Effect of different parameters on enzyme-assisted extraction of lycopene from tomato processing waste

The present study aims to optimize extraction process of lycopene by using solvents and examine the effect of enzyme treatment on the recovery if any. Different parts of tomato fruits like whole tomato, peel, pulp and industrial waste were screened for lycopene content. The extraction of lycopene was carried out with four different solvents to know their extraction efficiency. Two step extraction processes was followed for enzyme-assisted extraction of lycopene. In the first step waste samples were treated with enzymes i.e. cellulase and pectinase, whereas in second step extraction of lycopene was carried out by solvent. The optimization study with respect to concentrations and incubation time were carried out for both the enzymes. Also the effect of particle size and cooking methods on recovery of lycopene were studied. The results revealed that the tomato peel (417.97 μg/g) contains highest amount of lycopene followed by industry waste (195.74 μg/g), whole tomato (83.85 μg/g) and pulp (47.6 μg/g). When extraction was carried out by tri-mixture (i.e. acetone, ethanol and hexane) got higher recovery of lycopene than the other solvents. Maximum recovery of lycopene was obtained at 1.5% cellulase and 2% pectinase respectively at 4 h of incubation period. The results also indicated that finer the particle size, higher the recovery of lycopene, whereas all cooking methods reduced the recovery of lycopene. The above extraction process will be beneficial to the small scale entrepreneur to improve their socio-economical status.     

Valorization of grape pomace and orange peels: Improved production of hydrolytic enzymes for the clarification of orange juice

The production in solid state fermentation (SSF) of several hydrolytic enzymes by Aspergillus awamori on a mixture of grape pomace and orange peels has been studied in two configurations of bioreactor: packed bed and tray-type. When the effect of aeration in both reactors was compared, using the trays-type with an air flow rate of 3 mL/gds·min, average activities of 42.64 and 2.16 IU/gds were measured for xylanase and CMCase, respectively; however in the case of the column reactor the aeration must be doubled to obtain similar activity values. These differences were more significant in the case of exo-PG. The extracts obtained in this reactor were applied to orange juice and the cloudiness was markedly reduced, even improving the efficiency of a commercial enzyme preparation. Thus, while the turbidity of the fresh juice was 4625 NTU, treatment with the extracts reduced the value to 24.25 NTU. In a similar way the clarity increased to 95% after treatment with enzyme extracts. According to the results obtained, the proposed process for grape pomace and orange peels reutilization constitutes a viable alternative for many companies to revalorize their residues and to reduce their contaminant capacity.     

Effect of carbonization temperature on the nickel crystallite size of a Ni/C catalyst for catalytic hydrothermal gasification of organic compounds

A carbon based nickel (Ni) catalyst was prepared by ion exchanging Ni ions with the ion exchangeable sites in an ion exchange resin followed by carbonization of the resin. Effect of carbonization parameters such as temperature and time on nickel crystallite size and dispersion were studied. Samples were prepared at 500, 600, 700 and 800 °C to investigate the effect of carbonization temperature. The XRD pattern and TEM images of the catalysts showed that Ni particles become bigger in size as carbonization temperature increases. No effect of carbonization time on particle size was observed. The catalytic hydrothermal gasification (CHTG) experiments with 0.2% TOC organic water at 350 °C, 20 MPa, and 50 h⁻¹ liquid hourly space velocity (LHSV) showed that the conversion or activity decreased as particle size increased, from 99% for Ni500 (3.3 nm) to 25% for Ni800 (21.5 nm). The extended time experiments showed that the conversion or activity was stable for both Ni500 and Ni700 for 50 h run time. The XRD and TEM patterns of the two catalysts after 50 h gasification run showed that Ni500 with smaller particle size shows slightly higher sintering rate than Ni700 with bigger particles.     

Production of fermentable sugars from enzymatic hydrolysis of pretreated municipal solid waste after autoclave process

A ligno-cellulosic concentrate from municipal solid waste (MSW) obtained after an autoclave separation process was investigated for its potential as a feedstock to produce fermentable sugars for ethanol production. A maximum enzymatic hydrolysis conversion of 53% of the cellulose and hemi-cellulose was found using a particle size range of 150–300 μm hydrolyzed in a 100 ml buffer solution containing 6 wt% lingo-cellulosic MSW concentrate with 90 mg cellulase at pH 4.8 held at 40 °C for 12 h. The hydrolysis rate leveled off at longer hydrolysis time and with increased substrate concentration and was related to enzymatic access to substrate. Lower hydrolysis rate at smaller particle size indicates that the grinding process may change the surface chemistry or morphology of the fibers making them less available for enzyme access. A drop in the hydrolysis rate was observed for the particles above 300 μm associate with the longer diffusion time for the enzyme into the fiber particles. The findings indicate that 152 L of ethanol could be obtained from a ton of lingo-cellulosic concentrate from MSW.     

