Progress 01/01/22 to 12/31/22
Outputs
Target Audience:Scientists and engineers from academia and industry in food engineering and food processing and undergraduate and graduate students in STEM areas. The areaof emphasis is fabrication of nutrient bars from various flours with different compositions by using ultrasonic welding process to find the working window of operating parameters and to create textures varying from firm to soft. Changes/Problems:There are no major changes and problems encountered. What opportunities for training and professional development has the project provided?In addition to the graduate student with a chemical engineering background hired during the first year, a second graduate student with a material science and engineering background was hired during the second year of the project. Both students were trained in ultrasonication process and physical, mechanical and thermal processing analysis techniques. Students carried out experiments and analyzed the samples to develop correlations among processing and product properties and worked on measurement and modeling of temperature distribution within the mold during ultrasonic vibration process. A second undergraduate student in food engineering major was identified and hired to conduct analysis of particle size distribution of flours by conducting sieve analysis. How have the results been disseminated to communities of interest?Two journal articles are in preparation focusing on application of ultrasonic welding process to commercial flours to evaluate and optimize the condition based on flour type and the effects of food additives on the texture of bars. A presentation was delivered one of the graduate students in CoFE 22 meeting in September 2022 in Raleigh, NC. This conference participants included engineers and scientists from industry and academia and graduate students. Dr. Kaletunc received a Fulbright program specialist award which plans to develop lectures for graduate and undergraduate students at University of Ljubljana in Slovenia to disseminate the knowledge about application of ultrasonic welding process to flours for nutrient bar fabrication. What do you plan to do during the next reporting period to accomplish the goals?Further analysis still needs to be done to relate the power developed during the agglomeration process to the temperature. This would be achieved using a thermal camera to observe the process. Also, micro-computed tomography analysis (micro-CT) would be performed on the bar samples to determine the porosity and measure the extent of agglomeration. We determined that particle size is one of the major factors affecting integrity of the manufactured bar and the bar mechanical properties. Studies are in progress to understand this effect in more detail because this effect will be important for future exploration of addition of large size ingredients and their interaction with ultrasonic welding parameters.
Impacts
What was accomplished under these goals?
A state-of-the-art ultrasonic welding equipment (DUKANE iQ Series ES Servo Press) with 20kHz Ultrasonic frequency, 3.6kW power output with unique capabilities was used with various flours. Ultrasonic compression processing was applied to five commercially available flours including all purpose, whole wheat, buckwheat, corn, and oat flours. Flours were hydrated to a 22% by weight moisture level prior to processing. A 20-kHz titanium rectangular horn with a 1.5"x1.75" flat face connected to the welder was used to deliver vibration to the flour bed. A mold with tightly fitting internal dimensions to the horn was designed and built from teflon (PTFE) to hold flours during ultrasonic compression process. When an applied normal mechanical force of 222 N was reached on flour bed, ultrasonic vibration was triggered and flour bed was continued to be compressed with a velocity of 0.15 cm/s. The ultrasonic welding process is expanded to five commercially available flours including, wheat, whole wheat, corn, oat, and buckwheat flours to investigate their potential to fabricate nutrient bars and to determine their operating window in terms of ultrasonic welding parameters of weld energy and percent amplitude. Based on the commercial flours data obtained, an energy contour plot is created defining regions of intact bard with structural integrity, nonuniform bars and cracked bars. Mechanical properties analysis, mainly fracture stress values of bars showed that a range of bars with varying textures of firm to soft can be created by changing the type of flours and ultrasonic welding parameters. A statistical equation was developed, based on five flour data, to predict the fracture stress of the bar fabricated by using the ultrasonication parameters, the average particle size and the composition of flours. The major factors affecting the firmness of the products appears to be the energy level, particle size and the type of protein in flours. The bars with the highest firmness was fabricated using whole wheat flour while the bars from oat flour had the softest texture with seven times lower fracture stress level. The fracture stress of the bars decreased in the order of