Residual Moisture Content Research Articles

Parameters influencing the regeneration of a green roof’s retention capacity via evapotranspiration

Summary The extent to which the finite hydrological capacity of a green roof is available for retention of a storm event largely determines the scale of its contribution as a Sustainable Drainage System (SuDS). Evapotranspiration (ET) regenerates the retention capacity at a rate that is variably influenced by climate, vegetation treatment, soil and residual moisture content. Experimental studies have been undertaken to monitor the drying cycle behaviour of 9 different extensive green roof configurations with 80 mm substrate depth. A climate-controlled chamber at the University of Sheffield replicated typical UK spring and summer diurnal cycles. The mass of each microcosm, initially at field capacity, was continuously recorded, with changes inferred to be moisture loss/gain (or ET/dew). The ranges of cumulative ET following a 28 day dry weather period (ADWP) were 0.6–1.0 mm/day in spring and 0.7–1.25 mm/day in summer. These ranges reflect the influence of configuration on ET. Cumulative ET was highest from substrates with the greatest storage capacity. Significant differences in ET existed between vegetated and non-vegetated configurations. Initially, seasonal mean ET was affected by climate. Losses were 2.0 mm/day in spring and 3.4 mm/day in summer. However, moisture availability constrained ET, which fell to 1.4 mm/day then 1.0 mm/day (with an ADWP of 7 and 14 days) in spring; compared to 1.0 mm/day and 0.5 mm/day in summer. A modelling approach, which factors Potential Evapotranspiration (PET) according to stored moisture content, predicts daily ET with very good accuracy (PBIAS = 2.0% [spring]; −0.8% [summer]).

Characterization of the Physical Stability of a Lyophilized IgG1 mAb after Accelerated Shipping-Like Stress

Upon exposure to shaking stress, an IgG1 mAb formulation in both the liquid and lyophilized state formed subvisible particles. Because freeze-drying was expected to minimize protein physical instability under these conditions, the extent and nature of aggregate formation in the lyophilized preparation were examined using a variety of particle characterization techniques. The effects of formulation variables such as residual moisture content, reconstitution rate, and reconstitution medium were also examined. Upon reconstitution of shake-stressed lyophilized mAb, differences in protein particle size and number were observed by microflow digital imaging, with the reconstitution medium having the largest impact. Shake stress had minor effects on the structure of protein within the particles as shown by SDS-PAGE and FTIR analysis. The lyophilized mAb was shake stressed to different extents and stored for 3 months at different temperatures. Both extent of cake collapse and storage temperature affected the physical stability of the shake-stressed lyophilized mAb upon subsequent storage. These findings demonstrate that physical degradation upon shaking of a lyophilized IgG1 mAb formulation includes not only cake breakage, but also results in an increase in subvisible particles and turbidity upon reconstitution. The shake-induced cake breakage of the lyophilized IgG1 mAb formulation also resulted in decreased physical stability upon storage.

Development of an oven drying protocol to improve biodiesel production for an indigenous chlorophycean microalga Scenedesmus sp.

Drying of wet algal biomass is a major bottleneck in viable commercial production of the microalgal biodiesel. In the present investigation, an oven drying protocol was standardized for drying of wet Scenedesmus biomass at 60, 80 and 100°C with initial sample thickness of 5.0, 7.5 and 10.0mm. The optimum drying temperature was found to be 80°C with a maximum lipid yield of 425.0±5.9mgg−1 at 15h drying time for 5.0mm thick samples with 0.033kWh power consumption. Partial drying at 80°C up to 10% residual moisture content was efficient showing 93% lipid recovery with 8h drying and a power consumption of 0.017kWh. Scenedesmus biomass was also found to be rich in saturated and mono-unsaturated fatty acids. Thus, the drying protocol demonstrates its suitability to improve the downstream processing of biodiesel production by significantly lowering the power consumption and the drying time.

