Characteristics and gel properties of gelatin from goat skin as affected by spray drying

Gelatin powder from goat skin prepared by spray drying at various inlet temperatures (160–200°C) was characterized. Predominant particle sizes were in the range of 4.65–5.14?µm. Gelatin powder was mostly concave in shape with varying sizes, depending on inlet temperatures used. All gelatin powders were creamy whitish. Powder generally became more yellowish as the inlet temperature of spray drying increased (p?p?p?p?>?0.05). Goat skin gelatin spray dried with inlet temperatures of 160 or 180°C had higher gel strength than commercial bovine gelatin (p?相似文献   

Microencapsulation of Kaffir Lime Oil and Its Functional Properties

This paper describes the effects of spray drying temperature and wall materials on functional properties of kaffir lime oil microcapsules. The effects of spray drying were studied at inlet air temperatures at 160, 180, and 200°C. Two coating materials (konjac glucomannan and gum arabic) were employed in this study. The results indicate that kaffir lime oil had antibacterial activity against all tested pathogens and was able to inhibit Vibrio cholerae comparable to a standard antibiotic. The combination of konjac glucomannan and gum arabic (KGM+GA) can enhance the yield and retention of total oil in the microcapsules more than using konjac glucomannan alone as a wall material. Increasing inlet air temperature resulted in a decrease of antibacterial activity and amount of bioactive volatile compounds. Physical and chemical properties of the microcapsules did not differ significantly (p > 0.05) in terms of process yield, a _w , moisture content, efficiency in retention of total, surface and inner oil, water solubility index, and color except at inlet air temperature of 200°C. However, it was found that the kaffir lime oil microcapsules from KGM+GA produced at inlet temperature of 180°C had the best functional properties in terms of antibacterial activity and efficiency of retention of total encapsulated oil.     

Effects of Spray Drying Temperature and Additives on the Stability of Serine Alkaline Protease Powders

In this study, after production by recombinant Bacillus subtilis (BGSC-1A751), carrying pHV1431::subc gene in the complex medium and separation of solids from the fermentation broth, serine alkaline protease (SAP) was dried in order to investigate the stabilization during spray drying and subsequent storage. The effect of air inlet temperature of the spray dryer between T = 70 and 130°C and the effect of protective additives, glucose and maltodextrin, at 0–2% (w/v) on SAP activity during spray drying and storage stability of obtained SAP powders at 4°C for a long period (6 months) were evaluated. Increasing drying air inlet temperature generally resulted in an increase in activity loss; moreover, higher absorbance peaks observed at wave number 1061 cm^?1 of the IR spectrums when drying temperature is increased indicates the structural change in the SAP molecule. In most cases presence of additives provided higher activities both after drying and during storage period compared to no additive case. Drying the enzyme with 1% (w/v) glucose at T = 110°C resulted in the highest enzyme activity after drying and storage processes.     

A Study of the Limitations to Spray Dryer Outlet Performance

Abstract

The concept of the product moisture locus was tested in this work using a pilot-scale modified Niro spray dryer (diameter 0.8 m, height 2 m), where the residence time of the particles inside this spray dryer is lower compared with larger industrial spray dryers. The moisture contents of skim milk powder produced from spray drying skim milk (solids content 8.8% w/v) at different operating conditions, namely different swirl vane angles (0°, 25°, 30°), inlet air temperatures (170°C, 200°C, 230°C) and process fluid flowrates (1.4 kg h^?1, 1.6 kg h^?1, 1.8 kg h^?1), were compared with the predicted equilibrium moisture contents. In addition, the residence time of the particles was also increased in the spray dryer by decreasing the inlet air mass flowrate from 0.016 to 0.013 kg s^?1. The outlet moisture contents of the skim milk powder for all the 23 runs carried out in this work were within 0.4% of the equilibrium values. Thus, the skim milk powder particles were in close equilibrium with the gas inside the drying chamber. These equilibrium limitations are confirmed by other literature data (Boonyai, P. Comparative Evaluation of Soymilk Drying in a Spray Dryer and Spouted Bed of Inert Particles. M.Sc. Thesis. Asian Institute of Technology: Bangkok, Thailand, 2000; 90 pp; Harvie, D.J.E.; Langrish, T.A.G.; Fletcher, D.F. A computational fluid dynamics study of a tall-form spray dryer. Trans IChemE 2002, in press). The use of this finding to predict spray dryer performance is demonstrated by mass and energy balance calculations.     