whole wheat flour, buckwheat flour, all purpose flour, corn flour and oat flour. A parallel study was conducted between OSU and Natick to determine fracture stress changes during storage at different temperatures. Wheat flour containing 20% moisture (wb) was agglomerated into bars using ~2200J welding energy, yielding specimens with approximately 16.5% moisture contents. The samples were vacuum sealed in trilaminate pouches and stored in incubators at 70F, 100F, and 120F, and withdrawn at various intervals. Fracture stress (1) increased with time for all storage temperatures tested, and (2) increased with temperature of storage. It is possible that firming occurred due to either retrogradation or interaction between starch and gluten. Storage at 120F produced pronounced changes in the color of the bars: at 3 months, L (lightness) value had decreased 6.6%; A (redness) value had increased 209%; and B (yellowness) value had increased 66%. It is possible that Maillard browning at the higher storage temperature occurred due to interaction between gluten in the flour and residual small molecular weight starch entities (perhaps produced during the agglomeration process). The agglomeration process was also observed using a Photron high speed camera at 1000 frames per second (fps). The camera was directed at the side surface of the mold through a clear window. The high-speed imaging of all-purpose flour shows a slight color change from white to dark brown due to an increase in temperature. To measure temperature increases during the process, thermocouples were inserted into the center of the flour through holes drilled at the bottom of the mold. Temperature readings at 2750 J and 3000J at 60% ultrasonic vibration amplitude revealed the peak temperature during the process was consistently above 100oC. Such temperature levels cause chemical or physical transformation of flour components such as starches and proteins which was evident in the changing thermal transitions observed in differential scanning calorimetry results. The effects of ultrasonic parameters on the agglomeration process including, the data for ultrasonic energy, power, and weld distance during the welding process were extracted and plotted as a function of time. Four stages during the process were identified. In the first stage, the horn rapidly moves into the mold at a speed of 2.95 in/s. In the second stage, the horn speed reduces to 0.08 in/s, which is called the sensing speed in order to reach the 222 N set force that triggers ultrasonic vibration. In the third stage, which is the actual welding stage, ultrasonic vibration starts, and the welding speed is at 0.06 in/s. The input ultrasonic energy gradually builds to the set energy. In the final holding stage, the vibration has stopped while the welding pressure still applies. The holding time is 10 secs after which the horn is retracted from the mold. The mode used for the agglomeration process was welding by energy, which provides more consistent results. Three energy levels, 2500, 3000 and 3500 J, and three percent amplitude levels of 60, 80, and 100 which have been determined from previous experiments to be parameters for successful agglomeration, were selected for detailed analysis. Since energy is a function of time and power, the welding time varies based on the selected energy levels. The agglomeration process was also observed using a Photron high speed camera at 1000 frames per second (fps). The camera was directed at the side surface of the mold through a clear window. The high-speed imaging of all-purpose flour shows a slight color change from white to dark brown due to an increase in temperature. To measure temperature increases during the process, thermocouples were inserted into the center of the flour through holes drilled at the bottom of the mold. Temperature readings at selected energy and percent amplitude revealed the peak temperature during the process was consistently above 100oC. It was observed that welding temperature increased with increasing energy level reaching to 160 Celsius at 3500 J but it was not affected by percent amplitude level.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Thomas. J, Liu, X., Kaletunc, G. 2022. Optimizing Ultrasonic Welding Parameters for Manufacturing Cereal-Based Nutrient Bars, CoFE 22, Raleigh NC. September 19-21, 2022, Session 11, Processing of Food Proteins
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Progress 01/01/21 to 12/31/21
Outputs
