Abstract
During the generation of functional food ingredients by enzymatic hydrolysis, parameters such as choice of enzyme, reaction pH and the drying process employed may contribute to the physicochemical and bio-functional properties of the resultant protein hydrolysate ingredients. This study characterised the properties of spray- (SD) and freeze-dried (FD) whey protein hydrolysates (WPHs) generated using Alcalase® and Prolyve® under pH-stat and free-fall pH conditions. The enzyme preparation used affected the physicochemical and antioxidative properties but had no impact on powder composition, morphology or colour. SD resulted in spherical particles with higher moisture content (~6%) compared to the FD powders (~1%), which had a glass shard-like structure. The SD-WPHs exhibited higher antioxidative properties compared to the FD-WPHs, which may be linked to a higher proportion of peptides <1 kDa in the SD-WPHs. Furthermore, the SD- and FD-WPHs had similar peptide profiles, and no evidence of Maillard reaction product formation during the SD processing was evident. The most potent in vitro antioxidative WPH was generated using Alcalase® under free-fall pH conditions, followed by SD, which had oxygen radical absorbance capacity and Trolox equivalent (TE) antioxidant capacity values of 1132 and 686 µmol TE/g, respectively. These results demonstrate that both the hydrolysis and the drying process impact the biofunctional (antioxidant) activity of WPHs.
Highlights
Whey-based ingredients are widely used due to their high protein quality and digestibility [1,2,3,4]
Were higher (p < 0.05) than that of the FD-whey protein hydrolysates (WPHs), which ranged between 0.96 ± 0.15 and 1.55 ± 0.52%, this is in agreement with previous studies [30,31]
The higher moisture content in the SD powders may be linked to the smaller particle size and larger surface area, than in the FD powers, which may lead to increased hydroscopicity [31]
Summary
Whey-based ingredients are widely used due to their high protein quality (being a rich source of essential and branched-chain amino acids) and digestibility [1,2,3,4]. Whey proteins and their derivatives (including hydrolysates and peptides) have demonstrated numerous health benefits, e.g., associated with prevention and management of conditions such as cardiovascular disease, type II diabetes mellitus, cancer, inflammation, sarcopenia, obesity, etc. Whey proteins are reported to act as potent antioxidants by modulating a range of redox biomarkers, e.g., glutathione, superoxide dismutase, glutathione peroxidase, catalase, nitric oxide, malondialdehyde and reactive oxygen species [6,7]. The potent antioxidative properties of whey proteins has been associated with their hydrophobic amino acid residues [9], their ability to act as a source of cysteine residues to synthesise glutathione, a potent intracellular antioxidant compound and their ability to form Maillard reaction
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