INSTRUCTIONS FOR PREPARATION OF MANUSCRIPTS FOR DIRECT REPRODUCTION

ABSTRACT

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met me adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and die effect of moisture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m³/s-m². A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the airflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

Pressure drop through in-bulk flax seeds

The airflow resistance of in-bulk flax seeds (Linum usitatissimum) and the effect of airflow rate, bed depth, type of packing, and presence of foreign material (“fines” and “chaff”) were studied. A good fit of the experimental data (R > 0.993) was obtained through the model DPL = cQ + dQ ² (where DPL is pressure drop per unit of bed depth, Pa/m; Q is airflow rate, m³/s-m²; c and d are constants; and airflow range is 0.011–0.141 m³/s-m²). The airflow resistance increases when bulk density and bed depth increase. In dense packing the pressure drop is 1.3 to 1.5 times the pressure drop in loose packing. The resistance increases with the increase of fines and decreases with the increase of chaff.     

BULK DENSITY, POROSITY AND RESISTANCE TO AIRFLOW OF GARLIC SLICES

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met me adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and die effect of moisture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m³/s-m². A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the airflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

Resistance to airflow through bulk pistachio nuts (Kalleghochi variety) as affected by moisture content, airflow rate, bed depth and fill method

The prediction of airflow resistance is fundamental to the design of efficient drying and aeration systems for pistachio nuts. Using a laboratory unit, the pressure drop across a column of pistachio nuts (Kalleghochi variety) was investigated to determine the effect of moisture content, airflow rate, bed depth and fill method. Five levels of moisture contents (4.80, 14.50, 23.70, 37.60 and 45.60 w.b.%), four bed depths (25, 50, 75 and 100 cm) and two fill methods (loose and dense) were studied with airflow rates ranging from 0.08-1.00 m³/S m². Results indicated that resistance to airflow through a column of pistachio nuts increased with increasing bed depth, moisture content and airflow rate for both dense and loose fill method. Airflow rate was the most significant factor affecting the pressure drop of pistachio nuts followed by fill method and moisture content. The dense fill of pistachio nuts produced higher resistance to airflow compared with the loose fill. Among the three models (Shedd, Hukill and Ives, and Ergun equation) investigated to describe pressure drop data of pistachio nuts, Ergun equation was found to be the most suitable for describing the pressure drop data of pistachio nuts.     

GENERALIZED EQUATION FOR AIRFLOW RESISTANCE OF BULK GRAINS WITH VARIABLE DENSITY, MOISTURE CONTENT AND FINES

The pressure drop versus airflow data for several types of grains were compiled and a grain specific generalized pressure drop versus airflow equation was developed. The equation predicted pressure drop as a function of airflow when porosity, moisture content and fine concentration were specified. The effect of properties of airflow on the resistance of bulk grain to airflow was also considered in the generalized equation. A modified Leva's equation was developed. The similarity between the grain specific equation and the modified Leva's equation led to a method for estimating the shape factor for irregularly shaped particles.     

Bulk Density,Porosity and Resistance to Airflow of Garlic Slices

ABSTRACT

The bulk density of garlic slices at different moisture levels (ranging from approximately 3 to 65% MC wet basis) was determined by weighing the contents of a container of known volume. The porosity was calculated using its relationship with bulk and apparent densities. An analysis of variance (ANOVA) revealed that bulk density and porosity were affected significantly by moisture and slice thickness as well as the interaction of these variables. Bulk density varied in a positive linear fashion with moisture and thickness while a negative linear correlation was found for the calculated bulk porosity. The linear model met the adequacy criterion for characterising the behaviour of garlic. Using a laboratory unit, the vertical resistance to airflow through the product and the effect of misture and slice thickness were investigated for an airflow rates of 0.09 to 1.2 m₃/s-m₂. A higher resistance to airflow was noted for the wet product with the experimental data fitting to Shedd's model when the aifflow range was divided into two sub-flow rates and to a modified Ergun's equation for the full range.     