Target Audience:Target audience: Scientists and engineers from academia and industry in food engineering and food processing. The areas of emphasis is binding of food powders by use of ultrasonic vibration to form nutrient bars. Changes/Problems:There are no major changes and problems encountered. On the contrary, the new equipment purchase with unique capabilities will provide us an opportunity to investigate the ultrasonication process for nutrition bar formation in more detail to elucidate the fundamental principals behind the process. What opportunities for training and professional development has the project provided?A graduate student with a chemical engineering background was identified and hired. Student was trained in ultrasonication process and physical, mechanical and thermal processing analysis techniques. Student carried out experiments and analyzed the samples to develop correlations among processing and product properties. An undergraduate student in food engineering major was identified and hired to conduct analysis of particle size distrubition of flours. A second graduate student with a material science and engineering background is in the process of hiring to work on measurement and modeling of temperature distribution within the bar during ultrasonic vibration process. How have the results been disseminated to communities of interest?A journal article was prepared and published based on the preliminary data collected to prepare the grant proposal to disseminate the knowledge in food science and food engineering communities in academia and industry. A poster with the graduate student as the first author was accepted and presented in IFT virtual annual meeting in July 2021. What do you plan to do during the next reporting period to accomplish the goals?A brand new state-of-the-art ultrasonic welding equipment is purchased and investigation will be continued with the new equipment during the next reporting period. An ultrasonic press system (DUKANE iQ Series ES Servo Press with 20kHz Ultrasonic frequency, 3.6kW power output with unique capabilities is made operational. The machine is capable of operating welding by distance, welding by force, or welding by energy options. The speed of the horn also be controlled which provides the opportunity using constant or segmented speed options to control the sonication force. The machine can weld by time or energy or distance. Multiple recorded process signal data: velocity, energy, power, distance, amplitude and force The new variables based on the capabilities of new ultrasonication equipment (initial force, welding distance, welding time, amplitude) for processing conditions and the relevant process parameters (welding peak force, welding energy, sample temperature) will be determined. Then the input variables and relevant processing parameters will be optimized based on the desired output values which will be selected as compaction achieved and mechanical properties of bars manufactured. Equations describing the relationships among input variables, processing parameters, and nutritition bar physical properties will be developed as also defined part of the project goals.
Impacts
What was accomplished under these goals?
Ultrasonic compression parameters for all purpose flour and whole wheat flour were explored. Branson Model 900 Ultrasonic welder was used for agglomeration of flours to manufacture nutrition bars. Flours were hydrated to a 20% moisture level prior to processing. A 20-kHz titanium rectangular horn with a 1.5"x1.75" flat face connected to the welder was used to deliver vibration to the flour bed. A mold with tightly fitting internal dimensions to the horn was designed and built from teflon (PTFE) to hold flours during ultrasonic compression proces. A normal mechanical force of 102 or 112 lb force was applied on flour bed followed by ultrasonic vibration for a time frame between 0.5 and 3.5 seconds. Mechanical force-only compressed products were formed using a Carver mechanical press to produced to compare the effects of the two compression processes on bulk density and mechanical properties. Processing conditions were optimized by analyzing the physical, thermal and mechanical properties of the fabricated bars. Compaction of the bars were evaluated by comparing the bulk density of the flour in the mold with that of bar. Comparison of the bulk densities of bars manufactured with and without ultrasonic vibration showed that very large levels of mechanical compression (13,000 N) is required compared to 222 N force combined with a ultrasonic vibration for 1 second to produce a bar with similar bulk density of 0.85 g/cc. Fracture strength comparison of bars manufactured with conventional versus ultrasonication process exhibited a higher mechanical integrity for the ultrasonically agglomerated bars (2500 kPa) than mechanically agglomerated bars (500 kPa). During ultrasonic compression process, energy generated caused temperature increases of up to 90 centigrade causing chemical or physical transformation of flour components such as starches and proteins which was evident in the changing thermal transitions observed in differential scanning calorimetry results and scanning electron microscopy results.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Barrett,A., Ahnrud,G., Ziegler,D., Liu,X., Kaletunc, G. Ultrasonic agglomeration of model flour systems: Process parameter-product physico-thermal property relationships. J. Food Sci. 86(9):3868-3883.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2021
Citation:
Barrett,A., Thomas,J.C., Kaletunc, G. Effect of sucrose, fat, and Fibersol on physical, thermal and mechanical properties of ultrasonically compacted flour products. Institute of Food Technologies Annual Meeting. 2021, 19-21 July 2021. Poster Presentation
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