Showing papers in "Drying Technology in 2013"
TL;DR: In this paper, spray-drying conditions (air inlet temperature and feed flow rate) were optimized for the microencapsulation of the thermo sensitive probiotic lactobacilli strains Lactobacillus acidophilus stabilized in a 60:20:20 (w/w) maltodextrin: whey protein concentrate: D-glucose carrier.
Abstract: Inrecent years, the use of spray drying for the production of anhydrobiotics has gained the interest of functional food manufacturers, mainly due to cost efficiencies and enhanced product and process flexibility (e.g., enhanced shelf life). In the present work, spray-drying conditions (air inlet temperature and feed flow rate) were optimized for the microencapsulation of the thermo sensitive probiotic lactobacilli strains Lactobacillus acidophilus stabilized in a 60:20:20 (w/w) maltodextrin: whey protein concentrate: D-glucose carrier. A 23 full-factorial experimental design was constructed with air inlet temperature (120, 140, and 160°C) and feed flow rate (6, 7.5, and 9.0 mL/min) as the independent variables and total viable counts (TVC), water activity (a w ), and cyclone recovery (CR) defined as the dependent variables. The increase in air inlet temperature from 120 to 160°C induced a significant (p < 0.001) reduction in the TVC from 9.02 to 7.20 log cfu/g, which corresponds to a97.5% loss of the L. a...
148 citations
TL;DR: In this paper, the authors evaluated the stability of anthocyanins and antioxidant activity of blackberry powder, obtained by spray drying, using maltodextrin, gum arabic, or a blend of both carrier agents over a period of 5 months.
Abstract: The aim of this work was to evaluate the stability of anthocyanins and antioxidant activity of blackberry powder, obtained by spray drying, using maltodextrin, gum arabic, or a blend of both carrier agents over a period of 5 months. The inlet air temperature was 145°C and the concentration of carrier agent was 7% (w/w). Samples were stored at 25 or 35°C and at relative humidity of 32.8%. Anthocyanin degradation followed the first-order kinetic model. Temperature negatively influenced the stability of anthocyanins, because these pigments are highly thermosensitive. Antioxidant activity increased for the powders stored at 35°C, probably due to the occurrence of the Maillard reaction, leading to the formation of compounds with antioxidant activity. In general, maltodextrin provided greater stability for spray-dried blackberry powder, because particles produced with this carrier agent showed the longest half-life and the lowest anthocyanin degradation rate at 25°C. The use of maltodextrin or the combination o...
133 citations
TL;DR: In this article, the authors present a systematic review on the theoretical developments of mechanistic models related to the blocking filtration laws for describing the membrane fouling in membrane filtrations.
Abstract: Pore blocking is one of the critical factors governing the overall performance of membrane filtration systems. Pore blockage leads to a large resistance to filtration, giving rise to a sharp decline in the filtrate flux rate under constant pressure conditions and a severe increase in the pressure for operation under constant flux conditions during membrane filtration. In membrane filtration work, blocking filtration laws are widely used to interpret the membrane fouling in membrane filtration. This article presents a systematic review on the theoretical developments of mechanistic models related to the blocking filtration laws for describing the membrane fouling in membrane filtration. Equations for constant pressure and constant flux separations in the interstices of a membrane and on the surface are reported for the filtrate flow of Newtonian and power-law non-Newtonian fluids. The blocking filtration laws are useful also in the evaluation of the reduced pore size, maximum filtrate volume, and fouling p...
128 citations
TL;DR: In this article, the efficiency of two drying carriers, namely whey protein isolate (WPI) and maltodextrin (MD), alone or in combination, was evaluated during spray-drying of honey.
Abstract: The efficiency of two drying carriers, namely whey protein isolate (WPI) and maltodextrin (MD), alone or in combination, was evaluated during spray-drying of honey. No powder was recovered when pure honey was spray-dried. Honey powders were successfully obtained (powder recovery >50%) by adding MD and WPI alone at a Honey: MD ratio of 40:60 or at a Honey:WPI ratio of 70:30. The addition of a small amount of WPI (as low as 0.5% w/w) to MD reduced the amount of carriers required to spray-dry honey. Powder recovery increased from 0 (Honey:MD:WPI = 60:40:0) to 57.4 ± 4.7% when MD was replaced by 0.5% WPI (Honey:MD:WPI = 60:39.5:0.5). The surface tension of feed solutions, surface elemental composition, and glass transition temperature of spray-dried honey powders was analyzed. The mechanisms of such a significant effect of WPI on spray-drying of honey are attributed to the preferential migration of protein to the droplet/air interface and the limited inward movement of protein during moisture evaporation, in ...