The Rheology of Peat/Solvent Slurries

Slurries of finely milled Irish peat in Shell White Spirit (100F) were prepared and their rheological behaviour was evaluated in terms of shear rate, solids concentration, moisture content and particle size distribution of the solids. The moisture content of the peat was found to be of crucial significance in determining both the effective solids concentration and the stability of the suspensions. The viscosity of slurries composed of 7% moisture peat solids were almost independent of solids concentration and displayed Newtonian rheological behaviour, with a viscosity of approximately 0·012 N s m⁻². The viscosity of the suspending medium was 1·006×10⁻³ N s m⁻² at 20±1°C. The viscosity of the slurries composed of 55% moisture peat solids was observed to rise sharply, up to about 0·10 N s m⁻² with solids concentration. The shear rate dependence of these suspensions was more complex and their flow characteristics were evaluated in terms of empirical non-Newtonian models. It proved difficult to confidently distinguish between the Bingham Plastic and Casson models as each gave best fit regression curves which were almost identical. Particle size distribution analysis of the suspensions indicates the formation of peat aggregates in the 55% moisture samples which exhibited more rapid settling of the solid. © 1997 SCI     

Evaluation of air flow resistance across a green fig bed for selecting an appropriate pressure drop prediction equation

In this study the physical properties of green fig (Ficus carica L.) at different moisture contents were measured. Pressure drop across a bed of green fig was also evaluated. The moisture content and air flow ranges used in this study were 5.74-34.08% (db) and 0.2-1.1 (m³ s⁻¹ m⁻²), respectively. To measure resistance to air flow an appropriate test rig was designed and fabricated. A thick bed of seven depths of loose and random filling of fig bed were envisaged (5, 10, …, 35 cm). Principle dimensions, geometric mean diameter, sphericity, roughness factor of fig kernels and bulk density increased with an increase in moisture content, whereas kernel density and porosity decreased with an increase in fig moisture content. The air flow resistance across the bed increased with an increase in bed depth and moisture content. The modified Ergun model with higher values for coefficient of determination, lower values for root mean square error and mean relative deviation modulus was the best model for predicting pressure drop across green figs bed for the conditions studied.     

Modeling the Dehydration of Apple Slices by Deep Fat Frying

One of the objectives of immersion frying is to remove water from the food. Thus, predicting moisture loss is important when developing a model for that process. With the aim to model moisture transfer during apple frying, Granny Smith apple slabs were processed at 140, 150, 160, and 170°C. The moisture diffusivity was computed, ranging between 10.7 · 10^?9 and 17.7 · 10^?9 m² · s^?1. There was a close fit between the model and the experimental data (average %var 99.0). Model validation was carried out considering different slice thickness. Temperature influence was interpreted by the Arrhenius relationship with an activation energy of 25.4 kJ · mol^?1.     

PHYSICAL CHARACTERISTICS AND DRYING RATE OF ECHINACEA ROOT

ABSTRACT

Echinacea angustifolia or the purple coneflower is an important medicinal plant that boosts the immune system. It is believed that the active ingredients are predominantly located in the root. Physical characteristics and drying rates of the root of E. angustifolia from a farm in Saskatchewan, Canada were studied. Root consisted of a main (central) root and secondary root branches. Cleaned roots exhibited wide variations in mass ranging from 15 to 95 g. The central root diameter varied from 9 to 20 mm with an average of 14 mm. The average initial moisture content of the fresh root was 57% (wb). The specific densities of the fresh and completely dried root were 1040 and 1370 kg/m³, respectively; and the corresponding bulk densities of loosely piled roots were 305 and 410 kg/m³. Roots were dried in a convection oven at temperatures of 23, 30, 40, 50, 60 and 70°C. Equations for estimating drying rates, drying constants, and equilibrium moisture content were developed. Increased drying temperatures reduced echinacosides but did not affect alkamides 1 and 2 which are known to be also responsible for medicinal value of E. Angustifolia.     

Nitrification of fertilizer wastewaters in a biofilm reactor

The nitrification characteristics of fertilizer wastes were investigated in a biofilm system using a submerged aerated filter. The attachment of biomass on packing media was studied. Supplement of organic carbon in the form of glucose and yeast extract enhanced biofilm formation although the nitrifiers did not require organic carbon for growth. After an attachment period, continuous operation of the reactor at different loading rates and dissolved oxygen levels was investigated. The maximum achievable nitrification rate was strongly dependent on the dissolved oxygen. In the dissolved oxygen range of 3·2–3·5 mg dm⁻³, the maximum ammonia removal rate was about 0·17 kg NH₄ N m⁻³ day⁻¹. When the dissolved oxygen was increased to 4·9 mg dm⁻³, removal rates as high as 0·41 kg NH₄ N m⁻³ day⁻¹ could be obtained. Nitrite accumulation depended on the bulk nitrogen and dissolved oxygen concentrations.     

