Molecular and emulsifying properties of arachin and conarachin of peanut protein isolate from ultrasound-assisted extraction

The present study aimed to investigate the particle size, molecular weight distribution, secondary structure, and nanostructures of arachin and conarachin of peanut protein isolates produced using ultrasound-assisted extraction, as well as the characteristics of their emulsions. The results indicated that ultrasound-assisted extraction could improve the emulsifying properties of arachin and conarachin. Arachin obtained via ultrasound-assisted extraction had smaller particle size, lower content of high molecular weight material, a higher percentage of α-helix structure, and a higher number of exposed hydrophobic groups compared with those obtained using the regular alkali soluble and acid precipitation method. However, no obvious changes in the secondary structure of conarachin after ultrasound-assisted extraction were observed. The least amount of droplet flocculation and smallest values of the averaged particle size of emulsions stabilized by arachin and conarachin were obtained using an ultrasound time of 30 min, which also produced the highest absolute values of zeta potential. Ultrasound-assisted extraction changed the composition and structure of arachin, which led to a marked improvement in the emulsifying properties. Ultrasound-assisted extraction has a great application potential in the plant protein industry.