107 citations
TL;DR: In this paper, the influence of pulsed electric field (PEF) on the drying kinetics of apple tissue was studied and mathematical models that are commonly used in the literature were applied to describe the process.
Abstract: The aim of this work was to study the influence of pulsed electric field (PEF) on the drying kinetics of apple tissue. Therefore, mathematical models that are commonly used in the literature were applied to describe the process. PEF treatment of the samples was carried out at an intensity of E = 5–10 kV/cm and 10–50 pulse numbers. Subsequently, the apples were convectively dried at 70°C and air velocity of 2 m/s. Based on electrical conductivity measurement, the cell disintegration index Z p was computed. Midilli et al.'s(Drying Technology, Vol. 20, pp. 1503–1513, 2001) model was evaluated as the most adequate to describe the moisture transfer in PEF-treated and intact samples. PEF pretreatment induced a reduction in drying time of up to 12% when 10 kV/cm and 50 pulses were applied. For instance, after 60 min of drying, the dimensionless moisture ratio for PEF-treated (10 kV/cm, 50 pulses) samples was 0.18 compared to 0.26 for the untreated apples. The effective moisture diffusivity, calculated on the bas...
101 citations
TL;DR: In this paper, the authors evaluated the drying uniformity, shrinkage, rehydration, and textural properties of pulsed spouted microwave-vacuum-dried stem lettuce slices.
Abstract: Drying uniformity, shrinkage, rehydration, and textural properties were measured to evaluate the quality of pulsed spouted microwave–vacuum-dried stem lettuce slices. Drying was carried out in a 5-...
91 citations
TL;DR: In this paper, the influence of wall material concentration, inlet temperature, and feed rate on the properties of rosemary oil microencapsulated by spray-drying, with gum arabic as carrier, was evaluated.
Abstract: This study evaluated the influence of wall material concentration (10–30%), inlet temperature (135–195°C), and feed rate (0.5–1.0 L · h−1) on the properties of rosemary oil microencapsulated by spray-drying, with gum arabic as carrier. Powder recovery, surface oil, oil retention, and hygroscopicity varied from 17.25%–33.96%, 0.03%–0.15%, 7.15%–47.57%, and 15.87%–18.90%, respectively. The optimized conditions were determined to be a wall material concentration of 19.3%, an inlet air temperature of 171°C, and a feed flow rate of 0.92 L · h−1. At this condition, particles presented no fissures and the compositions of pure and microencapsulated oil were similar. The sorption isotherms could be described by the GAB model.
90 citations
TL;DR: In this article, the properties and stability of microcapsules containing fish oil co-encapped with phytosterol ester and limonene, prepared by spraydrying and freeze-drying methods, were investigated.
Abstract: The objectives of this study were to investigate the properties and stability of microcapsules containing fish oil co-encapsulated with phytosterol ester and limonene, prepared by spray-drying and freeze-drying methods. Whey protein isolate and soluble corn fiber were used as wall materials in the encapsulation process. The properties of microcapsules, including structure, glass transition, volatile/non-volatiles retention, microencapsulation efficiency, oxidation stability, color measurement, and sensory profiles, were evaluated after drying and during a seven-day accelerated storage trial. The finding reveals that drying methods have an effect on the retention of volatile fraction and the physical structure of the wall matrix consisted of WPI and SCF, consequently influencing the storage stability of the powders. Significantly higher retention of volatile fraction (p < 0.05) and lower surface oil were found in the spray-dried samples, resulting in the higher microencapsulation efficiency. However, sampl...
89 citations
TL;DR: 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 as discussed by the authors.
Abstract: 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-Kucuk 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 si...