Use of a continuous twin screw granulation and drying system during formulation development and process optimization

Since small scale is key for successful introduction of continuous techniques in the pharmaceutical industry to allow its use during formulation development and process optimization, it is essential to determine whether the product quality is similar when small quantities of materials are processed compared to the continuous processing of larger quantities. Therefore, the aim of this study was to investigate whether material processed in a single cell of the six-segmented fluid bed dryer of the ConsiGma™-25 system (a continuous twin screw granulation and drying system introduced by GEA Pharma Systems, Collette™, Wommelgem, Belgium) is predictive of granule and tablet quality during full-scale manufacturing when all drying cells are filled. Furthermore, the performance of the ConsiGma™-1 system (a mobile laboratory unit) was evaluated and compared to the ConsiGma™-25 system.A premix of two active ingredients, powdered cellulose, maize starch, pregelatinized starch and sodium starch glycolate was granulated with distilled water. After drying and milling (1000μm, 800rpm), granules were blended with magnesium stearate and compressed using a Modul™ P tablet press (tablet weight: 430mg, main compression force: 12kN). Single cell experiments using the ConsiGma™-25 system and ConsiGma™-1 system were performed in triplicate. Additionally, a 1h continuous run using the ConsiGma™-25 system was executed. Process outcomes (torque, barrel wall temperature, product temperature during drying) and granule (residual moisture content, particle size distribution, bulk and tapped density, hausner ratio, friability) as well as tablet (hardness, friability, disintegration time and dissolution) quality attributes were evaluated.By performing a 1h continuous run, it was detected that a stabilization period was needed for torque and barrel wall temperature due to initial layering of the screws and the screw chamber walls with material. Consequently, slightly deviating granule and tablet quality attributes were obtained during the start-up phase of the 1h run. For the single cell runs, granule and tablet properties were comparable with results obtained during the second part of the 1h run (after start-up). Although deviating granule quality (particle size distribution and Hausner ratio) was observed due to the divergent design of the ConsiGma™-1 unit and the ConsiGma™-25 system (horizontal set-up) used in this study, tablet quality produced from granules processed with the ConsiGma™-1 system was predictive for tablet quality obtained during continuous production using the ConsiGma™-25 system.

A comparative study between conventional pan coater and quasi-continuous small batch coater on the stability of tablets containing acetylsalicylic acid

The Supercell coater was developed as an in-line small batch tablet coater which uses air-fluidization for tablet coating. Coating time is very much reduced, with improved heat and mass transfer. It was hypothesized that the quasi-continuous Supercell coating process was more suitable for the aqueous coating of tablets containing moisture-sensitive drugs. Acetylsalicylic acid (ASA) was used as the model drug in this study. The extent of ASA degradation in Supercell coating was compared against that of tablets coated using the conventional pan coater. Less than 0.3% of ASA was degraded at the end of the coating process using either coater. The extent of ASA degradation was found to be more pronounced during storage. The Supercell coated tablets exhibited comparable or smaller percentage of ASA degradation than the pan coated tablets at the end of a storage period of 6months under accelerated stability conditions (40°C/75% RH) and 3years under ambient conditions (25°C/50% RH). The extent and rate of ASA degradation during storage were dependent on the processing conditions employed during Supercell coating. Increase in temperature generally led to a reduction in ASA degradation, while increase in spray rate and coating level caused more degradation. Greater extent of ASA degradation was observed on the surface of pan coated tablets compared with Supercell coated tablets due to greater moisture contact and the slower and wetter coating process. Changes to the processing conditions also influenced the residual moisture content (0.55–2.86%) of the tablets. However, no direct correlation between the residual moisture content of the tablets after coating and the extent of ASA degradation during storage was found.

Nanonization of curcumin by antisolvent precipitation: Process development, characterization, freeze drying and stability performance

The present work aims to investigate applicability of antisolvent precipitation method for preparation of nanosized curcumin and to control their characteristics by determining the influence of process and solvents on solid-state properties of curcumin nanoparticles. Effects of different experimental parameters on particle size were investigated using dynamic light scattering. Particle morphology was studied using SEM. Drug content in stabilized nanoparticles was determined using HPLC. Residual moisture content after lyophilisation was determined using Karl Fischer method and solid state properties were investigated using DSC, TGA, FTIR and powder-XRD. The resulting product showed a high drug load and contained the drug in amorphous form. The particle diameters of prepared curcumin nanoparticles were found in the range of 100–200nm. In vitro drug release studies indicated a sustained release profile of curcumin from the nanoparticles. Antisolvent precipitation produced amorphous curcumin nanoparticles whose size and morphology could be controlled using gelatine as stabilizer. Lyophilized curcumin nanoparticles with d-sorbitol as lyoprotectant possessed good redispersibility and showed up to 4 times faster in vitro curcumin release rate than that of unprocessed curcumin. Stability tests (at 2–8°C and ambient conditions) indicated that the product was stable for up to 6 months of storage.

