The Experts below are selected from a list of 44160 Experts worldwide ranked by ideXlab platform
Marybeth Lima - One of the best experts on this subject based on the ideXlab platform.
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the effect of ohmic heating on vacuum Drying Rate of sweet potato tissue
Bioresource Technology, 2003Co-Authors: Tuoxiu Zhong, Marybeth LimaAbstract:Ohmically heating fruit and vegetable tissue has been shown to increase hot-air Drying Rate, shift desorption isotherms, and increase juice extraction yields with respect to untreated, conventionally heated, and microwaved samples. The objective of this study was to determine if ohmically heating sweet potato tissue would enhance the vacuum Drying Rate of these samples with respect to untreated samples. Sweet potato cubes were ohmically heated to three endpoint temperatures using three electrical field strengths and were then placed in a freeze dryer. Moisture content vs. time data were collected and modeled. Results showed that the vacuum Drying Rates of ohmically heated samples were faster than raw samples for most treatment combinations, and that the maximum reduction of Drying time was 24%. Minimal ohmic treatment can result in a significant decrease in vacuum Drying time, which could have important economic and product quality implications.
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the effects of ohmic heating frequency on hot air Drying Rate and juice yield
Journal of Food Engineering, 1999Co-Authors: Marybeth Lima, Sudhir K. SastryAbstract:Ohmic pretreatment of fruit and vegetable samples has been shown to increase hot-air Drying Rate, shift desorption isotherms, and increase juice yields over raw samples or those pretreated with conventional or microwave heating. The frequency of alternating current has been found to alter heat and mass transfer properties. In this study, the hot-air Drying Rate of yam and the juice yields of apples were compared using a 60 Hz sine wave and a 4 Hz sawtooth wave to determine if lowering the frequency would result in additional improvements to these processes. The 4 Hz sawtooth wave resulted in a faster hot-air Drying Rate of yam cylinders than the 60 Hz sine wave. The Drying Rates of the 4 Hz pretreated samples were significantly greater during most of the Drying process, with the most pronounced differences occurring during intermediate stages of Drying. The electric field strength affected the Drying curves in the range tested at 4 and 60 Hz. Apple juice yield was improved by ohmic pretreatment, with 4 Hz sawtooth samples yielding significantly greater quantities than the 60 Hz sinusoidal pretreatment. Due to increased electrical conductivity at 4 Hz, pretreatments at this frequency require considerably less time than pretreatments at 60 Hz The efficiency of mass transfer processes appears to be significantly dependent on waveform and frequency of alternating current. These phenomena could have useful applications for food processing.
James A. Searles - One of the best experts on this subject based on the ideXlab platform.
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the ice nucleation temperature determines the primary Drying Rate of lyophilization for samples frozen on a temperature controlled shelf
Journal of Pharmaceutical Sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:Abstract The objective of this study was to determine the influence of ice nucleation temperature on the primary Drying Rate during lyophilization for samples in vials that were frozen on a lyophilizer shelf. Aqueous solutions of 10% (w/v) hydroxyethyl starch were frozen in vials with externally mounted thermocouples and then partially lyophilized to determine the primary Drying Rate. Low‐ and high‐particulate‐containing samples, ice‐nucleating additives silver iodide and Pseudomonas syringae , and other methods were used to obtain a wide range of nucleation temperatures. In cases where the supercooling exceeded 5°C, freezing took place in the following three steps: (1) primary nucleation, (2) secondary nucleation encompassing the entire liquid volume, and (3) final solidification. The primary Drying Rate was dependent on the ice nucleation temperature, which is stochastic in nature but is affected by particulate content and the presence of ice nucleators. Sample cooling Rates of 0.05 to 1°C/min had no effect on nucleation temperatures and Drying Rate. We found that the ice nucleation temperature is the primary determinant of the primary Drying Rate. However, the nucleation temperature is not under direct control, and its stochastic nature and sensitivity to difficult‐to‐control parameters result in Drying Rate heterogeneity. Nucleation temperature heterogeneity may also result in variation in other morphology‐related parameters such as surface area and secondary Drying Rate. Overall, these results document that factors such as particulate content and vial condition, which influence ice nucleation temperature, must be carefully controlled to avoid, for example, lot‐to‐lot variability during cGMP production. In addition, if these factors are not controlled and/or are inadvertently changed during process development and scaleup, a lyophilization cycle that was successful on the research scale may fail during large‐scale production. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:860–871, 2001
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annealing to optimize the primary Drying Rate reduce freezing induced Drying Rate heterogeneity and determine t g in pharmaceutical lyophilization