Solid state fermentation of waste bread pieces by Aspergillus awamori: Analysing the effects of airflow rate on enzyme production in packed bed bioreactors

The aim of this study was to optimise airflow rate for glucoamylase and protease production from waste bread via solid state fermentation by Aspergillus awamori in packed bed bioreactors. Airflow rates, between 0.40 and 3.00 vvm, were tested. In all experiments, the fungal growth was almost uniform throughout the solids. Fungi grew both on and within the substrate and fungal cakes were formed. The highest glucoamylase and protease activities were recorded as 130.8 U/g bread (db) and 80.3 U/g bread (db) in the experiments with 1.50 vvm airflow rate, respectively. These values are 27.2% and 32.3% higher than the glucoamylase and protease activities obtained in petri dish experiments with static air. At 1.50 vvm airflow rate, the dry weight of the solids had decreased to 46% of the initial value at the end of the fermentation. The temperature of the solids increased up to 37.5 °C with high axial temperature gradients due to high metabolic activity. The average moisture content of the solids first decreased to 150% (db) and then increased to 275% (db) by the end of the fermentation. Both above and below 1.50 vvm airflow rate, enzyme production and fungal growth were affected significantly. Also, a Gaussian-based mathematical model was developed to model the effects of airflow rate on enzyme production. The model fitted almost seamlessly to the experimental data. Thus, this study clearly showed the effects of aeration on glucoamylase and protease production from waste bread under solid state fermentations.     

Effect of Cu particle size on hydrogenation of dimethyl succinate over Cu–SiO2 nanocomposite

Copper–silica nanocomposite with different Cu particle size was synthesized by changing the concentration of Cu nitrate solution by precipitation-deposition method. In this preparation method, the average Cu particle size was estimated to be 11 nm, 23 nm and 33 nm for 0.05 M, 0.8 M, and 2.0 M of Cu nitrate solution, respectively, which was confirmed by XRD and TEM. When the catalytic activities of these materials, Cu(76)/SiO₂, were compared in hydrogenation of dimethyl succinate (DMS) at 265 °C and 25 bar, the product distribution as well as DMS conversion was highly dependent on Cu particle size. At WHSV 0.4 h^− 1, Cu(76)/SiO₂ with Cu particle size of 11 nm gave much higher tetrahydrofuran (THF) selectivity (93%) than that of 33 nm (20%) for the same DMS conversion (100%). The smaller Cu particles size was more advantageous to higher DMS conversion and higher THF selectivity, while the larger Cu particle size was more advantageous to higher γ-butyrolactone (GBL) selectivity. It is concluded that THF could be produced selectively by controlling only Cu particle size without adding the acidic promoters such as alumina to Cu metallic sites.     

Preparation of kanamycin powder by an optimized spray freeze-drying method

The physical and antibiotic properties of kanamycin powders obtained by spray freeze drying (SFD) were compared with those of raw kanamycin. The SFD procedures were optimized to prepare kanamycin for use as an inhaled drug. Scanning electron microscopy (SEM) and a laser particle size analyzer were applied to estimate physical structure and properties of the particle. In addition, the disk diffusion method was used to compare the antibiotic activity of raw kanamycin and that produced by SFD. According to SEM, the kanamycin particles had various sizes and shapes with porous structures at different SFD conditions. The diameters of the kanamycin powders were between 13.5 μm and 21.8 μm, and their aerodynamic particle sizes were between 3.58 μm and 6.39 μm. The antibiotic activities of the raw and spray freeze-dried kanamycin samples were not significantly different (P > 0.05). The optimized conditions for annealing temperature, annealing time, kanamycin concentration, pressure, and nozzle tip lift were ? 15 °C, 5 h, 10% kanamycin, 100 kPa, and, 1 mm, respectively.     

