New Orleans, Louisiana
June 26, 2016
June 26, 2016
August 28, 2016
A series of hands-on activities were developed to accompany a Unit Operations in Food Engineering course. The activities covered mechanical properties, pumping and heat transfer. This paper will include a description of the activity, the results, and an assessment of student learning. Each experiment was completed in a two-hour class period. Total expenditures on supplies for the three labs were less than $100. Equipment for one group of students would cost approximately $50, assuming basic laboratory equipment is available. Learning objectives, assessment of student learning and specific details of the experiments will be covered in the final paper.
The first experiment covered mechanical properties important to the food industry. After an introduction to the biochemistry of gluten formation, students used design of experiment principles to investigate the factors that influenced gluten strength, such as kneading and resting times, and related their results to theory. Next, they collected data to create a stress-strain graph and estimated Young’s modulus, which they compared to theoretical values. Finally, they collected data to create a creep curve and compared its shape to literature results.
The next portion of the course covered the mechanical energy balance. Since most foods are non-Newtonian, the course introduced students to the categories and characterization of non-Newtonian fluids. For the first experiment, groups of students made different concentrations of “Thicken-Up” solutions, a xanthan gum-based food thickener for adults with swallowing problems. They measured the solutions’ viscosity to obtain the characteristic parameters, and then used small centrifugal pumps to create characteristic curves. The students pumped ketchup with a diaphragm pump for the second experiment, measuring the flow rate obtained with different power outputs. For both experiments, the results were compared to pumping water, to see the effect of a non-Newtonian fluid on pumping output and efficiency.
The third portion of the class covered heat transfer in food preservation and cooking unit operations. The students were intrigued by the idea that during cooking and baking, the temperature of the food does not exceed the boiling point of water. To illustrate this, thermocouples were placed into the side of commercially made gnocchi. The temperature was recorded every ten seconds after the gnocchi were placed in boiling water for five minutes. The students modeled the process as unsteady-state conduction, estimating the properties of the gnocchi with its composition, similar to how thermal constants for food are estimated in industry.
The experiments addressed in this paper can be completed inexpensively yet obtain data that is consistent with theory and addresses major concepts within Unit Operations. The use of food allows students to more tangibly understand these concepts by relating them to common household products and activities.
Piergiovanni, P. R., & Jarboe, J. H. (2016, June), Experiments for a Unit Operations in Food Engineering Course Paper presented at 2016 ASEE Annual Conference & Exposition, New Orleans, Louisiana. 10.18260/p.26836
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