Journal of Pharmaceutical Sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:In a companion paper we show that the freezing of samples in vials by shelf-ramp freezing results in significant primary Drying Rate heterogeneity because of a dependence of the ice crystal size on the nucleation temperature during freezing.1 The purpose of this study was to test the hypothesis that post-freezing annealing, in which the product is held at a predetermined temperature for a specified duration, can reduce freezing-induced heterogeneity in sublimation Rates. In addition, we test the impact of annealing on primary Drying Rates. Finally, we use the kinetics of relaxations during annealing to provide a simple measurement of T(g)', the glass transition temperature of the maximally freeze-concentRated amorphous phase, under conditions and time scales most appropriate for industrial lyophilization cycles. Aqueous solutions of hydroxyethyl starch (HES), sucrose, and HES:sucrose were either frozen by placement on a shelf while the temperature was reduced ("shelf-ramp frozen") or by immersion into liquid nitrogen. Samples were then annealed for various durations over a range of temperatures and partially lyophilized to determine the primary Drying Rate. The morphology of fully dried liquid nitrogen-frozen samples was examined using scanning electron microscopy. Annealing reduced primary Drying Rate heterogeneity for shelf-ramp frozen samples, and resulted in up to 3.5-fold increases in the primary Drying Rate. These effects were due to increased ice crystal sizes, simplified amorphous structures, and larger and more numerous holes on the cake surface of annealed samples. Annealed HES samples dissolved slightly faster than their unannealed counterparts. Annealing below T(g)' did not result in increased Drying Rates. We present a simple new annealing-lyophilization method of T(g)' determination that exploits this phenomenon. It can be carried out with a balance and a freeze-dryer, and has the additional advantage that a large number of candidate formulations can be evaluated simultaneously.
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the ice nucleation temperature determines the primary Drying Rate of lyophilization for samples frozen on a temperature controlled shelf
Journal of Pharmaceutical Sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:The objective of this study was to determine the influence of ice nucleation temperature on the primary Drying Rate during lyophilization for samples in vials that were frozen on a lyophilizer shelf. Aqueous solutions of 10% (w/v) hydroxyethyl starch were frozen in vials with externally mounted thermocouples and then partially lyophilized to determine the primary Drying Rate. Low- and high-particulate-containing samples, ice-nucleating additives silver iodide and Pseudomonas syringae, and other methods were used to obtain a wide range of nucleation temperatures. In cases where the supercooling exceeded 5 degrees C, freezing took place in the following three steps: (1) primary nucleation, (2) secondary nucleation encompassing the entire liquid volume, and (3) final solidification. The primary Drying Rate was dependent on the ice nucleation temperature, which is stochastic in nature but is affected by particulate content and the presence of ice nucleators. Sample cooling Rates of 0.05 to 1 degrees C/min had no effect on nucleation temperatures and Drying Rate. We found that the ice nucleation temperature is the primary determinant of the primary Drying Rate. However, the nucleation temperature is not under direct control, and its stochastic nature and sensitivity to difficult-to-control parameters result in Drying Rate heterogeneity. Nucleation temperature heterogeneity may also result in variation in other morphology-related parameters such as surface area and secondary Drying Rate. Overall, these results document that factors such as particulate content and vial condition, which influence ice nucleation temperature, must be carefully controlled to avoid, for example, lot-to-lot variability during cGMP production. In addition, if these factors are not controlled and/or are inadvertently changed during process development and scaleup, a lyophilization cycle that was successful on the research scale may fail during large-scale production.
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Annealing to optimize the primary Drying Rate, reduce freezing‐induced Drying Rate heterogeneity, and determine T'g in pharmaceutical lyophilization
Journal of pharmaceutical sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:In a companion paper we show that the freezing of samples in vials by shelf-ramp freezing results in significant primary Drying Rate heterogeneity because of a dependence of the ice crystal size on the nucleation temperature during freezing.1 The purpose of this study was to test the hypothesis that post-freezing annealing, in which the product is held at a predetermined temperature for a specified duration, can reduce freezing-induced heterogeneity in sublimation Rates. In addition, we test the impact of annealing on primary Drying Rates. Finally, we use the kinetics of relaxations during annealing to provide a simple measurement of T(g)', the glass transition temperature of the maximally freeze-concentRated amorphous phase, under conditions and time scales most appropriate for industrial lyophilization cycles. Aqueous solutions of hydroxyethyl starch (HES), sucrose, and HES:sucrose were either frozen by placement on a shelf while the temperature was reduced ("shelf-ramp frozen") or by immersion into liquid nitrogen. Samples were then annealed for various durations over a range of temperatures and partially lyophilized to determine the primary Drying Rate. The morphology of fully dried liquid nitrogen-frozen samples was examined using scanning electron microscopy. Annealing reduced primary Drying Rate heterogeneity for shelf-ramp frozen samples, and resulted in up to 3.5-fold increases in the primary Drying Rate. These effects were due to increased ice crystal sizes, simplified amorphous structures, and larger and more numerous holes on the cake surface of annealed samples. Annealed HES samples dissolved slightly faster than their unannealed counterparts. Annealing below T(g)' did not result in increased Drying Rates. We present a simple new annealing-lyophilization method of T(g)' determination that exploits this phenomenon. It can be carried out with a balance and a freeze-dryer, and has the additional advantage that a large number of candidate formulations can be evaluated simultaneously.