Micronization of ketoprofen by the rapid expansion of supercritical solution process

The particle size of the pharmaceutical substances is important for their bioavailability (the percentage of the drug absorbed compared to its initial dosage). The absorption rate can be increased by reducing particle size of the drug particles. This study was conducted to investigate the effects of the extraction pressure (140–220 bar), extraction temperature (308–338 K), nozzle length (2–15 mm), effective nozzle diameter (450–1700 μm), and collection distance (1–10 cm) on the size and morphology of the precipitated ketoprofen particles. The characterization (size and morphology) of the particles was investigated using scanning electron microscopy (SEM). The average particle size of the original material was 115.42 μm, while the average particle size of the micronized particles is between 0.35 and 7.03 μm near to quisi-spherical, needle and irregular shape depending upon the experimental conditions.     

Influence of nanoparticle diameter on conjugated enzyme activity

Lactase conjugated to nanomaterials represents an area of significant potential to the food processing as a means to produce novel value-added products, reduce waste, and enable diagnostics. While it is recognized that, in general, matter exhibits unique properties when manipulated at the nanoscale, little is known about how reducing the size of the carrier to the nanoscale effects attached lactase. The purpose of this work is to investigate the influence of particle size on activity retention of lactase (Aspergillus oryzae) covalently conjugated to magnetic nanoparticles of varying sizes. Lactase was attached to carboxylic acid functionalized magnetic nanoparticles 18 nm, 50 nm, and 200 nm in diameter using carbodiimide chemistry. After attachment, activity retention was 73%, 39%, and 14% compared to the free enzyme for the 18 nm, 50 nm, and 200 nm conjugates, respectively. The apparent K_m was not significantly different as a function of particle size while the apparent k_cat decreased with increasing particle size. Reducing the particle size of magnetic nanoparticles can increase the activity retention of conjugated lactase. This work provides improved understanding of enzyme-nanoparticles systems and allows for enhanced design of lactase-conjugated materials.     

Influence of ultrasonic treatment on the structure and emulsifying properties of peanut protein isolate

Effects of ultrasonic treatment on emulsifying properties and structure of peanut protein isolate (PPI) were evaluated by analysis of particle size distribution, protein surface hydrophobicity, SDS-PAGE, circular dichroism spectra and environmental scanning electron microscopy. The emulsifying properties of the PPI were found to be improved by ultrasonic treatment. The mean particle size decreased from 474.7 nm to 255.8 nm while the molecular weight remained unaffected. The results of intrinsic fluorescence spectroscopy and surface hydrophobicity indicated that ultrasonic treatment induced tertiary structural changes of the proteins in PPI. Emulsifying activity index and emulsion stability index were found to be correlated fairly well with surface hydrophobicity (H₀) (r = 0.712 and r = 0.668, respectively).     

Influence of silicon carbide particle size on the microstructure and mechanical properties of zirconium diboride–silicon carbide ceramics

The influence of silicon carbide (SiC) particle size on the microstructure and mechanical properties of zirconium diboride–silicon carbide (ZrB₂–SiC) ceramics was investigated. ZrB₂-based ceramics containing 30 vol.% SiC particles were prepared from four different α-SiC precursor powders with average particle sizes ranging from 0.45 to 10 μm. Examination of the dense ceramics showed that smaller starting SiC particle sizes led to improved densification, finer grain sizes, and higher strength. For example, ceramics prepared from SiC with the particle size of 10 μm had a strength of 389 MPa, but the strength increased to 909 MPa for ceramics prepared from SiC with a starting particle size of 0.45 μm. Analysis indicates that SiC particle size controls the strength of ZrB₂–SiC.     

Effect of milling time and pH on the dispersibility of lead zirconate titanate in aqueous media for inkjet printing

Micrometre-sized Pb(Zr_0.53Ti_0.47)O₃ (PZT) powder was dispersed in water, stabilized with the ammonium polyacrylate (PAANH₄) and milled to reduce the particle size. The influence of the pH, the amount of PAANH₄, and the milling time on the zeta potential, the PZT particle size and the particle size distribution was studied. The agglomeration took place regardless the milling time at pH 3. The suspension, containing 5 vol.% of PZT and 5 wt.% of PAANH₄, milled at pH 10 for 240 min, was stable and contained particles with a narrow, log-normal particle size distribution with the median size of 160 nm. The dissociated carboxyl groups from the PAANH₄ interacted with the PZT particles as evidenced by Fourier transform infrared spectroscopy and electrosterically stabilized the particles in water at pH 10. The PZT particle size and the stability of the suspension fitted the requirements for the ink, suitable for ink-jet printing.     

