‐treated samples was low and the total shrinkage was near the undried sample (0.008). Cold plasma probably can reduce the energy consumption, drying time, and final drying costs of fresh food drying.Practical applicationDrying with a combination of methods can reduce the processing time. In this work, the plasma technology was combined with air drying and the results show lower process time, lower shrinkage, and lower energy consumption. Plasma technology in combination with traditional air drying can reduce the drying time of food material from 9,600 s to 3,600s. The energy consumption of plasma drying was significantly lower than air drying. It can be concluded from these results that this drying method can be applied to study the drying of different types of food material.

Drying of garlic slices by electrohydrodynamic‐hot air method

AbstractIn this study, garlic slices were dried with a new drying method, electrohydrodynamic‐hot air combined drying system, under different temperatures (55 and 60°C) and voltages (15, 20, 25, and 30 kV), and the effects of drying conditions on drying time, color parameters, rehydration capacity, energy values, and microstructure were investigated. In addition, experimental data were fitted into 10 different mathematical models that are widely used to select the appropriate model that could describe the drying behavior of garlic slices. The longest drying time required for constant moisture content was observed under 30 kV‐60°C treatment for 100 min, while the shortest drying time was observed under 15 kV‐55°C treatment for 160 min. Verma et al., Diffusion Approach, and Newton models were determined so as to find the most suitable model for the drying behavior of thin‐layer dried garlic samples at different temperatures and voltages. Increasing drying temperature caused a decrease in the a* and b* values of the garlic samples. The lowest energy consumption during the drying of the garlic slices was found at 30 kV‐55°C treatment combination. It was observed that the temperature and kV values have impact on the product microstructures.Practical ApplicationDrying is the preservation process to extend the shelf life of products. The traditional method is the most used one in the drying industry. The low energy efficiency of this method and the loss of quality due to the high contact of the hot air with the product have led to the research of new methods. Therefore, the electrohydrodynamic method is used as a new approach that results in high energy efficiency and a high‐quality product. As a result, integrating the electrohydrodynamic system into the hot air drying method will reduce the contact of the hot air with the product, thus prevents the negative effect of temperature and provides better quality products. In addition, this system can increase the drying efficiency and energy economy by reducing the drying time and energy consumption in drying procedure of garlic samples.

Effect of vacuum environment on air side heat and mass transfer characters of plain fin-tube heat exchangers

Air-side heat and mass transfer performance of plain fin-tube heat exchangers at different vacuum degree have been experimentally investigated. In this experiment, influence of air inlet humidity on air-side heat and mass transfer under vacuum environment is studied by controlling vacuum degree and air inlet humidity. Results show that: variation trend of air-side sensible heat transfer coefficient (ha), heat transfer j-factor (jh), mass transfer coefficient (hm) and mass transfer j-factor (jm) are not all time remain the same. Variation trend of ha, jh are the same with increase of vacuum degree when air inlet humidity changes, ha is gradually decreased and jh is gradually increased. Variation trend of hm is opposite with the increase of vacuum degree when the air inlet humidity changes. Under constant air inlet relative humidity conditions, hm is gradually increased. Under constant air inlet moisture content conditions, hm is gradually decreased. However, variation trend of jm is the same with increase of vacuum degree when air inlet humidity changes, both are increased. But slope of jm is greater under constant air inlet relative humidity conditions. Overall heat transfer performance is greatly affected by air inlet humidity changes. Under constant air inlet relative humidity conditions, when air inlet relative humidity increases from 50% to 70% and then to 90%, proportion of latent heat transfer increases from 30.98%∼53.99% to 36.53%∼56.95% and then increases to 44.19%∼64.04% with vacuum degree increases. As proportion of latent heat transfer increases, air-side total heat transfer performance is not obviously reduced. Under constant air inlet moisture content conditions, when air inlet moisture content increases from 15 to 20 g/kg, proportion of latent heat transfer is basically unchanged with increase of vacuum degree, at about 36% and 37%, respectively. So, total heat transfer performance on air side decreases obviously. In order to model air-side heat and mass transfer performance of the complex structure fin-tube heat exchangers, a simplified model is investigated under vacuum environment. Results show that influence of pressure changes on heat and mass transfer based on theory is basically consistent with the results of regression analysis based on experimental results. This study can provide guiding suggestions for the design of heat exchangers under vacuum environment.

THE IMPACT OF PRODUCTION TREATMENTS OF FEED CONCENTRATE PRODUCED FROM WASTE OF CEREAL PRODUCTION ON ITS BIOLOGICAL VALUE AND EFFICIENCY IN THE COMPOSITION OF COMPOUND FEED FOR CARP

