Marcus Karel - Academia.edu (original) (raw)
Papers by Marcus Karel
Biotechnology Progress, 2002
The gas transport properties of compacted tablets consisting of an amorphous mixture of maltodext... more The gas transport properties of compacted tablets consisting of an amorphous mixture of maltodextrin and sodium caseinate were studied by dissolving nitrogen gas in the tablets and then determining the gas release over time as a function of temperature and water activity. Gas was dissolved in the tablet matrix by heating the tablets under pressure, generally to temperatures above the glass transition temperature of the matrix, holding them at these conditions for a specified time and then rapidly cooling them while maintaining the external pressure. The solubility of nitrogen was found to be largely determined by the free volume of the matrix, which in turn can be influenced to some degree by thermal and pressure treatments during gas loading. At the levels of free volume studied, the dissolved nitrogen is densely packed in the free volume, the packing density being virtually independent of the externally applied pressure. Release of gas from the tablets at temperatures below the glass transition temperature is generally well described by Fickian diffusion. The effective diffusion coefficient of gas release is strongly dependent on the microstructure and porosity of the tablet matrix, and an approximate model describing the relationship between tablet structure and rate of gas release is formulated. The model is in semiquantitative agreement with the rates of gas diffusion obtained for tablets and dense granules. Owing to the structural heterogeneity and variability of the tablets and the history-dependent properties of the tablet matrix, the effective diffusion coefficients of gas release from the tablets showed a relatively large spread. The temperature dependence of diffusional release follows an Arrhenius relation below the glass transition temperature. This allows the prediction of the nitrogen retention in the tablets as function of time, temperature and pressure.
Autoxidation in Food and Biological Systems, 1980
Food Properties and Computer-Aided Engineering of Food Processing Systems, 1989
Food Engineering Series, 1997
Food engineering arose as an academic discipline in the second half of the present century; its i... more Food engineering arose as an academic discipline in the second half of the present century; its initial development was concerned with postharvest operations closely related to the interests held by the field of agricultural engineering with respect to food processing–equipment performance concerns. In the 1950s and 1960s, food engineering followed the trend developing in chemical engineering by focusing on food
The Chemical Engineering Journal and the Biochemical Engineering Journal, 1995
The solubility and the primary nucleation kinetics of pentaerythritol (PE) at 98% and 94% purity ... more The solubility and the primary nucleation kinetics of pentaerythritol (PE) at 98% and 94% purity in aqueous solution were investigated in the range 20-80 "C, and the effect of adding 1% formaldehyde or 2% formic acid was also examined. The solubility increases with decreasing purity of the product and on adding the cited compounds to the solution. The nucleation kinetics exhibit high values of nucleation order, ranging from 32 to 10 for nucleation temperatures in the range 1+61 "C; that is, the generation of nuclei becomes significant only after exceeding a threshold value of supersaturation, which increases as the temperature decreases.
"Proceedings of an international workshop on autoxidation proesses in food and related biolo... more "Proceedings of an international workshop on autoxidation proesses in food and related biological systems held octuber 29- 31. 1979, in Natick, Massachusetts. Several contrubutions were presented at the IFT basic synposium on food lipids held june 8- 9, 1979, in St. Louis, Missouri" Incluye bibliografía e índice
A nutritionally adequate and acceptable diet was evaluated and developed. A design for a multipur... more A nutritionally adequate and acceptable diet was evaluated and developed. A design for a multipurpose food plant is discussed. The types and amounts of foods needed to be regenerated in a partially closed ecological life support system (PCELSS) were proposed. All steps of food processes to be utilized in the multipurpose food plant of PCELSS were also considered. Equipment specifications, simplification of the proposed processes, and food waste treatment were analyzed.
Homogeneous samples of freeze dried human feces and urine were prepared to assure comparability o... more Homogeneous samples of freeze dried human feces and urine were prepared to assure comparability of results among various CELSS waste treatment research groups. A model of food processing wastes within a PCELSS was developed, and an initial batch of waste was prepared. An automated gas chromatographic system to analyze oxidizer effluents was designed and is operational. A state of the art quantitative elemental analysis capability, built around inductively coupled plasma emission spectroscopy and atomic absorption spectroscopy using electrothermal atomization, was demonstrated. A continuous flow wet oxidation system was constructed and is now operational. Potentially useful salt separation phenomena was observed.