87 citations
TL;DR: In this article, a review of the theoretical analysis of electroosmotic dewatering is presented, and various empirical research results addressing the effects of operational conditions and conditioning of sludge on both energy consumption and final water content of the sludge are reviewed.
Abstract: This work aims at providing an outline of engineering applications for electroosmosis, especially for sludge dewatering. A review of the theoretical analysis of electroosmotic dewatering is presented. The equations representing electroosmotic flow through porous media are initially discussed. Consolidation theory, which describes the progress of dewatering, is then described. In addition, various empirical research results addressing the effects of operational conditions and conditioning of sludge on both energy consumption and final water content of the sludge are reviewed. It is anticipated that this review will provide useful information to researchers pursuing solid–liquid separation of difficult-to-dewater materials such as sludge.
82 citations
TL;DR: In this article, the influence of drying methods on aroma compounds of thyme (Thymus vulgaris L.) was evaluated, and the drying methods tested were convective drying, vacuum-microwave drying, and freeze drying, as well as a combination of convective predrying and VM finish drying.
Abstract: The influence of drying method on aroma compounds of thyme (Thymus vulgaris L.) was evaluated. The drying methods tested were convective drying, vacuum–microwave drying, and freeze drying, as well as a combination of convective predrying and VM finish drying. Thyme's convective drying kinetics are described by a two-term exponential model, and VM drying kinetics consisted of two periods: a constant rate period until a critical moisture ratio (values of 0.311, 0.242, and 0.162 kg kg−1 for 240, 360, and 480 W, respectively) was obtained and a falling rate period beyond that point. Volatile compounds of thyme samples were extracted by hydrodistillation and analyzed by gas chromatography. Thirty-three compounds were tentatively identified; thymol, γ-terpinene, p-cymene, caryophyllene, and α-terpinene were the major components. The total quantity of volatiles of fresh thyme (1,167 mg 100 g−1 db) was reduced by most of the drying treatments, with the exception of VM at 240 and 360 W. The combined method with 40...
TL;DR: In this article, a mathematical model was developed to describe the drying kinetics of apple samples in a hot air dryer, taking into consideration material shrinkage and moisture- and temperature-dependent diffusion coefficients.
Abstract: In this study, a mathematical model was developed to describe the drying kinetics of apple samples in a hot air dryer. The model takes into consideration material shrinkage and moisture- and temperature-dependent diffusion coefficients. This model is capable of predicting the changes in moisture content and temperature with and without shrinkage inside the samples. The results of the model were compared with the experimental data to investigate the importance of shrinkage phenomena and effective diffusion coefficient on the drying kinetics. Disc-shaped apple samples were dried under air conditions at temperatures in the range of 60 to 80°C and the shrinkage of samples was measured experimentally. The results showed that the shrinkage had a significant effect on the effective diffusion coefficient and consequently affected the moisture and temperature distribution inside the material. Finally, a statistical analysis was performed and good agreement was found between the predicted and experimental results.
TL;DR: In this article, microencapsulation of extract pequi pulp by spray drying, using Arabic gum as a micro-encapsulating agent, was studied, and a factorial design was conducted with the following independent variables: inlet air temperature (140 to 200°C), surfactant concentration Tween 80 (0 to 5%), and microencapping agent concentration (10 to 20%).
Abstract: Microencapsulation of extract pequi pulp by spray drying, using Arabic gum as a microencapsulating agent, was studied. Tween 80 was used as a secondary emulsifier. A factorial design was conducted with the following independent variables: inlet air temperature (140 to 200°C), surfactant concentration Tween 80 (0 to 5%), and microencapsulating agent concentration (10 to 20%) on the responses; moisture content (0.3 to 1.9%), hygroscopicity (10.7 to 14.3 g adsorved water/100 g solids), process yield (25.8 to 56.1%), water activity (0.07 to 0.17), vitamin C (113.0 to 306.6 mg ascorbic acid/g pequi solids), and carotenoids content (10.9 to 74.3 mg carotenoids/g pequi solids). Only powder moisture content, hygroscopicity, water activity, and vitamin C content were statistically influenced by independent variables. Spray drying was optimized for maximum vitamin C and carotenoids content and minimal water content and hygroscopicity. Powder obtained under optimum conditions was characterized as to particle morphol...