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 New Model and Quality of Unfrozen and Frozen Cooked Rice Dried in a Microwave Vibro-Fluidized Bed Dryer

This study aimed to develop a suitable drying model for microwave vibro-fluidized bed drying in a single-mode applicator (MVFB-SMA drying) of cooked rice with and without prefreezing treatment and to investigate the effects of prefreezing treatment and drying temperature (110–185°C) on quality of dried cooked rice. During the process of drying cooked rice from 60 to 10% (wet basis), results indicated that drying rate increased, whereas drying time decreased with prefreezing treatment and increased drying temperature. The drying rate and drying time of unfrozen and frozen cooked rice ranged from 0.196 to 0.497 g water/g dry matter/min and 0.228 to 0.554 g water/g dry matter/min; and from 7 to 2.5 min and 5.5 to 2 min, respectively. A new model was proposed in this study (MR = exp(?k t ⁿ ) + bt + c) to compare with 11 commonly used drying models. The new model describes the MVFB-SMA drying data most satisfactorily. The values of effective diffusivity were between 1.70 × 10^?7 and 5.72 × 10^?7 m²/s for the unfrozen sample and between 1.99 × 10^?7 and 5.86 × 10^?7 m²/s for the frozen sample. Their activation energy values were 23.66 and 21.19 kJ/mol, respectively. Prefreezing treatment provided a whiter product with a less uniform porous structure and higher bulk density. Slower ability to rehydrate was also observed for the frozen cooked rice dried at 160 and 185°C. An increase in drying temperature resulted in changes in whiteness, microstructure, bulk density, and rehydration capability. No prefreezing treatment and drying at 160°C seemed to be the optimal process condition for cooked rice, ensuring whiteness, a porous structure, low bulk density, and high rehydration capability.     

Characteristics,Stability, and Release of Peanut Sprout Extracts in Powdered Microcapsules by Spray Drying

This study was carried out to investigate the characteristics of powdered microcapsules from peanut sprout extracts prepared by spray drying. The microcapsules were made from medium-chain triglyceride (MCT) as primary coating material and whey protein concentrate (WPC) or maltodextrin (MD) as selected secondary coating materials. The microcapsule studies conducted were microphotograph, scanning electron microscopy (SEM), Fourier-transform infrared (FT-IR), particle size, moisture contents, sorption, zeta potential, storage stability, and in-vitro study. The surface of microcapsules coated with WPC were rough and smooth, and particle size ranged from 2.86 to 8.59 µm. An FT-IR study revealed that absorption bands at 1,537 and 1,657 cm^?1 of microcapsules can be attributed to the protein amide I and II bands of WPC overlapped by the conjugated C?C. The moisture content was 1.33% in the microcapsules coated with WPC. The moisture sorption increased until 18% at the 90% RH. The yield of peanut sprout extracts from microcapsules was 89.01%. In the in-vitro study, the microcapsules released 2.48 and 6.01% at pH 2.0 and 4.0, respectively, in simulated-gastric fluid, and 61.07 and 89.24% at pH 6.0 and 8.0, respectively, in simulated-intestinal fluid. The preservation rate of the microcapsules dropped down to 60.43% from 89.01% during six months of storage. The stability of peanut sprout extracts in the microcapsules was over 80% at 4 and 20°C during 10-day storage. The zeta-potential of microcapsules was stable with ?30 mV. Based on the data obtained from the present study, the powdered peanut-sprout-extract microcapsules coated with WPC exhibited high stability during storage. Therefore, the powdered microcapsules by spray drying may be useful as a functional ingredient.     

Hybrid Solar Dryer for Quality Dried Tomato

A prototype of a hybrid solar dryer was developed for drying of tomato. It consists of a flat-plate concentrating collector, heat storage with auxiliary heating unit, and drying unit. It has a loading capacity of 20 kg of fresh half-cut tomato. The dryer was tested in different weather and operating conditions. The performance of the dryer was compared with an open sun-drying method. Drying performance was evaluated in terms of drying rate, color, ascorbic acid, lycopene, and total flavonoids. Tomato halves were pretreated with UV radiation, acetic acid, citric acid, ascorbic acid, sodium metabisulphite, and sodium chloride. Sodium metabisulphite (8 g L^?1) was found to be effective to prevent the microbial growth at lower temperature (45°C).     

