Effect of pulsed electric field on the rheological and colour properties of soy milk

Abstract

The effects of pulsed electric field (PEF) treatments on rheological and colour properties of soy milk were evaluated. Flow behaviour, viscosity and rheological parameters of PEF-treated soy milk were monitored using a controlled stress rheometer. For PEF treatments, electric field intensity of 18, 20 and 22 kV cm(-1) and number of pulses of 25, 50, 75 and 100 were used. For the measurements of rheological properties of soy milk shear rates between 0 and 200 s(-1) was used. The rheological behaviour of control and the PEF-treated soy milk were described using a power law model. The PEF treatments affected the rheological properties of soy milk. Apparent viscosity of soy milk increased from 6.62 to 7.46 (10(-3) Pa s) with increase in electric field intensity from 18 to 22 kV cm(-1) and increase in the number of pulses from 0 to 100. The consistency index (K) of soy milk also changed with PEF treatments. Lightness (L*), red/greenness (a*) and yellowness/blueness (b*) of soy milk were affected by PEF treatments.

Novel processing techniques and spinach juice: Quality and safety improvements

“…During all treatments, the apparent viscosity of the spinach juice was significantly ( P < 0.05) reduced with the increase of shear rate from 0 to 100 s −1 and led to a rapid breakdown of initial shearing. This response during PEF might be attributed to the combined effects of breakdown and reformation of weak linkage between proteins and molecular collisions and Brownian motion (Xiang, Simpson, Ngadi, & Simpson, 2011). The juice sample treated with US‐PEF in the present study indicated similar results already reported by Medina‐Meza et al.…”

Understanding the impact of moderate-intensity pulsed electric fields (MIPEF) on structural and functional characteristics of pea, rice and gluten concentrates

“…A decrease in free sulfhydryl groups is generally attributable to the formation of disulphide bridges at both intra-and intermolecular structural level. Covalent cross-linking would favour transient selfassembly of proteins, potentially leading to the formation of aggregates with modified surface activity and functional properties (Li et al 2007;Liu et al 2011;Wu et al 2016;Xiang et al 2011b). In gluten suspension at pH 6, the decrease of sulfhydryl groups was clearer as compared to the one observed in pea samples (Table 1).…”

“…These events can lead finally to a decrease in the ordered structures (α-helices), an increase in disorder ones (β-sheets, β-turns and random coils) and a higher exposure of surface free sulfhydryls (S-H) (Guan et al 2010;Liu et al 2013). As summarized by Giteru et al (2020), all these modifications generate the formation of transient structures and changes in the interfacial properties of the proteins, which influence their functional properties including surface hydrophobicity (Li et al 2007;Wu et al 2016), colloidal behaviour (Xiang et al 2011b), thermal stability (Liu et al 2011) and swelling index (Li et al 2007). To this regard, it is noteworthy that structural modification of enzymes, such as papain, POD, PPO, lysozyme and LOX, exposed to PEF was found to be responsible for their irreversible inactivation (Luo et al 2010;Yeom et al 1999;Yang 2008, 2010;Zhong et al 2007).…”

Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity

“…This structure transition resulted from the interaction between the ricin’s secondary structures and the nsPEFs. It was previously reported that polypeptide chains of protein could be affected by an external electric field 56 57 . Zhao et al revealed that the nsPEFs could trigger an augment in the dielectric constant of protein, thus inducing the unfolding of polypeptide, and then the secondary and tertiary structures of protein would vary 58 .…”