TL;DR: In this paper, the challenges and opportunities for adsorptive dehumidification for rotary desiccant de-humidifiers are discussed and a review of current approaches and emerging technologies in the development of high-performance adsorbents is presented.
Abstract: This review discusses the challenges and opportunities for adsorptive dehumidification for rotary desiccant dehumidifiers. As well, it presents an overview of current approaches and emerging technologies in the development of high-performance adsorbents for air dehumidification, including silica materials, activated carbons (ACs), supported haloid-based salts, zeolites, metal organic frameworks (MOFs), etc. The adsorption–desorption characteristics—that is, adsorption isotherms—and adsorption kinetics of different kinds of adsorbents are reviewed and further discussed. Some important issues to further advance the research and development of adsorptive dehumidification for rotary desiccant dehumidifiers are also summarized in this work.
TL;DR: In this article, the authors investigated the effects of IMIRD compared to air jet impingement drying alone (IMD) and conventional convective drying (CCVD) on potato being processed as potato chips in terms of drying characteristics, quality attributes (shrinkage, color, and hardness), and specific energy consumption (SEC) of the dryer.
Abstract: Air jet impingement combined with infrared drying (IMIRD) was developed as an alternative processing method to produce health-friendly potato chips in place of conventional deep-fat frying. This article investigates the effects of IMIRD compared to air jet impingement drying alone (IMD) and conventional convective drying (CCVD) on potato being processed as potato chips in term of drying characteristics, quality attributes (shrinkage, color, and hardness), and specific energy consumption (SEC) of the dryer. The experiments were carried out at three different air velocities (5, 10, 15 m/s) and infrared intensities (0.16, 0.27, and 0.33 W/cm2) at a fixed air temperature of 85°C. The experimental results show that the drying air velocity and infrared intensity had a significant effect on the moisture removal from potato slices. IMIRD, compared to IMD and CCVD, provided a higher drying rate, less shrinkage, lower hardness, and less color deterioration. An increase in air velocity at each infrared intensity cau...
TL;DR: In this paper, the energy balance characteristics of the biodrying process are reviewed and a framework of biodrying energy balance analysis methodology, modeling expressions for energy release and utilization, and identification of the main model parameters and the main factors that affect the energy imbalance of the process.
Abstract: Biodrying is a technology that makes use of bioenergy from organic waste with high water content to remove moisture and improve the utilization value and treatability of the waste. The essential feature of biodrying is the utilization of thermal energy, generated by aeration degradation of organic matter in waste, to evaporate water, thus achieving self-drying. The effectiveness of biodrying depends on the energy balance of the system, in which simultaneous heat and mass transfer are driven by biogenerated heat. We have focused on improving drying efficiency of these wastes and in this article we review the energy balance characteristics of the biodrying process. This encompasses the framework of biodrying energy balance analysis methodology, modeling expressions for energy release and utilization, and identification of the main model parameters and the main factors that affect the energy balance of the process. Finally, this review investigates possible ways to improve the efficiency of energy utilizatio...
TL;DR: In order to improve the drying efficiency of lignite and restrain the moisture re-adsorption of dewatered coal, Wang et al. as discussed by the authors investigated the change in pore structure throughout the entire process.
Abstract: In order to improve the drying efficiency of lignite and restrain the moisture re-adsorption of dewatered coal, the drying characteristics of typical Chinese lignite, the re-adsorption performances of dewatered samples and the change in pore structure throughout the entire processes were investigated in this study. Lignite samples with four different particle size fractions were dried in a fixed-bed reactor in the temperature range 60–160°C. The re-adsorbing moisture behaviors of dewatered coal samples containing different water contents were investigated at temperatures of 20–40°C and humidities of 55–95%. The changes in the pore structure of raw coal and different dried samples were measured by mercury intrusion porosimetry (MIP) and the relations between their re-adsorption performance and change in pore structure were explored. The moisture removal yields of lignite increased with an increase in drying time and temperature and was close to 100% above 120°C and over 100% after holding 40 and 15 min at ...
