Brief Paper: Understanding Temperature Development and Powder Dynamics During Ultrasonic Compression of Flour Systems
Authors: Adesina Joshua , Thomas J. C. , Liu Xun , Kaletunç Gönül 
Published: August 2024

Abstract
The transformation of agricultural produce through various unit operations into shelf-stable, convenient, and healthy products is vital to meet consumers’ dietary needs. Numerous traditional food processing and preservation methods, such as drying, frying, smoking, salting, pickling, and more, remain widely utilized for effectively handling raw food products. These methods primarily rely on the application of heat to reduce microbial growth and prevent the proliferation of foodborne pathogens, thereby ensuring food safety. However, thermal treatments consume significant energy, resulting in low production efficiency and prolonged processing times. Thermally sensitive food items, when exposed to heat treatment, may undergo physical and chemical changes, including changes in flavor, color, and texture. With the growing demand for healthier dietary choices and increased consumer awareness of nutrition, ongoing research is focused on emerging technologies that can maintain high-quality attributes with extended shelf life. The utilization of ultrasonic technology in food processing has received attention within the research community. Ultrasonic treatment is a novel food processing methodology, harnessing the energy produced by ultrasonic waves to beneficially influence food texture, structural organization, and flavor attributes with a temperature increase in a short time. This technique holds significant promise for enhancing food production efficiency and elevating the quality of food products by prolonging their shelf life. This study is aimed at understanding the dynamics of flour heating and bonding through the application of high-intensity, low-frequency ultrasonic waves to create an agglomerated and compacted model food bar. In this novel process, various flour specimens with varying protein, fat, and fiber contents at the same moisture content were subjected to predetermined welding conditions of ultrasonic energy and vibration percent amplitude. Temperature development within these specimens during the agglomeration process was measured using thermocouples and the temperature increase was recorded. Flour systems with higher welding forces exhibited higher temperatures under identical energy and vibration amplitude, which depended on the flour composition. High-speed videos were recorded at high magnification to examine the behavior of flour particles under the influence of ultrasonic vibrations. The rapid surface interactions among flour particles lead to the conversion of mechanical energy into heat through surface friction depending on the particle size. This investigation provides valuable insights into the complexities of flour heating and agglomeration under high-intensity, low-frequency ultrasonic vibration, with potential applications in optimizing various food processing techniques. It emphasizes the significance of understanding solid-state bonding for enhancing the efficiency of food processing operations and the quality of the products.