Hot-Air Drying and Rehydration Characteristics of Red Kidney Bean Seeds

The effects of pretreatments such as citric acid and hot water blanching and air temperature on drying and rehydration characteristics of red kidney bean seeds were investigated. Drying experiments were carried out at four different drying air temperatures of 50°C, 60°C, 70°C, and 80°C. It was observed that drying and rehydration characteristics of bean seeds were greatly influenced by air temperatures and pretreatments. Four commonly used mathematical models were evaluated to predict the drying kinetics of bean seeds. The Weibull model described the drying behaviour of bean seeds at all temperatures better than the other models. The effective moisture diffusivities (D_eff) of bean seeds were determined using Fick's law of diffusion. The values of D_eff were between 1.25 × 10^?9 and 3.58 × 10^?9 m²/s. Activation energy was estimated by an Arrhenius-type equation and was determined as 24.62, 21.06, and 20.36 kJ/mol for citric acid, blanch, and control samples, respectively.     

Preparation of Phospholipid Microcapsule by Spray Drying

An experimental study of spray drying was carried out aimed at improvement of the phospholipid microencapsulation process. Three kinds of wall materials, maltodextrin blended with sodium caseinate, gelatin, and soy protein, respectively, were used to prepare phospholipid emulsion. Through examining the emulsion stability, a stable emulsion with the sodium caseinate contained system was obtained under 2.5 of mass ratio between maltodextrin and sodium caseinate, 70–80°C of emulsification temperature, 2.5% of emulsifier concentration, and 40 MPa of homogenization pressure. Phospholipid microcapsules with a mean size of 62 µm in apparent geometric diameter and good fluidity, dispersion, and dissolubility were prepared under 140°C of air inlet temperature, 30°C of feed temperature, and 20% of solids concentration. Up to 90% of phospholipid microencapsulation efficiency is achieved. In addition, phospholipid microcapsules have good dissolubility, fine appearance, and excellent fluidity and dispersion.     

Effect of Different Drying Methods on Rheological and Textural Properties of Balangu Seed Gum

The purpose of the present study was to investigate the effect of different drying methods on the rheological and textural properties and color changes in Balangu seed gum. Three drying methods, including air drying (40–80°C), freeze drying, and vacuum drying, were used. The apparent viscosity decreased from 0.161 to 0.056 Pa s with increasing temperature from 40 to 80°C (shear rate = 60 s^?1) and freeze-dried gum exhibited the highest viscosity among all dried gums (0.203 Pa s). Different time-independent rheological models (power law, Bingham, Herschel-Bulkley, Casson, and Vocadlo) were used to fit the experimental data and the results revealed that the Herschel-Bulkley model was the most suitable to describe the flow behavior of Balangu seed gum over the whole experimental range (r > 0.98). The hardness values of air dried Balangu seed gum gels varied from 33.1 to 40.4 g and were significantly lower compared to the freeze-dried and vacuum-dried gums (46.9 and 46.6, respectively). The consistency of samples decreased from 386.27 to 245.33 g · s when the drying air temperature increased from 40 to 80°C. The results indicated that the freeze-dried gum exhibited the highest hardness and consistency. The color of air-dried gum was darker (lower L* value) compared to the freeze- and vacuum-dried samples.     

Combined Infrared-Convective Drying of Murta (Ugni molinae Turcz) Berries: Kinetic Modeling and Quality Assessment

Murta (Ugni molinae Turcz) berries were dried under convective and combined convective-infrared conditions at 40, 50 and 60°C and 400–800 W in order to determine the drying characteristics and to compare the dried product's quality. To model the drying kinetics, seven mathematical equations were fitted to experimental data. According to statistical tests performed, the Midilli-Kuçuk model best fitted experimental data and was closely followed by the logarithmic model. Effective moisture diffusivity also showed dependency on drying conditions and varied between 7.59 × 10^?10 to 44.18 × 10^?10 m²/s and 11.34 × 10^?10 to 85.41 × 10^?10 m²/s for air-convective drying and combined infrared-convective drying. As to quality attributes of the berries, total surface color difference (ΔE) and total phenolic content (TPC) were determined. It was found that chromaticity coefficients a* and b* changed significantly, showing ΔE to be dependent on the mode of heat supply. TPC under all drying conditions decreased and was significantly different from the initial value in fresh samples. However, at a constant drying temperature, an increase in infrared power enhanced retention of TPC in samples. In particular, working at 40°C/800 W resulted in dried samples with the highest TPC.     