Size distribution and sites of origin of droplets expelled from the human respiratory tract during expiratory activities

A new expiratory droplet investigation system (EDIS) was used to conduct the most comprehensive program of study to date, of the dilution corrected droplet size distributions produced during different respiratory activities.Distinct physiological processes were responsible for specific size distribution modes. The majority of particles for all activities were produced in one or more modes, with diameters below 0.8 μm at average concentrations up to 0.75 cm^?3. These particles occurred at varying concentrations, during all respiratory activities, including normal breathing. A second mode at 1.8 μm was produced during all activities, but at lower concentrations of up to 0.14 cm^?3.Speech produced additional particles in modes near 3.5 and 5 μm. These two modes became most pronounced during sustained vocalization, producing average concentrations of 0.04 and 0.16 cm^?3, respectively, suggesting that the aerosolization of secretions lubricating the vocal chords is a major source of droplets in terms of number.For the entire size range examined of 0.3–20 μm, average particle number concentrations produced during exhalation ranged from 0.1 cm^?3 for breathing to 1.1 cm^?3 for sustained vocalization.Non-equilibrium droplet evaporation was not detectable for particles between 0.5 and 20 μm, implying that evaporation to the equilibrium droplet size occurred within 0.8 s.     

Ball milling assisted hydrothermal synthesis of ZrO2 nanopowders

The formation of ZrO₂ nanopowders under various hydrothermal conditions such as temperature, time, autoclave rotation speed, heating rate and particularly assistance of ball milling during reaction was investigated. Full ZrO₂ formation (with monoclinic phase) from zirconium solution was completed at shorter times with increasing temperature such as after 4 h at 150 °C, 2 h at 175 °C and less than 2 h at 200 °C. Crystallite size increased from 2.9 to 4 nm with increasing reaction temperature from 125 °C to 200 °C, respectively. Ball milling assisted hydrothermal runs were performed to understand the effect of mechanical force on phase formation, crystallinity and particle size distribution. Monoclinic ZrO₂ was formed in both milled and non-milled runs when zirconium solution was used. Mean particle size for the 2 M solution was measured to be 94 nm for the milled and 117 nm for the non-milled powders. However, when amorphous aqueous zirconia gels (precipitated at pH 5.8) were used, tetragonal phase was also formed in addition to monoclinic phase. Mean particle size was measured to be 0.7 μm (d₉₀≅1.3 μm) for the milled and 7.9 μm (d₉₀≅13 μm) for the non-milled powders. Ball milling during hydrothermal reactions of both zirconium solution and aqueous zirconium gel resulted in smaller crystallite size and mean particle size and, at the same time, effectively controlled particle size distribution (or agglomeration) of nanopowders.     

Production of cellulases from coconut coir pith in solid state fermentation

Coconut coir pith, available in abundance especially in tropical countries, was studied as a substrate for the production of cellulase[1,4(1,3;1,4)-β-D -glucan 4-glucanohydrolase, EC 3.2.1.4] and β-D -glucosidase(β-D -glucoside glucohydrolase, EC 3.2.1.21) in solid state fermentation. The effects of fermentation time, nutrient level, substrate particle size and inoculum size have been examined for optimal production of these enzymes by the fungal strain Aspergillus niger NCIM 1005. The highest filter paper activity (FPA) of 4.11 IU g^?1, carboxyl methyl cellulose (CMCase) activity of 15·55 IU g^?1 and cellobiase activity of 9·31 IU g^?1 were obtained after 7 to 8 days of fermentation. Reese and Mandel's mineral solution in the substrate to mineral solution ratio of 1:10 (w/v) supported high cellulase and cellobiase activities. An inoculum size of 20–50% (v/v) based on the volume of mineral medium and substrate average particle size of 375 μm were optimum for enzyme production.     

Effect of particle size on the mechanical properties of reaction bonded boron carbide ceramics

In the present communication, effect of boron carbide particle size on the mechanical properties such as hardness, fracture toughness and flexural strength of reaction bonded boron carbide (RBBC) ceramics were investigated. RBBC composites were produced by the reactive infiltration of molten silicon into porous preform containing boron carbide and free carbon. Boron carbide powders with mean particle size of 18.65 μm, 33.70 μm and 63.35 μm were chosen for the RBBC composites. The experimental results show that hardness increases from 1261.70±64.74 kg/mm² to 1674.90±100.00 kg/mm² and fracture toughness drops from 5.76±0.26 MPa m^1/2 to 3.4±0.37 MPa m^1/2. However, flexural strength decreases from 403.41±5.70 MPa to 256.15±25.05 MPa with the increase in particle size. Indentation induced cracks in RBBC are mainly median type and number of cracks increase with the increase of starting particle size.     