Developing acceptable and reliable engineered foods, adapting present technology and food science... more Developing acceptable and reliable engineered foods, adapting present technology and food science to expected space conditions, and food conversion operations are summarized.
The feasibility of developing acceptable and reliable engineered foods for use in controlled ecol... more The feasibility of developing acceptable and reliable engineered foods for use in controlled ecological support systems (CELSS) was evaluated. Food resupply and regeneration are calculated, flow charts of food processes in a multipurpose food pilot plant are presented, and equipment for a multipurpose food pilot plant and potential simplification of processes are discussed. Food-waste treatment and water usage in food processing and preparation are also considered.
A system of conversion of locally regenerated raw materials and of resupplied freeze-dried foods ... more A system of conversion of locally regenerated raw materials and of resupplied freeze-dried foods and ingredients into acceptable, safe and nutritious engineered foods is proposed. The first phase of the proposed research has the following objectives: (1) evaluation of feasibility of developing acceptable and reliable engineered foods from a limited selection of plants, supplemented by microbially produced nutrients and a minimum of dehydrated nutrient sources (especially those of animal origin); (2) evaluation of research tasks and specifications of research projects to adapt present technology and food science to expected space conditions (in particular, problems arising from unusual gravity conditions, problems of limited size and the isolation of the food production system, and the opportunities of space conditions are considered); (3) development of scenarios of agricultural production of plant and microbial systems, including the specifications of processing wastes to be recycled.
The research program entitled 'Development of a Prototype Experiment for Treating CELSS (Cont... more The research program entitled 'Development of a Prototype Experiment for Treating CELSS (Controlled Ecological Life Support Systems) and PCELSS (Partially Controlled Ecological Life Support Systems) Wastes to Produce Nutrients for Plant Growth' consists of two phases: (1) the development of the neccessary facilities, chemical methodologies and models for meaningful experimentation, and (2) the application of what methods and devices are developed to the interfacing of waste oxidation with plant growth. Homogeneous samples of freeze-dried human feces and urine have been prepared to ensure comparability of test results between CELSS waste treatment research groups. A model of PCELSS food processing wastes has been developed, and an automated gas chromatographic system to analyze oxidizer effluents was designed and brought to operational status. Attention is given the component configuration of the wet oxidation system used by the studies.
Food technology, 1989
What needs to be done to establish food irradiation on a truly commercial basis so that those liv... more What needs to be done to establish food irradiation on a truly commercial basis so that those living on planet Earth can fully realize the benefits of this versatile process? This question is answered in the first part of this paper. The second part covers the potential contributions of irradiated foods to feed humans in space.
Journal of chromatography, Jan 15, 1983
Trends in Food Science & Technology, 1995
Caking of free-flowing powders during storage is a deleterious phenomenon that is ubiquitous in t... more Caking of free-flowing powders during storage is a deleterious phenomenon that is ubiquitous in the feed, fertilizer and pharmaceutical industries, and of economical importance for low-moisture foods. Among other subjects related to caking of amorphous powders, the following ...
Proceedings of the Royal Society B: Biological Sciences, 1975
ABSTRACT Food production and preservation in the 1980s will require greatly increased flexibility... more ABSTRACT Food production and preservation in the 1980s will require greatly increased flexibility in materials and processes, because of the likely occurrences of shortages in specific raw material and energy resources, and of specific crises with respect to environmental and public health impacts of food processes. Concentration and separation processes will be of increasing importance in food production from new sources, including waste streams and single cell organisms grown on various substrates. Freeze concentration will have a particularly great potential in food and pharmaceutical products requiring mild treatment and maximum preservation of flavour qualities. New techniques for efficient conduct of freeze concentration have been developed in pilot plant studies and will become commercialized in the next decade. Membrane separation and concentration, as well as other complex food production schemes using membranes as part of the overall process will become increasingly important. The present paper will summarize the important features of freeze-concentration and membrane processes, and present examples of applications likely to become important in the 1980s.