TL;DR: In this paper, the effects of osmotic dehydration with or without pulsed vacuum (PV) on hot-air drying kinetics and quality attributes of cherry tomatoes were investigated.
Abstract: The effects of osmotic dehydration (OD) with or without pulsed vacuum (PV) on hot-air drying kinetics and quality attributes of cherry tomatoes were investigated. Both OD and PVOD pre-treatments were performed for 3 h at 50°C in 50 and 70o Brix sucrose solutions with a solution-to-fruit mass ratio of 4:1, and PVOD was applied for 15 min before OD at atmospheric pressure. Samples were further dried at air temperature of 70°C. Effective moisture diffusivity (D eff) of osmotically dehydrated samples increased gradually while the Deff curve of fresh samples had a plateau stage during hot air drying. Lower glass transition temperature, Tg, values of osmotically dehydrated samples indicated that they needed a lower storage temperature. Both OD and PVOD pre-treatments had advantages in shortening drying cycles and improving quality of products. Compared with air drying, osmo-air drying decreased the total drying time, color change, and hardness of dried samples by 32.26%, 18.11%, and 88.21%, respectively, and in...
TL;DR: The effect of temperature on blueberry drying rate, shrinkage, and color changes was evaluated from drying experiments for both high bush (Vaccinium corymbosum L.) and wild blueberries as mentioned in this paper.
Abstract: The effect of temperature on blueberry drying rate, shrinkage, and color changes was evaluated from drying experiments for both high bush (Vaccinium corymbosum L.) and wild (Vaccinium angustifolium) blueberries. Drying temperature significantly affected texture and color of both varieties. Temperatures above 55°C caused a significant color change (ΔE > 25) within 30 min of the beginning of drying, followed by a significant drop in density from 1.02 to 0.38 g/cm3. In contrast, drying at temperatures below 50°C resulted in nonsignificant color changes and an eventual density increase to 1.26 g/cm3. It follows that blueberry color could be used as an early stage indicator of quality degradation in the process of drying.
TL;DR: In this article, pomegranate peels were dried by freeze drying at 20°C, air and vacuum drying at 40, 60, and 90°C and the moisture sorption isotherm was measured and modeled using the Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-De Boer (GAB) models.
Abstract: Pomegranate peels were dried by freeze drying at 20°C; air and vacuum drying at 40, 60, and 90°C; and sun drying. The moisture sorption isotherm was measured and modeled using the Brunauer–Emmett–Teller (BET) and Guggenheim–Anderson–De Boer (GAB) models. Two solvents (methanol and ethanol) and water were used to extract the phenolic compounds in pomegranate fruit peel. Fresh peels contained 5,990, 4,530, and 8,460 mg gallic acid equivalent (GAE)/100 g dry-peel solids for methanol, ethanol, and water extracts, respectively. The total phenolic content of ethanol extracts of freeze-dried peels was comparable to that of fresh peels (4,900 mg GAE/100 g dry-peel solids), whereas air- and vacuum-dried peels had significantly lower phenolic contents. Peels air dried at 60°C had the highest phenolic content (2,320–4,650 mg/100 g dry-peel solids) compared to samples air dried at 40 or 90°C (1,160–4,480 mg/100 g dry-peel solids), whereas vacuum-dried peels did not show any trends with temperature. In general, methan...
TL;DR: In this article, a powder-based bulk storage approach based on spray drying was evaluated and demonstrated for the first time that monoclonal antibodies (mAbs) can be spray dried with >90% powder collection yield using a laboratory-scale spray dryer, which outperformed three benchtop units in yield and water content reduction.
Abstract: Biologic drug substances (DSs) are stored and transported as frozen bulk in various containers, each having disadvantages. We evaluated a powder-based bulk storage approach based on spray drying and demonstrate for the first time that monoclonal antibodies (mAbs) can be spray dried with >90% powder collection yield using a laboratory-scale spray dryer, which outperformed three benchtop units in yield and water content reduction. Cyclone design was critical to collection yield, which remained sensitive to sample formulations. High yield was achieved for three mAbs formulated at a 2:1 mAb: trehalose weight ratio. Increasing the amount of trehalose beyond this ratio decreased yield by increasing the amount of powder retained in the drying chamber, apparently due to increased particle tackiness. Despite a high inlet temperature, the physical stability of spray-dried mAbs was comparable to or greater than that of freeze-dried counterparts. Water content of the spray-dried powder was affected more by gas reside...