Hiroshi Nabetani - One of the best experts on this subject based on the ideXlab platform.
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improvements of Drying Rate and structural quality of microwave vacuum dried carrot by freeze thaw pretreatment
Lwt - Food Science and Technology, 2019Co-Authors: Yasumasa Ando, Shoji Hagiwara, Hiroshi Nabetani, Itaru Sotome, Tomoya Okunishi, Hiroshi Okadome, Takahiro Orikasa, Akio TagawaAbstract:Abstract Freeze-thaw pretreatment was applied to microwave-vacuum Drying (MVD) of carrot, and the Drying Rate, structure of the dried material, rehydration Rate, and mechanical properties after rehydration were evaluated. Pretreatment increased the Drying Rate, owing to the acceleRated moisture transfer Rate of the tissue because of damage to the cellular structure during freezing. Structural observation using X-ray CT demonstRated the pretreatment was also effective in preventing structural deformation during MVD. The rehydration Rate of the prefrozen-thawed sample was markedly increased due to the larger surface area formed with less shrinkage. Initial elastic moduli of the prefrozen-thawed MVD sample and air dried sample after rehydration mechanically determined were significantly lower than those of the non-treated MVD sample and air dried sample, indicating that the mechanical properties do not depend on the Drying method, but on the presence or absence of freeze-thaw pretreatment.
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impact of blanching and freeze thaw pretreatment on Drying Rate of carrot roots in relation to changes in cell membrane function and cell wall structure
Lwt - Food Science and Technology, 2016Co-Authors: Yasumasa Ando, Yuka Maeda, Koichi Mizutani, Naoto Wakatsuki, Shoji Hagiwara, Hiroshi NabetaniAbstract:Abstract The effect of blanching and freeze-thaw pretreatment on the Drying Rate of carrots and the relationship between Drying Rate and state of cell membranes, cell wall and pectin methylesterase (PME) activity in the pretreated tissues were investigated. Frozen-thawed samples showed the highest Drying Rate and samples blanched at higher temperature showed a higher Drying Rate. Samples blanched at 60 °C showed a lower Drying Rate than fresh samples. Electrical impedance analysis and microscopic observation suggested that cell membrane injury and changes in pectin structure in the cell walls due to the pretreatments greatly affected the permeability and Drying Rate of the samples. Also, the significantly high Drying Rate of frozen-thawed samples was attributed to the formation of ice crystals that facilitated water migration. The samples blanched at 60 °C showed the highest residual PME activity, suggesting that the decrease in Drying Rate for these samples was attributable to the inhibition of water migration due to the cross-linked structure of pectins formed by PME activity.
Theodore W. Randolph - One of the best experts on this subject based on the ideXlab platform.