Design of a Kinetic Model for Degradation of Substances During Spray Drying Using Yeast Biosuspension, Oil-in-Water Emulsion, and Alumosilicate Suspension

Spray drying is a widespread technology for the dehydration of materials with a high initial content of solvent in order to improve product stability during storage, simplify batching, and reduce transportation costs. The high rate of evaporation, contact with oxygen in the air, as well as overheating of the material in the case of unacceptable process conditions can lead to the destruction of valuable components, their oxidation, and loss of volatile substances. The article presents an approach to determine the kinetics of degradation of the substances as a function of the current state of the material (temperature, residual moisture content, and rates of changes) during the spray-drying process. It was shown that this approach can be applied to various types of materials with different properties. The obtained kinetic equations were used to predict the quality of product dried in pilot-scale spray equipment.

Microencapsulation of Lactobacillus plantarum (MTCC 5422) with fructooligosaccharide as wall material by spray drying

Microencapsulation is a promising technique for delivery of live microbial supplements through foods. Prebiotics like ‘fructooligosaccharide (FOS)’ can be used as a wall material to produce synbiotics. However, the low glass transition temperature (Tg) of FOS causes stickiness when used as wall material during spray drying. This problem was alleviated by FOS in combination with whey protein isolate (WPI) or denatured whey protein isolate (DWPI) for encapsulating the probiotic bacteria Lactobacillus plantarum (MTCC 5422). Microencapsulation was performed with wall materials FOS, FOS + WPI, FOS + DWPI at two different core-to-wall ratios of 1:1 and 1:1.5. FOS + WPI and FOS + DWPI microcapsules of 1:1 core-to-wall ratio exhibited higher encapsulation efficiency, lower residual moisture content and narrow range of particle size distribution than 1:1.5. However, microcapsules of 1:1.5 core-to-wall ratios enhanced the storage stability and tolerance of probiotic cells in the simulated gastric and intestinal conditions. FTIR analysis confirmed the presence of whey proteins and FOS in the microcapsules after spray drying. On overall comparison, FOS + DWPI microcapsules of 1:1 core-to-wall ratio had higher encapsulation efficiency (98.63%) but 1:1.5 ratio exhibited better storage stability and protection in simulated gastric, as well as intestinal condition than the other encapsulates.

Scalable organic solvent free supercritical fluid spray drying process for producing dry protein formulations

In this study, we evaluated the influence of supercritical carbon dioxide (scCO2) spray drying conditions, in the absence of organic solvent, on the ability to produce dry protein/trehalose formulations at 1:10 and 1:4 (w/w) ratios. When using a 4L drying vessel, we found that decreasing the solution flow rate and solution volume, or increasing the scCO2 flow rate resulted in a significant reduction in the residual water content in dried products (Karl Fischer titration). The best conditions were then used to evaluate the ability to scale the scCO2 spray drying process from 4L to 10L chamber. The ratio of scCO2 and solution flow rate was kept constant. The products on both scales exhibited similar residual moisture contents, particle morphologies (SEM), and glass transition temperatures (DSC). After reconstitution, the lysozyme activity (enzymatic assay) and structure (circular dichroism, HP-SEC) were fully preserved, but the sub-visible particle content was slightly increased (flow imaging microscopy, nanoparticle tracking analysis). Furthermore, the drying condition was applicable to other proteins resulting in products of similar quality as the lysozyme formulations. In conclusion, we established scCO2 spray drying processing conditions for protein formulations without an organic solvent that holds promise for the industrial production of dry protein formulations.

Improved Fine Coal Dewatering by Ultrasonic Pretreatment and Dewatering Aids

The effects of ultrasonic pretreatment and surface active reagents to improve the efficiency of fine coal dewatering in high frequency vibrating screen have been carried out. The results showed that hydrophobic surface active reagents increased the contact angle and decreased surface tension of the solution reducing the moisture content of fine coal particles. Polyethylene glycol 400 monooleate (PEG-400) was found to be the most effective reagent. Furthermore, when ultrasonic pretreatment was introduced to the fine coal slurry, the residual total moisture content of the fine coal was further decreased.

