Influence of transglutaminase‐assisted ultrasound treatment on the structure and functional properties of soy protein isolate

Abstract

In this study, the effects of transglutaminase (TG) cross‐linking on physicochemical, conformational, and functional properties of soybean protein isolate (SPI) with or without ultrasound pretreatment were investigated. Electrophoresis and free amino group analysis confirmed that the SPI was cross‐linked by TG treatment. The cross‐linked SPI showed a visible decrease in solubility and increase in apparent viscosity compared with the untreated SPI. TG catalyzed the SPI to unfold the constitutive polypeptides, resulting in a more random secondary structure. With ultrasound pretreatment, the cross‐linked SPI exhibited higher solubility (from 41.80% to 54.42%), emulsifying activity index (from 45.82 to 64.10 m2/g) and better foaming capacity (from 31.81% to 44.23%) than the untreated SPI, and the sulfhydryl group contents and surface hydrophobicity of the SPI were increased. Practical applications This study aimed to explore the effect of TG cross‐linking with or without ultrasound pretreatment on the physicochemical structure and functional properties of commercial SPI. The results demonstrated that a combination of ultrasound and TG treatments may be a valid way for the functional modification of SPI, which would be conducive to enhance its application as a novel functional ingredient in a broad range of food systems.

Effects of different nut oils on the structures and properties of gel‐like emulsions induced by ultrasound using soy protein as an emulsifier

“…High‐intensity ultrasound (HIU) refers to the sound wave at the power of 10‐1000 W/cm 2 and the frequency of 20‐100 kHz (Soria & Villamiel, 2010), which can be used for emulsification and homogenisation because of its cavitation effects (Chandrapala et al ., 2012). Some studies (Jambrak et al ., 2009; Tang et al ., 2009; Mu et al ., 2010; Ding et al ., 2019) and our previous works (Hu et al ., 2013a,b; Zhang et al ., 2016) noticed that HIU of soy protein could reduce aggregation, improve the hydrophobicity and solubility, which might result in denser 3D gel network to increase the gelation properties of soy protein. Moreover, some researches and our previous work demonstrated that stable emulsions could be prepared by HIU (Lin & Chen, 2008; Sui et al ., 2017; Taha et al ., 2018; Benetti et al ., 2019).…”

Influence of high-intensity ultrasound on the IgE binding capacity of Act d 2 allergen, secondary structure, and In-vitro digestibility of kiwifruit proteins

“…The cavitation effects can disrupt interactions between the local sequences of amino acids and between different parts of the protein molecule, resulting in the changes in the secondary structures of proteins [47] . However, in soy protein isolate, Ding et al (2019) found that while ultrasonication decreased the contents of α-helixes and β-sheets, random and coil β-turn structures contents increased [48] . In jackfruit seed proteins, Resendiz-Vazquez et al (2019) reported that ultrasound processing (200–600 W, 15–30 min) significantly enhanced the content of alpha-helixes and random coils, but decreased the beta-sheet content [49] .…”

Enhancing the foaming properties of brewer's spent grain protein by ultrasound treatment and glycation reaction

“…However, the variation in the free SH and S-S contents existed in diverse proteins, ultrasonic conditions and processing environments. For example, previously reported results indicated that the exposure of free sulfhydryl groups buried in soybean protein isolates treated with ultrasound increased the SH content, 40 which might be attributed to the ultrasonic cavitation and shear effects that reduced the particle size of protein molecules. 18 Moreover, glycation treatment remarkably increased the SH content of BSGP, but the S-S content showed no significant variation.…”