Whey protein peptides as components of nanoemulsions: A review of emulsifying and biological functionalities

Milk proteins are used to make emulsions, and may be used to make nanoemulsions. Nanoemulsions are a nanotechnology with food applications, and possess superior physicochemical and sensorial properties compared to macro- and microemulsions. They are also able to deliver bioactive compounds when consumed. In this review, three aspects of food nanoemulsions will be examined: (1) the production and properties of food nanoemulsions, (2) emulsifiers/surfactant (ionic, non-ionic, phospholipid, polysaccharide, and protein) used in nanoemulsions production. The suitability of proteins and protein hydrolysates as nanoemulsifiers is discussed, with a particular focus on whey protein, (3) the potential of whey protein derived peptides as both emulsifiers and bioactive compounds in nanoemulsion delivery systems. Lastly, the potential delivery of bioactive peptides and other bioactive compounds within nanoemulsion systems is also discussed

Screening of whey protein isolate hydrolysates for their dual functionality: Influence of heat pre-treatment and enzyme specificity

Heat pre-treated and non heat pre-treated whey protein isolate (WPI) were hydrolysed using α-chymotrypsin (chymotrypsin), pepsin and trypsin. The in vitro antioxidant activity, ACE-inhibition activity and surface hydrophobicities of the hydrolysates were measured in order to determine if peptides with dual functionalities were present. Dual functional peptides have both biological (e.g. antioxidant, ACE-inhibition, opioid activities) and technological (e.g. nanoemulsification abilities) functions in food systems. Heat pre-treatment marginally enhanced the hydrolysis of WPI by pepsin and trypsin but had no effect on WPI hydrolysis with chymotrypsin. With the exception of the hydrolysis by trypsin, heat pre-treatment did not affect the peptide profile of the hydrolysates as analysed using size exclusion chromatography, or the antioxidant activity (P > 0.05). Heat pre-treatment significantly affected the ACE-inhibition activities and the surface hydrophobicities of the hydrolysates (P < 0.05), which was a function of the specificity of the hydrolysing enzyme. Extended hydrolysis (up to 24 h) had no significant effect on the DH and the molecular weight profiles (P > 0.05) but in some instances caused a reduction in the antioxidant activity of WPI hydrolysates. The chymotrypsin hydrolysate showed a broad MW size range, and was followed by pepsin and then trypsin. The bioactivities of the hydrolysates generally decreased in the order; chymotrypsin > trypsin > pepsin. This study showed that by manipulating protein conformation with pre-hydrolysis heat treatment, combined with careful enzyme selection, peptides with dual functionalities can be produced from WPI for use as functional ingredients in the manufacture of functional foods