SINGLE-LAYER DRYING BEHAVIOR OF MEXICAN TEA LEAVES (CHENOPODIUM AMBROSIOIDES) IN A CONVECTIVE SOLAR DRYER AND MATHEMATICAL MODELING

Single-layer solar drying experiments were conducted for Mexican tea leaves (Chenopodium ambrosioides) grown in Marrakech. An indirect forced convection solar dryer was used in drying the Mexican tea leaves at different conditions such as ambient air temperature (21° to 35°C), drying air temperature (45° to 60°C) with relative humidity (29 to 53%), airflow rate (0.0277 to 0.0556 m ³/s), and solar radiation (150–920 W/m²). The experimental drying curves showed only a falling rate period. In order to select the suitable form of drying curves, 14 mathematical models were applied to the experimental data and compared according to their statistical parameters. The main factor in controlling the drying rate was found to be the temperature. The drying rate equation was determined empirically from the characteristic drying curve. The diffusion coefficient of the Chenopodium ambrosioides leaves was estimated and varied between 1.0209 × 10^?9 and 1.0440 × 10^?8 m ²·s^?1.The activation energy was found to be 89.1486 kJ·mol^?1.     

A NUMERICAL STUDY OF THE AIRFLOW PATTERNS IN A SAUSAGE DRYER

ABSTRACT

This paper describes the use of a computational fluid dynamics code (Star-CD)in the food industry. We assessed the capability of CFD to predict airflow patterns in a modern sausage dryer by comparing numerical results with experimental air velocity data. Qualitative and quantitative comparisons showed that simulated values agreed closely with measurements although some discrepancies appeared for specific flow conditions. Using CFD, it was established that these differences couid be attributed to slow time-variations in the blower airflow rate. These comparisons also revealed errors in measurement.     

Determination of dielectric properties of corn seeds from 1 to 100 MHz

The dielectric properties of corn seeds were determined in the ranges of 9.71-21.51% wet basis (w.b.) for moisture content, 772.5-902.2 kg/m³ for bulk density and 1-100 MHz for frequency of applied electric field using a coaxial capacitor sample holder. Effects of the parameters such as moisture content, bulk density and frequency on the dielectric properties were investigated. The dielectric constant, loss factor and loss tangent were greatly affected by the moisture content, frequency and bulk density. The moisture content was the most significant factor affecting the dielectric properties of corn seeds. The dielectric constant, loss factor and loss tangent increased with increasing moisture content and bulk density. The second and third-order polynomial equations were proposed to describe the existing relationship between dielectric properties and moisture content. Dielectric measurements provided new information concerning moisture content and bulk density dependent behaviour of dielectric properties of corn seeds that may be useful in sensing of the moisture content.     

Nitrosamines in new motor-cars

Volatile nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR), N-nitrosodiethylamine (NDEA) and possibly N-nitrosodibutylamine (NDBA), have been found as airborne contaminants inside new (1979 model) motor-cars. NDMA was found in the front passenger area of 37 of the 38 motor-cars at levels ranging from 0·07 to 0·83 μg/m³ (mean 0·29 μg/m³), NMOR was present at levels between a trace and 2·5 μg/m³ (mean 0·65 μg/m³) in 16 vehicles and 0·04–0·39 μg NDEA/m³ (mean 0·11 μg/m³) was detected in 17 of the cars. Traces of NDBA (<0·01 μg/m³) were also tentatively identified in three of the vehicles. The exposure of man to volatile N-nitrosamines from motor-cars is estimated to be similar to that from bacon and beer.     

Experimental and fundamental critical analysis of diffusion model of airflow drying

Scientific literature of agromaterial drying present contradictory conclusions in terms of the kinetic effect of airflow velocity. Some authors confirmed that it does not trigger any modification of drying, while some articles tried to establish empirical models of the effective diffusivity D_eff versus the airflow velocity, what is fundamentally erroneous. By analyzing internal and external transfer phenomena, this research aimed at recognizing that once air velocity is higher than a critical airflow velocity (CAV), the internal transfers become the limiting phenomenon. CAV depends on the effective diffusivity and the product size. It was calculated in the cases of two studied raw materials (apple and carrot), differently textured by instant controlled pressure drop (DIC). Values of CAV greatly depend on diffusivity of water within the matrix. At temperature T?=?40°C, they were 1?m/s for untreated carrot and 2.1?m/s for DIC-textured carrot, whose D_eff values were 1.31 and about 3?×?10^?10?m²/s, respectively. Also, at temperature T?=?40°C, they were 2.1?m/s for untreated apple and 3?m/s for DIC-textured apple, whose D_eff were 1.4 and about 10.4?×?10^?10?m²/s, respectively.     

