Applications of ultrasound for the functional modification of proteins and nanoemulsion formation: A review

Abstract

This review surveys the most recent developments in low frequency, high power ultrasound for the functional modification of proteins derived from a number of food sources (e.g. dairy, animal, cereal, legume, tuber and fruit), and subsequently for the fabrication of nano-sized emulsion droplets. Aside from an overview of the fundamentals of ultrasound, including a cursory outline of ultrasonic cavitation, heat generation and acoustic energy determination via calorimetry, examples of ultrasound treatment for improvements in the dissolution, hydration, hydrophobicity, emulsifying and rheological performance of proteins are described. Ultrasound possesses the industrial capability to improve the functional properties of proteins, and this review emphasises the improvement to the surface active properties of proteins, which is attributed to decreases in protein aggregate size and increases in hydrophobicity, demonstrating increased molecular mobility. Finally, the utilisation of ultrasound for the fabrication of nanoemulsions is assessed with a particular focus on the intrinsic relationship between process configuration (i.e. batch or continuous), processing parameters (i.e. acoustic power and residence time) and emulsion formulation (i.e. emulsifier type and concentration). A better understanding of the effect of industrially relevant high molecular weight biopolymers (i.e. proteins) within ultrasonic emulsification processes would increase the utilisation of ultrasound as a fabrication technique for nano-sized emulsion droplets.

Characterisation of flow behaviour and velocity induced by ultrasound using particle image velocimetry (PIV): Effect of fluid rheology, acoustic intensity and transducer tip size

“…Furthermore, similar to the previously discussed velocity gradient plots for water ( Fig. 4), (1) poor bulk mixing was observed in the volume above the tip of the ultrasonic transducer, (2) a conical profile was observed for the acoustic-beam emanating from the tip of the transducer, and (3) a lack of accurate flow determination in the immediate vicinity of the sonotrode for reasons as previously discussed (Fig. 5).…”

“…Low frequency (≤100 kHz) high power (>10 W cm -2 ) ultrasound is a technology which has garnered significant interest over the past decade owing to its capacity to perform a multitude of processing applications [1], including dispersion [2], dissolution [3], molecular modifications [4,5], and emulsification [6,7]. Ultrasonic treatment of liquid media operates through the generation of numerous cavitation sites, arising due to pressure differentials during the propagation of an acoustic wave front through the liquid [8].…”

Recent advances in phenolic–protein conjugates: synthesis, characterization, biological activities and potential applications

“…endopeptidases, transglutaminase and oxidase) are oen selected to modify food proteins. [5][6][7][8][9] Phenolic compounds are ubiquitous secondary metabolites in plants, which are synthesized through pentose phosphate, shikimate and phenylpropanoid pathways. 10,11 Structurally, phenolic compounds comprise an aromatic ring with one or more hydroxyl substituents, ranging from simple phenolic molecules to highly polymerized compounds.…”

W/O/W Multiple Emulsions as the Functional Component of Dairy Products

“…This should improve food safety, increase shelf life, and enable economic savings [81][82][83][84]. Hence, this method is considered to be industrially useful, but further work is still required since this technique has only been tested under laboratory conditions [85][86][87][88].…”