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the ice nucleation temperature determines the primary Drying Rate of lyophilization for samples frozen on a temperature controlled shelf
Journal of Pharmaceutical Sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:Abstract The objective of this study was to determine the influence of ice nucleation temperature on the primary Drying Rate during lyophilization for samples in vials that were frozen on a lyophilizer shelf. Aqueous solutions of 10% (w/v) hydroxyethyl starch were frozen in vials with externally mounted thermocouples and then partially lyophilized to determine the primary Drying Rate. Low‐ and high‐particulate‐containing samples, ice‐nucleating additives silver iodide and Pseudomonas syringae , and other methods were used to obtain a wide range of nucleation temperatures. In cases where the supercooling exceeded 5°C, freezing took place in the following three steps: (1) primary nucleation, (2) secondary nucleation encompassing the entire liquid volume, and (3) final solidification. The primary Drying Rate was dependent on the ice nucleation temperature, which is stochastic in nature but is affected by particulate content and the presence of ice nucleators. Sample cooling Rates of 0.05 to 1°C/min had no effect on nucleation temperatures and Drying Rate. We found that the ice nucleation temperature is the primary determinant of the primary Drying Rate. However, the nucleation temperature is not under direct control, and its stochastic nature and sensitivity to difficult‐to‐control parameters result in Drying Rate heterogeneity. Nucleation temperature heterogeneity may also result in variation in other morphology‐related parameters such as surface area and secondary Drying Rate. Overall, these results document that factors such as particulate content and vial condition, which influence ice nucleation temperature, must be carefully controlled to avoid, for example, lot‐to‐lot variability during cGMP production. In addition, if these factors are not controlled and/or are inadvertently changed during process development and scaleup, a lyophilization cycle that was successful on the research scale may fail during large‐scale production. © 2001 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:860–871, 2001
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annealing to optimize the primary Drying Rate reduce freezing induced Drying Rate heterogeneity and determine t g in pharmaceutical lyophilization
Journal of Pharmaceutical Sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:In a companion paper we show that the freezing of samples in vials by shelf-ramp freezing results in significant primary Drying Rate heterogeneity because of a dependence of the ice crystal size on the nucleation temperature during freezing.1 The purpose of this study was to test the hypothesis that post-freezing annealing, in which the product is held at a predetermined temperature for a specified duration, can reduce freezing-induced heterogeneity in sublimation Rates. In addition, we test the impact of annealing on primary Drying Rates. Finally, we use the kinetics of relaxations during annealing to provide a simple measurement of T(g)', the glass transition temperature of the maximally freeze-concentRated amorphous phase, under conditions and time scales most appropriate for industrial lyophilization cycles. Aqueous solutions of hydroxyethyl starch (HES), sucrose, and HES:sucrose were either frozen by placement on a shelf while the temperature was reduced ("shelf-ramp frozen") or by immersion into liquid nitrogen. Samples were then annealed for various durations over a range of temperatures and partially lyophilized to determine the primary Drying Rate. The morphology of fully dried liquid nitrogen-frozen samples was examined using scanning electron microscopy. Annealing reduced primary Drying Rate heterogeneity for shelf-ramp frozen samples, and resulted in up to 3.5-fold increases in the primary Drying Rate. These effects were due to increased ice crystal sizes, simplified amorphous structures, and larger and more numerous holes on the cake surface of annealed samples. Annealed HES samples dissolved slightly faster than their unannealed counterparts. Annealing below T(g)' did not result in increased Drying Rates. We present a simple new annealing-lyophilization method of T(g)' determination that exploits this phenomenon. It can be carried out with a balance and a freeze-dryer, and has the additional advantage that a large number of candidate formulations can be evaluated simultaneously.
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the ice nucleation temperature determines the primary Drying Rate of lyophilization for samples frozen on a temperature controlled shelf
Journal of Pharmaceutical Sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:The objective of this study was to determine the influence of ice nucleation temperature on the primary Drying Rate during lyophilization for samples in vials that were frozen on a lyophilizer shelf. Aqueous solutions of 10% (w/v) hydroxyethyl starch were frozen in vials with externally mounted thermocouples and then partially lyophilized to determine the primary Drying Rate. Low- and high-particulate-containing samples, ice-nucleating additives silver iodide and Pseudomonas syringae, and other methods were used to obtain a wide range of nucleation temperatures. In cases where the supercooling exceeded 5 degrees C, freezing took place in the following three steps: (1) primary nucleation, (2) secondary nucleation encompassing the entire liquid volume, and (3) final solidification. The primary Drying Rate was dependent on the ice nucleation temperature, which is stochastic in nature but is affected by particulate content and the presence of ice nucleators. Sample cooling Rates of 0.05 to 1 degrees C/min had no effect on nucleation temperatures and Drying Rate. We found that the ice nucleation temperature is the primary determinant of the primary Drying Rate. However, the nucleation temperature is not under direct control, and its stochastic nature and sensitivity to difficult-to-control parameters result in Drying Rate heterogeneity. Nucleation temperature heterogeneity may also result in variation in other morphology-related parameters such as surface area and secondary Drying Rate. Overall, these results document that factors such as particulate content and vial condition, which influence ice nucleation temperature, must be carefully controlled to avoid, for example, lot-to-lot variability during cGMP production. In addition, if these factors are not controlled and/or are inadvertently changed during process development and scaleup, a lyophilization cycle that was successful on the research scale may fail during large-scale production.