The following article presents a new raw component in compound feed for carp – feed concentrate produced from cereal production waste. The feed concentrate is based on several types of cereal fodder meal - wheat, pea, barley, as well as wheat bran and unshelled oat grain. The feed concentrate is balanced according to the needs of carp and can be used as feed for carp instead of wheat grain or as a part of compound feed for carp. Heat-moisture processing of compound feed before extrusion is one of the main stages that further ensure the stability of technological processes and the final quality of the feed concentrate. The amino acid composition was determined at various temperatures of the feed concentrate after heat-moisture treatment of + 40, 60, 70 and 80º С at a constant moisture content of the concentrate of +282° С. Amino acid score has been calculated for feed concentrates that have been exposed to various heat treatments. The amino score was calculated in relation to the carp's need for essential amino acids. It was found that an increase in the temperature of the concentrate during heat-moisture treatment leads to a decrease in the content of essential amino acids. For example, the total content of methionine and cysteine in the composition of the feed concentrate at a temperature of +75° C was 0.46%, with the minimum allowable total content of these amino acids in the composition of feed 0,5%. Heat-moisture treatment at a product temperature above +75° C leads to a decrease in the content of essential amino acids and the biological value of the feed concentrate.The process of extrusion of feed concentrate from waste of cereal production has been studied. The glucose content in the feed concentrate was studied at various extrusion modes. The glucose content indicates the degree of modification of the starch during the extrusion process, and the more glucose the product contains, the better it is absorbed by the carp. When extruded with an increase in temperature, the starch passes into a viscous-flowing (gelatinized) state, forming a so-called melt, the cooling of which also leads to the formation of a three-dimensional gel network. The feed concentrate granule becomes monolithic in structure; it becomes quite hard and can harm the intestines of carp. Therefore, it contains wheat bran in an amount of 1%, as a component that is able to weaken the feed concentrate granule. The degree of starch destruction in the composition of the extruded feed concentrate with the addition of wheat bran reached its maximum and the granule became porous, its hardness decreased. It was detected that when the temperature of the feed concentrate after extrusion rises above +100°C, the biological value of the feed concentrate decreases, and it becomes unbalanced in the content of such essential amino acids as lysine, threonine, methionine and cysteine. Therefore, the optimum product temperature after extrusion is +90-100˚C.The effectiveness of extruded feed concentrate was determined in the composition of granulated feed for two- and threeyear-old carp. The feed ratio of the compound feed containing the feed concentrate was 0.9 units, which is 64% lower than of the control compound feed, which includes a non-extruded grain group that is not balanced in terms of carp needs.

Three-dimensional Movement and Distribution of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) Adults in Stored Wheat Under Constant Temperatures and Moisture Contents.

Understanding the movement and distribution of insects inside a grain bin is crucial to develop an effective stored grain management protocol. The three-dimensional movement and distribution of adult Cryptolestes ferrugineus (Stephens) at 20 and 30°C were determined in a 0.7 × 0.7 × 0.7 m3 (internal dimensions) wooden box filled with wheat of uniform moisture contents (12.5 ± 0.1%, 14.5 ± 0.1%, and 16.5 ± 0.1% wet basis). The wheat at a constant moisture content was filled into 343 mesh cubes (0.1 × 0.1 × 0.1 m3) and placed inside the wooden box. The center mesh cube in the box had one hundred adult insects introduced at the beginning of the movement. After 24 h, the 343 mesh cubes were removed from the wooden box in less than 45 min. Finally, the contents of each mesh cube were sieved, and the insects counted. Each experiment was replicated three times. A maximum of 17% of insects stayed at the introduced cube (center of the wooden box). About 50-88% of the introduced adults moved downward from the introduction location at the studied temperatures and moisture contents. This 24 h study showed that C. ferrugineus movements in three dimensions follow a diffusion pattern in the horizontal direction and move downward due to the 'drift' effect and geotaxis in the vertical direction.

DEVELOPMENT OF WOOD GRINDING. 3. FURTHER TESTING OF GRINDING MODELS

"The study is the continuation of a sequence of works devoted to describing the mechanisms occurring during stone grinding of wood. This part was aimed at further testing of pressurised grinding of spruce wood, which was conducted under controlled laboratory conditions. Testing of the developed theoretical model for power ratio (Pc/Pt) versus energy specific production (Ġw/Pt) produced linears for data representing constant wood moisture content. However, the linears showed almost identical results for fresh woods, and also for drier wood, e.g. wood containing saturated fibres and air-dried wood, although one would expect some differences due to the widely varying constant moisture, from 65% to 15% moisture content. Simplification of the model resulted in (cw + X cm) ΔTp-w ≈ Pt / Ġw, and it led to specific linears, when the members as such were correlated between themselves at several constant wood moisture contents. The results were briefly as follows. Increasing wood feed rate – 0.7, 1.0 and 1.3 mm/s – decreased the specific energy requirement, while increased stone surface speed – 20 and 30 m/s – increased it. The left-hand member or the “X-factor” as named in this context, correlated with the right-hand member or the specific energy requirement and resulted in declining linears. The lower the wood moisture content – 65, 58, 44, 28 and 15% – the smaller was the linear declination, and also the difference due to stone surface speed. The application of an energy balance could be useful in searching for a working wood grinding model. Such a model would enable critical examination of wood grinding conditions. Also, it would help understanding the mechanism of various factors, such as grinding parameters, wood properties and stone burr and sharpness. It seems that there are factors that are not known well enough for further development of grinding. Shower water flow and temperature affect the stone surface temperature as known, but their significance for the energy balance or grinding mechanism are not known. Also, the thin film of pulp slurry between the stone surface and the heat activated wood layer is evidently a significant factor that is connected to the local energy transfer. "

Performance Evaluation of a Small-Scale Mechanical Fish Feeder

The performance evaluation of an existing mechanical fish feeder was carried out. Floating feeds of sizes 2 mm, 4 mm, and 6 mm at constant moisture content of 13 % were fed into the feeder. The feeder was powered by a 3-phase, 1.5 kW reducing gear electric motor at speed 40 rpm, 50 rpm, 60 rpm, 70 rpm and 80 rpm machine. It was observed that the horizontal screw conveyor effectively transported the material from the hopper to the discharged point. The results obtained from the tests showed an optimal performance of the machine at speed 50 rpm with dispensing efficiency of 93.1 % for 2 mm feed size, while the throughput was 75.76 kg/h at motor speed of 80 rpm also for the 2 mm fish feed size. The ANOVA at p ≤ 0.05 showed that machine speed has significant effect on its dispensing efficiency and the throughput capacity. The cost of production of the mechanical fish feeder was ₦262,300 which made it affordable for young entrepreneurs.