Biotechnology Progress, 2002
The gas transport properties of compacted tablets consisting of an amorphous mixture of maltodext... more The gas transport properties of compacted tablets consisting of an amorphous mixture of maltodextrin and sodium caseinate were studied by dissolving nitrogen gas in the tablets and then determining the gas release over time as a function of temperature and water activity. Gas was dissolved in the tablet matrix by heating the tablets under pressure, generally to temperatures above the glass transition temperature of the matrix, holding them at these conditions for a specified time and then rapidly cooling them while maintaining the external pressure. The solubility of nitrogen was found to be largely determined by the free volume of the matrix, which in turn can be influenced to some degree by thermal and pressure treatments during gas loading. At the levels of free volume studied, the dissolved nitrogen is densely packed in the free volume, the packing density being virtually independent of the externally applied pressure. Release of gas from the tablets at temperatures below the glass transition temperature is generally well described by Fickian diffusion. The effective diffusion coefficient of gas release is strongly dependent on the microstructure and porosity of the tablet matrix, and an approximate model describing the relationship between tablet structure and rate of gas release is formulated. The model is in semiquantitative agreement with the rates of gas diffusion obtained for tablets and dense granules. Owing to the structural heterogeneity and variability of the tablets and the history-dependent properties of the tablet matrix, the effective diffusion coefficients of gas release from the tablets showed a relatively large spread. The temperature dependence of diffusional release follows an Arrhenius relation below the glass transition temperature. This allows the prediction of the nitrogen retention in the tablets as function of time, temperature and pressure.
Autoxidation in Food and Biological Systems, 1980
Food Properties and Computer-Aided Engineering of Food Processing Systems, 1989
Food Engineering Series, 1997
Food engineering arose as an academic discipline in the second half of the present century; its i... more Food engineering arose as an academic discipline in the second half of the present century; its initial development was concerned with postharvest operations closely related to the interests held by the field of agricultural engineering with respect to food processing–equipment performance concerns. In the 1950s and 1960s, food engineering followed the trend developing in chemical engineering by focusing on food
The Chemical Engineering Journal and the Biochemical Engineering Journal, 1995
The solubility and the primary nucleation kinetics of pentaerythritol (PE) at 98% and 94% purity ... more The solubility and the primary nucleation kinetics of pentaerythritol (PE) at 98% and 94% purity in aqueous solution were investigated in the range 20-80 "C, and the effect of adding 1% formaldehyde or 2% formic acid was also examined. The solubility increases with decreasing purity of the product and on adding the cited compounds to the solution. The nucleation kinetics exhibit high values of nucleation order, ranging from 32 to 10 for nucleation temperatures in the range 1+61 "C; that is, the generation of nuclei becomes significant only after exceeding a threshold value of supersaturation, which increases as the temperature decreases.
"Proceedings of an international workshop on autoxidation proesses in food and related biolo... more "Proceedings of an international workshop on autoxidation proesses in food and related biological systems held octuber 29- 31. 1979, in Natick, Massachusetts. Several contrubutions were presented at the IFT basic synposium on food lipids held june 8- 9, 1979, in St. Louis, Missouri" Incluye bibliografía e índice
A nutritionally adequate and acceptable diet was evaluated and developed. A design for a multipur... more A nutritionally adequate and acceptable diet was evaluated and developed. A design for a multipurpose food plant is discussed. The types and amounts of foods needed to be regenerated in a partially closed ecological life support system (PCELSS) were proposed. All steps of food processes to be utilized in the multipurpose food plant of PCELSS were also considered. Equipment specifications, simplification of the proposed processes, and food waste treatment were analyzed.
Homogeneous samples of freeze dried human feces and urine were prepared to assure comparability o... more Homogeneous samples of freeze dried human feces and urine were prepared to assure comparability of results among various CELSS waste treatment research groups. A model of food processing wastes within a PCELSS was developed, and an initial batch of waste was prepared. An automated gas chromatographic system to analyze oxidizer effluents was designed and is operational. A state of the art quantitative elemental analysis capability, built around inductively coupled plasma emission spectroscopy and atomic absorption spectroscopy using electrothermal atomization, was demonstrated. A continuous flow wet oxidation system was constructed and is now operational. Potentially useful salt separation phenomena was observed.
