Effects of ultrasound on the thermal and structural characteristics of proteins in reconstituted whey protein concentrate

Abstract

The sonication-induced changes in the structural and thermal properties of proteins in reconstituted whey protein concentrate (WPC) solutions were examined. Differential scanning calorimetry, UV-vis, fluorescence and circular dichroism spectroscopic techniques were used to determine the thermal properties of proteins, measure thiol groups and monitor changes to protein hydrophobicity and secondary structure, respectively. The enthalpy of denaturation decreased when WPC solutions were sonicated for up to 5 min. Prolonged sonication increased the enthalpy of denaturation due to protein aggregation. Sonication did not alter the thiol content but resulted in minor changes to the secondary structure and hydrophobicity of the protein. Overall, the sonication process had little effect on the structure of proteins in WPC solutions which is critical to preserving functional properties during the ultrasonic processing of whey protein based dairy products.

Physico-chemical properties of gelatin from bighead carp (Hypophthalmichthys nobilis) scales by ultrasound-assisted extraction

“…This was due to ultrasound and longer time providing more power to facilitate more high-molecular weight fragments degradation, resulting in weakening the gel network. However, there was no significant difference between WB1 and UB1, this might be because ultrasound produce protein aggregation at low temperature for short time (Chandrapala et al 2011). Protein patterns and free amino group content The molecular weight of gelatin was analyzed by SDS-PAGE (Fig.…”

“…It was also noticed that gelatin extracted by UB showed slightly lower content of protein at the range of 70 KDa-85 KDa, for ultrasound had great effects on hydrolysis of gelatin. However, the β-chain was still observed in UB5, due to the large shear forces generated from cavitation breaking inter and intramolecular bonds, which in turn may lead to fragmentation of clusters and aggregates (Chandrapala et al 2011). Free amino groups of six samples are shown in Fig.…”

“…However, there was no difference between WB1 and UB1, indicating ultrasound had no effect on gel strength in a short time. It was attributed to ultrasound lead to high mount of aggregation of protein (Chandrapala et al 2011). There was no difference between WB5 and UB3, which indicated ultrasound-assisted extraction could shorten extraction time and guarantee the quality of the gelatin.…”

Preparation and characterization of whey protein isolate films reinforced with porous silica coated titania nanoparticles

“…The CA of WPI films without nanoparticles was 40° ± 3°, decreasing slightly as the level of sonication amplitude increases. This decrease in the contact angle could be due to the restructuring of the proteins at higher sonication levels that lead to less exposure of hydrophobic regions of the protein to the surface (Chandrapala et al, 2011). WPI film swelling was observed during the contact angle measurements using a water droplet.…”

Anti-solvent sonocrystallisation of lactose

“…In another study, lactose yield was found to be increasing with a decrease in pH from 16% (w/v) lactose concentration without protein content and acetone as an anti-solvent (Patel and Murthy, 2009). It is reported that the use of sonication in whey protein concentrate solutions does not appear to change the protein structure to a significant degree, which can influence the functional properties of dairy systems during processing (Jayani et al, 2011). …”