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.     

Chemical Pretreatments Affecting Drying Characteristics of Chilli (cv. Huarou Yon)

One- (70°C) and two-temperature regimes (70 and 50°C) were used to dry chilli (Capsicum annuum cv. Huarou Yon) using a laboratory tray dryer compared to conventional sun drying. A pretreatment was done by soaking chilli in antibrowning solutions before drying. It was found that the drying rate of chilli soaked in chemical solutions was increased and the drying period of chilli was decreased. Page's model was found to fit well with the experiment for one- and two-temperature drying using least squares analysis. The highest value of the coefficient of determination (R² > 0.99), the lowest value of standard error of estimation (SEE < 0.00031), and the lowest value of the mean relative deviation (P < 10%) were obtained. The effective moisture diffusivities of chilli drying at 70°C and two-stage drying were between 6.01–7.22 × 10^?10 m²/s and 3.16–3.89 × 10^?10 m²/s, respectively. In contrast, the lowest value of effective moisture diffusivity of chilli was obtained by the conventional sun-drying method (0.597 × 10^?10 m²/s). The highest value of moisture diffusivity was observed for chilli soaked in sodium metabisulfite (NaMS) mixed with CaCl₂ solution for both one- and two-temperature regimes. The color of chilli was improved by using chemical pretreatments, in particular, chilli soaked in NaMS mixed with CaCl₂ solution.     

Thin-Layer Drying of Green Peas and Selection of a Suitable Thin-Layer Drying Model

The thin-layer drying of three varieties of green peas was carried out in hot air-drying chamber using an automatic weighing system at five temperatures (55–75°C) and air velocity of 100 m/min. The green peas were blanched and sulphited before drying. The variety Pb-87 dried at 60°C was judged to be best for quality on the basis of sensory evaluation and rehydration ratio. The Thomson model was found to represent thin-layer drying kinetics within 99.9% accuracy. The effective diffusivity was determined to be 3.95 × 10^?10 to 6.23 × 10^?10 m²/s in the temperature range of 55 to 75°C. The activation energy for diffusion was calculated to be 22.48 kJ/mol. The variation in shrinkage exhibited a linear relationship with moisture content of the product during drying. The Dincer number at drying air temperature 60°C and drying air velocity 100 m/min was determined to be 2,838,087. The difference between temperatures of drying air and that of green pea kernels was found to decrease with drying time for all the drying temperatures taken for investigation.     

Effect of Dipping Temperature and Dipping Time on Drying Rate and Color Change of Grapes

Thompson seedless grapes (Vitis vinifera) were pretreated in potassium carbonate and ethyl oleate solutions for 1, 2, and 3 min at 30, 40, 50, and 60°C and dried in a convective air dryer at 60°C. The effect of dipping time and solution temperature on drying rate and color kinetics were investigated. Grapes dipped into the solution at 60°C for 2 and 3 min had the fastest drying rate. Among the seven semi theoretical models compared, the Midilli equation best described the drying curves of grapes for all dipping pretreatments. Color data were obtained using a machine vision system in CIE L*a*b* color space. Regardless of the dipping time and temperature applied, all raisins had varying degrees of brown coloring. At all dipping times and temperatures the highest R ² value was obtained for a* values, which followed zero-order reaction kinetics during drying.     

Convective Drying of Wastewater Sludge: Introduction of Shrinkage Effect in Mathematical Modeling

