Ultrasonic agglomeration of model flour systems: Process parameter-product physico-thermal property relationships.

Abstract

Ultrasonic compression was applied to wheat flour to create an agglomerated and compacted model food system. This novel process combines physical compression with ultrasonic vibration to permanently weld particles together, thereby producing a robust compact. Fundamental relationships among operating parameters, energy imparted to the specimens, and physical properties of the agglomerated products were developed. Integrated agglomeration energy was determined to be a linear function of percent maximum horn amplitude and ultrasonication time, and integrated energy in turn influenced product physical properties, such as density and fracture strength, in highly significant linear relationships. Microscopic, computer tomographic, and differential scanning calorimetric analyses confirmed progressive compaction of and thermal stability changes in the flour matrix with increased processing energy. Specimens agglomerated at higher energy levels were furthermore demonstrated to have higher fracture strength than conventionally (pressure-only) compressed specimens despite similar densities, due to the robust interparticle bridging produced by agglomeration. PRACTICAL APPLICATION: Ultrasonic agglomeration represents a potential improvement over standard compression in the manufacturing of meal-supplementing energy bars. Ultrasonic agglomeration effectively adheres particles together without incorporation of low-nutrient- density syrups and binders. Agglomerated and compacted products also have superior mechanical stability, which can improve texture and physical stability during product handling.