TL;DR: In this paper, the performances of industrial dryers, namely the inclined bed dryer (IBD) and the fluidized bed dryers (FBD) combined with IBD, in terms of drying kinetics, energy consumption, and quality of paddy were investigated.
Abstract: The performances of industrial dryers, namely the inclined bed dryer (IBD) and the fluidized bed dryer (FBD) combined with IBD, in terms of drying kinetics, energy consumption, and quality of paddy were investigated in this study. Drying parameters used in a single-stage paddy drying using IBD and a two-stage drying using FBD combined with IBD were analyzed to assess the existing performances of the drying techniques. The overall performances of the current drying practices exhibited inconsistent results with the operating parameters, such as drying air temperature, drying time, and air flow rate among the drying process lines. Distinct variations in moisture reduction and energy consumption of the drying systems were identified. Poor performance of the industrial fluidized bed dryer was observed in the case of drying in low capacity that caused higher specific energy consumption. However, the quality of milled rice obtained from both drying systems was found to be almost similar. Minimal process time (i....
TL;DR: In this paper, a discontinuous cross-flow convective dryer was used to identify the internal diffusion coefficient and the convective mass transfer coefficient from the experimental data, and a comparison between fitted drying curves, well represented by Newton's model, and analytical solutions of the equation of diffusion, applied to a finite cylinder, was made.
Abstract: 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 b...
Abstract: High-strength concrete generally has a low water-to-cement ratio, which in turn increases the possibility of early-age cracking due to its high autogenous shrinkage. In this article, the effect of internal curing using presoaked lightweight aggregate (PSLWA) in high-strength concrete on shrinkage and interior humidity is investigated by continuously measuring the deformation and interior humidity of the test specimen under plastic film sealing and surface drying conditions since specimen cast. Four mixture proportions with an induced curing water-to-cement ratio (W IC/C) of 0, 0.04, 0.08, and 0.12 were used in experiments. The experimental results show that the decrease in interior humidity was gradually reduced with an increase in W IC/C. Accordingly, both autogenous and drying shrinkage of concrete gradually decreased with an increase in W IC/C. Internal curing cannot completely eliminate autogenous shrinkage because part of the autogenous shrinkage is developed within the humidity-saturated stage in ea...
TL;DR: In this paper, a diffusional model taking into account the solid shrinkage and both the external and internal water transfer resistances was used to accurately represent the water transfer in carrot during drying (average mean relative error (MRE) of 3.3± 0.6%).
Abstract: The drying curves and the degradation kinetics of three different quality attributes (total carotenoids (TC) and total polyphenols (TP) contents and antioxidant activity (AA)) of carrots during drying at different temperatures (from 40 to 90°C) have been experimentally evaluated and modeled. A diffusional model taking into account the solid shrinkage and both the external and internal water transfer resistances was used to accurately represent the water transfer in carrot during drying (average mean relative error (MRE) of 3.3 ± 0.6%). The effective moisture diffusivity was found to follow the Arrhenius relationship (Ea = 76.0 kJ/mol) and the mass transfer coefficient a linear dependence with air temperature. The Weibull model was used to satisfactorily simulate the degradation kinetics of the three quality attributes considered (average MRE of 2.8 ± 1.2% for TC content, 5.7 ± 1.0% for TP content, and 3.6 ± 1.8% for AA); these were the Ea of 52.7 kJ/mol for TC; 22.1 kJ/mol for TP; and 27.5 kJ/mol for AA k...
TL;DR: In this paper, it has been observed that the cracking characteristics of fine-grained soils, defined as a function of evaporation rate, depend on the soil type (i.e., its mineralogy), environmental conditions, and the thickness of the specimen.