Drying of two kinds of wastewater sludge was studied. The first part was an experimental work done in a discontinuous cross-flow convective dryer using 1 kg of wet material extruded in 12-mm-diameter cylinders. The results show the influence of drying air temperature for both sludges. The second part consisted of developing a drying model in order to identify the internal diffusion coefficient and the convective mass transfer coefficient from the experimental data. A comparison between fitted drying curves, well represented by Newton's model, and the analytical solutions of the equation of diffusion, applied to a finite cylinder, was made. Variations in the physical parameters, such as the mass, density, and volume of the dried product, were calculated. This allowed us to confirm that shrinkage, which is an important parameter during wastewater sludge drying, must be taken into account. The results showed that both the internal diffusion coefficient and convective mass transfer coefficient were affected by the air temperature and the origin of the sludge. The values of the diffusion coefficient changed from 42.35 × 10^?9 m² · s^?1 at 160°C to 32.49 × 10^?9 m² · s^?1 at 122°C for sludge A and from 33.40 × 10^?9 m² · s^?1 at 140°C to 28.45 × 10^?9 m² · s^?1 at 120°C for sludge B. The convective mass transfer coefficient changed from 4.52 × 10^?7 m · s^?1 at 158°C to 3.33 × 10^?7 m · s^?1 at 122°C for sludge A and from 3.44 × 10^?7 m · s^?1 at 140°C to 2.84 × 10^?7 m² · s^?1 at 120°C for sludge B. The temperature dependency of the two coefficients was expressed using an Arrhenius-type equation and related parameters were deduced. Finally, the study showed that neglecting shrinkage phenomena resulted in an overestimation that can attain and exceed 30% for the two coefficients.     

Lactose hydrolyzed milk powder: Thermodynamic characterization of the drying process

Industrial production of lactose hydrolyzed milk powder (LHMP) remains challenging. Due to the presence of the monosaccharides glucose and galactose, lactose-free powders tend to suffer stickiness, caking, and browning during drying and storage. We sought to find ideal conditions spray dryer inlet air temperature (θ_air,in) and concentrated milk flow rate (m_CM) for LHMP production. We tested θ_air,in settings of 115–160°C and m_CM of 0.3–1.5?kg?·?h^?1, and also applied mass and energetic balances. LHMP generally exhibited higher mass and energetic losses than the control (milk powder containing lactose), as a consequence of the relatively low dryability of LHMP. For a lab scale spray dryer, the ideal conditions settings for LHMP production were θ_air,in?=?145?±?2°C and m_CM?=?1.0?kg?·?h^?1, taking into account the mass yield and energetic cost (kJ?·?kg^?1 of powder) of the process. These ideal conditions are a potential tool for the industrial development of lactose-free dairy powders.     

Drying Behavior of Meat Samples at Various Fiber Directions and Air Conditions

The aim of this study was to investigate the effects of meat fiber directions and air conditions on moisture and temperature developments, shrinkage, and effective diffusivity constants compared to homogenous minced meat samples. The lean meat with three fiber directions and minced meat samples were dried at temperatures of 48 and 70°C and air flow rates of 0.5, 1.0, and 1.7 m/s. The minced meat samples showed 1.0 ± 0.19 to 4.4 ± 0.03°C higher temperature values and 2.3 ± 0.004 to 6.2 ± 0.003% lower moisture losses than the lean meat samples in all fiber directions. The lowest temperatures were observed in lean meat with h ₁ (normal flow, normal drying) fiber direction. The highest moisture loss and diffusion coefficient were observed in lean meat with h ₂ (parallel flow, normal drying) and v (normal flow, parallel drying) fiber directions, which also possessed the shortest drying times (10.4 and 13.4 h, respectively). The estimated diffusion coefficient values ranged between 1.11 × 10^?9 and 5.54 × 10^?9. The results indicated that lean and minced meat samples differed in their drying behaviors in a tray dryer under the tested conditions with >90% reproducibility (or ≤10% coefficient of variation).     

Low-Temperature Spray Drying for the Microencapsulation of the Fungus Beauveria bassiana

Low-temperature spray drying was used to microencapsulate the conidia of Beauveria bassiana. In order to prolong the activity of the conidia and improve their shelf life, various polymers (including hydroxypropyl methyl cellulose [HPMC], chitosan, dextrin, skimmed milk, and polyvinylpyrrolidone [PVP K90]) were examined as encapsulation matrices. Different inlet/outlet temperatures, compositions of the carrier systems, and conidia concentrations were examined with respect to spore viability. Moreover, the production characteristics, such as particle size distribution, entrapment efficiency, and shape, were investigated. The best encapsulated products were obtained using a matrix composed of 10% dextrin, 10% skimmed milk, and 5% PVP K90 as the coating material. The conidia exhibited 80% viability, even after storage for 6 months at 4°C. The microspheres obtained by spray drying were spherical with smooth or wrinkled surfaces. The mean particle size was in the range of 2.5–10 μm. The yield (%) using dextrin/SM/PVP K90 as coating material having maximum viability was 68 ± 4, whereas that with dextrin only as coating material was 85 ± 3.