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Annealing to optimize the primary Drying Rate, reduce freezing‐induced Drying Rate heterogeneity, and determine T'g in pharmaceutical lyophilization
Journal of pharmaceutical sciences, 2001Co-Authors: James A. Searles, John F. Carpenter, Theodore W. RandolphAbstract:In a companion paper we show that the freezing of samples in vials by shelf-ramp freezing results in significant primary Drying Rate heterogeneity because of a dependence of the ice crystal size on the nucleation temperature during freezing.1 The purpose of this study was to test the hypothesis that post-freezing annealing, in which the product is held at a predetermined temperature for a specified duration, can reduce freezing-induced heterogeneity in sublimation Rates. In addition, we test the impact of annealing on primary Drying Rates. Finally, we use the kinetics of relaxations during annealing to provide a simple measurement of T(g)', the glass transition temperature of the maximally freeze-concentRated amorphous phase, under conditions and time scales most appropriate for industrial lyophilization cycles. Aqueous solutions of hydroxyethyl starch (HES), sucrose, and HES:sucrose were either frozen by placement on a shelf while the temperature was reduced ("shelf-ramp frozen") or by immersion into liquid nitrogen. Samples were then annealed for various durations over a range of temperatures and partially lyophilized to determine the primary Drying Rate. The morphology of fully dried liquid nitrogen-frozen samples was examined using scanning electron microscopy. Annealing reduced primary Drying Rate heterogeneity for shelf-ramp frozen samples, and resulted in up to 3.5-fold increases in the primary Drying Rate. These effects were due to increased ice crystal sizes, simplified amorphous structures, and larger and more numerous holes on the cake surface of annealed samples. Annealed HES samples dissolved slightly faster than their unannealed counterparts. Annealing below T(g)' did not result in increased Drying Rates. We present a simple new annealing-lyophilization method of T(g)' determination that exploits this phenomenon. It can be carried out with a balance and a freeze-dryer, and has the additional advantage that a large number of candidate formulations can be evaluated simultaneously.
Yasumasa Ando - One of the best experts on this subject based on the ideXlab platform.
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improvements of Drying Rate and structural quality of microwave vacuum dried carrot by freeze thaw pretreatment
Lwt - Food Science and Technology, 2019Co-Authors: Yasumasa Ando, Shoji Hagiwara, Hiroshi Nabetani, Itaru Sotome, Tomoya Okunishi, Hiroshi Okadome, Takahiro Orikasa, Akio TagawaAbstract:Abstract Freeze-thaw pretreatment was applied to microwave-vacuum Drying (MVD) of carrot, and the Drying Rate, structure of the dried material, rehydration Rate, and mechanical properties after rehydration were evaluated. Pretreatment increased the Drying Rate, owing to the acceleRated moisture transfer Rate of the tissue because of damage to the cellular structure during freezing. Structural observation using X-ray CT demonstRated the pretreatment was also effective in preventing structural deformation during MVD. The rehydration Rate of the prefrozen-thawed sample was markedly increased due to the larger surface area formed with less shrinkage. Initial elastic moduli of the prefrozen-thawed MVD sample and air dried sample after rehydration mechanically determined were significantly lower than those of the non-treated MVD sample and air dried sample, indicating that the mechanical properties do not depend on the Drying method, but on the presence or absence of freeze-thaw pretreatment.
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impact of blanching and freeze thaw pretreatment on Drying Rate of carrot roots in relation to changes in cell membrane function and cell wall structure
Lwt - Food Science and Technology, 2016Co-Authors: Yasumasa Ando, Yuka Maeda, Koichi Mizutani, Naoto Wakatsuki, Shoji Hagiwara, Hiroshi NabetaniAbstract:Abstract The effect of blanching and freeze-thaw pretreatment on the Drying Rate of carrots and the relationship between Drying Rate and state of cell membranes, cell wall and pectin methylesterase (PME) activity in the pretreated tissues were investigated. Frozen-thawed samples showed the highest Drying Rate and samples blanched at higher temperature showed a higher Drying Rate. Samples blanched at 60 °C showed a lower Drying Rate than fresh samples. Electrical impedance analysis and microscopic observation suggested that cell membrane injury and changes in pectin structure in the cell walls due to the pretreatments greatly affected the permeability and Drying Rate of the samples. Also, the significantly high Drying Rate of frozen-thawed samples was attributed to the formation of ice crystals that facilitated water migration. The samples blanched at 60 °C showed the highest residual PME activity, suggesting that the decrease in Drying Rate for these samples was attributable to the inhibition of water migration due to the cross-linked structure of pectins formed by PME activity.
