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Destabilization of Oil-in-Water Emulsions Formed Using Highly Hydrolyzed Whey Proteins
1Department of Food Technology, Massey University, Palmerston North, New Zealand, Department of Food Science, University of Guelph, Ontario, Canada, and New Zealand Dairy Research Institute, Palmerston North, New Zealand.
Journal of Agricultural and Food Chemistry
|February 7, 2001
Summary
Whey protein hydrolysate (WPH) stabilizes oil-in-water emulsions, with higher WPH concentrations reducing coalescence and creaming. Increased homogenization pressure, however, accelerated destabilization, highlighting the critical role of WPH concentration in emulsion stability.
Area of Science:
- Food science and technology
- Colloid and surface science
Background:
- Oil-in-water emulsions are widely used in food products.
- Stabilizing these emulsions is crucial for product quality and shelf-life.
- Whey protein hydrolysate (WPH) is a potential emulsifier, but its effectiveness depends on preparation conditions.
Purpose of the Study:
- To investigate the impact of whey protein hydrolysate (WPH) concentration and homogenization pressure on the stability of soy oil-in-water emulsions.
- To understand the relationship between WPH properties at the emulsion droplet surface and overall emulsion stability.
Main Methods:
- Preparation of oil-in-water emulsions with varying WPH concentrations (0.5-5 wt %) and homogenization pressures (10.3-34.3 MPa).
- Destabilization studies using laser light scattering and confocal laser microscopy over 24 hours.
- Analysis of WPH composition at the droplet surface using high-performance liquid chromatography (HPLC).
Main Results:
- Emulsions with <2% WPH exhibited significant oiling off and coalescence.
- Higher WPH concentrations (2-5%) reduced coalescence and creaming, with 5% WPH showing only slight flocculation.
- Increased homogenization pressure enhanced coalescence, while higher WPH concentration decreased it.
- WPH surface concentration increased with WPH concentration but decreased with homogenization pressure.
- HPLC analysis revealed higher concentrations of high molecular weight peptides at the droplet surface.
Conclusions:
- Whey protein hydrolysate (WPH) concentration is a key factor in stabilizing oil-in-water emulsions, with optimal stability observed at 5% WPH.
- Homogenization pressure negatively impacts emulsion stability by increasing coalescence.
- The enrichment of high molecular weight peptides at the droplet surface contributes significantly to emulsion stability.
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