Modeling the impacts of soil hydraulic properties on temporal stability of soil moisture under a semi-arid climate

Summary Despite the significant spatiotemporal variability of soil moisture, the phenomenon of temporal stability of soil moisture ( TS SM ) has been widely observed in field studies. However, the lack of understandings of the factors that control TS SM has led to some contradictory findings about TS SM . To resolve this issue, numerical models may offer an alternative way to complement field studies by quantifying different controls on TS SM . In this study, a 1-D vadose zone model was adopted to simulate daily soil moisture contents, which were used to compute the mean relative difference ( MRD ) and standard deviation of relative difference ( SDRD ) of soil moisture. Different from recent modeling studies, a soil dataset was employed with 200 samples of correlated soil hydraulic parameters for sandy soils. Compared to the results of previous modeling studies, more reasonable patterns of MRD and SDRD that resembled field observations were produced. By varying soil hydraulic parameter values, different patterns of MRD and SDRD could also be generated, implying variations in soil hydraulic properties could partly control the patterns of MRD and SDRD . More specifically, the residual soil moisture content ( θ r ) was found to be the primary control on MRD , mainly due to the semi-arid climate that was simulated. By fixing θ r , however, a highly nonlinear relationship emerged between MRD and the shape factor n in the van Genuchten model, which resulted in the positively skewed distributions of MRD widely observed for sandy soils in field experiments. Moreover, both the range and skewness of the distributions of MRD were affected by the range of n . In addition, with increasing n , a positive correlation between MRD and the shape factor l in the van Genuchten model was also found. The simulation results suggested that the control of soil hydraulic properties on MRD might weaken for areas under bare surface conditions or for regions with more humid climates due to elevated soil moisture contents. Therefore, the impacts of soil hydraulic properties on TS SM may vary under different climate regimes.

Optimization of spray drying conditions for production of Bidens pilosa L. dried extract

Spray drying is a technique commonly used to produce powdered phytopharmaceutical ingredients from medicinal plants. Product quality is related to operating conditions and the drying carriers used. Bidens pilosa L. is a South American plant with proved antiinflamatory, antimalaric, antitumoral and hepatoprotector activities. The aim of this work was to optimize the processing variables inlet drying temperature, plant extract feed flow rate and drying composition on the properties of the powdered B. pilosa compositions. Experimental planning, regression and multiple response analysis were used in data processing and to optimize the drying conditions. The responses evaluated were total flavonoid content, antioxidant activity, concentration of selected plant compounds, particle size, residual moisture content, solubility, flow properties, product recovery and drying efficiency. Results showed that inlet drying temperature was the factor that showed significant influence in most of the responses. The concentration of the bioactive marker compounds monitored decrease conversely with inlet spray drying temperature. Powders obtained at low inlet drying temperatures presented higher residual moisture and particle size, favouring flow properties. The optimized conditions based on the mathematical models fitted to experimental data were: Aerosil®:Cellulose 13:37%, extract feed rate 8.95mg/min and inlet gas temperature of 155.2°C.

An Integrated Process Analytical Technology (PAT) Approach to Monitoring the Effect of Supercooling on Lyophilization Product and Process Parameters of Model Monoclonal Antibody Formulations

The aim of the present study was to apply an integrated process analytical technology (PAT) approach to control and monitor the effect of the degree of supercooling on critical process and product parameters of a lyophilization cycle. Two concentrations of a mAb formulation were used as models for lyophilization. ControLyo™ technology was applied to control the onset of ice nucleation, whereas tunable diode laser absorption spectroscopy (TDLAS) was utilized as a noninvasive tool for the inline monitoring of the water vapor concentration and vapor flow velocity in the spool during primary drying. The instantaneous measurements were then used to determine the effect of the degree of supercooling on critical process and product parameters. Controlled nucleation resulted in uniform nucleation at lower degrees of supercooling for both formulations, higher sublimation rates, lower mass transfer resistance, lower product temperatures at the sublimation interface, and shorter primary drying times compared with the conventional shelf-ramped freezing. Controlled nucleation also resulted in lyophilized cakes with more elegant and porous structure with no visible collapse or shrinkage, lower specific surface area, and shorter reconstitution times compared with the uncontrolled nucleation. Uncontrolled nucleation however resulted in lyophilized cakes with relatively lower residual moisture contents compared with controlled nucleation. TDLAS proved to be an efficient tool to determine the endpoint of primary drying. There was good agreement between data obtained from TDLAS-based measurements and SMART™ technology. ControLyo™ technology and TDLAS showed great potential as PAT tools to achieve enhanced process monitoring and control during lyophilization cycles.