Analysis of the physical properties of an in-vessel composting matrix

Efficient compost production requires a thorough understanding of the process dynamics in terms of the feedstock materials used and the interactions of the physical properties involved. The main properties affecting the composting process are temperature, moisture content, bulk density, porosity and oxygen availability. In this study, the correlations between a selected set of physical properties of a batch-composting matrix were determined. The key physical changes in the composting materials for a blend of woodchips, chicken manure and mixed green vegetables have been monitored during a 36-day composting period in a 200-L rotary drum. The daily measurements conducted on the solid samples included temperature, pH, volatile solids, bulk density, moisture content, free airspace and substrates particle density while the carbon dioxide release was monitored weekly using jar respiration tests. The results from the compost process monitoring were a maximum temperature rise to 66.3 °C over the first 3 days, a marked decrease in free airspace from 76.3% to 40.0% at the end of the process, a variation in average composting material particle density from 1097 kg/m³ to 2325 kg/m³, and an increase in wet bulk density from 255 kg/m³ to 628 kg/m³. Correlations developed among free airspace, wet bulk density, dry bulk density and wet moisture content were in agreement with previously determined equations from literature. Free airspace varied linearly with both dry and wet bulk densities (R² value of 0.89 and 0.95, respectively) while the free airspace-wet moisture content profile followed a fourth degree polynomial trend with a correlation coefficient of 0.63.     

THE MOISTURE SORPTION ISOTHERMS OF CEFOTAXIME SODIUM SALT

ABSTRACT

The water sorption isotherms of the cefotaxime sodium salt were determined at 30 and 40° C. Cefotaxime sodium salt was maintained at equilibrium relative humidities ranging from 40 to 80 %. Equilibrium moisture content was determined by the Karl Fischer method. The moisture sorption isotherms showed that the equilibrium moisture decrease while the temperature increase. The experimental curves of equilibrium humidity were fitted by different models (Bradley, Halsey, Henderson, Kuhn, Smith and Iglesias and Chirife and GAB). Parameters of each equations were determined by non-linear regression analysis. The best fit was obtained by Iglesias and Chirife model. The isosteric heat of moisture sorption calculated by Claussius Clapeyron equation varied from 64·45 to 48·03 kJ/mol when moisture content changed from 7 to 9·5 %.     

Effect of Pulsed Electric Field and Osmotic Dehydration Pretreatment on the Convective Drying of Carrot Tissue

The influence of pulsed electric field (PEF) and subsequent centrifugal osmotic dehydration (OD) on the convective drying behavior of carrot is investigated. The PEF was carried out at an intensity of E = 0.60 kV/cm and a treatment duration of t _PEF  = 50 ms. The following centrifugal OD was performed in a sucrose solution of 65% (w/w) at 40°C for 0, 1, 2, or 4 h under 2400 × g. The drying was performed after the centrifugal OD for temperatures 40–60°C and at constant air rate (6 m³/h).

With the increase of OD duration the air drying time is reduced spectacularly. The dimensionless moisture ratio Xr = 0.1 is reached for PEF-untreated carrots after 370 min of air drying at 60°C in absence of centrifugal OD against 90 min of air drying after the 240 min of centrifugal OD. The PEF treatment reduces additionally the air drying time. The total time of dehydration operations can be shortened when OD time is optimized. For instance, the minimal time required to dehydrate untreated carrots until Xr = 0.1 is 260 min (120 min of OD at 40°C and 140 min of drying at 60°C). It is reduced to 230 min with PEF-treated carrots.

The moisture effective diffusivity D _eff is calculated for the convective air drying based on Fick's law. The centrifugal OD pretreatment increases drastically the value of D _eff . For instance, 4 h of centrifugal OD permitted increasing the value of D _eff from 0.93 · 10^?9 to 3.85 · 10^?9 m²/s for untreated carrots and from 1.17 · 10^?9 to 5.10 · 10^?9 m²/s for PEF-treated carrots.     

Effect of airflow rate on drying air and moisture content profiles inside a cross-flow drying column

Rice at 20.5 and 16.3% initial moisture contents (IMCs) was dried using 57°C/13% RH air at airflow rates (Qs) of 0.36, 0.46, and 0.56 (m³/s)/m² for 30, 60, and 90?min, respectively, in an experimentally simulated cross-flow drying column. Q significantly affected the drying air and rice moisture content profiles within the drying column; for a particular drying duration, the range of MCs within the column decreased as Q increased. Q also impacted the extents of intra-kernel material state gradients created and thus had potential impacts on kernel fissuring and consequent head rice yield reduction. In addition, the impact of Q on the above-mentioned profiles was dependent on the rice IMC.