Effect of operating parameters on PVP/tadalafil solid dispersions prepared using supercritical anti-solvent process

Supercritical anti-solvent (SAS) process was employed to produce tadalafil solid dispersion sub-micron particles. Three independent variables for the SAS process (temperature, pressure, and drug concentration) were varied in order to investigate the effects on particle size and morphology of PVP/tadalafil solid dispersion (drug to polymer ratio 1:4). The mean particle size decreased with decreasing temperature (50 → 40 °C) and concentration (15 → 5 mg/mL) and increasing pressure (90 → 150 bar). Depending on the experimental variable, the mean particle size varied from 200 nm to 900 nm, and the dominant experimental variable was determined to be the drug concentration. Moreover, at a concentration of 15 mg/mL with any other process conditions, tadalafil tended to partially aggregate in crystalline form with irregular particle shapes. The results of in vitro dissolution experiments showed good correlation with mean particle size and crystallinity of the SAS-processed particles, in that the highest drug concentration showed the least dissolution rate and vice versa. Therefore, among the three variables studied, the drug concentration is the major factor that produces sub-micron particles in the SAS process.     

Self-oscillations of methane oxidation rate over Pd/Al2O3 catalysts: Role of Pd particle size

Oscillations of the methane oxidation rate were studied under methane-rich conditions on Pd/Al₂O₃ catalysts differing in Pd particle size. It was demonstrated that the temperature interval where oscillations occur narrows from 300–360 °C for the catalyst with Pd particle aggregates from 50–100 nm to 345–355 °C for the catalyst with isolated Pd particles of ~ 5 nm in size. At the same time, the period of oscillations showed ~ 6-fold increase. Structural transformations of Pd in the oscillation cycle were similar to those observed on bulk Pd used as a catalyst in the same reaction.     

Effects of inert filler addition on the structure and properties of porous SiOC ceramics derived from silicone resin

Porous SiOC ceramics were obtained from a new self-blowing precursor silicone resin DC217, by pyrolysis at 1200 °C in argon. Silicon carbide powders were incorporated into the silicone resin as inert fillers. The effects of the mean particle size of SiC fillers on the porosity, compressive strength and microstructure of the porous ceramics were investigated. With the mean particle size of SiC powders increasing from 5 μm to 10 μm, the porosity (total and open) of the porous ceramic increased and the compressive strength decreased. However, the porosity, compressive strength and cell morphology of the porous ceramics showed no evident changes when the mean particle size of fillers increased from 10 μm to 15 μm. Micrographs indicated that, when the mean particle size of fillers exceeded 5 μm, the porous ceramics could have a well-defined and regular pore structure. Furthermore, comparing with the porous ceramics which fabricated under the same condition with the SiOC powders as fillers, the cell morphology was similar. But the compressive strength and the oxidation resistance of the porous ceramics with SiC powders as fillers were much better.     

Significance of hot pressing parameters and reinforcement size on sinterability and mechanical properties of ZrB2–25 vol% SiC UHTCs

The influences of hot pressing parameters and SiC particle size on the bulk density, the average ZrB₂ grain size and Vickers hardness of ZrB₂–25 vol% SiC ultrahigh temperature ceramic composites were investigated. In this paper, the Taguchi methodology (An L9 orthogonal array) was used to specify the contributions of four parameters: the hot pressing temperature, holding time, applied pressure and SiC particle size. The experimental procedure included nine tests for four parameters with three levels which were employed to optimize the process parameters. The statistical analyses recognized the hot pressing pressure and temperature as the most consequential parameters affecting the density and hardness of ZrB₂–SiC composites. The SiC particle size and holding time were specified as the most effective parameters on the average ZrB₂ grain size. The bulk density, average ZrB₂ grain size, Vickers hardness and fracture toughness of the sample, hot pressed at optimal conditions (1850 °C, 90 min, 16 MPa and 200 nm), reached about 5.36 g/cm³, 10.03 µm, ~17.1 GPa and 5.9 MPa m^1/2, respectively. The confirmation test, carried out under optimum conditions, showed that the experimental results were relatively equal to the predicted values from the Taguchi prediction model. Finally, the mechanisms of enhanced fracture toughness of the hot pressed ZrB₂–SiC ceramic composites were discussed.