This work investigated the effects of low-frequency ultrasound (US) induced conformational variation of duck liver globular proteins (DLGPs) on the binding behavior of n-alkenals based on multi-spectroscopic analysis combined with headspace solid phase microextraction technique. Results suggested that US-treatments, with the frequency of 40 kHz and the power density of 26.7 W/L, induced obvious tertiary and quaternary structure changes of DLGPs, as revealed by fluorescence and ultraviolet–visible absorption spectroscopy, whereas the secondary and primary structures of DLGPs remained almost unaffected, suggesting the presence of molten-globule (MG) intermediates due to US-treatment. Meanwhile, the particles size and absolute values of ζ-potential exhibited significant increases as the functions of ultrasonic durations. According to multivariate results, the conformational variations, involving natural, MG and post-MG states, could be differentiated successfully. The US-induced conformational changes of DGLPs allowed it easier to interact with volatile n-alkenals, attributed to the enhanced hydrophobic interaction and covalent binding. Correspondingly, the headspace fractions of n-alkenals were greatly reduced after ultrasound pretreatments, with different degrees ranging from 5.61 to 59.39%, depending on chemical structures and processing conditions. This work suggests the great potential of specific conformational variations of DLGPs induced by ultrasonic pretreatments to modulate flavor features of protein-based products.

Kinetic response of conformational variation of duck liver globular protein to ultrasonic stimulation and its impact on the binding behavior of n-alkenals

Native amaranth protein (APN) is a nutritional ingredient with potential applications for the structuration and functionalization of food products. However, its solubility is poor, which limits its use in the food industry. The effect of ultrasonication (US) at 50% amplitude for 10 min (APUS), pH-shifting at pH 2 and 12 (APpH2 and APpH12), and the combination of both (APpH2US and APpH12US) on the structural, physicochemical, and functional properties of APN were investigated. Alkaline pH-shifting combined with US decreased the hydrodynamic diameter of APN from 1167.0 ± 15.6 nm to 438.3 ± 8.4 nm (APpH12US), whereas acidic pH-shifting increased the hydrodynamic diameter up to 2490.0 ± 5.3 nm (APpH2). Fractions of α-helix, β-sheet, β-turn, and random coil structures of APN were affected by pH12-shifting and US, but pH2-shifting did not. Exposed sulfhydryl groups of the APN diminished, while disulfide bonds increased as a result of pH-shifting alone or combined with US. Zeta potential values revealed that the isoelectric point of APN (4.0) was increased for APpH12 (4.2) and APpH12US (4.5) and decreased for APUS (3.5). The highest solubility was achieved by APpH12US. Foaming capacity and stability were significantly increased in all treatments, except APpH2.

Modifying the structure, physicochemical properties, and foaming ability of amaranth protein by dual pH-shifting and ultrasound treatments

Comparison of oil-in-water emulsions prepared by ultrasound, high-pressure homogenization and high-speed homogenization

Native amaranth protein (AP N ) is a nutritional ingredient with potential applications for the structuration and functionalization of food products. However, its solubility is poor, which limits its use in the food industry. The effect of ultrasonication (US) at 50% amplitude for 10 min (AP US ), pH-shifting at pH 2 and 12 (AP pH2 and AP pH12 ), and the combination of both (AP pH2US and AP pH12US ) on the structural, physicochemical, and functional properties of AP N were investigated. Alkaline pH-shifting combined with US decreased the hydrodynamic diameter of AP N from 1167.0 ± 15.6 nm to 438.3 ± 8.4 nm (AP pH12US ), whereas acidic pH-shifting increased the hydrodynamic diameter up to 2490.0 ± 5.3 nm (AP pH2 ). Fractions of α-helix, β-sheet, β-turn, and random coil structures of AP N were affected by pH12-shifting and US, but pH2-shifting did not. Exposed sulfhydryl groups of the AP N diminished, while disulfide bonds increased as a result of pH-shifting alone or combined with US. Zeta potential values revealed that the isoelectric point of AP N (4.0) was increased for AP pH12 (4.2) and AP pH12US (4.5) and decreased for AP US (3.5). The highest solubility was achieved by AP pH12US. Foaming capacity and stability were significantly increased in all treatments, except AP pH2 . • Acid and alkaline pH-shifting improved amaranth protein (AP) solubility. • Combined pH-shifting and ultrasound treatment improved AP foaming properties. • pH-shifting and ultrasonication increased the in vitro AP digestibility. 

Phenolic modification of myofibrillar protein enhanced by ultrasound: The structure of phenol matters.

Ultrasonic effects on the headspace volatilome and protein isolate microstructure of duck liver, as well as their potential correlation mechanism.

A structural explanation for enhanced binding behaviors between β-lactoglobulin and alkene-aldehydes upon heat- and ultrasonication-induced protein unfolding

Le Xu

Papers

Kinetic response of conformational variation of duck liver globular protein to ultrasonic stimulation and its impact on the binding behavior of n-alkenals

Ultrasonic effects on the headspace volatilome and protein isolate microstructure of duck liver, as well as their potential correlation mechanism.

A structural explanation for enhanced binding behaviors between β-lactoglobulin and alkene-aldehydes upon heat- and ultrasonication-induced protein unfolding

Association of lipidome evolution with the corresponding volatile characteristics of postmortem lamb during chilled storage.