Progress 08/01/04 to 07/30/06
Outputs
This project was solely intended for collaboration between NSF and its equivalent in Turkey. There was only travel fund for the PI to Turkey and subsistence allowance for a month in the U.S. for the Turkish counterpart. Two professors and a student from the Department of Food Engineering, Middle East Technical University, Ankara, visited Cornell University for several weeks and did joint research in our laboratory. In turn, PI Datta visited the same department in Turkey for about a week and 1) presented a short course on modeling in food engineering and shared teaching materials in the form of a book; 2) a research seminar to the engineering colleagues; and 3) worked toward completing two manuscripts that are now published. A summary of the research is now presented. The nature of pore spaces in breads baked using various heating modes (microwave-infrared (MIR), microwave-jet impingement (MJET) and jet impingement (JET)) were characterized in terms of total porosity,
fraction of closed, blind and flow-through pores, and pore size distributions using several novel and old techniques (liquid extrusion porosimetry, scanned image analysis, pycnometry, volume displacement method and scanning electron microscopy or SEM). For the breads studies here, a very significant pore size distribution exists covering diameters of a few microns to several thousand microns. It appears that the pore size distribution is bimodal and only a combination of techniques can provide comprehensive information, i.e., any one technique cannot cover the large range of pore size, total porosity and flow-through vs. closed pores. A significant fraction of the pores was found to be closed. Breads baked in JET had the highest total porosity followed by MJET and MIR. Other measurements on breads baked in JET also lay on one end of the spectrum (either smallest or largest), which is consistent with SEM pictures where JET baked breads looked quite different from the ones baked in
other ovens. Physical properties of breads during baking were also measured using the three different heating modes mentioned above. Transient values of dielectric constant, dielectric loss factor, specific bulk volume, porosity, thermal conductivity and moisture content were determined. For all heating modes, thermal conductivity and dielectric properties of breads decreased sharply within the first 2-3 minutes of baking and then remained constant. These measurements will be eventually incorporated into a model for bread baking that includes multiphase transport in a porous medium with large deformation.
Impacts
Enhanced engineering understanding of heat and mass transfer processes in food manufacturing would greatly facilitate increased automation of the processes, thereby achieving improved and consistent quality, developing newer products and processes more easily, and reducing wastage. Newer food processing machines can be built that would provide desired quality at the touch of a button, saving food preparation time and therefore improving quality of life. Process and product optimization would be less of a trial and error and design cycle would be shorter, using computer-aided engineering tools developed based on the process understanding achieved here. Additionally, due to the fundamental approach taken here, the scientific knowledge base developed will contribute to the understanding in the general area of transport in deformable porous media under rapid internal and/or surface heating, covering many biomaterial applications such as the shrinkage of collagen tissue in
radiofrequency heating (in medicine), the drying of wood, and, non-biomaterial applications such as the curing of concrete and cement.
Publications
- Datta, A. K. 2007. Porous media approaches to studying simultaneous heat and mass transfer in food processes. I: Problem formulations. Journal of Food Engineering. 80(1): 80-95.
- Datta, A. K. 2007. Porous media approaches to studying simultaneous heat and mass transfer in food processes. II: Property data and representative results. Journal of Food Engineering. 80(1):96-110.
- Datta, A. K., S. Sahin, G. Sumnu and S. O. Keskin. 2005. Porous media characterization of breads baked using novel heating modes. Journal of Food Engineering. 79( 1):106-116.
- Sumnu, G., A. K. Datta, S. Sahin, S. O. Keskin and V. Rakesh. 2005. Transport and related properties of breads baked using various heating modes. Accepted in the Journal of Food Engineering.
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Progress 01/01/05 to 12/31/05
Outputs
The nature of pore spaces in breads baked using various heating modes (microwave-infrared (MIR), microwave-jet impingement (MJET) and jet impingement (JET)) were characterized in terms of total porosity, fraction of closed, blind and flow-through pores, and pore size distributions using several novel and old techniques (liquid extrusion porosimetry, scanned image analysis, pycnometry, volume displacement method and scanning electron microscopy or SEM). For the breads studies here, a very significant pore size distribution exists covering diameters of a few microns to several thousand microns. It appears that the pore size distribution is bimodal and only a combination of techniques can provide comprehensive information, i.e., any one technique cannot cover the large range of pore size, total porosity and flow-through vs. closed pores. A significant fraction of the pores was found to be closed. Breads baked in JET had the highest total porosity followed by MJET and
MIR. Other measurements on breads baked in JET also lay on one end of the spectrum (either smallest or largest), which is consistent with SEM pictures where JET baked breads looked quite different from the ones baked in other ovens.
Impacts
By understanding how various heating modes can be combined to obtain a particular structure of bread, quality in bread making can be more predictable and controllable.
Publications
- No publications reported this period
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