Stem cell engineering towards the optimization of the ex-vivo expansion of human hematopoietic stem/progenitor cells for cellular therapies

Clinical and non-clinical work within the last decade has changed the conventional thinking about platelets. In addition to hemostasis, platelets are now recognized as playing a major role in wound healing, immune modulation and tissue regeneration. Autologous platelets are gaining acceptance for various wound healing applications while allogeneic platelets are still reserved for infusion for hemostasis. The biggest disadvantage is that these platelets have a shelf life of 5 days. Lyophilization is one technique that has been evaluated to increase the shelf life of platelets and almost all lyopilization techniques use some kind of preservative or sugars. We have developed a process of lyophilization for allogenic platelets which are past their useful life for infusion but are still quite well suited for seeding provisional matrix within wounds. This process doesn’t use special additives and optionally includes terminal sterilization to yield an efficient, safe, off-the-shelf, freeze-dried product. This product was characterized by residual moisture content and presence of key growth factors (PDGF, TGF-b1, FGF and VEFG). All these growth factors are able to stimulate cell proliferation, matrix remodeling and angiogenesis in wound healing. An extensive analysis of these growth factors in the product postprocessing indicated that their values (per 106 platelets) were very close to values obtained from fresh platelet rich plasma from healthy volunteers. Comparisons of growth factors were conducted to detect differences between methods of sterilization and different vial materials used in the lyopilization process. Functional assays were conducted to verify the activity of the freeze-dried product. All tests showed that the processed product maintains the growth factor levels and cell stimulation activity appropriate for seeding the provisional matrix in a topical or surgical wound.

EFFECT OF TEMPERATURES ON THE DRYING BEHAVIORS AND QUALITY OF CITRUS PEELS

The changes in citrus peels (CP) moisture content, drying rate, moisture ratio, drying time and energy consumption at various drying air temperatures was studied. The effect of drying temperatures and residual moisture contents on the quality of CP after drying was also evaluated. The test samples were dried in a laboratory scale hot air dryer at air temperature in the range of 40–70oC and a constant air velocity of 1m/s to desired moisture for save storage and final moisture level of drying conditions. Cakes prepared from blendes containing different proportion (0, 10, 15 and 20%) of dried orange and mandarin peels were also evaluated for chemical composition and sensory attributes. The results indicated that, the drying temperature was very effective in removing moisture from citrus peels. The drying time was decreased by 50% and specific energy consumption decreased by about 28.5% with increasing drying temperature from 40 to70oC for drying citrus peels. The simple exponential equation satisfactorily described the drying behavior of CP as indicated by the higher coefficient of determination.The optimal drying temperature was 60°C to reach 10±0.2%, w.b, moisture level, which reduced drying time and saved energy consumption and product quality. Meanwhile, overdrying to reach final moisture levels of citrus peels (5.4±0.2%)with higher drying air temperature sharply increased the losses of vitamin C, carotenoids and essential oils. Incorporation 15% of dried orange and mandarin peels in cakes formula increased dietary fiber by 33.5 and 29.6%, ether extract by 2.9 and 4.6% and ash by 30.6 and 29.0%, respectively, while protein and total carbohydrates contents were slightly decreased. Highly acceptable cakes could be obtained by incorporating 15% of orange and mandarin peels dried to 10%, w.b., moisture content in the cakes formulation and it can be used as value-added food ingredients.

Quantitative on-line vs. off-line NIR analysis of fluidized bed drying with consideration of the spectral background

Quantitative dehydration studies of dibasic calcium phosphate anhydrous (DCPA) in a small-scale cold-model fluidized bed dryer with process air control were conducted. Near-infrared spectroscopy (NIRS) with partial least squares regression (PLSR) was used to predict DCPAs’ residual moisture content. Loss-on-drying (LOD) was employed as a reference method and confirmed the actual moisture content of DCPA. First, dynamic PLSR modeling was carried out, i.e., the NIR spectra were on-line recorded and predicted throughout the drying process. Secondly, PLSR off-line modeling was performed, i.e., samples were consecutively thief-probed from the processor, put into glass vials and analyzed off-line. Furthermore, two background spectra were collected prior to the in- and off-line measurements in an attempt to increase the method’s sensitivity, i.e., (i) dry DCPA that was fluidized at respective process air velocity (on-line) or inside a glass vial (off-line) and (ii) Spectralon® – a highly reflecting standard reference material made of fluoropolymer. Benefits and drawbacks of the in- and off-line approaches with different spectral backgrounds are discussed in detail. The results indicated that (i) the thief-probed sample amount from the processor and thus the sample weight and (ii) the downtime between thief-probing a sample and its actual analysis via NIRS and LOD can bias the moisture content predictions.