Developing acceptable and reliable engineered foods, adapting present technology and food science... more Developing acceptable and reliable engineered foods, adapting present technology and food science to expected space conditions, and food conversion operations are summarized.
The feasibility of developing acceptable and reliable engineered foods for use in controlled ecol... more The feasibility of developing acceptable and reliable engineered foods for use in controlled ecological support systems (CELSS) was evaluated. Food resupply and regeneration are calculated, flow charts of food processes in a multipurpose food pilot plant are presented, and equipment for a multipurpose food pilot plant and potential simplification of processes are discussed. Food-waste treatment and water usage in food processing and preparation are also considered.
A system of conversion of locally regenerated raw materials and of resupplied freeze-dried foods ... more A system of conversion of locally regenerated raw materials and of resupplied freeze-dried foods and ingredients into acceptable, safe and nutritious engineered foods is proposed. The first phase of the proposed research has the following objectives: (1) evaluation of feasibility of developing acceptable and reliable engineered foods from a limited selection of plants, supplemented by microbially produced nutrients and a minimum of dehydrated nutrient sources (especially those of animal origin); (2) evaluation of research tasks and specifications of research projects to adapt present technology and food science to expected space conditions (in particular, problems arising from unusual gravity conditions, problems of limited size and the isolation of the food production system, and the opportunities of space conditions are considered); (3) development of scenarios of agricultural production of plant and microbial systems, including the specifications of processing wastes to be recycled.
The research program entitled 'Development of a Prototype Experiment for Treating CELSS (Cont... more The research program entitled 'Development of a Prototype Experiment for Treating CELSS (Controlled Ecological Life Support Systems) and PCELSS (Partially Controlled Ecological Life Support Systems) Wastes to Produce Nutrients for Plant Growth' consists of two phases: (1) the development of the neccessary facilities, chemical methodologies and models for meaningful experimentation, and (2) the application of what methods and devices are developed to the interfacing of waste oxidation with plant growth. Homogeneous samples of freeze-dried human feces and urine have been prepared to ensure comparability of test results between CELSS waste treatment research groups. A model of PCELSS food processing wastes has been developed, and an automated gas chromatographic system to analyze oxidizer effluents was designed and brought to operational status. Attention is given the component configuration of the wet oxidation system used by the studies.
Food technology, 1989
What needs to be done to establish food irradiation on a truly commercial basis so that those liv... more What needs to be done to establish food irradiation on a truly commercial basis so that those living on planet Earth can fully realize the benefits of this versatile process? This question is answered in the first part of this paper. The second part covers the potential contributions of irradiated foods to feed humans in space.
Journal of chromatography, Jan 15, 1983
Trends in Food Science & Technology, 1995
Caking of free-flowing powders during storage is a deleterious phenomenon that is ubiquitous in t... more Caking of free-flowing powders during storage is a deleterious phenomenon that is ubiquitous in the feed, fertilizer and pharmaceutical industries, and of economical importance for low-moisture foods. Among other subjects related to caking of amorphous powders, the following ...
Proceedings of the Royal Society B: Biological Sciences, 1975
ABSTRACT Food production and preservation in the 1980s will require greatly increased flexibility... more ABSTRACT Food production and preservation in the 1980s will require greatly increased flexibility in materials and processes, because of the likely occurrences of shortages in specific raw material and energy resources, and of specific crises with respect to environmental and public health impacts of food processes. Concentration and separation processes will be of increasing importance in food production from new sources, including waste streams and single cell organisms grown on various substrates. Freeze concentration will have a particularly great potential in food and pharmaceutical products requiring mild treatment and maximum preservation of flavour qualities. New techniques for efficient conduct of freeze concentration have been developed in pilot plant studies and will become commercialized in the next decade. Membrane separation and concentration, as well as other complex food production schemes using membranes as part of the overall process will become increasingly important. The present paper will summarize the important features of freeze-concentration and membrane processes, and present examples of applications likely to become important in the 1980s.