Abstract: Several theories and models that define cracking characteristics of fine-grained soils have been proposed by earlier researchers. However, it has been realized that cracking characteristics of these soils are mainly influenced by the environmental conditions to which they are exposed and on their mineralogical composition. To demonstrate this, investigations were conducted on soils of entirely different characteristics and their cracking characteristics, under varied environmental conditions, resorting to “image analysis.” Based on the study, it has been observed that the cracking characteristics of fine-grained soils, defined as a function of evaporation rate, depend on the soil type (i.e., its mineralogy), environmental conditions, and the thickness of the specimen.
TL;DR: Water sorption isotherms, glass transition, and microstructures of Refractance Window (RW) and freeze-dried Philippine “Carabao” mango powders were investigated in this paper.
Abstract: Water sorption isotherms, glass transition, and microstructures of Refractance Window (RW)– and freeze-dried Philippine “Carabao” mango powders were investigated. Water sorption isotherms were developed by the isopiestic method, while thermal transition of the powders, at various water activities (a w = 0.11–0.86), was determined using differential scanning calorimetry (DSC). The sorption isotherms of RW- and freeze-dried (FD) mango powders exhibited a type III sigmoidal curve, showing higher and lower adsorption capacities above and below 0.5 a w , respectively. A significant difference (p < 0.05) in water content of RW- and freeze-dried mango powders for equivalent water activities was obtained above 0.5 a w . The onset glass transition temperature (T gi ) of RW- and freeze-dried mango powder solids decreased as the water content increased. There were no significant differences (p ≥ 0.05) in T gi of RW- and freeze-dried mango powder solids at constant water activities, except for a w = 0.86. Microscop...
TL;DR: In this article, a stable dehydrated probiotic product, with high concentration of microorganism, using spray drying was obtained from healthy Chilean salmon, achieving a viability of approximately 109 CFU/g and less than 5% humidity.
Abstract: With the aim of producing a functional fish food, autochthonous Lactobacillus plantarum LPS 47, isolated from healthy Chilean salmon, was stabilized using spray drying. In order to increase the resistance of microorganisms to high temperatures, osmotic stress during fermentation and different protective agents were evaluated (lactic solids: skim milk and whey, maltodextrin, pectin, and arabic gum). We found that bacteria that were not exposed to osmotic stress during culture, and that were spray-dried in the presence of cheese whey (20% w/w) as a protective material, gave the best results in terms of viability, humidity, and stability during storage. Dehydrated material reached a viability of approximately 109 CFU/g (colony-forming units per gram) and less than 5% humidity, values that were maintained over 10 weeks of storage at 4°C in a non-controlled atmosphere. Results show that it is possible to obtain a stable dehydrated probiotic product, with high concentration of microorganism, using spray drying ...
TL;DR: In this article, an advanced exergy analysis was applied to a pilot-scale heat pump drying system used in food drying for the first time to evaluate its performance at different drying temperatures.
Abstract: Exergy analysis has been used as a powerful tool to study and optimize various types of energy systems. However, the methodology of splitting the exergy destructions (the so-called advanced exergy analysis) allows for a further understanding of the exergy destruction values to improve the system efficiency. In this study, advanced exergy analysis was applied to a pilot-scale heat pump drying system used in food drying for the first time to evaluate its performance at different drying temperatures. The results showed that inefficiencies within the compressor and condenser were mainly due to the internal operating conditions and the efficiencies in the evaporator and heat recovery system could be improved by structural improvements of the whole system and remaining system components.
TL;DR: In this article, a comparative analysis between the various optimization tools so far proposed is given, with a view to a better understanding of factors that still limit the use of these techniques at the manufacturing scale.
Abstract: The problem of process design for the freeze-drying of pharmaceutical products is here addressed. A comparative analysis between the various optimization tools so far proposed is given. The above analysis aims to give some guidelines to lyophilization professionals in the choice of the best design strategy compatible with their objectives and the technology available. In particular, this study examines the strengths and weaknesses of design space and of the different model-based control techniques so far proposed with a view to a better understanding of factors that still limit the use of these techniques at the manufacturing scale. With this regard, the above methods are compared in terms of robustness and scalability of the cycle, number and type of input parameters, management of product and equipment constraints, as well as batch unevenness. The first part of the study is carried out by means of mathematical simulations, as this approach makes it possible to better investigate the controller performan...