Effect of Hydrodynamics During Crystallization on Mechanical Dewatering of Salicylic Acid

Mechanical cake dewatering is always desired to reduce the load on thermal dewatering (drying). Any change in the upstream process such as crystallization can have a significant influence on the filtration as well as cake dewatering characteristics. The present study deals with the effect of hydrodynamics (mixing intensity) during salicylic acid crystallization on the air dewatering characteristics in the subsequent pressure filtration. The mixing conditions during crystallization were varied by using three different types of agitators (anchor impeller [AI], curved blade turbine [CBT], and bar turbine [BT]) and by varying the speed of agitation. The effect of operating pressure and dewatering time on the final moisture content of the cake was also studied. The crystal properties (crystal size and size distribution) were found to vary with the mixing intensity, which further influenced the cake dewatering kinetics as well as the residual moisture content. An AI, which is a laminar flow impeller, produced crystals with a wide size distribution and higher mean particle size, which resulted in cake with high porosity and hence higher moisture content. The high porosity (as well as high cake permeability) caused early air breakthrough, which resulted in ineffective dewatering of cake. Therefore, in this case the residual moisture in cake was found to be higher (27%) even at higher dewatering pressure (1.5 bar gauge) and longer dewatering time (90 s). A BT creates high turbulence during mixing and produced crystals with a relatively narrow size distribution and lower mean particle size, which provided low-porosity cakes. Such cakes could be efficiently dewatered and the final cake moisture content was found to decrease to about 15%, a significant improvement in the filterability of the cake. The dewatering data were modeled according to the correlation between irreducible cake saturation and capillary number for predicting the cake dewatering characteristics (residual moisture as well as dewatering kinetics) and the results were compared with the experimental data.

UV-initiated polymerization of hydrophobically associating cationic flocculants: Synthesis, characterization, and dewatering properties

A new composite flocculant was synthesized by the copolymerization of acrylamide (AM), acryloyloxyethyltrimethyl ammonium chloride (DAC), and butylacrylate (BA) under ultraviolet (UV) radiation with 2,2′-azobis(2-methylpropionamide) dihydrochloride (V-50) as photo-initiator. This flocculant was named P(AM–DAC–BA). Nuclear magnetic resonance hydrogen spectroscopy (1H NMR), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) were used to observe the structure and morphology of P(AM–DAC–BA). Parameters affecting the intrinsic viscosity ([η]) and conversion of P(AM–DAC–BA), such as monomer concentration, photo-initiator concentration, pH, illumination time, and incident light intensity in a quartz or glass reactor were examined. Results showed that the optimum conditions were 30wt% total monomers, 2.0wt% hydrophobic monomer, 0.5wt‰ photo-initiator, pH 4.4, 100min of illumination time, and 1160μWcm−2 incident light intensity. To study the dewatering performance of P(AM–DAC–BA), the textile sewage sludge dewatering was evaluated by measuring both the residual turbidity and moisture content of the filter cake. At 50mgL−1 P(AM–DAC–BA) and pH 11.6, the residual turbidity of the supernatant and moisture content of the dewatered filter cake reached 5.5NTU and 73.2%, respectively. Dewatering tests demonstrated the superiority of P(AM–DAC–BA) flocculant synthesized in the quartz reactor over that synthesized in the glass reactor.

Freeze‐drying concentration of Rangpur lime juice

SummaryThe use of freeze‐drying for concentrating lime Rangpur juice was investigated. This procedure allowed obtaining concentrated Rangpur lime juices between 23 and 51.3 °Brix, without affecting their organoleptic and nutritional characteristics. The efficiency of the procedure was inversely related to the film thickness of the matrix to be lyophilised. The sublimation speed per unit area diminished with the reduction in the residual moisture content of the juice. The mathematical model that fitted to the concentration procedure allowed to predict the time required for concentrating Rangpur lime by freeze‐drying starting from samples of different thickness. When compared with other citric juices evaluated, the Rangpur lime juice was the most suitable for freeze‐drying concentration. The results could be used to devise optimal industrial freeze‐drying cycles for processing Rangpur lime juices at different concentrations.

Research on Soil-Water Characteristic Curve of Unsaturated Mixed-Soil in West Sichuan

A series of tests are conducted to get the physical composition, physical form and the soil-water characteristic curve in different dry density of three typical composite unsaturated soils in west Sichuan. Test data shows that the variation of physical composition, particle size and dry density can result in great change of soil-water characteristic curve. The bigger the dry density is, the more hydrophilic mineral the soil has, the more gentle the soil-water characteristic curve is, and the higher its residual moisture content is. In addition, under the same water content, matrix suction decreases with less clay content and more content. For the three typical composite unsaturated soils, with relatively bigger water content, the change of soil-water characteristic curve resulting from variation of dry density is less, but with the water content getting smaller, the change becomes clearer.